Physical properties and some heavy metals in mortars incorporating cement from co-incineration process using industrial wastes as alternative fuels and raw materials
Abstract:
This research investigated selected heavy metals in cement paste and compressive strength in mortars incorporating cement from co-incineration process using industrial wastes as alternative fuels and raw materials. Additionally leachate study of heavy metals to environmental at the end of life of concrete was conducted. The heavy metals such as Barium, Cobalt, Chromium, Copper, Manganese, Nickel, Lead, Selenium, Strontium, Vanadium, and Zinc were found in cement with Manganese and Strontium having the highest concentrations. Amount of Manganese was found at 315 to 501 mg/kg and Strontium 148 to 303 mg/kg. It was also found that the amounts of heavy metals depended on primary raw materials and alternative raw materials used in the process. The results on fates of heavy metals showed that the heavy metals tended to incorporate with iron and manganese oxide. As curing progressed, the bond of the heavy metals became stronger. Most of the mortar specimens did not perform well on the compressive strength tests since their compressive strengths were lower than the 28-day standard of 285.51 kilograms per square centimeter (28 MPa). This may be due to the presence of high concentrations of Copper that retarded hydration, thus delaying setting time and decreasing early strength. In contrast, high concentrations of Barium and Vanadium were found to improve early strength, resulting in higher compressive strengths. The result of leaching test following the Notification No.6 of the Ministry of Industry (1997) showed that no heavy metal concentrations in the leachates exceeded the standards. However, selenium was found at 1.5 to 4.0 mg/L which exceeded the standard of 1 mg/L when TCLP was performed