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No abstract

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.

No abstract

This paper presents an experimental study of the influence of Steel Basic Oxygen Slag (BOS) and Portland cement (OPC) on the compressive strength and the hydration mechanisms of blended Grounded Granulated Blast Furnace Slag (GGBS) pastes. The compressive strength, the mineralogical changes due to hydration, the setting times, the alkalinity of the raw materials and the pore solution, and the volume stability were measured on binary and ternary mixes. It is concluded that the steel slag can be used as an activator of GGBS and the optimum composition of those materials was determined with a proposed parameter called "slag index". The properties measured in blended OPC-GGBS-BOS mixes showed encouraging results to be used industrially. The mechanisms of hydration of the blended slag mixes are discussed and a hydration model of the blended system GGBS-BOS is proposed.