Getting over a Betrayal Essay

This song brings forth a feeling of that even though a loss of a loved one is a heart wrenching experience there is nothing a person can do to change the outcome of what has happened. My Immortal† seems to be more about losing one’s own sense of identity and self-worth due to the loss and/or betrayal of a loved one than about the actual loss of the loved one: These wounds won’t seem to heal/ This pain is just too real/There’s just too much that time cannot erase (7-9) By the end of the song, the survivor of the story is emotionally drained and paralyzed with the fear by the memory of the betrayer. The survivor of the incident just wants those memories of hurt and betrayal to go away. This pain is felt in the opening stanzas of the song. And if you have to leave/I wish that you would just leave/Your presence still lingers here/ And it won’t leave me alone (3-6). The theme of â€Å"My Immortal† is the struggle of trying to get rid of the feeling of betrayal and of guilt. The betrayer has hurt or betrayed her in a way that she can never recover from the emotional damage. You used to captivate me/ By your resonating light/ Now I’m bound by the life you left behind (14-16) For the rest of the girls’ life, she will be imprisoned by him. She sacrificed everything for him. After years of being together, he throws everything she has done for him back in her face. She know feels like that she will never be free of him Your face it haunts/My once pleasant dreams (15, 16) The effect of this song brings forth many different emotions. This song brings to light that if one lets a past betrayal or losses rule their life, there will never be any peace for the individual. The individual needs to let go of the hurt, even though they are feeling that they were alone the entire time they were with that one person. I’ve tried so hard to tell myself that you’re gone/ But though you’re still with me/ I’ve been alone all along ( 24-26) It hurts being betrayed by a loved one. The reality that she was all alone in her love when he was with her†¦ and ironically, now that he’s left her, she isn’t alone: He torments her with the memories of his betrayal (perhaps complicated by her genuine love for who she thought he was. ) These wounds won’t seem to heal/ This pain is just to real/ There’s just too much that time cannot earse (21-23) Works Cited Evanescence.

Constitucion Casa Mac Iver, Chile

Castro Seccion 5 Fernandez Ricardo Altman Hidalgo Rojas Parraguez Idea La idea surge a raiz de la experiencia cercana de una de nuestras companeras de grupo.Ella es familiar directo de los Mac-Iver y todos los veranos solia pasar parte de las vacaciones con la familia en la casona de Constitucion la que albergaba a mas de 60 personas (tal como lo mostraban en â€Å"Chile intimo: Las vacaciones† de TVN). Lamentablemente, esta tradicion esta limitada, ya que la colonial casona, se encuentra con danos graves producto del terremoto del 27 de febrero. ObjetivoNuestro objetivo principal es querer demostrar que a pesar de la vida rapida e inexpresiva que vivimos dia a dia, es necesario conectarse con la familia y las raices, contacto que creemos es primordial para tener un desarrollo pleno, es asi como tomamos como ejemplo la casona de Constitucion un lugar familiar e importante que en estos momentos significa para la familia Mac-Iver mucho mas que un punto de encuentro ya que ahora es la fuente donde desembocaran todas sus energias para volver a ponerla de pie. Constitucion (1794)Constitucion se encuentra en la orilla de la desembocadura del Rio Maule en el Oceano Pacifico. La ciudad se encuentra limitada por varios cerros, siendo el mas importante el cerro Mutrun, situado cerca de la desembocadura. Los lugares tipicos mas importantes de Constitucion son: la Piedra de la Iglesia, el Penon de Calabocillos, la Piedra de los Enamorados y la Piedra del Elefante. La zona donde se encuentra la ciudad fue antes de la llegada de los espanoles un lugar de pesca y refugio de los indigenas changos y mapuches.Hubieron muchos intentos por establecer un poblado permanente en la zona, en 1791 se establecio una propuesta oficial a cargo de Santiago Onederra. En 1793, el gobernador de Chile Ambrosio O'Higgins autoriza la fundacion de la villa bajo el nombre de Nueva Bilbao. En 1828, se le rebautiza con el nombre actual en honor a la Constitucion de 1828 que se estrenaba en ese entonces. [pic] El Fundador [pic] Henry Mac Iver (1815 – 1877), el fundador de la familia de ese apellido en Chile, fue un marino de origen escoces, que por azar llego a al costa de Valparaiso, durante 1835 debido a un naufragio.Mac Iver se quedo en Chile recuperandose de su accidente y en 1847 se le otorga la nacionalidad chilena, lo que le permitiria comprar varias 37 embarcaciones a lo largo de su vida. En 1841 conocio a Leonor Rodriguez (1819 – 1887) y el 2 de febrero de de 1843 se casa con ella. Ese mismo Henry comienza la construccion de la que seria â€Å"La Casa Mac Iver†. El 15 de Julio de 1844 nace su primogenito, Enrique Mac Iver, luego lo hace su segunda hija Flora Mac Iver el 20 de junio de 1846. Despues nacerian 6 hijos mas. Al fallecer, su viuda, Leonor, lo reemplazaria en la cabeza de la familia hasta su muerte por colera en 1887.Ambos estan sepultados en el cementerio de Constitucion [pic] Enrique Mac Iver [pic] El primogenito de Henry Mac Iver , capitan escoces, Enrique Mac Iver Rodriguez (Constitucion, 15 de Julio de 1844 – Santiago, 21 de Agosto de 1922), quinto dueno de la casa, fue quien refacciono y amplio decididamente. Este hombre se destacaria a lo largo de su vida como importante abogado y destacado congresista por 46 anos, alcanzando lo mas altos puestos como politico: diputado, senador, ministro del estado y pre-candidato presidencial en dos ocasiones.Ademas seria Gran Mestre de la Masoneria Chilena (1887-1894), debiendo decretar que la masoneria descansara mientras duro la guerra civil de 1891, para evitar que la grave contienda se infiltrara en ella. Quizas una de sus actuaciones publicas mas importantes se encuentre en su firme papel de opositor a la presidencia de Jose Manuel Balmaceda. Contrajo matrimonio con Emma Ovalle Gutierrez, con quien tuvo descendencia. Historia de la casa La propiedad en un principio estuvo constituida por un pedazo de terreno con tres frentes exclusivamente: el principal ( hacia Bulnes), el lateral por la calle Prieto, y hacia el sur, por la calle O`Higgins.Este terreno fue la parte original (Patio del Medio), el patio del cuidador y el sector bodegas, hoy Patio de los Crespones, junto a una arboleda en la parte trasera de la casa. De manera simultanea Henry Mac Iver comenzo a edificar en un terreno aledano (Bulnes esquina Prieto) una casa que dejaria para renta, hoy el Patio del Nispero. Al fallecimiento de su mujer Leonor, se llevo a cabo el remate de la casa junto con otras propiedades. La casa se dividio entre los hijos del matrimonio.Enrique, Leonor y David se quedaron con la casa y sus otros hermanos fueron compensados con otras propiedades en el mismo pueblo. Con el tiempo Enrique le compraria a sus hermanos la propiedad, quedandose como unico dueno de ella (1917). Seria el quien modernizaria la Casa, dandole la fisonomia con la actualmente la conocemos. Los terremotos de Talca de 1929 y de Chillan de 1939, especialmente el primero, dejaron a l a casa a muy mal traer. Los muros de adobe del Patio del Medio estan todos amarrados con grandes vigas de roble, lo que no ocurre con los de los patios aterales. Luego de ambos terremotos, se ataron con largos tensores de acero. En 1954 el Rio Maule se desbordo, llegando hasta la Plaza misma; la gente que andaba en botes por las calles.La Casa sufrio la inundacion, soportandola relativamente bien; el Patio del Medio se salvo por estar en altura, pero los restantes no. En vida Enrique Mac Iver la casa alcanzo su maximo esplendor, asi como extension. La Casa Mac Iver constituye un ejemplo, de los que hay pocos en Chile, de una propiedad que se ha mantenido desde su construccion en manos de la misma familia. pic] Entrada Principal [pic] Escritoria Enrique Mac Iver [pic] Salon Principal [pic] Ante Salon [pic] Comedor principal [pic] Patio del Cuidador [pic] Patio del Medio [pic] Patio de los Crespones La Familia Mac Iver Ubicada en plena ciudad, la casa Mac Iver es todo un simbolo. De e stilo colonial, con sus adobes intactos y zonas que denotan el evidente paso del tiempo, sigue siendo el centro de reunion de una enorme familia que no se pierde ni por nada el veraneo en este caseron de 165 anos.Son ocho generaciones que han sabido mantenerla y respetar su espiritu, habitando con orgullo cada uno de sus 40 dormitorios, 16 banos, 3 comedores, tres patios y salones. En Constitucion, a la casa de los Mac Iver se llega preguntando. Son pocos los que no conocen esta construccion colonial de un piso, que por 165 anos ha ocupado la manzana comprendida por las calles Bulnes, Pinto, Prieto y que hoy muestra sus muros de adobe descascarados, con graffitis en alguna esquina y ventanas tapeadas para evitar que rompan sus vidrios.Asi oculta un mundo interior desconocido para quienes pasan frente a ella, un pasado glorioso que inspira curiosidad. Ha sido gracias a las reglas que se han traspasado y respetado, que todo luce mas o menos como en los tiempos de sus abuelos, bisabuel os, tatarabuelos y choznos. Los ninos no entran al salon, a la salita ni al escritorio (sectores que lucen intactos) hasta que cumplen los 14 anos. La tradicion dice que tampoco, hasta esa edad, pueden sentarse a la mesa del comedor grande, que