Investigation of ultrasonication energy effect on workability, mechanical properties and pore structure of halloysite nanotube reinforced cement mortars

The unique chemical and physical properties of halloysite nanotube (HNT) have aroused the interests of researchers in various fields to fabricate new high-performance composites. In this research project rheological, mechanical, and microstructural properties of HNT reinforced cementitious composites with varied ultrasonication energies were investigated. Based on the mini-slump and flow table tests, it was found that the workability of fresh HNT containing cement mortars reduced by increasing the ultrasonication energy owing to conversion of HNT agglomerations into smaller ones. Obtained results of mechanical tests revealed that HNT-reinforced samples have generally shown higher strength compared to the control sample. Moreover, the incorporation of 1, 2 and 3 wt% HNT in the samples at the level of ultrasonication energy equal to 0.8 Joule/mL per unit HNT percentage by weight of cement resulted in the maximum mechanical improvement by 25.83, 41.25 and 47.98% for compressive strength and 12.52, 20.71 and 22.47% for flexural strength, respectively. Helium porosity and mercury intrusion porosimetry tests showed that increasing the ultrasonication energy diminishes the porosity of the sample. Not only do the results of the current study show the effect of ultrasonication energy on the engineering properties of HNT cementitious composites, but it also helps researchers find the HNT concentration–independent optimum ultrasonication energy.