Hybrid Reinforcement of Sisal and Polypropylene Fibers in Cement-Based Composites

Abstract

Several studies using vegetable fibers as the exclusive reinforcement in fiber-cement composites have shown acceptable mechanical performance at the first ages. However, after the exposure to accelerated aging tests, these composites have shown significant reduction in the toughness or increase in embrittlement. This was mainly attributed to the improved fiber-matrix adhesion and fiber mineralization after aging process. The objective of the present research was to evaluate composites produced by the slurry dewatering technique followed by pressing and air curing, reinforced with combinations of polypropylene fibers and sisal kraft pulp at different pulp freeness. The physical properties, mechanical performance, and microstructural characteristics of the composites were evaluated before and after accelerated and natural aging. Results showed the great contribution of pulp refinement on the improvement of the mechanical strength in the composites. Higher intensities of refinement resulted in higher modulus of rupture for the composites with hybrid reinforcement after accelerated and natural aging. The more compact microstructure was due to the improved packing of the mineral particles with refined sisal pulp. The toughness of the composites after aging was maintained in relation to the composites at 28 days of cure.

Micro/Nanofibrilas Celulósicas De Eucalyptus Em Fibrocimentos Extrudados

“…Uma confi guração com três cutelos (vão inferior igual a 150 mm) foi empregada na determinação dos valores médios de módulo de ruptura (MOR), limite de proporcionalidade (LOP), módulo elástico (MOE), energia específi ca e deformação específi ca total dos compósitos quando estes sofram ruptura. As confi gurações e os cálculos seguem os procedimentos sugeridos em RILEM (1984) e são descritos em detalhes em trabalhos anteriores (TONOLI et al, 2010;TONOLI et al, 2011). Foram avaliados em torno de 5 corpos de prova para cada série / tratamento, sendo estes testes realizados após o total de 10 dias de cura (3 dias em saco plástico selado e 7 dias em cura térmica).…”

“…Esse comportamento pode estar relacionado com a re-precipitação dos produtos de hidratação do cimento nos poros da matriz e ao redor das micro/ nanofi brilas durante a exposição as intempéries, resultando no aumento da adesão/interação entre as micro/nanofi brilas e a matriz cimentícia. O aumento da rigidez dos compósitos de cimento fi bro-reforçado com o tempo de envelhecimento é amplamente reportado na literatura (TONOLI et al, 2009;TONOLI et al, 2011), e foi identifi cado com sucesso pela técnica não-destrutiva adotada neste trabalho.…”

Mechanical behaviours of green hybrid fibre-reinforced cementitious composites

“…The absorbed energy during the flexural tests is obtained from the integration of the area below the load versus deflection curve at the point corresponding to a reduction in load carrying capacity to 30% of the maximum reached [27]. Four-point bending tests were also conducted at the age of 7 days, 14 days, and 28 days, respectively.…”

“…Therefore, the composites with both fly ash and natural fibres may exhibit improved mechanical properties, especially after long-term curing. Although the synergic effect of different fibres [2,27,28] or the coupled effect of natural fibre and recycled material such as granulated blast furnace slag [29] on the mechanical behaviour of the composites has been investigated, the combined influence of high volume of fly ash and natural fibres on the mechanical behaviour of cementitious composites has not been studied systematically yet and this need to be further investigated.…”

Effect of carbon nanotube on physical and mechanical properties of natural fiber/glass fiber/cement composites

“…For this reason, some fibers such as carbon, polypropylene and natural fibers were introduced to substitute for glass fiber in cementitious composites (Tonoli et al 2011;Zakaria and Abdul Awal 2011).…”