Effect of steel slag on pores and strength of fly-ash-based adsorbent geopolymers

A study was undertaken into the preparation and properties of fly-ash-based geopolymers that can be used to make multistage-pore materials able to adsorb gases such as carbon dioxide. The influence of steel slag on the mechanical properties and microstructure of the final precursor products was investigated and characterised by mechanical strength tests, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry–differential thermal analysis, scanning electron microscopy–energy-dispersive X-ray spectroscopy and mercury intrusion porosimetry. The results showed that a low dose of steel slag significantly promoted the early compressive strength of a multistage-pore geopolymer. However, when the slag dose reached 30%, the strength decreased dramatically. The pore classification effect was more obvious when the capillary pores in the geopolymer disappeared and the pores mainly existed in the form of gel pores and voids.