aun con sus treinta sillas, prohibe el ingreso a los menores.Habia otras construcciones senoriales importantes alrededor, que ya no existen, cuando Constitucion era un rico balneario de la alta sociedad talquina. Las propiedades que valian, se botaron. Actualmente, la familia organiza sus visitas repartiendose los tres patios que articulan la casa: el del medio (que es el original), el del Nispero y el de los Crespones, que se unieron al nucleo central hacia 1904. Los 40 dormitorios y 16 banos que los rodean estan asignados a cada una de las ramas Mac Iver, y si bien no todas las piezas estan en el mismo estado de conservacion, hay algunas que se han recuperado.En una de ellas dormia una de las hijas de Enrique Mac Iver Rodriguez, que hoy man tiene el mismo mobiliario de fines del siglo XIX, las cortinas y sus camas de bronce. En esta familia hay una renovacion de las ganas por venir. Para los Mac Iver tiene un valor sentimental mas alla del historico y arquitectonico. â€Å"Nosotros vamos a Constitucion, pudiendo ir a otros lados, porque tenemos un contacto fisico con algo que nos recuerda a nuestros antepasados y seres mas queridos† cuenta un Mac Iver Punto de encuentro y entretencion, los veraneos aqui son esperados durante todo el ano.Grandes y chicos lo han hecho el mejor lugar para pasar sus vacaciones, con los tradicionales paseos en lancha, las idas a la playa y al rio, las excursiones, la peregrinacion cada Viernes Santo al cerro Mutrun. Los almuerzos a las dos en punto previo toque del gong, las noches de peliculas en el â€Å"Patio del Medio†. Todos los muebles, rincones y habitaciones hablan de una historia familiar que se renueva cada vez que vuelven. Antes era febrero el mes de apertura oficia l de sus puertas y nadie iba durante el ano.Hoy, con casi cien â€Å"huespedes† habituales, la casa da la bienvenida desde septiembre y cierra sus salones en Semana Santa [pic] 27 de Febrero de 2010 El sismo del 27 de Febrero es considerado como el segundo mas fuerte en la historia del pais y uno de los cinco mas fuertes registrados por la humanidad. El terremoto ocurrio a las 03:34 a. m, tuvo una magnitud de 8,8. El epicentro fue en el mar frente a Curanipe y Cobquecura a 150 kilometros de Concepcion. El sismo tuvo una duracion de 2 minutos 45 segundos.Las zonas mas afectadas por el terremoto fueron las regiones de Valparaiso, Metropolitana de Santiago, O'Higgins, Maule, Biobio y La Araucania. En las regiones del Maule y el Biobio, el terremoto alcanzo una intensidad de IX en la escala de Mercalli, devastando gran parte de ciudades como Constitucion, Concepcion, Cobquecura y el puerto de Talcahuano. Los muertos ascendieron a una cantidad de 521. Hay alrededor de medio millon de viviendas severamente danadas. Y se estiman 2 millones de damnificados. El terremoto fue la peor tragedia natural vivida en Chile desde 1960.Al terremoto lo siguio un tsunami que destruyo aun mas los pueblos costeros afectados por el movimiento. . Esta masa de agua a gran velocidad golpeo la costa chilena, alcanzando las localidades costeras de las regiones del Maule y el Biobio. En Constitucion, la cifra de muertos fue de 172. Luego de que el impacto del terremoto destruyera gran parte de las viviendas, media hora despues vino la primera de tres olas que entraron a Constitucion, superando los 8 metros cada una. Estas hicieron subir considerablemente el nivel del mar la que se transformo en una pared de agua que entro hasta la Plaza de Armas de la ciudad.Gran parte de los fallecidos corresponden unas doscientas personas que al momento del terremoto estaban acampando en la isla del Maule, ubicada sobre la ribera de este. Las antiguas edificaciones de adobe de Constitucion quedaro n totalmente destruidas. Mas de la mitad del casco historico quedo en el piso, incluyendo diversos monumentos historicos y centenarias construcciones de origen colonial. El maremoto que afecto a Constitucion tambien produjo serios danos en las plantas de celulosa de CELCO, por lo que debieron suspenderse las actividades industriales (principal sustento de los maulinos junto a la pesca).Despues de que fue afectada por las 3 olas del tsunami. La casa de los Mac Iver soporto el terremoto, pero se vino abajo luego que el agua que desbordo el Maule. Se midio un metro de agua dentro de la casa. Las paredes de adobe no aguantaron y muchas se vinieron abajo, otras quedaron con serios danos estructurales. Salvar la construccion original de adobe con paja (unica en Chile) es imposible ademas de muy costosa. Hoy se buscan otras posibilidades para la reconstruccion de la casa, obra evaluada en 400 millones de pesos. Casa Mac Iver Post – Terremoto [pic] [pic] [pic] pic]j [pic] Estructura del proyecto documental El documental comenzaria con imagenes de archivos del terremoto y tsunami ocurrido el 27 de Febrero del 2010, seguido de una pequena introduccion a la ciudad de Constitucion y la llegada del primer Mac Iver (inicio del arbol genealogico) todo esto apoyado por imagenes de archivo y contado por un narrador en off que seria un familiar de la 8? generacion de los Mac Iver. El desarrollo abarcaria al cuidado que la familia a tenido por mantener el patrimonio familiar y cultural que significa esta casona colonial en la zona.Las principales secuencias del documental mostrarian las consecuencias del terremoto y tsunami que afecto a Constitucion y de forma especifica a la vivienda. Tomando como principal fuente de credibilidad los testimonios de integrantes de la familia que se encontraba habitando la casa en esa fecha. Para concluir se tratara la forma en que la familia Mac Iver planean la reconstruccion de la casona como un patrimonio mas que familiar, las etapas qu e tendran que pasar y la forma en que conseguiran ayuda para mantener en pie la casona. Referencia Documental â€Å"When the Levees Broke: A Requiem in Four Acts† (2006)Si bien en el documental de las victimas del huracan katrina se nos muestra el general de la catastrofe, es decir, varias familias y el procedimiento de su rescate, la idea es tomar como referencia la estetica del documental con las entrevistas bien trabajadas en fotografia y locaciones, ya sean en estudio o en la zona cero. El uso de material de archivo es importante por que nos retrata la vida de la familia Mac – Iver antes de la catastrofe, la idea es tratar de obtener archivos desde los inicios de la casona para denotar la tradicion y prestigio de la familia que gracias al naufragio de Henry Mac- Iver llego a Chile en el ano1835.Los archivos actuales de la casona son fundamentales para uno de los objetivos claves del documental, que es obtener ayuda del fondo de reconstruccion que propuso el gobiern o. La construccion del documental es lineal, tal como el documental referente Desde la catastrofe en si, a traves del material de archivo con entrevista a la gente y a responsables de los fondos de reconstruccion, al voluntariado y a integrantes de la familia protagonista.Bibliografia – www. constitucion. cl – www. emol. com – www. theclinic. cl – â€Å"Chile Intimo: Las Vacaciones†, TVN – Archivos familia Mac Iver

Polymer Concrete

POLYMER COCNCRETE 1. Introduction Despite being thought of as a modern material, concrete has been in use for hundreds of years. The word concrete comes from the Latin concretus, which means â€Å"mixed together† or compounded. Concrete is an extremely popular structural material due to its low cost and easy fabrication. Concrete is made up of sand or stone, known as aggregate, combined with cement paste to bind it. Aggregate can be of various sizes. It is broadly categorized as fine (commonly sand) and coarse (typically crushed stone or gravel).The greater proportion of concrete is aggregate which is bulky and relatively cheaper than the cement. As much of the constituents of concrete come from stone, it is often thought that concrete has the same qualities and will last forever. Concrete has been called artificial stone, cast stone, reconstructed stone and reconstituted stone. However, concrete must be thought of as a distinct material to stone. It has its own characteristic s in terms of durability, weathering and repair. Concrete is a relatively durable and robust building material, but it can be severely weakened by poor manufacture or a very aggressive environment.A number of historic concrete structures exhibit problems that are related to their date of origin. It is referred that the concrete is porous. The porosity is due to air-voids, water voids or due to the inherent porosity of gel structure itself. On account of the porosity, the strength of concrete is naturally reduced. It is conceived by many research workers that reduction of porosity results in increase of strength of concrete. Therefore, process like vibration, pressure application spinning etc. , have been practiced mainly to reduce porosity.All these methods have been found to be helpful to a great extent, but none of these methods could really help to reduce the water voids and the inherent porosity of gel which is estimated to be about 28%. The impregnation of monomer and subsequen t polymerization is the latest technique adopted to reduce the inherent porosity of the concrete to improve the strength and other properties of concrete. These problems can be solved by application of polymer in concrete construction. A polymer is a large molecule containing hundreds or thousands of atoms formed by combining one, two or occasionally more kinds of small molecule (monomers) into chain r network structures. The main polymer material used in concrete construction are polymer modified concrete and