Reference: Cement and Concrete Research, Vol. 29 (11), 1863-1867, 1999.

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PROTECTED PASTE VOLUME IN CONCRETE: EXTENSION TO INTERNAL CURING USING SATURATED LIGHTWEIGHT FINE AGGREGATE


D.P. Bentz ¹ and K.A. Snyder
Building and Fire Research Laboratory
100 Bureau Drive Stop 8621
National Institute of Standards and Technology
Gaithersburg, MD 20899-8621 USA

ABSTRACT

One difficulty in the field use of high-performance concrete is the extensive self-desiccation and autogenous shrinkage that may occur due to its low w/c ratio and the addition of silica fume to the mixture proportions. Several researchers have proposed the use of saturated lightweight aggregates to provide "internal" curing for the concrete. In this communication, simple equations are developed to estimate the replacement level needed to ensure adequate water for complete curing of the concrete. Additionally, a 3-D concrete microstructural model is applied to determining the fraction of the cement paste within a given distance from the lightweight aggregate surfaces. The simulation results are compared with analytical approximations developed previously. This new concept for curing is similar to the protected paste volume concept conventionally applied to characterizing air void systems in air-entrained concrete.

Keywords: Aggregate (D); Concrete (E); Curing (A); Mixture Proportioning (A)

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