Investigation of sulphate resistance of the nano reinforced blended concrete

Abstract

In the present study, the control mix (M 30 grade), optimum blended concrete mix containing cement, vetrified tiles powder, silica fume and fly ash and blended concrete mix reinforced with Multi Walled Carbon Nano Tubes were considered and investigated the resistance offered by them against the sulphate attack. The specimens of the respective mixes were immersed in 10% Na2SO4 for a period of 180 days. The optimum blended mix obtained from the previous study contains 60% cement, 7% silica fume, 25% vetrified tiles powder and 8% fly ash. The reinforced blended mixes were developed by incorporating well dispersed Multi Walled Carbon Nano Tubes in the dosage percentages of 0.01%, 0.02%, 0.03%, 0.05% and 0.1% by weight of binder content. The resistance offered by the mixes against the sulfate attack was evaluated in terms of visual investigation, loss in weight, compressive strength and ultrasonic pulse velocity test. Mass loss was observed to vary between 0.3% and 0.7% for the blended specimens and less than 0.2% for the nano engineered blended concrete specimens at 180 days of immersion period when compared to the control mix. The microstructural investigation was carried out using SEM-EDX and XRD to determine the morphology and the formation of the crystalline phases of the matrix after immersion in the solution. From the study carried out it was observed that the reinforced blended mix containing 0.05% of the carbon nano tubes have outperformed all other mixes by exhibiting the highest resistance to the sulfate attack in terms loss of mass, compressive strength and the quality of the concrete. The mix have shown the highest compressive strength value of about 54 MPa at the end of the immersion period which is about 23% higher than the control mix. It can be concluded that the concrete developed not only reduce the carbon foot print on the environment but also contribute towards the high resistance against the sulfate attack.