Abstract
The reduction in relative humidity within drying concrete depends mainly on the depth from the exposed surface, exposure duration, temperature and environmental humidity; this limits hydration and coarsens pore structure, thus impairing durability. OPC paste, of 0.59 water/cement ratio, was cured for 2 days and then exposed to controlled relative humidity environments. After 14 and 90 days exposure, hydration of the individual compounds was measured using quantitative X-ray diffraction and thermogravimetry. Methanol adsorption was used to monitor porosity and gel formation. Even a small drop in relative humidity below 95% r.h. significantly limited cement hydration. Gel porosity increased with amount of hydration and, for a given level of hydration, decreased with drying. Curing below 80% r.h. produced a coarsened pore structure with a large-diameter porosity three times greater than that obtained with saturated curing.
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Patel, R.G., Killoh, D.C., Parrott, L.J. et al. Influence of curing at different relative humidities upon compound reactions and porosity in Portland cement paste. Materials and Structures 21, 192–197 (1988). https://doi.org/10.1007/BF02473055
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DOI: https://doi.org/10.1007/BF02473055