Sustainable Concrete Using High Volume Supplementary Cementitious Materials

摘要

The use of fly ash in concrete has received significant attention over recent years due to environmental concerns regarding its disposal, and on the other hand its potential use as a supplementary cementitious material due to its ability to provide significant benefits to concrete properties. While a fly ash content of less than 25% of the total cementitious content is routinely used in concrete, high volumes of fly ash (HVFA) are not commonly used due to perceived lower early-age strengths. The objective of this research was to demonstrate, using maturity based modeling, that the beneficial effects of high in-place hydration effects observed in structural elements may be able to compensate for the slower rate strength gain of class F fly ash concrete (which are typically observed on standard laboratory conditions). Match-cured cylinders were used in this process to estimate the early-age in-place strength of HVFA concrete and to confirm the maturity predicted strengths. The results have shown that the standard and field-cured cylinder strengths underestimate the in-place concrete strength. Higher in-place temperatures due to the mass characteristics of structural elements resulted in increased and satisfactory in-place early age strengths for construction, measured by match-cured cylinders and pull out testing, and predicted by maturity modeling.