Effect of Alum Sludge and Metakaolin as a Partial Replacement Cement Adding Superplastizer

The most important activities that improve the economy of Malaysia is the construction industry. Hence it will cause the usage of the concrete increase. When the concrete usage increase, it also increase the cement use because cement is the primary material that forms the concrete and during the production of the cement, it will cause the emission of carbon dioxide which will harm the environment as well as people in Malaysia. After that, alum sludge also caused a lot environment problem because it is lack of potential to be reused in other industry and it needs to be treated before it disposed of, which will cause the financial problem to the government. After the treatment, the economical ways to dispose of it is by using landfill method. But due to a limited landfill site in Malaysia and it is the temporary solution for the disposal of the waste, it becomes a problem to Malaysia and the number of the alum sludge keeping increase year by year because of the population increase year by year too. The purpose of the study is to find out the effectiveness of this combination. The research method that use in this study is by taking out some experiment such as slump test also known as workability test, compressive strength test, flexural strength test, ultrasonic pulse velocity (UPV) test (direct and semi-direct method) and scanning electron microscope (SEM) with the concrete day-age 7, 14 and 28 days. The result gets these test is the 10% alum sludge as a partial replacement for metakaolin in concrete adding superplasticizer (Sika Viscocrete 208) is the best replacement level in term of the workability compressive strength, Flexural strength, speed of the UPV and in scanning electron microscope. After 10% replacement level, the reading all suffer a downturn. Additionally, when the day-age of the concrete increase, the reading will be increase too. This happens to all the replacement level and the 10% replacement level with 28 day-age achieve the highest reading in this study. The contribution and implications of the findings are the using the 10% of the alum sludge as a partial replacement for metakaolin in concrete adding superplasticizer (Sika Viscocrete 208) is the best replacement level compare to others.