Characterization of geopolymer with 100 % thermoactivated construction spoil powder: Effects of alkali dosage, silicate modulus and curing temperature

The traditional landfilling and stockpiling methods for disposing of construction spoil have caused a series of environmental issues, and thus, recycling construction spoil in a sustainable approach is a challenging issue within the resource utilization of construction waste. Utilizing thermoactivated construction spoil powder (TCSP) as a precursor for sustainable geopolymer production provides a novel approach to reusing construction spoil and reduces the need for traditional mineral precursors. This study is developed to quantify the effects of alkali dosage, silicate modulus and curing temperature on the properties of TCSP-based geopolymer which is made with 100 % TCSP as precursor. The TCSP, after 800 °C thermal activation, contains active metakaolin, CaO and C2S, showing good alkali-activated activity. Substituting an appropriate dosage of TCSP for metakaolin can enhance the micro-structure and macro-properties of metakaolin-based geopolymer, and replacing metakaolin with 100 % TCSP causes a degeneration in the performance of TCSP-based geopolymer. However, the 100 % TCSP-based geopolymer still shows a dense micro-structure and good compressive strength (55.97 MPa). A moderate rise in alkali dosage and silicate modulus causes an improvement of the micro-structure of TCSP-based geopolymer. When the alkali dosage-silicate modulus is 1.2M–8%, 1.4M-8%, 1.4M-4%, the MIP-measured porosity of TCSP-based geopolymer paste is 16.06 %, 13.91 % and 26.37 %, respectively. An appropriate rise in alkali dosage and silicate modulus can enhance the strength and permeability resistance of TCSP-based geopolymer mortar, but the further rise in alkali dosage and silicate modulus does not cause an obvious performance improvement. Elevating curing temperature from 20 °C to 95 °C, as well as reducing the water to binder ratio, are two effective methods for improving the micro-structure, strength and permeability resistance of TCSP-based geopolymer. •Development of sustainable geopolymer made with 100 % thermoactivated construction spoil powder (TCSP).•Effects of alkali dosage, silicate modulus and curing temperature on performance of TCSP-based geopolymer.•Achieving sustainable TCSP-based geopolymer with good micro-structure and macro-properties.