Flexible canvas produced from uncured-natural rubber composites filled with high calcium oxide fly ash/cement hybrid filler

Abstract

Concrete canvas (CC) is an attractive composite based on a combination of textile and cement, applying for the slope protection and ditch lining. However, there is no binder between both the materials and its high thickness causes a strong detachment of cement particles, and the complex designing of CC shapes is limited. Therefore, the possibility of incorporating natural rubber (NR) as a binder for extending the applications of cement-based composites has been considered. In the present work, NR composites with fly ash (FA) and cement (CM) are prepared through an internal mixer and a two-roll mill with a total filler concentration of 1000 phr. It can be found that, FA/CM hybrid filler is successfully adhered together through the NR matrix, and it promotes the flexible canvas composites with controlled thickness and provides complex shapes. The existing calcium oxide (CaO) present in the filler reacts with water molecules, and the NR composites become hardened and restrict the deformation and decomposition. The optimum ratio of FA/CM hybrid filler has been fixed at 300/700 phr, which has recognized as the product-like concrete canvas. Tensile properties, dynamic properties and thermal stability are improved upon the incorporation of hybrid fillers and its flexibility is found to be sustained on soaking with water. The structural changes are confirmed from the infrared spectrum which clearly explains the transformation of CaO to the CSH network structure in the NR composites. Un-crosslinked composites exhibited similar mechanical properties compared to the chemically crosslinked NR with sulfur curing system. Thus the composites can be used as the flexible canvas, although it has not been vulcanized. To clarify this statement, tensile properties, abrasion resistance and bending propagation of NR composites, NR vulcanizates and commercial concrete canvas are compared. The composites exhibited comparable properties with superior flexibility performance. Along with the waste utilization, the uses of FA, provides an opportunity of using FA/CM as the flexible canvas.