Experimental analysis of latex-solid content effect on early-age and autogenous shrinkage of very-early strength latex-modified concrete

• The overall trends of hydration temperature were similar regardless of latex-solid contents.
• Total and autogenous shrinkage increased with the increase in latex-solid content.
• The minimum six hours of wet curing is needed to minimize early-age shrinkage cracking.

Very-early strength latex-modified concrete (VES-LMC) was developed for the purpose of creating a fast-track overlay of a concrete bridge deck, concentrating on the workability and strength gain so that the bridge can be opened to traffic within hours of placement. The mixture of VES-LMC might accompany very high heat of hydration at early-age because of its inherent rapid hardening property, and could be susceptible to autogenous shrinkage because of its relatively low water to cement ratio. From the field survey, some transverse and map cracking due to concrete material and construction issues were investigated in the bridge deck repaired with VES-LMC. This research focused on the effect due to material issue during early age.This study evaluated the effect of the latex-solid contents of both the constant and variable slumps on the hydration heat and early-age shrinkages of VES-LMC by carrying out a simple heat of hydration test and early-age shrinkage experiment. The results are as follows:The overall trends of hydration temperature were similar regardless of latex-solid contents within this study, although the initial setting by the latex-solid content varied a little. Total and autogenous shrinkage increased with the increase in latex-solid content. The total shrinkage occurs very quickly, with up to 80% of the maximum shrinkage during the first six hours after concrete placement, and the remaining 20% of shrinkage occurring during the next 18 h. It is, therefore, highly recommended to maintain the minimum six hours of wet curing of concrete in order to minimize early-age shrinkage and shrinkage cracking.