Improvement in compressive strength of Styrene-Butadiene-Rubber (SBR) modified mortars by using powder form and nanoparticles

Styrene-butadiene-rubber (SBR) latex modified mortars and concretes are used because of their excellent flexural and durability properties. However, their usage is limited due to lower compressive strength, expensiveness, and aqueous state. The study aims to find the solution to these demerits of liquid SBR polymer. Purposefully, the effect of solid SBR-powder and aqueous SBR-latex, with and without admixtures, on the workability, water absorption, and compressive strength (at 28 and 56 days) of mortar is studied. The SBR-latex and SBR-powder are used at 1 to 10% of cement replacement. The nano-Silica (2%), nano-Titania (2%), and Zinc-Stearate (0.5%) are used as admixtures. Mortar samples are analyzed by SEM and FTIR studies. SBR-latex (5 to 10%) decreases the compressive strength of mortar, while SBR-powder (1 to 20%) increases it. Formulae are developed to estimate the 28days compressive strength, flowability, and water absorption of mortars at different SBR-powder percentages. SBR-powder modified mortar shows low water absorption but comparable flowability to that of SBR-latex. The nano-Silica, nano-Titania, and Zinc-Stearate further enhance the flowability and compressive strength of modified mortar. The increase in compressive strength is associated with the increase in the mortar's hydration when SBR powder is used along with the nanoparticles.