Lecturer, Sichuan Institute of Building Materials, Mianyang,
Professor, The Norwegian Institute of Technology, Division of Building Materials, Trondheim,
Associate professor, University of California, Berkeley, CA
Due to high cement contents and reduced heat capacity, high-strength lightweight concrete is often exposed to elevated curing temperatures. In the production of lightweight concrete the aggregate is often wetted before use, but sometimes dry aggregate is also applied. In order to find out whether elevated curing temperatures in combination with varying moisture conditions of the aggregate would affect the concrete permeability, an experimental investigation was carried out. The results showed that maximum curing temperatures of up to 80°C did not adversely affect the compressive strength when dry aggregate was used, while a temperature above 50°C reduced the compressive strength when wet aggregate was employed. Temperatures above 65°C increased the permeability in both cases of aggregate moisture condition. At 20°C the compressive strength was higher for the wet aggregate concrete (103.8 MPa) compared to that of the dry aggregate concrete (95.3 MPa), but the permeability was also higher for the wet aggregate concrete (150%). When all the moisture was removed at 105°C, the wet aggregate concrete absorbed approximately 15% more water by capillary absorption than the dry aggregate concrete. Backscattered electron images showed a very dense transition zone between cement paste and aggregate both for the dry and the wet aggregate concrete.
Paper ID: CCA10563J