polymer concrete. Polymer modified concrete may be divided into two classes: polymer impregnated concrete and polymer cement concrete. The first is produced by impregnation of pre-cast hardened Portland cement concrete with a monomer that is subsequently converted to solid polymer. To produce the second, part of the cement binder of the concrete mix is replaced by polymer (often in latex form).Both have higher strength, lower water permeability, better resistance to chemicals, and greater freeze-thaw stability than conventional concrete. Polymer concrete (PC), or resin concrete, consists of a polymer binder which may be a thermoplastic but more frequently is a thermosetting polymer, and a mineral filler such as aggregate, gravel and crushed stone. PC has higher strength, greater resistance to chemicals and corrosive agents, lower water absorption and higher freeze-thaw stability than conventional Portland cement concrete.The pioneering work for the development of polymer concrete was taken up by United States Bureau of Reclamation (USBR). The initial exploratory works carried out at the Brookhaven National Laboratory (BNL) in cooperation with USBR and US in Atomic Energy Commission (AEC) revealed great improvement in compressive strength, permeability, impact resistance and abrasion resistance. The development of concrete-polymer composite material is directed at producing a new material by combining the ancient technology of cement concrete with the mod ern technology of polymer chemistry. 2.Types of Polymer Concrete Four types of polymer concrete materials are being developed presently. They are: a) Polymer Concrete (PC) b) Polymer Cement Concrete (PCC) c) Polymer impregnated Concrete (PIC) d) Partially Impregnated and surface coated polymer concrete The composites using polymer can be: polymer concrete (PC), when the binder is a polymer that replaces the cement paste, polymer modified concrete (PMC/ PCC), when the polymer is used near cement, polymer impregnated concrete (PIC), when the cement concrete is treated by soaking and polymerization.These composites have some advantages compared to ordinary cement concrete such as,rapid hardening, high mechanical strengths, chemical resistance, etc. Among the disadvantages is their high cost. The utilization domain of polymer concrete is continuously diversifying: PMC is widely used for floor and bridge overlays; acrylic latex has been used to produce mortars which can be sprayed on arc hitectural finish ; PIC was first widely used in bridge decks, pipes and conduits for aggressive fluids, floor tiles, building cladding, hazardous waste containment, post-tensioned beams and slabs, and stay-in place formwork.Polymer concrete is similar to ordinary cement concrete because it contains fine and coarse aggregates, but the hydraulic binder is totally substituted with a polymer material. The aggregates are bounded together by the polymer matrix. Polymer concrete contains no cement or water. The performances of polymeric concrete depend on the polymer properties, type of filler and aggregates, reinforcing fiber type, curing temperature, components dosage, etc. Polymer binder can be a thermoplastic, but more frequently a thermosetting polymer.The polymers most frequently used are based on four types of monomers or pre polymer system: methyl methacrylate, polyester prepolymerstyrene, epoxyde prepolymer hardener and furfuryl alcohol . The aggregates used in dry state can be s ilicates, quartz, crushed stone, gravel, limestone, calcareous, granite, clay, etc. In the composition can be used also the filler. Different types of fine materials can be used such as: fly ash, silica fume, phosphogyps, cinder, etc. Filler, especially fly ash, can improve the properties of polymer concrete . 3. History †¢ PC was used as early as 1958 in the USA to produce building cladding. Both PC and PCC have been in commercial use since the 1950s †¢ PIC was developed and has been in use since the 1970s †¢ Polymer concrete products have been used for decades in engineering construction like machine foundations, in the building industry for facade products and sanitary parts, in electrical engineering for isolation devices and especially in the chemical industry for all types of ducts due to its favourable properties, especially its corrosion resistance as well as its strength and elasticity †¢ The development of polymer concrete products, mostly pipe, dates b ack to the early 1960`s.The objective was to achieve a substantial increase in resistance to chemical attack †¢ With the development of trenchless technologies (micro-tunneling and pipe jacking) in 1970`s, polymer concrete pipes became popular in sewer systems.As such over the past years, the process of production and manufacturing of polymer concrete products like pipes, manholes and structures have been fundamentally improved †¢ Today it is used for cultured marble for counter tops, lavatories, as repair material, overlays for bridge and floors in sport arenas and stadiums, laboratories, hospitals, factories; also precast PC was used for drains, underground boxes, manholes, acid tanks and cells, tunnel lining, shells, floor tiles, architectural mouldings and machine tools and bases 4.Significance †¢ Depending on the materials employed, PC can develop compressive strengths of the order of 140 MPa within hours or even minutes and is therefore suitable for emergency co ncreting jobs in mines, tunnels, and highways †¢ PCC possess excellent bonding ability to old concrete, and high durability to aggressive solutions; it has therefore been used mainly for overlays in industrial floors, and for rehabilitation of deteriorated bridge decks. In the case of PIC, by effectively sealing the micro-cracks and capillary pores, it is possible to produce a virtually impermeable product which gives an ultimate strength of the same order as that of PC. PIC has been used for the production of high-strength pre-cast products and for improving the durability of bridge deck surfaces †¢ PCC possess excellent bonding ability to old concrete, and high durability to aggressive solutions; it has therefore been used mainly for overlays in industrial floors, and for rehabilitation of deteriorated bridge decks. In the case of PIC, by effectively sealing the micro-cracks and capillary pores, it is possible to produce a virtually impermeable product which gives an ult imate strength of the same order as that of PC. PIC has been used for the production of high-strength pre-cast products and for improving the durability of bridge deck surfaces †¢ Polymer concrete (PC) is a mixture of aggregates with a polymer as the sole binder. To minimize the amount of the expensive binder, it is very important to achieve the maximum possible dry packed density of the aggregate. . Polymer Concrete (PC) Polymer concrete is an aggregate bound with a polymer binder instead of Portland Cement as in conventional concrete. The main technique in producing PC is to minimize void volume in the aggregate mass so as to reduce the quantity of polymer needed for binding the aggregates. This is achieved by properly grading and mixing the aggregates to attain the maximum density and minimum void volume. The graded aggregates are prepacked and vibrated in a mould.Monomer is then diffused up through the aggregates and polymerization is initiated by radiation or chemical mean s. A silane coupling agent is added to the monomer to improve the bond strength between the polymer and the aggregate. In case polyester resins are used no polymerization is required. An important reason for the development of this material is the advantage it offers over conventional concrete where the alkaline Portland cement on curing, forms internal voids. Water can be entrapped in these voids which on freezing can readily cracks the concrete.Also the alkaline Portland cement is easily attacked by chemically aggressive materials which results in rapid deterioration, whereas polymers can be made compact with minimum voids and are hydrophobic and resistant to chemical attack. The strength obtained with PC can be as high as 140 MPa with a short curing period. However, such polymer concretes tend to be brittle and it is reported that dispersion of fiber reinforcement would improve the toughness and tensile strength of the material.The use of fibrous polyester concrete (FPC) in the c ompressive region of reinforced concrete beams provides a high strength, ductile concrete at reasonable cost. Also polyester concretes are visco-elastic in nature and will fail under sustained compressive loading at stress levels greater than 50 per cent of the ultimate strength. Therefore polyester concrete should be considered for structures with a high ratio of live load to dead load and for composite structures in which the polymer concrete may relax during long-term loading.Experiments conducted on FPC composite beams have indicated that they are performance effective when compared to reinforced concrete beam of equal steel reinforcement percentage. Such beams utilize steel in the region of high tensile stress, fibrous polyester concrete (FPC) with its favourable compressive behavior, in the regions of high compressive stress and Portland cement concrete in the regions of relatively low flexural stress. Properties of Polymer Concrete: †¢ Due to good chemical resistance and high initial strength and modulus of elasticity, industrial use of PC has been mainly in overlays and repair jobs. Thermal and creep characteristics of the material are usually not favorable for structural applications