Research Publications (Engineering and Built Environment)
Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/215
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Item Evaluating the performance of high-volume fly ash (HVFA) concrete, for South African fly ash(IJRTEM, 2016-07) Zulu, Sabelo; Allopi, DhirenDue to the benefits provided by the usage of FA in concrete, the usage of HVFA concrete is increasing within the concrete industry. This study looked at the effects of increasing the content of FA in concrete, beyond the conventional 30% amount, to find an optimum amount suitable for use in concrete structures, without compromising the quality of concrete. Concrete mixes of 25MPa, 35MPa and 50MPa with FA partially substituting the cement at 30%, 40%, 50% and 60%, were produced and numerous concrete properties were evaluated in a laboratory environment, to determine an optimum amount of HVFA that can be used and still obtain better or comparable concrete to ordinary concrete. Concrete testing for compressive strength, durability, slump, setting time and drying shrinkage was performed at laboratories over a period of one year. Also a cost comparison between the ordinary concrete and FA concrete was done. Test results showed that HVFA concrete can perform well in structures with good compressive strength and durability result even if the amount of cement is less than of fly ash. It can also be economical to utilize HVFA concrete, especially in larger project.Item Effects and benefits of using high content of fly ash in concrete(Thomson Reuters, 2016-01) Zulu, Sabelo; Allopi, DhirenThe usage of fly ash products by the South African cement and construction industries has saved the country over 6 million tons of harmful greenhouse gas emissions. The recycling of it as cement extenders provides an immediate benefit for the environment while still improving the quality of concrete, and increasing the amount used in concrete can promote sustainable development. This study evaluated properties of 35MPa/9,5mm concrete with fly ash substituted at 30%, 40%, 50% and 60%. Increasing the fly ash content can result in more workable and less permeable concrete. The compressive strength and durability index results showed that the fly ash content can be increased beyond 50% and still achieve the required strength and produce durable concrete. Substituting high volumes of cement with fly ash in concrete can provide good quality concrete and a relief to the environment without compromising the quality and cost of concrete.