Mechanical Properties and Durability Characteristics of High- Volume Fly Ash Concrete Made with Ordinary Portland Cement and Blended Portland Fly Ash Cement

摘要

The high-volume fly ash concrete (HVFAC) was developed by Malhotra and his associates in the mid 1980s. Typically, this concrete is made with low water-to-cementitious materials ratio, low cement content, and high fly ash content. This type of concrete has all the attributes of high-performance concrete, in addition to being environmentally friendly. In 2002, mainly because of its environmentally friendly aspects, CANMET was awarded a project by the Canadian International Development Agency (CIDA), to implement the HVFAC technology in India in order to reduce the CO2 emissions related to cement production in that country. This project was funded by the Canada Climate Change Development Fund, and was administrated by CIDA. In one of the project activities, undertaken to adapt the HVFAC to Indian materials and conditions, studies were carried out in a number of Indian laboratories. This paper presents the results of one such investigation performed at the Bengal Engineering and Science University, Shibpur, near Kolkata, India. Concrete of grades M20, M40 and M60 (nominally 20, 40 and 60MPa) using fly ash with ordinary portland cement (OPC) and a fly ash blended cement, called portland-pozzolana cement (PPC) in India, were investigated in this study. For each grade of concrete made with OPC, four concrete mixtures were made, namely a control concrete without fly ash, and concrete incorporating 30,40 and 50% fly ash. For each grade of concrete made with PPC, three concrete mixtures were made including one made with PPC only, one with cementitious materials incorporating 40% fly ash, and the third with cementitious materials incorporating 50% fly ash. For each concrete mixture, the compressive strength at several ages (up to 91 days), splitting-tensile strength, flexural strength and resistance to chloride-ion penetration at 28 and 91 days were determined. The results illustrate that forthe same grade of concrete, with the same total amount of cementitious materials, and the same proportion of fly ash, the use of PPC in combination with fly ash resulted in increased compressive strength at early ages and somewhat lower chloride-ion penetrability at 28 days.