Capillary Porosity Depercolation/Repercolation in Hydrating Cement Pastes via Low Temperature Calorimetry Measurements and CEMHYD3D Modeling

Published

August 9, 2006

Author(s)

Dale P. Bentz

Abstract

The percolation state of the capillary porosity in a hydrating cement paste has a large influence both on transport properties and on durability performance. Percolation can be examined both experimentally, using low temperature calorimetry (LTC) for example, and using microstructure models such as the NIST CEMHYD3D computer model for cement hydration and microstructure development. In this paper, the two approaches are compared for ordinary portland cement pastes with a variety of water-to-cement mass ratios (w/c), two different curing temperatures, and either saturated or sealed curing conditions. The influence of sealed curing is seen to be particularly important, as cement pastes that initially hydrate to depercolate the capillary pores may later undergo self-desiccation and aging that repercolates them. The model and experimental results compare favorably, both in terms of the individual predicted degrees of hydration as a function of curing time and the connected porosity volume fractions. Using a calibration factor obtained by correlating the LTC peak heights for saturated specimens to the CEMHYD3D predictions of percolated porosity volume fraction, the volume of damaged porosity in the specimens exposed to sealed curing is estimated.

Citation

Journal of the American Ceramic Society

Volume

89

Issue

No. 8

Pub Type

Journals

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Keywords

building technology, capillary porosity, cement hydration, curing, low temperature calorimetry, modeling, percolation

Citation

Bentz, D. (2006), Capillary Porosity Depercolation/Repercolation in Hydrating Cement Pastes via Low Temperature Calorimetry Measurements and CEMHYD3D Modeling, Journal of the American Ceramic Society, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=860634 (Accessed April 19, 2024)