The synergic influence of carbon nanotube and nanosilica on the compressive strength of lightweight concrete

Nanomaterials, owing to their extraordinary properties are known to improve the performance of concrete, are widely used in cementitious materials. Many studies have been conducted so far to understand the effects of inclusion of nanomaterials on the concrete while less studies have been conducted on Light Wight Concrete (LWC) especially on the synergic effect of nanomaterials. The influence of carbon nanotubes (CNT) and nanosilica (NS) as reinforcement fillers to increase the compressive strength of lightweight concrete using expanded clay were investigated in this study. Eight batches of samples were made by mixing CNT and NS using ultrasonication technique into the concrete mix, with one being a control system without nano reinforcement fillers to be used as a reference batch. The optimum substitution percentage of 3% for nano reinforcements was incorporated into the concrete by varying the ratio of CNT and NS. The compressive strength tests were conducted according to BS EN 12390: 2000 and BS EN 12350: 2009. From the results, it was found that incorporating 1% NS and 2% CNT, the highest compressive strength of 10.72 MPa can be achieved at 28 days, with percentage of 39% as compared to control sample. However, the incorporation of 3% CNT resulted in a negative effect on the compressive strength gain by a significant drop in compressive strength of -16% at 28 days. Field emission scanning electron microscope (FESEM) test was conducted to further observe the compressive strength behaviour for the obtained results.