of PC. †¢ Polyester concretes are visco-elastic and will fail under a sustained compressive loading at stress levels greater than 50 percent of the ultimate strength. Sustained loadings at a stress level of 25 percent did not reduce ultimate strength capacity for a loading period of 1000 hr. 6. Polymer Cement Concrete (PCC) Polymer cement concrete is made by mixing cement, aggregates, water and monomer, such plastic mixture is cast in moulds.Cured, dried and polymerized. The monomers that are used in PCC are: a) Polyster-styrene. b) Epoxy-styrene c) Furans d) Vinylidene Chloride However, the results obtained by the production of PCC in this way have been disappointing and have shown relatively modest improvement of strength and durability. In many cases material s poorer than ordinary concrete are obtained. This behavior is explained by the fact that organic materials (monomers) are incompatible with aqueous systems and sometimes interfere with the alkaline cement hydration process.Recently Russian authors have reported the production of a superior Polymer cement concrete by the incorporation of furfural alcohol and aniline hydrochloride in the wet mix. This material is claimed to be specially dense and non-shrinking and to have high corrosion resistance, low permeability and high resistance to vibrations and axial extension. Washington State University in cooperation with Bureau of Reclamation tested the incorporation of several monomers into Wet Concrete for preparing PCC for fabrication of distillation units for water desalination plants.However, it is reported that only epoxy resin produced a concrete that showed some superior characteristics over ordinary concrete. †¢ The materials and the production technology for concrete in PCC are the same as those used in normal Portland Cement concrete except that latex, which is a colloidal suspension of polymer in water, is used as an admixture. †¢ Earlier latexes were based on polyvinyl acetate or polyvinylidene chloride, but these are seldom used now because of the risk of corrosion of steel in concrete in the latter case, and low wet strengths in the former. Elasto-meric or rubberlike polymers based on styrenebutadiene and polyacrylate copolymers are more commonly used now. Latex: †¢ A latex generally contains about 50 % by weight of spherical and very small (0. 01 to 1 m in diameter) polymer articles held in suspension in water by surface-active agents. †¢ The presence of surface-active agents in the latex tends to incorporate large amounts of entrained air in concrete; therefore, air detraining agents are usually added to commercial latexes. 10 to 25 percent polymer (solid basis) by weight of cement is used in typical PCC formulations †¢ The addition of latex provides a large quantity of the needed mixing water in concrete. †¢ The application of PCC is limited to overlays where durability to severe environmental conditions is of primary concern. †¢ PCC is made with as low an addition of extra mixing water as possible; the spherical polymer molecules and the entrained air associated with the latex usually provide excellent workability. Concrete Mix and Curing: †¢ Typically, water-cement ratios are in the range0. 40 to 0. 5, and cement contents are on the order of 390 to 420 kg/m3. †¢ The hardening of a latex takes place by drying or loss of water. †¢ Dry curing is mandatory for PCC; the material cured in air is believed to form a continuous and coherent polymer film which coats the cement hydration products, aggregate particles, and even the capillary pores. Properties: †¢ The most impressive characteristics of PCC are its ability to bond strongly with old concrete, and to resist the entry o f water and aggressive solutions. †¢ It is believed that the polymer film lining the capillary pores and micro-cracks does an excellent job in impeding the fluid flow in PCC. These characteristics have made the PCC a popular material for rehabilitation of deteriorated floors, pavements, and bridge decks. 7. Polymer Impregnated Concrete (PIC) Polymer impregnated concrete is one of the widely used polymer composite. It is nothing but a pre-cast conventional concrete, cured and dried in oven, or by dielectric heating from which the air in the open cell is removed by vacuum. Then a low viscosity monomer is diffused through the open cell and polymerized by using radiation, application of heat or by chemical initiation. Mainly the following types of monomer are used: a) Methylmethacrylate (MMA) ) Styrene c) Acrylonitrile d) T-butyl styrene e) Other thermoplastic monomers The amount of monomer that can be loaded into a concrete specimen is limited by the amount of water and air that h as occupied the total void space. It is necessary to know the concentration of water and air void in the system to determine the rate of monomer penetration. However, the main research effort has been towards obtaining a maximum monomer loading in concrete by the removal of water and air from the concrete by vacuum or thermal drying, the latter being more practicable for water removal because of its rapidity.Another parameter to consider is evacuation of the specimen prior to soaking in monomer. This eliminates the entrapment of air towards the centre of the specimen during soaking which might otherwise prevent total or maximum monomer loading. The application of pressure is another technique to reduce monomer loading time. 8. Partially Impregnated (or Coated in Depth CID) and Surface Coated (SC) Concrete Partial impregnation may be sufficient in situations where the major requirement is surface resistance against chemical and mechanical attack in addition to strength increase.Even with only partial impregnation, significant increase in the strength of original concrete has been obtained. The partially impregnated concrete could be produced by initially soaking the dried specimens in liquid monomer like methyl methacrylate, then sealing them by keeping them under hot water at 70 C to prevent or minimize loss due to evaporation. The polymerization can be done by using thermal catalytic method in which three per cent by weight of benzoyl peroxide is added to the monomer as a catalyst. It is seen that the depth of monomer penetration is dependent upon following: a) Pore structure of hardened and dried concrete ) The duration of soaking, and c) The viscosity of the monomer The potential application of polymer impregnated concrete surface treatment (surface coated concrete, SC) is in improving the durability of concrete bridge decks. Bridge deck deterioration is a serious problem everywhere, particularly due to an abrasive wear, freeze-thaw deterioration, spalling and corrosion of reinforcement. Excellent penetration has been achieved by ponding the monomer on the concrete surface. Due care should be taken to prevent evaporation of monomer when ponded on concrete surface.A 5 cms thick slab, on being soaked by MMA for 25 hours produced a polymer surface coated depth of 2. 5 cms. Significant increases in the tensile and compressive strengths, modulus of elasticity and resistance to acid attack have been achieved. The application of monomer for field application like in bridge decks poses more problems than laboratory application. A typical surface treatment in the field can be done in the following manner. a) The surface is dried for several days with electrical heating blanket. b) Remove the heating blanket and cover the slab with 0. 4 cum oven-dried light-weight aggregate per 100 sqm. c) Apply initially 2,000 to 3,000 ml of the monomer system per square meter. d) Cover the surface with polyethylene to retard evaporation. e) Shade the surface to prevent temperature increase which might initiate polymerization prematurely, that may reduce penetration into the concrete. f) Add periodically additional monomer to keep the aggregate moist for minimum soak time of 8 hours. g) Apply heat to polymerize the monometer: Heating blanket, steam or hot water can be used for this purpose. Some of the promising monomer systems for this purpose are: ) Methylmethacrystalate (MMA), 1% Benzoyl peroxide (BP), 10% Trimethylopropane thimethacrylate (TMPTMA). b) Isodecyl methacrystalate (IDMA), 1% BP, 10% TMPTMA c) Isobutylmethacrystalate (IBMA), 1% BP, 10% TMPTMA BP acts as a catalyst and TMPTMA is a cross linking agent which helps in polymerization at low temperature of 52%C. 9. Properties of Polymer Impregnated Concrete Since polymer impregnated concrete (PIC) is one of the most important category of polymer concrete, the properties of PIC are discussed below. Stress – Strain Relationship The stress strain curve for MMA –impreg nated concrete tested to failure is shown in fig. elow.. PIC has a nearly linear stress strain relationship to failure. There is very little departure from linearity upto 90% of ultimate strength and there is no abrupt change at the proportional limit. The stress strain curves for Styrene TMTMPTMA impregnated concrete also show the same characteristics as for MMA impregnated concrete. The modulus of elasticity increased from 27 GPa for un-impregnated specimen to 49 GPa for MMA impregnated specimens. [pic] Compressive Strength The effect of polymer loading on the compressive strength in PIC is given in the following figure.Using methylemethacrystalate as monomer and with a polymer loading of 6. 