Abstract
This article summarizes the results of an experimental program developed on latex-modified mortars. Fluidity tests, compressive strength tests, flexural strength tests, water absorption tests, adhesion tests on clay bricks and cementitious substrates were carried out. The test bodies were prepared by the pre-wetting method with different latex contents while partially substituting Portland cement by two types of latex: Styrene-Butadiene (SBR) and Styrene Acrylic (SA). In addition, samples of ordinary mortars are made in parallel as references.
 The experimental results showed that the substitution of cement in mortars produced a notable improvement on fluidity and adhesion. In the case of clay substrates, a cohesive failure in the support above 10% substitution has been reported, whereas the rupture is always at the interface for all the mixtures tested on cementitious substrates. An improvement was also noted on the flexural tensile strength beyond 60 days. On the other hand, the compressive strength of the polymer mortars decreased with the substitution rate of cement for all the maturities studied. As for the absorption of water, the results show a clear reduction in the percentage of water absorption by increasing the substitution rate
Highlights
Synthetic polymeric additives such as latexes, redispersible polymer powders, water-soluble polymers, and liquid resins have been introduced into cement mortar to obtain the polymermodified mortars
Mortars modified by styrene butadiene (SBR) and styrene acrylic (SA) showed an adhesion increase to bricks of 84% and 82%, respectively, for a 20% replacement rate for both latex compared to ordinary control mortars
For concrete substrates, the failure is reported at the interface, for all the mortars modified by the SA, which means that the failure is not cohesive, whereas the Styrenebutadiene rubber (SBR) develops a cohesive failure in the substrates of mortars modified with latex levels greater than 10%
Summary
Synthetic polymeric additives such as latexes, redispersible polymer powders, water-soluble polymers, and liquid resins have been introduced into cement mortar to obtain the polymermodified mortars. The evaporation of the mixing water from the cement paste-latex emulsion system along with the cement hydration leads to film and co-matrice formation (Benali and Ghomari, 2017; Eren, 2017) These two elements fill the open and capillary pores of the matrix, improving the cohesion between the aggregates and the cement paste at the interface, and increasing the compactness of the hardened material. Latex-modified cementitious materials have better water retention, sufficient entrainment of air, and a better fluidity (Benali and Ghomari, 2017; Parghi and Alam, 2016; Diab, 2013; Ramli and Tabassi, 2012b) This investigation aims to study the effect of using two types of synthetic latex: styrene butadiene (SBR) and styrene acrylic (SA), as materials replacing Portland cement at the proportions of 0, 2.5, 5, 10, 15 and 20 % (by weight). Our hope is to use them for repair works and to manufacture protective mortars and coatings as well
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