Main Article Content
In this study, the effect of papermaking waste sludge (PWS), petrochemical ash, and metakaolin (MK) replacement with portland cement in the manufacturing of fiber-cement composite (FCC) was investigated. Moreover, the toxicity of materials and FCC was evaluated. Modulus of rupture (MOR), (MOE), fracture toughness (FT), internal bonding strength (IB), water absorption after 24h immersion in water (WA24), and density of FCCs were measured. X-ray diffraction patterns were also obtained. To study the potential toxicity of ash, TCLP was applied. According to the main results, Composites produced with 6% PWS content showed superior mechanical properties. Higher contents of PWS resulted in the reduction in fiber-matrix interfacial adhesion, increasing void contents, and hence lower strength properties. Replacing petrochemical ash and MK up to 10% provided optimum combinations and lightweight composites. In addition, X-ray diffraction patterns confirmed pozzolanic reactions of materials. Toxicity investigation showed that concentration of heavy metals in FCC leachate were reduced compared with ash. Pozzolanic reaction of materials had positive influence on solidification and stabilization of heavy metals. In conclusion, FCC containing 6% PWS, 10% ash, and 10% MK, with the highest pozzolanic activity, were considered as the optimum combination. Moreover, successful stabilization and solidification of heavy metals occurred. Therefore, it is possible to reuse PWS and petrochemical ash in FCC manufacturing which in turn reduce environmental pollution.