4%, strength of the order of 144 MPa have been obtained using radiation technique of polymerization. (The control specimen had compressive strength of 38 MPa). The compressive strength obtained with thermal catalytic process was 130 MPa. [pic] [pic] Styrene impregnated specimens exhibit simila r trends, except that the strength levels were somewhat lower. The polymerization by radiation method produced a concrete of higher strength than the produced by thermal catalytic method.Perlite concrete impregnated with MMA and polyester styrene have also shown considerable increases in compressive strengths. It is found the higher strengths are obtained with MMA impregnated sample than with polyester styrene. The average compressive strength for a 1:8 non-air entrained perlite concrete samples, impregnated with MMA was 56 MPa for polymer loading of 63% compared to control specimen of compressive strength 1. 2 MPa. Tensile Strength The increase in tensile strength in the case of PIC has been observed to be as high as 3. times that of the control specimen for polymer loading of 6. 4% MMA i. e. impregnated concrete have shown tensile strength of the order of 11. 6 MPa compared to the strength of control specimen of 3 MPa using radiation process of polymerization. Thermal catalyticall y initiated polymerization, produced concrete with tensile strength 3. 6 times that of the control specimen and 7. 3% less than that of radiation produced concrete. Polymer Concrete : Polyester resin concrete with binder continent varying from 20 to 25% have shown tensile strengths in the range of 9 to 10 MPa at 7 days.Polymer Cement Concrete: Polymer cement concrete using latex has given tensile strength of 5. 8 MPa with a latex / cement ratio of 0. 25; compared to the control specimen of 4. 4 MPa strength. The increase in tensile strength is very modest. Flexural Strength Polymer impregnated concrete with polymer loading of 5. 6% MMA and polymerized by radiation have shown flexural strength 3. 6 times more than that of the control specimen, i. e. the flexural strength was increased to 18. 8 MPa from 5. 2 MPa. Polymer Concrete (PC) Polymer resin concrete has been reported to give flexural strength of the order of 15 MPa at 7 days.Creep Compressive Creep deformation of MMA impregnat ed concrete and styrene-impregnated concrete has been observed to be in direction opposite to that of the applied road i. e, Negative Creep. After the typical initial movement during load application, these concretes expand under sustained compression. The reason for this negative creep in PIC is not very clear though it may be possible that it is due to residual stresses generated in the concrete after polymerization of monomers. The increased volume may also be due to phase changes induced by pressure. This behaviour has been noticed at a relatively loiw loading of 5. MPa. Otherwise creep deformation of PIC concrete is generally one-tenth of conventional concrete, when compared on a basis of deformation per unit load. Creep deformation generally stabilizes after two to three months. Shrinking due to Polymerisation Shrinkage occurs through two stages of impregnation treatment i. e. , through initial drying and through polymerisation. The shrinkage through polymerisation is peculiar to PIC and could be several times greater than the normal drying shrinkage. It has been seen that for the same base material, different monomer systems cause different amounts of shrinkage.It is expected that the shrinkage due to polymerisation will be less for a base that has higher modulus of elasticity. Durability The saturation of the hydrated cement with corrosion resistant polymer probably acts as a protective coating and results in excellent improvement in durability. a) Frees Thaw Resistance: Polymer impregnated concrete has shown excellent resistance to freeze-thaw MMA impregnated and radiation polymerized specimens have withstood 8110 cyclens of freeze-thaw compared to 740 cycles in case of unimpregnated concrete. Even partially impregnated concrete withstood 2310 cycles. ) Resistance to Sulphate Attack: Keeping a failure criteria of 0. 5% expansion, it has been observed that there is atleast 200 percent improvement in the resistance of polymer impregnated concrete and 89 % improvement in the case of partially impregnated concrete over the conventional concrete. c) Acid Resistance: The acid resistance of PIC has been observed to improve by 1200 percent when exposed to 15% HCI for 1395 days. Water Absorption A maximum reduction of 95 percent in water absorption has been observed with concrete containing 5. 9 percent polymer loading. Co-efficient of Thermal Expansion:Polymer impregnated concrete has higher co-efficient of thermal expansion compared to conventional concrete. Compared to the unimpregnated concrete having a value of 4. 02 X 10-6, a 5. 5% MMA, radiation polymerized concrete has a co-efficient of thermal expansion of 5. 63 X 10-6, and styrene impregnated specimens have shown a value of 5. 10 X 10-6. Resistance to Abrasion Polymer impregnated concrete has shown appreciable improvement in resistance to abrasion. A 5. 5% MMA impregnated concrete has been found to be 50 to 80 per cent more resistance to abrasion than the control specimen.Even s urface impregnated concrete slabs have shown an improvement of 20 to 50%. Wear and Skid Resistance. Though there may be apprehension that polymer filled voids in polymer concrete might produce a slippery surface, on actual wear track test, it was found that the treated surfaces show excellent skid resistance compared to the unimpregnated surfaces. The wear after 50,000 simlated vehicular passes has been less than 0. 025cm. Fracture of Polymer impregnated Concrete Polymer impregnation of concrete changes its microstructure radically resulting in a change in the cracking behaviour of the impregnated concrete under load.Impregnation improves the strength of the mortar matrix and also the strength of the paste-aggregate interface by elimination of microcracks. Polymer probably enters the aggregates also and forms a network of polymer fibres across the interface, thus strengthening it. Radiographic studies have shown that micro cracking starts first around 70 to 80% of the ultimate load, very often in the mortar phase. When an advancing crack reaches an aggregate, it does not follow the aggregate boundary as in ordinary concrete, but usually propagates through the aggregate.This indicates that the paste aggregate interface bond is significantly improved by polymer impregnation. It has been observed that PIC indicates nearly linear behaviour to failure, which is typical of brittle material. The brittle nature of PIC presents a severe design limitation. It would be ideal to produce a material with the slow failure mode of normal concrete while retaining the high strength and modulus of elasticity of PIC. One method to achieve this ideal is to adjust the past aggregate bond so that the failure mode is through the interface like in ordinary concrete.In principle, this can be achieved by using a very strong and tough aggregate, so that the advancing crack is diverted round to the paste-aggregate interface. The fracture mode of PIC can also be altered by incorporating a small quantity (1% by volume) of fibres in the matrix. The fibres do not affect the modulus of elasticity of concrete due to their low concentration, but serve to inhibit crack propagation through the mortar by acting as crack arrestors. 10. Sequence of Operations Drying and evacuation:The time and temperature needed for removal of free water from the capillary pores of moist-cured products depend on the thickness of the elements. At the drying temperatures ordinarily used (i. e. , 105 C), it may require 3 to 7 days before free water has been completely removed from a 150- by 300-mm concrete cylinder. Temperatures on the order of 150 C can accelerate the drying process so that it is complete in 1 to 2 days. Soaking the dried concrete in a monomer: The in situ penetration of concrete in the field may be achieved by surface ponding, but precast elements are directly immersed in the monomercatalyst mixture.Commercial monomers contain inhibitors that prevent premature polymerization dur ing storage; the catalyst serves to overcome the effect of the inhibitor. Sealing the monomer: To prevent loss of monomer by evaporation during handling and polymerization, the impregnated elements must be effectively sealed in steel containers or several layers of aluminum foil; In the rehabilitation of bridge decks this has been achieved by covering the surface with sand. Polymerizing the monomer: Thermal – catalytical polymerization is the preferred technique.The time for complete polymerization of the monomer in the sealed elements exposed to steam, hot water or air, or infrared heat at 70 to C may vary from a few to several hours. In the case of a MMA-benzoyl peroxide mixture, no differences in strength were found between specimens polymerized at C with hot air for 16 hr or with hot water for 4 hr. 11. Application of Polymer Impregnated Concrete Keeping in view the numerous beneficial properties of the PIC, it is found useful in a large number of applications, some of wh ich have been listed and discussed below: a) Pre-fabricated structural elements. ) Pre-stressed Concrete c) Marine works d) Desalination Plants e) Nuclear Power plants f) Sewage works-pipe and disposal works. g) Ferro cement products h) For water proofing of structures i) Industrial applications a) Pre-fabricated Structural Elements: For solving the tremendous problem of Urban Housing shortage, maintaining quality, economy and speed, builders had to fall back on pre-fabricated techniques of construction. At present due to the low strength of conventional concrete, the pre-fabricated sections are large