For the improvement of toughness and volume stability of alkali-activated slag with styrene-acrylic emulsion

Alkali-activated slag (AAS) is a green and environmentally friendly cementitious material, but its poor toughness and volume stability limit the practical application. Due to the flexibility and weathering resistance, SAE is widely used to promote the toughness of cementitious materials. Thus, SAE could be a potential additive in AAS system to improve the toughness and volume stability. In this work, different dosages of SAE were used to improve toughness and volume stability of AAS system. The toughness of AAS was evaluated by mechanical F/C ratio and fracture energy. The volume stability was characterized by one-dimensional drying shrinkage test and two-dimensional plate cracking test. The results indicated that the addition of 10 wt% SAE could enhance the F/C ratio (by 120.0%) and the fracture energy (by 242.3%) of AAS at 28 days, and this promotion of toughness could be attributed to physical adhesion and chemical bonding between SAE and hydration products. 5 wt% SAE could also reduce the drying shrinkage rate (by 10.3%) and crack area (by 99.4%) at 28 days, and the improvement of volume stability was due to the refinement effect of SAE on pore structure of AAS. This study provides a reference for the systematic evaluation method for the toughness and volume stability of AAS, and offers guidance for the application of SAE in AAS. •SAE improves toughness and volume stability of AAS.•The toughness of AAS is evaluated by mechanics and fracture energy.•The volume stability is evaluated in one and two dimensions.•Crack area is quantitively evaluated by image processing software.•Connection between SAE and AAS includes physical adhesion and chemical bond.