Title: Influence of Curing Methods on Moisture Loss and Drying Shrinkage of Shotcrete at Early Age

Author(s): Bruce Menu, Thomas Jacob-Vaillancourt, Marc Jolin, and Benoit Bissonnette

Publication: Materials Journal

Volume: 117

Issue: 4

Appears on pages(s): 95-103

Keywords: cracking; curing; drying; evaporation; moisture loss; shotcrete; shrinkage; surface protection

Date: 7/1/2020

Abstract:
The experimental program reported in this paper sought to evaluate the efficiency of a range of curing methods in view of minimizing the evaporation rate at the surface of freshly placed shotcrete and preventing the detrimental consequences of early-age shrinkage. CSA A23.1-14 states that severe drying conditions should be considered to exist when the surface moisture evaporation rate exceeds 0.50 kg/m2/h (0.1 lb/ft2/h). In fact, the environmental conditions that lead to such evaporation rates are regularly experienced on construction sites, requiring that adequate protection of the concrete surface be carried out in a timely manner after placement. This research effort is aimed at quantifying the influence of selected curing methods upon the early-age moisture loss and the resulting shrinkage. The results show that early-age volume change of freshly sprayed shotcrete can be significantly reduced by adequate surface protection. Among the investigated methods, moist curing is found to be the most effective.