Construction and Demolition Wastes as Resources for the Development of Green Building Materials

This study deals with the alternative management of the construction and demolition wastes. In particular, it suggests the reuse of waste bricks and tiles as raw materials for the production of geopolymers which constitute a class of building materials with low environmental footprint. In order to evaluate the geopolymerization potential of the raw materials, alkali dissolution tests which determine the Si and Al leachability were conducted. The brick waste presented a slightly higher affection compared to the tile waste by the alkaline attack. In any case, the degree of dissolution is higher in NaOH than in KOH solutions. The geopolymer synthesis was optimized through the Taguchi multifactorial designing model of experiments based on the compressive strength of the final products. The results showed that the factors with the highest contribution on the mechanical behavior of the specimens are the alkalinity (R/Al) and the soluble silicon content ([Si]/R2O) of the activation solutions. The delivery of the products with enhanced compressive strength values (41 MPa) is achieved for the following synthetic factor combination: [Si]/R2O =1, R/Al=1.0, Na/Na+K=0.5, Τ=90oC and t =72h