Experimental Investigation on Mechanical Properties of SBR-Modified Mortar with Fly Ash for Patch Repair Material

Abstract

This work determines the replacement ratio of fly ash of 25% in SBR-modified cement mortars based on the past re-search, including SBR emulsion (SBR-E) and SBR powder (SBR-P). In addition to the Japanese guidelines for the repair material, the past researches related to polymer-modified cement mortars are also used to determine an appropriate mix proportion of the patch repair material for deteriorated RC building structures. According to the experimental re-sults in this work, it can be observed that increasing the S/W ratio of SBR is useful to improve the flexural bonding strength effectively; however, the compressive, flexural and tensile strength of cement mortars decreases. Besides of the mechanical strength, the workability and economy are considered to determine the S/W ratio of 10% of SBR-P for cement mortars with fly ash. Additionally, according to the regression results, its corresponding compressive, flexural, tensile and flexural bonding strengths are 36.5, 9.68, 3.35 and 2.8 MPa, respectively. For most of RC buildings with an age of over 30 years in Taiwan, since their average testing compressive strength is around 20 MPa, the suggested mix proportion of SBR-modified cement mortars with fly ash can provide enough performances for the patch repair.