Replacement of plastic fillers (PS, PP, PE and PV) resulted in decrease of density (1.288–1.576 g/cm 3) as shown in Table 5. The values of compressive strengths of for alkali-activated kaolin (KS) and alkali-activated metakaolin (MKS) containing silica sand at ageing times of 7, 28, 63, 91, 154, 217, 273 and 364 days are given in Table 4 .Web