Rheological properties and shrinkage crack resistance of welan gum-modified cementitious materials

Abstract

Biological additives are considered environmentally sustainable and play a significant role in enhancing the performance of cementitious materials. This study focused on utilizing welan gum (WG) as a biological thickening agent to evaluate its impact on the rheological characteristics, resistance to shrinkage cracking, and mechanical properties of cementitious materials. The findings indicate that the incorporation of WG can improve the cohesion and stability of cementitious materials while reducing shear-thinning behavior. WG has less effect on cement hydration. However, WG may form agglomeration, leading to the increase in the water loss rate and dry shrinkage of cementitious materials. A high dosage of WG could decrease water loss rate due to film formation, but excessive WG might introduce pores and increase dry shrinkage. WG demonstrated the ability to delay cracking caused by dry shrinkage in cementitious materials. The crack resistance is enhanced by the elevation of the deformation capacity of cementitious materials. A comprehensive analysis revealed that a mass fraction of 0.10 % WG is the most effective in cement paste with a water-cement ratio of 0.4. The cohesion, water retention, and resistance to shrinkage cracking are improved, while mechanical properties are maintained in this situation.