Comparative Analysis of the Use of Expansion Agents in Repair Solutions of Dry Building Mixtures for Improving Hardening Conditions

Abstract

The article examines the possibility of increasing the compatibility of repair solutions based on dry mixes with damaged concrete and reinforced concrete structures by improving the curing conditions of such materials through comparative analysis of adhesive strength and linear shrinkage of cement samples using different types of superabsorbents, namely SAP Newsorb based on sodium polyacrylates from the Japanese manufacturer Newstone, Chinese MNC-SAP based on potassium polyacrylates from MUHU Construction Materials and AquaGel based on cross-linked copolymer of acrylamide and potassium acrylate from the Australian Baroid. The data obtained during experimental studies show that the use of investigated SAP superabsorbents additives due to the improvement of hydration conditions in the cement matrix of the repair material can partially compensate the growth of shrinkage deformations, which, in turn, slightly improves the indicators of the adhesive strength of the bond with the surface of the damaged structure. A positive effect of the use of the specified polymer admixtures on the investigated cement solutions was established. Compared to the base sample, on average, for each of the studied days of hardening, the shrinkage rate of all samples containing SAP was reduced by 35%, which justifies their use in order to facilitate the creation and further high-quality functioning of the repair system. The addition of the studied SAPs allows to improve the adhesion index by 1.5-2.3 times compared to the basic one, which should ensure the maximum ability of the repaired system to perceive the workload. The optimal contents of SAP additives in the composition of the studied cement mortars to reduce shrinkage and increase the adhesive strength were determined. The compositions of non-structural repair cement mortars of class RM3 and R1-R2 in terms of adhesive strength and classes RM1-RM2 in terms of shrinkage deformation in accordance with Ukrainian and European standards were obtained.

Comparative Analysis of Methods of Measuring Adhesion of Repair Solutions From Dry Building Mixtures to Concrete Surfaces

“…Слід також відмітити, що з початкових 200 зразків досліджуваних ремонтних композитів втрату адгезійного зчеплення з еталонними плитами за типом AF-S та CF-S показав 181 зразок, що складає 90,5%. Спираючись на деякі попередні дослідження адгезійної міцності [21,22], можна сказати, що цей показник є порівняно високим.…”