Use of reservoir sludge as a partial replacement of metakaolin in the production of geopolymers

Reservoir sludge was first calcined at 850 °C for 6 h and then employed as 50%, 70% and 100% replacement of metakaolin in the production of geopolymers. Various proportions of slag, metakaolin and calcined reservoir sludge (CRS) particles were mixed with different alkaline activating solutions to produce reservoir sludge-based geopolymers (RSBG). Furthermore, the compressive strengths of RSBG geopolymers were measured and compared. Based on the experimental results, proper alkaline activating solutions that produce higher compressive strengths of RSBG geopolymers with various replacement percentages of metakaolin by CRS particles and different water/binder ratios were determined. At the same time, the effects of water/binder ratio, stirring time and curing temperature on the compressive strengths of RSBG geopolymers were investigated. In addition, the flow values and compressive strengths of RSBG mortars were measured and then compared to those of Portland cement mortars to evaluate the efficiency of using RSBG geopolymers as binders in mortars.