Effect of different curing methods on the compressive strength development of pulverized copper slag concrete

The results of laboratory studies conducted to evaluate the effects of different curing conditions on the compressive strength development of concrete made with pulverized copper slag as partial replacement for ordinary Portland cement (OPC) is presented. Concrete cube specimens were made with copper slag replacing cement in the following proportions; 2.5, 5, 10 and 15% compared to the control (0%) specimen under normal laboratory conditions and cured in three different conditions, namely; water, solar chamber and ambient air up 90 days. Test performed included X-ray Fluorescence (XRF) and sieve analysis respectively for the chemical oxide composition and fineness for both the pulverized copper slag and ordinary Portland cement. Specimens were tested for compressive strength up to 90 days of curing, with the temperature and humidity of the surrounding curing environment recorded for each of the three curing method used. The experimental results indicate a significant drop in the compressive strength as the copper slag content increases for all curing methods. Moreover, for the control samples, the percentage decrease in the compressive strength for the 3-day curing for water cured sample, compared to the solar chamber and ambient air were respectively 31% and 28%. However, beyond 28 up to 90 days of curing, the water cured samples yielded a higher compressive strength, followed by the solar chamber and ambient air. The percentage increase in the compressive strength up to 90 days of curing for water cured specimen, compared to the solar chamber and ambient air were respectively 8.5% and 12%. This trend was similar for all percentage replacement of cement with the pulverized copper slag