Strength of latex-modified

Ohamal ll l studied the effect of monomer ratio in EVA, SBR, and poly (styrene-butyl acrylate, SAE) latexes on the strengths of latex-modified mortars (Fig. 4.10). The monomer ratio affects the strengths of the latex-modified mortars to the same extent as the polymer-cement ratio. The maximum strengths of EVA- and poly(styrene-butyl acrylate)-modified mortars are obtained at a bound ethylene content of 13% and a bound styrene content of 55% respectively. The strengths of SBR-modified mortar increase with a rise in the bound styrene content. These results are similar to those obtained by Cherkinskii, et al.f i The tensile strength of the dry films made from SBR latexes increases sharply when the bound styrene content is raised, and there is a positive correlation between the strength of the films and the flexural strength of SBR-modified mortars with polymer-cement ratios above 10% as shown in Fig. 4.11.li l... 

Figure 4.10 Effects of monomer ratio in EVA, SBR and poly(styrene-butyl acrylate, SAE) latexes on flexural and compressive strengths of latex-modified mortars.

Figure 4.14 Relation between surfactant content of latexes and flexural strength of latex-modified mortars.

It appears that the molecular weight of the latex polymers does not have an effect on the strength of latex-modified mortar and concrete. ... 

The strength of latex-modified systems is affected to a lesser extent by the type of cement, except when high-alumina cement is used as shown in Fig. 4.16.126]... 

Figure 4.181 1 indicates the effect of the fineness modulus of sand on the strength of latex-modified mortars. The flexural and compressive strengths tend to increase with rising fineness modulus, that is, with increasing particle size of the sand, like unmodified mortar. 

Table 4.4 Relationship Between Various Strengths of Latex-Modified Concretes. 

WagnerP" expanded Powers and Brownyard s theory for ordinary cement paste,and developed a general expression to predict the compressive strength of latex-modified mortars, using the water-cement ratio and the content of entrained air ... 

Effect of Sand-Cement Ratio. When the sand-cement ratio increases, the flexural and compressive strengths of latex-modified mortars are remarkably reduced, and the effect of the polymer-cement ratio on the strengths gradually becomes smaller. 

Figure 4.21 Relation between binder-void ratio and compressive strength of latex-modified concretes.

Figure 4.54 Polymer-cement ratio vs. bond strength of latex-modified mortars to reinforcing bars.

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