The effect of halloysite nano clay, nano-Sio2 and nano-Cao on cement-based mortars

Nanomaterials have various super structural, physical and microstructure properties according to their macro dimensions when used in cementitious material. Nanomaterials have been extensively researched since the last few decades. In this study, the properties of cementitious mortars produced by using halloysite nano-clay, nano-SiO2 and nano-CaO (single and binary) were investigated. For this purpose, by considering previous literatures studies and previously done experiments; the amount of nanomaterial was selected as 1%, 3%, and 5% of the binder weight. The water/binder ratio was 0.38. The compressive strength (7, 28 and 60 days), high temperature (250, 500 and 750°C) and freezing-thawing cycles effect, hydration heat and ultrasonic velocity values were investigated on the mortar samples. The results show that the compressive strength increases at all mixing ratios when using nanomaterials. The highest strength was detected in mixtures of 3% HNK and 5% NC. It was found that the increase in compressive strengths in binary mixtures is less than in single mixtures. Also, the ultrasonic velocity values are in accordance with the results of compressive strength and the use of nanomaterial does not cause a significant change in the hydration heat and it is increased only in samples containing CaO. The samples containing nanomaterials exposed to freeze-thaw cycles and high temperatures were found to show higher resistance than the control group. According to the test results of mortar samples exposed to high temperatures, it was observed that the samples are not affected much up to 250°C, the compressive strength and UPV values of the single and binary samples decrease from 500°C to 750°C and that the cracks and fractures formed and, the maximum strength reduction was detected in samples containing CaO exposed to 750°C.