Utilization of bagasse ash as a pozzolanic material in concrete

The physical properties of concrete containing ground bagasse ash (BA) including compressive strength, water permeability, and heat evolution, were investigated. Bagasse ash from a sugar factory was ground using a ball mill until the particles retained on a No. 325 sieve were less than 5wt%. They were then used as a replacement for Type I Portland cement at 10, 20, and 30wt% of binder. The water to binder (W/B) ratio and binder content of the concrete were held constant at 0.50 and 350 kg/m³, respectively.The results showed that, at the age of 28 days, the concrete samples containing 10–30% ground bagasse ash by weight of binder had greater compressive strengths than the control concrete (concrete without ground bagasse ash), while the water permeability was lower than the control concrete. Concrete containing 20% ground bagasse ash had the highest compressive strength at 113% of the control concrete. The water permeability of concrete decreased as the fractional replacement of ground bagasse ash was increased. For the heat evolution, the maximum temperature rise of concrete containing ground bagasse ash was lower than the control concrete. It was also found that the maximum temperature rise of the concrete was reduced 13, 23, and 33% as compared with the control concrete when the cement was replaced by ground bagasse ash at 10, 20, and 30wt% of binder, respectively. The results indicate that ground bagasse ash can be used as a pozzolanic material in concrete with an acceptable strength, lower heat evolution, and reduced water permeability with respect to the control concrete.     

Effects of LOI of ground bagasse ash on the compressive strength and sulfate resistance of mortars

Raw bagasse ash collected from the Thai sugar industry has a high loss on ignition (LOI) of ～20%. When ground and ignited at 550 °C for 45 min, the LOI was reduced to ～5%. These high and low LOI of ground bagasse ashes were blended in the ratios of 1:2 and 2:1 by weight to give ground bagasse ashes with LOIs of 10% and 15%, respectively. Each of these ground bagasse ashes was used to replace Portland cement type I at 10%, 20%, 30%, and 40% by weight of binder to cast mortar.The results showed that the development of compressive strengths of mortars containing ground bagasse ash with high LOI was slower than that of mortar containing ground bagasse ash with low LOI. However, at the later age, both types of ground ash mortars displayed similar compressive strengths. Mortars containing high LOI (～20%) of ground bagasse ash at 20% and 30% by weight of binder could produce higher compressive strengths than a control mortar after 28 and 90 days, respectively. Mortar bars containing ground bagasse ash at 10% showed a greater potential sulfate resistance and displayed a reduce expansion compared to a control mortar. However, mortar bars containing high LOI (larger than 10%) of ground bagasse ashes showed greater deterioration from sulfate attack than the mortar bars containing low LOI (less than 10%) of ground bagasse ashes, especially at high replacement levels (30–40%).