Effect of Styrene–Butadiene Rubber Latex on Mechanical Properties of Cementitious Materials Highlighted by Means of Nanoindentation

ABSTRACT: In this paper, micro-mechanical properties of styrene–butadiene rubber (SBR) latex-modified cement pastes identified by means of the nanoindentation (NI) technique are related to macro-mechanical properties of SBR latex-modified mortars obtained from standard test methods, considering an SBR latex/cement ratio varying from 0 % to 20%. For this purpose, the average value of the hardness and the so-called indentation modulus of the different material phases of the cement paste, i.e. calcium–silicate–hydrate (CSH), portlandite, anhydrous cement, etc., obtained from NI are compared with the compressive and flexural strengths, on the one hand, and the dynamic elastic modulus of SBR latex-modified mortars, on the other hand. This comparison revealed a linear correlation between the dynamic elastic modulus and the indentation modulus and between the compressive strength, flexural strength and hardness. Thus, the obtained results clearly indicate the finer-scale origin of the macroscopic elastic and strength properties, linking the mechanical prop-erties at the so-called mortar scale to the cement-paste scale. KEY WORDS: macro-mechanical properties, micro-mechanical properties, nanoindentation, polymer-modified cementitious materials, styrene–butadiene rubber late