Effects of Noncrosslinked Polyvinyl Alcohol Fluid Loss Additive on the Compressive Strength and Viscosity of Class G Cement Slurries

Summary

Limiting the fluid loss from the cement slurry to the adjacent formation by using additives is essential for maintaining the slurry’s water/cement ratio. The present work focuses on the effect of noncrosslinked polyvinyl alcohol additive (PVOH), a widely used fluid loss additive (FLA), on the compression strength and rheological behavior of Class G cement pastes. Results of the current study show that the PVOH surfactant characteristic and its absorptive mechanism interfere not only with the hydration process but also with the physical properties and compressive strength of cement pastes, such as porosity, permeability, and early age strength, which revealed the importance of using a defoamer when PVOH is present in the mixture. In the absence of a defoamer, the PVOH additive generates foam in the mixed cement paste samples, which results in increased porosity and reduced compressive strength of the hardened cement paste. Moreover, regarding rheology, increasing the PVOH concentration increased the effective viscosity when evaluating flow curves. Therefore, this study demonstrates a systematic method for assessing the possible effects of cement paste additives, such as PVOH and defoamer, providing a physical and mechanical approach rather than just chemical to evaluate additives’ influence on the mixtures. This method should consider different additives in combination with PVOH to test cement paste stability and to obtain specific working recipes.