PVAC-modified strength

The effect of plasticizer (i.e., dibutyl phthalate) content in PVAC latexes on the strengths of PVAC-modified mortars is represented in Fig. 4.12.i i Like SBR-modified mortars, the strengths are governed by the nature of polyvinyl acetate (with variation of the plasticizer content), and is reduced with an increase in the plasticizer content. 

Figure 4,12 Effect of plasticizer content in PVAC latexes on flexural and compressive strengths of PVAC-modified mortars.

Figure 4.20 Relation between void-binder ratio and compressive strength of latex-modified mortars (expect PVAC-modified mortar) with sand-cement ratio of 3.

Under long-term outdoor exposure, involving frost action and car-bonation, latex-modified mortar shows increased resistance to weathering in comparison with conventional mortar and concrete. The weatherability of the latex-modified mortars is shown in Fig. 4.69The exposure test was done at the Building Research Institute Outdoor Exposure Site in Ibaraki Prefecture, Japan. Except for PVAC-modified mortars, the flexural and compressive strengths of most latex-modified mortars under outdoor exposure conditions tend to become nearly constant at one year or more, and a weatherability factor is greater or similar to that of unmodified mortar. 

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