Autoclaved aerated concrete waste (AACW): An alternative filler material for the natural rubber industry

Abstract

Material waste from the production of autoclaved aerated concrete, a porous material, should be considered as a valuable byproduct for use as a filler material for the rubber industry. Natural rubber (NR) composites filled with different loading (over the range of 0-60 phr) of autoclaved aerated concrete waste (AACW) as a new eco-friendly material were produced using two roll mills and then were studied for their cure characteristics, mechanical and aging properties, and morphology, and also compared with commercial fillers, calcium carbonate (CaCO 3 ), and silica (SiO 2 ). In most cases, the cure characteristics and mechanical and aging properties of the SiO 2 -filled NR composites were significantly better than those of the AACW-and CaCO 3 -filled NR composites. However, these properties for AACW-filled composites appeared to be higher than CaCO 3 -filled composites. The reason for this could be due to a larger surface area which is both porous and of an irregular shape of the AACW filler used. Scanning electron microscope images showed that the morphology of the rubber filled with SiO 2 was finer and more homogenous compared with the rubber filled with AACW or CaCO 3 . Overall results revealed that the reinforcement ability of AACW-filled NR composites was generally better when compared with CaCO 3 -filled NR composites; therefore, AACW can be used effectively as a cheaper filler for production of rubber products where end-use properties of a rubber product is specifically required. POLYM. COMPOS., 36:2030-2041, 2015. V C 2014 Society of Plastics Engineers INTRODUCTIONThailand is one of the largest natural rubber (NR) exporters in the world, and the price of NR has dropped dramatically during the past few years. NR can be stretched extensively without breaking and will return quickly to its original length on releasing the stretching force. It has been widely used to manufacture products, due to its versatility as a rubber material [1,2]. However, NR is mostly used for industrial materials and domestic products in which oxygen, ozone, heat, and UV light from the environment cannot be avoided. Rubber materials are rarely used in their pure form, however, it is often found with the addition of a filler, the processing ability and physical properties of the polymer materials are improved and their cost is reduced while maintaining a high level of product quality and performance [3][4][5][6][7][8][9][10]. All of the advantages offered by the use of fillers can be exploited only if the particles are distributed homogenously in the polymer matrix, which involves increasing the number of chains, to share the load of a broken polymer chain. Thus, the distribution of filler in the rubber matrix plays an important role in reinforcement. Generally, the main factors controlling the filler distribution, which affects the physical properties of the final rubber products, are found to be a function of the polymer properties, filler characteristics (particle size or specific surface area, structure, and surface activity), f...

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