The absorption characteristics and sorptivity of cover concrete obtained by the Initial Surface Absorption Test (ISAT), the Covercrete Absorption Test (CAT) and the sorptivity test have been studied and compared. Two types of concrete, namely OPC control and Low Water Concrete (LWC) of grade 35 have been tested. The laboratory work has shown close agreement between the ISAT and sorption results but the CAT yields higher results. An analytical model has been developed based on the mechanisms of capillary suction and pressure driven flow. In this model water entering concrete during the tests is assumed to be concentrated in a well defined volume. This volume is fully saturated and is separated from the surrounding concrete by a wetting front at which capillary suction occurs. By applying the physical equations for capillary suction pressures and permeability the experimental results are explained in terms of the basic properties of the concrete. The model gives good agreement with the experimental results.
Highlights• PEG 400 admixture was used in concrete mixes produced for hot weather conditions • Dry materials, mixing water and curing temperatures simulated hot weather • Properties of PEG samples were found to be superior to the control concrete • Results cannot to attributed only to prevention of pore water escape by PEG 400 • A proposal was made to explain the results based on information from the literature ABSTRACT Hot climates prevail in many regions of the globe. The average summer temperature of hot arid areas is in the range of 40-50°C with temperatures exceeding these values under direct solar radiation. Curing concrete in these regions may be challenging due to limited availability of suitable water for curing and/or rapid loss of curing water by evaporation. For many years self-curing admixtures were recommended as an alternative to water curing, however, limited studies have been conducted on their performance in hot weather conditions. In this investigation, the effects of a hot climate on the fresh and hardened properties of self-curing (SC) concrete and normal conventional concrete (NC) in hot weather were studied. A watersoluble polymer self-curing agent, polyethylene glycol (PEG 400), was added to the SC mixes. The testing parameters were concrete dry materials (25 or 50 O C) and/or mix water temperatures (5, 20 or 35 O C) at the time of mixing. NC samples were continuously water cured at 25 or 50 O C, whereas the SC ones were air cured at the same temperatures. The tested properties were workability, compressive strength, splitting tensile strength, and flexural strength. It was found that SC outperformed NC under varying conditions. The results could not be simply attributed to the retention of mix water by the self-curing admixture. A more comprehensive explanation for the observations is proposed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.