and heavy, resulting in costly handling and erection.These reasons have prevented wide adoption of pre-fabrication in many countries. At present, the technique of polymer impregnation is ideally suited for pre cast concrete, it will find unquestionable use in industrialization of building components. Owning to higher strength, much thinner and lighter sections could be used which enabl es easy handling and erection. They can be even used in high rise building without much difficulties. b) Pre-stressed Concrete: Further development in pre-stressed concrete is hindered by the inability to produce high strength concrete, compactable with the high tensile steel available for pre-stressing.Since PIC provides a high compressive strength of the order of 100 to 140 MPa, it will be possible to use it for larger spans and for heavier loads. Low creep properties of PIC will also make it a good material for pre-stressed concrete. c) Marine Works: Aggressive nature of sea water, abrasive and leaching action of waves and inherent porosity, impair the durability of conventional concrete in marine works. PIC possessing high surface hardness, very low permeability and greatly increased resistance to chemical attack, is a suitable material for marine works. ) Desalination Plants: Desalination of sea water is being resorted to augment the shortage of surface and ground water in many countries. The material used in construction of flash distillation vessels in such works has to withstand the corrosive effects of disilted water, brine and vapour at temperature up to 1430 C. Carbon steel vessels which are currently in use are comparatively costly and deteriorate after prolonged use. Preliminary economic evaluation has indicated a savings in construction cost over that of conventional concrete by the use of PIC. ) Nuclear Power Plants: To cope up with the growing power requirements for industrial purposes, many countries are resorting to nuclear power generation. The Nuclear contained vessel (Pressure vessel) is a major element, which is required to withstand high temperatures and provide shield against radiations. Another attendant problem of nuclear power generation is the containment of spent fuel rods which are radioactive over long period of time to avoid radiation hazards. At present heavy weight concrete is being used for this purpose, which is not very eff ective.PIC having high impermeability coupled with high strength and marked durability provides an answer to these problems. f) Sewage Disposal Works: It is common experience that concrete sewer pipes deteriorate due to the attack of effluents and when buried in sulphate infested soils. Further in the sewage treatment plant, concrete structures are subjected to severe attack from corrosive gases particularly in sludge digestion tanks. Polymer-impregnated concrete due to its high sulphate and acid resistance, will prove to be a suitable material in these situations. ) Impregnation of Ferro-cement products: The ferro-cement techniques of construction is being extensively used in the manufacture of boats, fishing trawlers, domestic water tanks, grain storage tanks, man hole cover, etc. , Ferro cement products are generally this (1 to 4 cms) and as such are liable to corrode. Application of polymer impregnation techniques should improve the functional efficiency of ferro-cement products . h) Water Proofing of Structures: Seepage and leakage of water through roof and bathroom slabs, it a nagging problem and has not been fully over come by the use of conventional water proofing methods.The use of polymer impregnated mortar should solve this problem. i) Industrial Applications: Concrete has been used for floor in tanneries, Chemical Factories, dairy farms and in similar situations for withstanding the chemical attack, but performance has not been very satisfactory. The newly developed PIC will provide a permanent solution for durable flooring in such situations. 12. Case Studies: Two case studies are presented as follows: 1. Properties of Fiber Reinforced Polymer Concrete studied by Marinela Barbuta and Maria Harja 2. Polymer Concrete for Structural Restoration and Corrosion Protection of Concrete Support Columns.I. Properties of Fiber Reinforced Polymer Concrete studied by Marinela Barbuta and Maria Harja The experimental results of studies regarding polymer concrete with cellulose fibers are presented. The compositions used in the present study derive from a previous one which investigated a large number of compositions using different dosages of resin and filler. The mechanical characteristics such as: compressive strength, flexural strength and split tensile strength were investigated on fiber reinforced polymer concrete made with different dosages of resin and filler, the fiber dosage being constant for all mixtures.Materials The experimental researches on polymer concrete were made by using the following materials: polymer, fly ash as filler, crushed aggregates and fiber type ARBOCEL. The polymer was type epoxy resin, called ROPOXID, made in Romania by POLICOLOR Bucharest . The hardener was type ROMANID 407, also made by POLICOLOR Bucharest. The fly ash (FA) from the power plant CET Holboca, Jassy, was added to the fine aggregates. The fly ash is an inorganic waste produced by burning pulverized coal in power stations. Fly ash consists of many small, glass-like particles ranging in size from 0. 01 to 100 ? m.Chemically FA contains oxides, hydroxides, carbonates, silicates, and sulphates of calcium, iron and aluminum. The content in carbon is given from loss ignition. FA is a heterogeneous mixture of amorphous and crystalline phases and is generally considered to be a ferroaluminosilicate element. The mineralogical, physical and chemical properties of FA depend on the nature and composition of the coal, conditions of combustion, type of emission control devices, storage and evacuation methods. Storage methods may affect weathering rates, especially under humid conditions where soluble constituents may be leached.The principal characteristics of FA are: colour gray to black, function of carbon unburned, particles sizes between 0. 01 to 100 ? m; the shape of particles is spherical, specific surface is between 4,800. . . 5,200, the density is between 2,400 and 2,550 kg/m3 [ The aggregates were used in two sorts: 0. . . 4 mm and 4. . . 8 mm, with continuous granulosity, obtained from crushed river gravel by S. C. EMBERON SRL Jassy. The ARBOCEL fibers are natural cellulose fibers, produced by J. Rettenmaier & S? ohne GMBH. ARBOCEL is produced from cellulose in various qualities (fiber lengths, thicknesses, purities, etc. The properties of ARBOCEL cellulose fibers are: mean fiber length of 10 ? m, completely safe, insoluble in water and organic solvents, resistant to dilute acids and bases. The fiber was used in proportion of 3% from the mass of resin plus the hardener. Experimental Samples For the study of polymer concrete properties nine compositions (BPFF) were prepared in the experimental program (Table 1). [pic] The polymer concrete with different compositions as is given in Table 1, was prepared by mixing firstly the resin with hardener, then after complete homogenization the fibers were introduced in the mixture as shown in fig below [pic] Fig 1. Cellulose fiber mixing with resin. The fly ash w as added to the mix of aggregates and the resin and aggregates were mixed by the mechanical mixer. After complete mixing, the polymer concrete was poured in formworks. For each composition the density was determined. The following mechanical characteristics were experimentally tested: compressive strength on cube sample of 70. 7 mm sizes, flexural strength and split tensile strength on prismatic samples of sizes 210? 70? 70 mm, according to standard prescriptions. [pic] Fig. 2. – Samples of polymer concrete with fibers. Results and DiscussionsAccording to EN 12390/2001 the mechanical characteristics of polymer concrete with cellulose fiber, experimentally determined namely: compressivestrength (fc), flexural strength (fti) and split tensile strength (ftd) are given in Table below . [pic] From the experimental results the following observations can be made: a) The values of compressive strengths for polymer concrete with fibers (Fig. 3) vary between 62. 62 MPa (for BPFF7) and 46. 41 MPa (for BPFF2). Fig. 3. – Variation of compressive strength for polymer concrete with fiber. [pic] Fig. 3. – Variation of compressive strength for polymer concrete with fiber. ) With the increasing of resin and fly ash dosage the compressive strengths increase (Figs. 4 and 5). [pic] Compressive strength, MPa Fig. 4. – Variation of compressive strength for polymer concrete with fiber vs. the resin content, for 6. 4% FA. [pic] Fig. 5. – Variation of compressive strength for polymer concrete with fiber vs. the FA content, for 12. 4% resin. d) The values of flexure strengths for polymer concrete with fibers (Fig. 6)vary between 17. 57 MPa (for BPFF9) and 13. 55 MPa (for BPFF8), so, the decrease of resin dosage results in the increase of flexure strength. pic] Fig. 6. – Variation of flexural strength for polymer concrete with fiber. [pic] [pic] Fig. 7. – Variation of split tensile strength for polymer concrete with fiber: a – vs. t he resin content; b – vs. the sample number. d) The values of split tensile strengths for polymer concrete with fibers (Fig. 7) vary between 6. 94 MPa (for BPFF9) and 4. 