4.7: Introduction to the Benefits of Modifying Cementitious Materials with Polymer Dispersions

4.7 Introduction to the Benefits of Modifying Cementitious Materials with Polymer Dispersions

Latexes are utilised in the formation of a multitude of cementitious materials [1, 4, 8-10, 20, 32, 45]. The advantages of incorporating polymers into the mix are a general improvement in the flexibility of the resultant cementitious material and a reduction in the modulus of elasticity. An improvement in the bond adhesion of the polymer modified cementitious material to the chosen substrate, (i.e., brick, concrete), along with an enhanced chemical/carbonation resistance is also observed.

Non-ionic polymer dispersions are generally used in combination with hydraulic cements as those possessing a charge do not have the desired chemical stability and can adversely react with the ionic species, (i.e., Ca ²⁺ Al ³⁺), which are involved in the formation of the C-S-H [8, 20]. Hence non-ionic surfactants are generally used in the manufacture of most polymer dispersions as the nature of the surfactant governs the resultant charge of the polymer formed during the emulsion polymerisation process.

The polymer (either in a liquid or powder form) utilised as a cement additive will also depend on the cost and the material in which it is likely to be incorporated into [9, 14]. Acrylics are the most expensive polymer dispersion due to their exceptional physical properties followed by SA and SBR, then VAE and subsequent copolymers of vinyl acetate. PVA homopolymers are generally the most economical as their performance tends to be limited in relation to the polymers mentioned previously. The following...