Paper by SUN ZOLLINGER from ISCR 12th 2014 Prague Czech Republic
Excessive early early-age concrete surface moisture evaporation can be a source of key issues in the paving of concrete pavemen t, such as plastic shrinkage cracking and spalling related delamination; the use of liquid membrane membrane-forming curing compounds is one of the most prevalent methods to protect hydrating concrete surfaces . However, the present standard test, ASTM C 156 156-98, Standard Test Method of Water Retention by Concrete Curing Materials has some inherent limitations in assessing curing effectiveness of concrete particularly under field conditions . To better employ curing practices and qualify the use of different curi ng compound compounds, a framework for new evaluation protoc ol is proposedproposed. The new protocol co nsiders of using a calculated effectiveness index (EI) and measured dielectric constant (DC) curves with the associated ? valuevalues to represent the effectiveness of a curi ng compoundcompound. As a means of validation, m oisture loss and surface abrasion resistance measurements made on prepared concrete specimen specimens were found to have significant correlation correlations with EI, where greater values of EI were associated with less amount of moisture and abrasion weight loss loss. DC measurements were made and fitted to a modified Weibull distribution function to obtain a regression parameter, ?. Lower values of ?, which represent a lower rate of reduction in DC measurements were found to be relat related to less amount of moisture loss of the specimens. A coupled EI - ? relationship was also proposed to determine the adequacy of the rate of application of a curing compound used in field conditions.