29 N/mm2 (for BFF7); the increase of resin dosage results in the increase of split tensile strength. The experimental researches lead to the following observations: a) For the maximum epoxy resin dosage (16. %) compressive strength is reduced near minimum value, the flexure strength is medium, but the split tensile strength has high value. b) For the minimum epoxy resin dosage (12. 4%) compressive strength is reduced under the medium value, the flexure strength is also reduced, and the split tensile strength has value over the medium. c) For the maximum fly ash dosage (12. 8%) compressive strength and flexurestrength are medium, but the split tensile strength is near the highest value. d) For the minimum fly ash dosage (6. 4%) compressive strength and flexure strength are under the medium and the split tensil e strength is near medium value. ) For the same dosage of epoxy resin the maximum compressive strength and flexure strength were obtained for maximum fly ash dosage. It results that for increasing the compressive strength and flexure strength at same dosage of resin and fiber, it must be used the maximum dosage of fly ash. f) For the split tensile strength it must be used a medium fly ash dosage; The values of mechanical characteristics of polymer concrete are smaller then those of mechanical characteristics obtained for polymer concrete with silica fume and polymer concrete with fly ash . The author concluded that The experimental researches concerning the polymer concrete had investigatedthe mechanical characteristics of epoxy polymer concrete prepared with cellulose fibers and fly ash as filler. †¢ When the same dosage of cellulose fibers is used, the content of resin must be increased. Also for obtaining good mechanical properties the filler is used with higher dosages. â⠂¬ ¢ The experimental values of mechanical strengths for polymer concrete with cellulose fibers were smaller then that for polymer concrete without fibers. This type of fibers is not a good choice for polymer concrete reinforcement. II.Polymer Concrete for Structural Restoration and Corrosion Protection of Concrete Support Columns by David E. Snider and Heather M. Ramsey of Sauereisen Inc. A large copper mine and refinery in the western United States had a dilemma. Their cell house, which contains over 1,500 cells, each holding more than 20,000 gallons of electrolyte, had experienced severe corrosion and structural degradation of the support columns for the tanks. These columns support the cells in their solvent extraction and electrowinning process. This process entails immersion of a stainless steel cathode or â€Å"starter plate† into the electrolyte.Pure copper is deposited onto the starter plate during this 10-day digestion process. The collected copper is then further r efined at a separate location. Over time, highly acidic leakage from the cells had corroded the support columns to the point that their ability to adequately withstand the imposed load was in doubt. Additionally, the refinery desired to upgrade the facility’s ability to withstand seismic activity. The leakage, primarily copper sulfate and 25% sulfuric acid at a pH of 1. 0 or less, corroded not only the concrete but more significantly the reinforcement bar (rebar) encased in the concrete.Corrosion of the rebar resulted in an increase of internal pressure due to expansion of the corrosion products, therefore putting the concrete in high tensile stress. The direct effect of this stress was cracking and spalling of the concrete. Figure 1 shows a typical degradated column requiring restoration. [pic] The original construction of the columns used the rebar spaced 6-inches on center vertically and 18-inches on center horizontally. The refinery’s standard repair procedure was to remove corrosion products from the concrete and steel and then to top them with a polymer-modified portland-cement mortar.This standard repair method requires two (2) to three (3) days per column, and although temporarily affective, did not meet the company’s desire for a long-term solution. They decided upon a new approach using a polymer concrete (PC), which is a bisphenol A based-epoxy. This material is designed for maximum flowability, mechanical properties and chemical resistance. The PC repair system utilizes the polymer concrete for encapsulation, chemical protection, mechanical support and resistance to physical abuse. Figures 2 illustrates the method by which the stainless steel rebar was attached to the columns after surface-preparation.Stainless steel rebar was imbedded into the concrete floor using an epoxy mortar. Channels were saw-cut vertically in the concrete column. These channels provided a recess into which the rebar was bent and then secured into place with the epoxy mortar. Grouting of the rebar with this high strength epoxy mortar also served to provide tensile stress relief. By lowering stress relief, corrosion rates are reduced. [pic] Figure 2. Stainless steel rebar bent and grouted into the channels. To further ensure structural integrity and to upgrade seismic capabilities, the company chose to use fiberglass reinforcement (FRP) strips and wraps nder the PC. The strips were installed vertically on the columns and a fiberglass fabric was wrapped around the columns horizontally. The columns were formed and the polymer concrete was poured into place completely encapsulating the columns, the rebar and the FRP. This method required two (2) days per column. To date, 75 columns have been repaired using this method. Figures 3 and 4 show the forming and pouring of the PC. Figure 5 shows the PC after the form has been removed and the FRP that was applied to the columns. [pic] Figure 3. The forms placed around the column. . [pic] As me ntioned earlier, an important property of the PC is the flowability. The test for this property is ASTM C-143 and measures the â€Å"slump† of the polymer concrete. (Figure 6). A slump of 6 inches is considered to be flowable. This particular polymer concrete exhibits a slump of 8-inches, which is very flowable. Figures 6, 7 and 8 illustrate the flowability of the polymer concrete mixture. Table 1 lists some of the other physical properties of the polymer concrete used on this repair that were important considerations. [pic] Property at 7-days Value Property at 7- Days | Value | |Density |135 pounds/cft (2. 2gm/sq. cm) | |Compressive Strength |12,000 psi (84. 4 N/sq mm) | |Flexural Strength |3,000 psi (21. 1 N/ Sq. mm) | |Modulus of Elasticity |1. 08x 10(6)psi 7600 N/Sq mm | |Shrinkage` |0. 9 % | |Tensile Strength |2,400 psi (16. 9 N/Sq. mm) | The PC is roughly three times as strong as a portland cement mix (about 4,000 psi (281 kg / sq. cm. 28. 1 N/sq mm)) and is not chemic ally affected by the electrolyte. These properties make it an ideal product for the column restoration. As expected, none of the 75 columns repaired to date have exhibited any signs of failure and have required no maintenance since the repair program commenced in early 2007.Coatings will typically have a service life of 8 to 15 years depending upon the exposure and physical abuse. However, in this case, typical service life of coatings was six months. Their service life is also affected and somewhat limited as a result of application thickness. Coatings are generally applied at thicknesses ranging from a few mils up to a few hundred mils. Polymer concretes, however, are applied at a minimum thickness of 1 inch and may be applied as thick as 18 inches. The thickness of barrier coatings determines the overall permeability, which is a measure of water vapor’s ability to pass through a material.If the coating is less than 250 mils, the method used to determine permeability is bas ed on the water-vapor transmission (WVT) test ASTM E-96 or ASTM D-1653. Permeance is calculated from WVT. Permeability is obtained by multiplying permeance by thickness. A permeability of 10-8 (1. 49 x 10- 17 grams/Pa†¢s†¢m) or less is generally considered to provide a good barrier coating. Also due to the thickness, and other considerations, the service life of a polymer concrete is longer and requires far less maintenance. Experience with PCs by this manufacturer has shown no failures after 15 years of service.Laboratory evaluations coupled with field observations indicate the service life of PCs to be typically greater than 25 years. Figure 9 illustrates the completed column, including a protective topcoat for the FRP reinforced concrete. Although not needed for functionality, the topcoat was extended over the PC for aesthetics and coating integrity. [pic] Figure 9. Completed column repair. Many users of polymer concretes will entirely replace portland concrete with a f ull thickness of the polymer concrete. This is particularly true when extended downtimes are prohibitive. The lengthy cure time for standard portland based ement prior to receiving a protective coating is unacceptable for many facilities. After placement, polymer concretes may be placed into full chemical service after a 24-hour cure. Furthermore, with the strengths achieved with PC, it is usually possible to reduce the overall thickness to about ? of that commonly used with portland concretes. Typical thicknesses for PCs range from 1-inch to 4-inches. Polymer concretes may be engineered, formed and placed in the same manner that one would employ with a portland concrete structure. They also are reinforced in the same manner as portland concretes.Polymer concrete thicknesses are typically much less than that of the Portland concrete, therefore smaller diameter rebar is often used. At a thickness of 1 inch, one would use lesser thick rebar instead of a reasonably higher thick rebar c ommonly found with portland concrete constructions. Due to the ease of installation, the facility’s local preferred contractor was able to perform the work. The author concluded that Polymer concretes, which do not contain portland cement, have demonstrated tenacity as a protective barrier material in this difficult application and many others.This application required corrosion protection from a severely aggressive electrolyte, as well as protection from physical abuse. Other essential requirements were a system affording both ease of use and a quick turnaround time. Polymer concretes are also proving to be cost effective alternatives to using portland cement-based concretes with chemical-resistant topcoats for corrosion protection. The cost of maintenance for polymer concretes per year of service life is significantly less than that of concrete with applied barrier coatings, which may require multiple re-applications over the same number of years of service.Conclusion: 1. T he major factor that has been responsible for the extensive use of polymer-based materials in civil engineering is their advantages, viz . increased tensile strength, compressive strength, freeze-thaw durability, and decreased water permeability to a negligible value. 