Reuse of Powders and Recycled Aggregates from Mixed Construction and Demolition Waste in Alkali-Activated Materials and Precast Concrete Units

Rafael Robayo-Salazar, William Valencia-Saavedra and Ruby Mejía de Gutiérrez ()
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Rafael Robayo-Salazar: Composite Materials Group (GMC-CENM), Universidad del Valle, Cali 76001, Colombia
William Valencia-Saavedra: Composite Materials Group (GMC-CENM), Universidad del Valle, Cali 76001, Colombia
Ruby Mejía de Gutiérrez: Composite Materials Group (GMC-CENM), Universidad del Valle, Cali 76001, Colombia

Sustainability, 2022, vol. 14, issue 15, 1-24

Abstract: This article describes the recycling of coarse and fine fractions and powder from construction and demolition waste (CDW) using alkaline activation technology (geopolymerization). The CDW sample used corresponds to a mixture (mixed waste) of concrete (Co), ceramics (Ce) and masonry (M). Co, Ce and M (CDW-Mixed) powders were used as geopolymer precursors. As an alkaline activator, a mixture of sodium hydroxide (NaOH) and sodium silicate (Na 2 SiO 3 ) was used. From CDW-Mixed, a hybrid cement added with 10% ordinary Portland cement (OPC) was synthesized to promote curing at room temperature (25 °C). From the alkali-activated hybrid cement and the incorporation of mixed recycled aggregates (gravel and sand), applications of mortars, concretes, fiber-reinforced materials and prefabricated units, such as solid blocks, perforated (hollow) blocks and pavers, were produced. The results of the physical–mechanical characterization validate the application potential of these CDW-based materials in the construction sector. Compressive strengths of up to 40.5 MPa for mortar and 36.9 MPa for concrete were obtained after 90 days of curing at room temperature ≈ 25 °C. Similarly, a life cycle analysis (LCA) associated with raw materials demonstrated the environmental sustainability (44% lower carbon footprint) of mixed alkali-activated CDWs compared to conventional materials based on OPC.

Keywords: concrete waste; ceramic waste; masonry waste; geopolymers; hybrid cement; recycled aggregates; construction and demolition waste (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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