POLYPROPYLENE FIBERS

Soil is extremely complex, heterogeneous substance which has been subjected to varieties of nature. Properties of soil do not change only with location to location but also with respect to depth, climate and drainage condition of soil. Soil stabilization is the process by which strength properties of soil can be improved with the use of adding some materials like polypropylene, wheat husk fiber, copper slag etc. There is a rapid increase in waste quantity of plastic fibers, if this waste can be utilize for stabilization of soil than problem of solid waste can be resolve and also cost of soil stabilization can be reduced. This study presented a review of literature on soil stabilization using polypropylene and wheat husk fiber.

Concrete is basically a brittle material and possesses very low tensile strength. To overcome this weakness, we generally introduce reinforcement to the concrete. For this study, we are aiming to analyze the strength parameters of concrete under the influence of fibers as a reinforcing material. During the last 30 years, different types of fibers and fiber materials were introduced and are being continuously produced in the market as new applications. Usage of fibers in concrete helps to improve resistance to cracking and fragmentation. For this study, Polypropylene fiber is used as a reinforcing material. We have used M40 and M25 concrete and a comparative study on strength parameters is made with and without the presence of these fibers. The compressive, flexural strength tests were performed by using fiber weight content from 5%.

— Among all the construction materials that are available for construction, we know that concrete is a widely used construction material for building of various civil engineering structures. Concrete will give better durability and also its costs during construction as well as maintenance are very low when compared to other construction materials. As we know that concrete is strong in construction and weak in tension and tends to fail because of its deficiencies such as low tensile strength, low strain at fracture. The weakness of concrete is due to the presence of micro cracks at mortar aggregate interface. To overcome the existing problems addition of fibers in the concrete has been come in to practice. In fiber reinforced concrete the fibers are added to the concrete mix so that those are discontinuous fibers will be uniformly distributed in the mix and improve the concrete properties in all directions. To get more improvement in the mechanical properties work has been done by combining two different types of fibers knows as hybridization. In present experimental work for M25 grade of concrete can be designed according to IS 10262:2009 with four different proportions of hybrid fibers are added with concrete ingredients. The proportion of steel and polypropylene fibers are added by 50% each with different hybridization ration i.e. 0%,0.5%, 1.0 %, 1.5% and steel fibers are added by volume of concrete and polypropylene is added by weight of cement. For strength parameters compressive, tensile, flexural, impact strength specimens are casted and cured for 28 days and tested for hardened concrete and for fresh concrete slump and compaction factor test is carried to know the workability of hybrid fiber reinforced concrete. For durability study Sorptivity test is carried out to know the absorption of water by capillary. To evaluate the strength parameters different tests are conducted and results are tabulated. From the present work results show that 1.5 % addition of hybrid fiber gives maximum results in all the strength parameters compare to other different hybrid ratios.

This research deals with the effect of Polypropylene Fibers on the properties of concrete. Polypropylene
fibers are synthetic fibers which possess high tensile strength, high modulus of elasticity and also good
bonding when added to concrete. In this research work, Polypropylene fibers of two different length 6mm
and 12 mm were added to concrete in different proportions and then the performance of concrete in terms
of strength and cracks propagation were analyzed. For this purpose, three batches of FRC (Fiber reinforced
concrete) and one batch of PC (Plan concrete) were made. PC (Plan concrete) sample was used a bench
mark with which the other FRC concrete composite were compare in terms of strength and performance.
FRC-1 concrete composite contained 50% 6mm length of Polypropylene fibers and 50% 12mm length of
Polypropylene fibers. FRC-2 concrete composite had 75% 6mm length of Polypropylene fibers and 25%
12mm length of Polypropylene fibers. Similarly, FRC-3 Concrete contained 25% 6mm length of
Polypropylene fibers and 75% 12mm length of Polypropylene fibers. Large number of samples were
prepared in laboratory and tests were carried out at the curing age of 28 days. Several laboratory tests were
done on the concrete samples such as compression test, split tensile test, modulus of rupture and pure shear
test. After analyzing the data from laboratory tests and experiments, it was evident that the performance of
concrete in term of strength and cracking behavior were improved after the adding of Polypropylene fibers.

Avaliou-se a influência do uso de fibras de polipropileno para reforçar rejeitos de minério de ferro. A influência sobre os parâmetros de resistência e no comportamento volumétrico foram avaliados sob a condição não drenada. Realizaram-se ensaios triaxiais consolidados não drenados (CIU) sob tensões médias efetivas de 50, 100, 200 e 400 kPa em amostras não reforçadas e reforçadas. As envoltórias de resistência, mostraram que a adição de 0,5% de fibra de polipropileno incrementa o ângulo de atrito de 33,4º a 42,6º, enquanto, a variação no intercepto coesivo é desprezível. No comportamento volumétrico, as fibras incrementam a tendência contrativa inicial da matriz porque fornecem um confinamento adicional sobre os grãos de rejeito incrementando a poropressão, embora, esse efeito não é constante. Após a mudança de comportamento, na transferência de fase, a tendência dilatante final da matriz prevalece e as fibras passam a serem agentes supressores desta tendência porque continuam-se esticando durante o cisalhamento confinando mais partículas. No que respeita à estrutura, o rejeito não reforçado perde totalmente a rigidez inicial com uma deformação axial de 5%, enquanto amostras reforçadas perdem a rigidez em 12% mostrando a vantagem de adicionar as fibras. As melhorias alcançadas fazem da fibra uma alternativa de reforço interessante para zonas onde não se consiga colocar reforços planares ou para manutenção de taludes afetados por deslizamentos.

O processo de obtenção de ouro gera rejeitos que são filtrados e compactados em aterros com alturas até de 50 m. Os constituintes das rochas, durante processo para retirar o ouro, perdem as propriedades originais apresentando muitas vezes baixa ou nula coesão sendo os taludes, dos aterros compactados com estes rejeitos, vulneráveis por deslizamentos ou por risco de trincamento interno sob fortes mudanças de temperatura. O reforço com geossintéticos planares pode gerar planos de fraqueza entre as camadas enrijecidas pela compactação, enquanto que, o reforço por fibras discretas causa uma melhor distribuição das tensões dentro da matriz. Este trabalho analisa o comportamento mecânico de um rejeito de minério de ouro reforçado com fibras de polipropileno mediante ensaios de cisalhamento direto convencional e de plano cisalhado com superfície polida sob condição inundada utilizando tensões normais verticais de 25, 50, 100, 200 e 400 kPa. O teor de fibras foi 0,5 % do peso seco da matriz. Os resultados mostram um comportamento tensão-deslocamento bi-linear no rejeito não reforçado. No caso reforçado, a adição de fibra elimina a bi-linearidade,  consegue uma resposta uniforme do rejeito, incrementa os ângulos de atrito máximo e residual, e muda a tendência volumétrica contrativa para dilatante. En conclusão, o uso desta alternativa de reforço pode ser considerada na melhoria das caraterísticas de resistência de zonas críticas em aterros compactados com este rejeito.