2. Owing to its excellent resistance to chemical attack i. e sulphate attack, acidic attack, saline water, radiation from nuclear substances polymer concrete has great potential over Portland cement for the design of structures in such industries, desalination plants, nuclear plants, underwater structures, overlays in bridge decks. . There are many type of application of repairing material available such as grout, motar, concrete, sprayed concrete and cement based material. Among these, resin based materials are performed much better than the others. 4. The cost of maintenance for polymer concretes per year of service life is significantly less than that of concrete with applied barrier coatings, which may require mult iple re-applications over the same number of years of service. 5. Extended use of pre stressed elements could be permitted with the reduced permeability possible. 6.The incorporation of dyes with the plastics used for polymerization opens another aesthetic aspect of concern to civil engineers and architects, as does the potential size decrease for greater span/depth ratios. 7. The only barrier to be focussed on is its higher cost in comparison to OPC and further research for economic production of polymer concrete would help to overcome this problem. References 1. â€Å"Properties of Fiber Reinforced Polymner Concrete†, Msrinela Barbuta and Maria Harja, Univerisity Technica, Tomul LIV(LVIII) Fasc,3, 2008, Constructii Architectura. . Muttukumar M. , Mohan D. J. , Polymer Res. 12, (2004) 3. â€Å"Polymer Concrete for Structural Restoration and corrosion protection of Concrete Support Columns† of David E. Snider and Heather M. Samsey of Sauereisen Inc. , 4. â€Å"Polymer concrete and its potential in the Construction industry†, Luke M. Snell,1 H. Aldridge Gillespie, and Robert Y. Nelson, Department of Civil Engineering, West Virginia University, Morgantown, West Virginia, and School of Civil Engineering and Environmental Science, University of Oklahoma Norman

Assignment prompt Essay Example | Topics and Well Written Essays - 250 words

Assignment prompt - Essay Example The extensive use of the apocalyptic setting is a bit confusing and the query revolves round its purpose more than anything else. For â€Å"Harrison Bergeron†, the only query that would come to a reader’s mind is that why does the author show the death or rather the brutal murder of his only protagonist who attains almost a stature of superhero. Does this incident bear any special symbolic connotation? â€Å"August 2026: There Will Come Soft Rains† by Ray Bradbury falls in the genre of science fiction but if one delve deep into the plot of the text and try to gaze behind the apparent presentation of the story, it is not easy to find the symbolic interpretation of the story. Bradbury uses the personification deliberately to display the emptiness. Bradbury wanted to reveal the readers that amidst the hustle and bustle of the house, something is amiss and this indicates a persistent absence of human being and human emotion. Bradbury wanted to portray that the fate of the house and the fate of humanity is synonymous. The impact of the complete absence of human characters makes the story all the more symbolic. The intention of the author to portray that too much mechanical life will destroy human civilization is also aptly displayed through the absence of human characters. The effect of the absence of human character on the plot of the story is far reaching and the absence makes the inner theme of the story line poignant. Here, the personified objects of the house are the characters. The protagonist of the house can be considered as the empty house whose inhabitants are dead because of nuclear reaction. The story line, due to the personification of inanimate objects not only renders a proper appearance of a science fiction but also helps to carry forward the underlying powerful message of the story that humans are slaughtering the planet and all the innovation and technologies created to make life easy and better,

Competitors and Strategic Performance Management Essay

Competitors and Strategic Performance Management - Essay Example Competitors and Strategic Performance Management is one of the crucial strategies for the success of organizations operating in competitive environments. McDonald has built a competitive edge through robust Strategic Performance Management that aligns the performance of its employees to the corporation’s strategic objectives and organization’s vision. McDonald is without any doubt making significant strides in innovation, business expansion, and cost reduction to outmatch its competitors and increase its market share. Proactive approach in managing its business threats keeps McDonald remain valued in the market. In addition, the corporation understands that, there is a need to keep continuing monitoring its business external environment (competitors) to ensure that it formulates the most relevant strategies to promote and cope with stiff competition (Love, 1999). In order to understand its business environment, McDonald analyses its business competitors as those that co mpete with its â€Å"customers spending power.† Some of the identified competitors are; brand competitors, industry competitors and form competitors. The industry competitors are regarded as the most critical ones since they offer almost similar products and services. The corporation further analyses competitors’ characteristics as serving the same customers, having superior or same technologies in products preparation, similar distribution channels, and same target market. McDonald further recognizes the need to examine their competitors existing strategies and objectives. The corporation analyses competitors’ strengths and weaknesses in regard to its business (McDonald, 1996). By undertaking competitors’ analysis, McDonald understands that it will be able to do business forecasts on the competitors’ plans and strategies. Based on the Cohesion Case analysis of MCD, its three major strengths include; large/strong customer base covering approximately 118 countries. For example in Europe, there is an increase in the number of restaurants from 6,650 to 6,485 which reflects a considerable increase in customer base.  

Egoism Essay Example | Topics and Well Written Essays - 500 words

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Related to Bussiness Ethics (see the assignment creteria) - Essay Example Since 1999 Microsoft has been at the centre of a number of legal disputes with both the US Government and the European Commission. At the heart of the disagreements have been accusations that Microsoft had been exploiting its monopoly power in order to reduce competition, and consequently choice, in the marketplace. Microsoft was accused of anti competitive behavior in the United States and had severe financial penalties inflicted on them in an anti trust law court action in Europe. Whilst the financial penalties were relatively easy for Microsoft to bear, the company continued to face accusations of poor ethics and unfair tactics) In your opinion, how important is it to stakeholders in a company that the ethics of the CEO match those of the organization? Explain your answer with reference to Bill Gates during his tenure as CEO at Microsoft. How well a business corporation performs in financial terms is significant for a broad group of people that includes potential/existing investors, creditors, employees or managers. With differing information needs and purposes, each category of stakeholders should be provided with data that is comprehensive, relevant and reliable, so as to allow an informed opinion to be reached on the corporations financial performance. However, all too often, the customer is left out of this equation. The situation is no different in the case of Microsoft Corporation, which has tremendous reach and market share, but whose customers have very little say in the affairs of the company. Bill Gates’ personal efforts as a philanthropist is widely appreciated,– both in terms of money and energy. Yet, the history of Microsoft since its inception shows that the organization is a purely economic enterprise, whose sole purpose is profits and whose foresight stops with the next quarter. This dev iation in behavior between the Chief Executive Officer and his organization is the