Durability of geopolymer cementitious materials synergistically stimulated by Ca2+ and Na+

Fewer studies related to the durability of multi-source solid waste geopolymer cementitious materials and the massive accumulation of industrial solid waste are urgent problems to be solved in practice in Inner Mongolia, China. In this paper, blast furnace slag (BFS), fly ash (FA), and calcium carbide slag (CCS) are used as the main raw materials to prepare geopolymer cementitious materials (BFCG) with Calcium Carbide Slag as the Ca-source alkali activator and NaOH as the Na-source alkali activator, considering their durability properties. By assessing the indicators of mechanical performance, engineering performance, and the synergistic mechanism of Ca2+ and Na+ in multi-source solid waste geopolymer, four sets of BFCG ratio optimization schemes are selected. XRD, FT-TR, SEM-EDS, and other testing methods are used to analyze its freeze–thaw resistance and acid–alkali-salt corrosion resistance. The following conclusions are drawn: the BFCG prepared under the synergistic excitation of Ca2+ and Na+ has better resistance to freezing and thawing, as well as acid-alkali-salt corrosion, both of which are in accordance with the standard specifications for road construction in China. After the freeze–thaw cycles, BFCG still has more three-dimensional network-like silica-aluminate structures, a compact micromorphology, and small pores. Its strength loss rate is 0.56 %–15.56 %, the mass loss rate is 0.19 %–1.26 %, and the relative dynamic modulus is 79.56 %–100.25 %. In a NaOH environment, the crystal type of BFCG did not change significantly, and the resistivity coefficients are 115.78 %–143.54 %. In a Na2SO4 environment, the decalcification or dealumination of C-A-S-H gel leads to the formation of a gel rich in silicon, magnesium, and aluminum phases, with a corrosion resistance coefficient of 101.8 %–119.96 %. In a HCl environment, HCl erosion inhibits the growth of hydration product crystals, with corrosion resistance coefficients ranging from 73.83 % to 97.24 %. BFCG-D has the best resistance to freezing and thawing as well as acid and alkali corrosion. BFCG-D has the best resistance to freezing and thawing as well as acid and alkali corrosion. These studies show that BFCG offers a promising solution for improving the durability of road base materials and reducing industrial solid waste.