Abrasion resistance and compressive strength of unprocessed rice husk ash concrete

This paper investigates the effects of adding natural rice husk ash collected from uncontrolled burning and without previous grinding (NRHA) as cement replacement in concrete. To obtain an adequate particle size, NRHA was mixed with coarse aggregate for a convenient period of time before adding the other components. Compressive strength, water absorption, porosity, and abrasion resistance expressed as weight loss were examined. Test results show that decreasing the particle size through mixing with coarse aggregate improved the compressive strength, reduced the permeability, and increased the abrasion resistance of concrete. By mixing NRHA with aggregate for 8 min, abrasion resistance improved by 10.35 and 23.62% over the control concrete at 28 and 91 days, respectively. Incorporating NRHA in concrete by grinding with coarse aggregate during the mixing process could be suitable for making normal-strength concrete and for applications where abrasion resistance is an important parameter. In addition, using NRHA as a partial replacement cement contributes to the reduction of CO2 emissions due to the production of cement

Evaluation of Sulfate Resistance of Mortar Containing Palm Oil Fuel Ash from Different Sources

In this study, laboratory tests were conducted to evaluate the sulfate resistance of three types of mortar containing palm oil fuel ash (POFA) collected from different palm oil mills. The compressive strength of three different concretes containing different types of POFA was also investigated. For comparison purpose plain Portland cement mortar and concrete were used as a reference. Ground POFA was used to partially replace Portland cement type I, 20 % by weight of binder. For testing the durability of mortar exposed to sulfate attack, the expansion of standard mortar bars immersed in 5 % sodium sulfate Na 2 SO 4 and magnesium sulfate MgSO 4 solutions for up to 15 weeks was determined. Moreover, FESEM micrograph and EDS analysis were carried out. The results of 28 days compressive strength of two concretes containing POFA showed higher compressive strength than that of plain Portland cement concrete. The expansion levels of blended mortars were in general lower than plain Portland cement mortar. The FESEM and EDS analysis showed good correlation to the results of expansion tests. © 2012 King Fahd University of Petroleum and Minerals