Laboratory investigation on the use of recycled fillers in improving the performance of Stone Mastic Asphalt (SMA)

The present research was conducted with the aim of investigating the effect of the type of filler on the mechanical properties of the stone mastic asphalt (SMA). For this purpose, five types of fillers, including silica filler (SF) as the base filler in the control sample, Portland cement (OPC) and limestone powder (LSP) as common fillers, and recycled glass powder (RGP) and calcium carbide waste (CCR) as recycled fillers, were used in their pure form or combined with each other. In order to investigate the resistance of the samples against rutting, the Marshall test was used to obtain the Marshall strength (MS) and especially the Marshall coefficient (MQ). Also, resistance to cracking and moisture sensitivity were also evaluated by performing the Indirect Tensile Strength (ITS) test in dry and saturated conditions and obtaining the Tensile Strength Ratio (TSR). The results have shown that the samples containing recycled fillers had the best performance in improving the properties of SMA asphalt. such that the use of the combination of recycled fillers, in addition to improving the properties of SMA compared to samples containing silica fillers, The values of MS, MQ, ITS, and TSR have increased by 36, 19, 24, and 31%, respectively, compared to the best results obtained using common fillers. Therefore, the use of RGP and CCR compounds as fillers in SMA asphalt, in addition to helping to protect the environment, natural resources and economic savings, can also be technically very effective in improving the service life of asphalt mixtures.