Effects of aluminum and barium stearates on hydrophobic material production

Abstract

Despite their porous and hydrophilic structures, cement-based mortar and concrete materials are highly susceptible to water and aggressive ions, significantly reducing their lifespan. Applying hydrophobic admixtures to cement-based products can substantially enhance their water-repellent performance. This study investigated the mechanical and microstructural properties of aluminum stearate (Al St) and barium stearate (Ba St) based on their water repellency. Powder solutions of Al St and Ba St were combined with water-repellent admixtures of ordinary Portland cement (OPC) paste and mortars at 0.5 %, 1 %, and 1.5 % dosages to create bulk water-repellent mortars suitable for building protection and appropriate for any construction work. The effects of the admixtures on the hydration and structure of the mortars were assessed through scanning electron microscopy (SEM), thermogravimetric analysis/differential thermal gravimetry (TG-DTG), X-ray diffraction (XRD) analysis, and Fourier transform infrared (FTIR) spectroscopy. The effectiveness of these compounds against the action of water was determined using various methods, such as mercury intrusion porosimetry, capillary water absorption tests, contact angle measurements, and water absorption tests. These admixtures form water-repellent layers within the capillary pores, which can reduce mortar permeability, particularly under nonhydrostatic conditions. Here, water capillary coefficient of Al St and Ba St 0.5 % are 0.0003 and 0.0003 respectively which is much higher that OPC. Furthermore, the resistance of the water-repellent mortars to salt crystallization was evaluated. All water-repellent admixtures provided adequate water-repellent protection, even though the water-repellent compounds and their dosages altered several physical characteristics and hydration kinetics. These materials had higher water-repellent properties but lower compressive strengths than OPC such as Al St 0.5 % result is 99.28%at 7days and on the other hand Ba St %0.5 at 3 and 56 days test results increase 109.89 % and 104.65 % respectively. Furthermore, their RCPT and contact angle were larger than those of OPC like RCPT value of Ba ST 0.5 % increased significantly 19.31 % and Al St 1 % contact angle is 108.41°. Moreover, by promoting cement hydration, Al St and Ba St may mitigate the loss of strength in concrete. Nevertheless, no research has been conducted on Al St and Ba St as hydrophobic admixtures for modifying cement mortar. This can offer insightful information about improving the mortars' natural water-repellent qualities and durability. The experiments revealed that Al St and Ba St materials are suitable for construction applications, considering their technology and characteristics.