Chloride Diffusion in Concrete Modified with Polyacrylic Superabsorbent Polymer (SAP) Hydrogel—The Influence of the Water-to-Cement Ratio and SAP-Entrained Water

Abstract

This paper examines the influence of polyacrylic superabsorbent polymers (SAP) on the properties concerning chloride diffusion in cementitious materials. The conducted study investigated the influence of SAP on chloride diffusion in concretes of the initial w/c = 0.4 (for which the changes in compressive strength due to the SAP presence were negligible). The impact on the diffusivity of concrete of several variables was analyzed: the material characteristics of SAP, additional water added to the concrete to make up for the amount of water stored in the SAP structure, and the method of SAP dosing to the mix (either in a non-saturated form or in a hydrogel form). We found that, in the case of modifying concrete with polyacrylic SAP of a median particle size in dry conditions of 330 µm and without additional water, the coefficient of chloride ion diffusion was reduced to 65% of the reference value. The negative influence (increase) of increasing w/ctot by the amount of water initially entrained by SAP on the chloride diffusivity of concrete was identified. The conducted study indicates the premise of the mechanism of the water release from SAP in cementitious composites.

Durability of Concrete with Superabsorbent Polymer (SAP) Assessed Using Depth of Carbonation and NDT Ultrasonic Methods

“…Concrete resistance to carbonation was tested and assessed on the basis of the procedure in EN 13295:2004 standard [35]. This method is used to test the ordinary concretes, but lately, it has also been used to assess the concretes modified with SAP [36,37]. The carbonation test each time was carried out on three cuboidal concrete specimens with dimensions of 100 mm × 100 mm × 500 mm.…”