Comparison of Strength–Maturity Models Accounting for Hydration Heat in Massive Walls

Abstract

The objective of this study was to evaluate the capability of different strength-maturity models to account for the effect of the hydration heat on the in-place strength development of high-strength concrete specifically developed for nuclear facility structures under various ambient curing temperatures. To simulate the primary containment-vessel of a nuclear reactor, three 1200-mm-thick wall specimens were prepared and stored under isothermal conditions of approximately 5°C (cold temperature), 20°C (reference temperature), and 35°C (hot temperature). The in situ compressive strengths of the mock-up walls were measured using cores drilled from the walls and compared with strengths estimated from various strength-maturity models considering the internal temperature rise owing to the hydration heat. The test results showed the initial apparent activation energies at the hardening phase were approximately 2 times higher than the apparent activation energies until the final setting. The differences between core strengths and field-cured cylinder strengths became more notable at early ages and with the decrease in the ambient curing temperature. The strength-maturity model proposed by Yang provides better reliability in estimating in situ strength of concrete than that of Kim et al. and Pinto and Schindler.Keywords: high-strength concrete, in situ strength, mock-up, hydration heat, maturity, curing temperature. List of Symbols

Optimization of Curing Regimes for Precast Prestressed Members with Early-Strength Concrete

“…This agrees with the observations made by other researchers (Tank and Carino 1991;Yi et al 2005;Liao et al 2008;Kwon et al 2014). Values of E tabulated in Case I in Table 3 show linearly decreasing tendency with increase in T max for all concrete strengths, which agrees with the experimental observations made by Jonasson et al (1995), Kim et al (2001) and Yang et al (2016). It can also be observed that E decreases with increase in f 0 cd (or with decrease in W/C) at a given T max , which was also in agreement with previous observations made by Kim et al (2001), Abdel-Jawad (2006) and Kwon et al (2014).…”

Modeling of Compressive Strength Development of High-Early-Strength-Concrete at Different Curing Temperatures

“…Whereas Yi et al (2005) observed that S u depends mainly on curing temperature, Kwon et al (2014) and Liao et al (2008) suggested S u as a function of temperature and humidity after their experimental observations. ''Activation energy has been proposed as a function of temperature T c by Freiesleben and Pedersen (1977) and Jonasson et al (1995), T c and t by Kim et al (2001), the chemical components of the cementitious materials and Blaine value by Schindler (2004) and Poole (2006), the water-cement ratio (W/C), T c , and degree of hydration by Abdel-Jawad (2006), and T c and concrete age by Yang et al (2016). Frequency factor was suggested as a function of both T c and humidity by Liao et al (2008) and a function of humidity only by Kwon et al (2014).…”

An Automated Wireless System for Monitoring Concrete Structures Based on Embedded Electrical Resistivity Sensors: Data Transmission and Effects on Concrete Properties

“…However, real-time monitoring of concrete strength using non-destructive methods is still a big challenge and a major source of uncertainty. In this context, maturity methods for in situ estimation of concrete strength, based solely on temperature, have been widely used [12][13][14][15] and many commercial solutions have been developed. But these might not always be the most accurate, as the maturity and related compressive strength are also influenced by concrete mixture and the weather (as reported by Yang et al [12], differences of up to 30% between estimated and real strength could be obtained when using maturity methods for certain types of cement and curing conditions).…”