Effect of calcium stearate on cellulose acetate-based mortars

The purpose of this study is to investigate the properties of cellulose acetate-based mortars with the addition of calcium stearate (CS), superplasticizer (SP) and metakaolin (MK). Previous research has shown that cellulose acetate (CA) fibers from industrial cigarette butts (CB) treatment can be incorporated into standard mortars at a rate of 1.3 wt%. CS was added in various proportions by weight (0.5, 1, 1.5 wt%), and their influence on cement hydration and microstructure was studied using various investigative techniques. The addition of CS was found to be beneficial in reducing the amount of water absorbed by CA, despite the significant absorption of these fibers. Furthermore, a CS rate of 1 wt% decreased CA-based mortar shrinkage. Additionally, 1 wt% CS improved by 18% the compressive strength of CA-based mortars manufactured with SP compared to the reference CA-mortar. CA fibers and CS seem to modify mortar microstructure by creating a plurimodal pore size distribution and reducing capillary pores. The CS addition, however, resulted in more cracks and reduced workability due to the weakening of the bond between the cement paste components. MK-mortars showed a slight 15% reduction in compressive strength and 13% reduction in bending strength; along with a 20% increase in shrinkage. By incorporating CA fibers as an additive along with CS or MK, CA-based mortars can improve some properties, including shrinkage and mechanical strength. Further, this approach offers a potential solution to CB pollution by reducing the environmental impact of this waste. •CA and CS addition increases the porosity and modifies the pore size distribution.•1 wt% CS by weight of cement leads to better hydration of the CA-based mortars.•CS addition reduces the amount of interconnected capillary pores.•1 wt% CS reduces the shrinkage of CA-based mortars.•10_MK_SP achieves optimal workability, shrinkage and mechanical performance.