A New Laboratory Study on the Effect of Polyvinyl Alcohol and Cellulose Ether Dosages on the Fresh and Hardened State Properties of Sustainable Flyash Mortar

Abstract Sustainable Construction with cement-based composites implies the reduction of the negative impact of the whole construction process on the environment while achieving economic and social sustainability. Notably, multiple studies have been conducted on individual application of polyvinyl alcohol and cellulose ethers in mortars but none have considered their combined effect on flyash mortar. This study shows the effect of polyvinyl alcohol and cellulose ether on sustainable fly ash mortar's fresh and hardened state properties with defoamer and naphthalene-based water reducer. Utilizing natural river sand with particle sizes ranging from 0.08 to 5mm, cementitious mortar with up to 50% Ordinary Portland cement replacement using Class F fly ash was prepared. Characterisation of the sand reveals mud particle content (< 0.2%) for densification aid. Optimal dosages were determined: 0.6% Naphthalene-based water reducer and 0.62% defoamer of total binder weight. Excess defoamer adversely affected viscosity and bulk density, impacting fresh and hardened mortar properties. Combined polyvinyl alcohol and cellulose ether dosage not exceeding 0.37% of binder weight in the presence of water reducer and defoamer was found to avoid adverse effects. These findings offer insights for optimizing fly ash mortar formulations in sustainable engineering construction applications.