Alternative cements based on alkali-activated red clay brick waste

The synthesis of alkali-activated and hybrid cements based on red clay brick waste was investigated using sodium hydroxide and sodium silicate solution as alkaline activators. The effect on the compressive strength of Na2O/SiO2 and SiO2/Al2O3 molar ratios and type of curing was evaluated. The combined presence of Portland cement (20%) and sodium silicate yielded a maximum compressive strength of 102.6 MPa at 28 days and 25 degrees C; this value is two times higher than the strength obtained in mixtures without Portland cement and 73 times higher than when sodium hydroxide is used. The results demonstrated the feasibility of using these materials to produce structural and non-structural construction elements. (C) 2016 Elsevier Ltd. All rights reserved.