A hydrophobic release agent containing SiO2-CH3 submicron-sized particles for waterproofing mortar structures

Abstract

Hydrophobic release agents were developed from SiO2-CH3 submicron-sized particles containing hydrophilic and hydrophobic functional groups dispersed into a vegetable oil as support. The SiO2-CH3 submicron-sized particles were synthesized by changing the molar ratio between the precursors Tetraethyl orthosilicate (TEOS) and Methyltriethoxysilane (MTES) from 0.66 to 5 (MTEOS-0.66 to MTEOS-5), being the relative amount of SiO2-CH3 quantified by FTIR technique. Mortar specimens having hydrophobic properties were manufactured using 3 wt.% of the above SiO2-CH3 submicron-sized particles. Additionally, the concentration effect was studied by using MTEOS-0.66 within 3-10wt.%. The hydrophobic properties of the mortar specimens were checked by measuring the contact angle within water droplets and surface. The particle size increased with the MTES/TEOS molar ratio and according to the hydrophobic properties, the proper release agent must be synthesized by using MTEOS-2.5 dispersed into the vegetable oil and having a concentration of 3wt.%. This hydrophobic release agent led mortar surfaces with contact angles higher than 145º. Waterproofing and mechanical studies on concrete specimens allowed to conclude that this demoulding agent do not have a high 2 penetration depth but improved the concrete waterproofing properties, without depletion in the compressive strength.

Surface Modification of Lightweight Mortars by Nanopolymers to Improve Their Water-Repellency and Durability

“…Therefore, in recent years the use of various hydrophobic agents, to minimize the decomposition rate of porous materials, has been widely discussed [36][37][38]. Furthermore, the concentration and type of the active substance in the agent constitute a very crucial factor.…”

“…Furthermore, the concentration and type of the active substance in the agent constitute a very crucial factor. In the literature, there can be noted examples of different additives and admixtures that can be used for hydrophobisation, such as superhydrophobic nano-silica [29], particle-siloxane [31], silica particles in rice husk ash modified using fluoroalkyl silane [30], methyl-silicon resin [36], alkyl-alkoxy-siloxane [36], SiO 2 -CH 3 submicron-sized [38], alkyl-alkoxy-siloxane oligomer and methyl silicone resin in an organic solvent [37], cyanoacrylates [39], polydimethylsiloxane [35], ammonium polyphosphate [40], SiO 2 / polymethyl-hydro siloxane synthesized by sol-gel [41], Nano-SiO 2 within organic films [42].…”

Hydrophobicity Improvement of Cement-Based Materials Incorporated with Ionic Paraffin Emulsions (IPEs)

“…The hydrophobicity of cement-based materials is predominantly improved by surface hydrophobic modification and internal hydrophobic modification [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Generally, surface hydrophobic modification involves the surface treatment of cement-based materials, such as coating, dipping and spraying.…”

The Synthesis of a Superhydrophobic and Thermal Stable Silica Coating via Sol-Gel Process

“…However, the hydrophobic behaviour can be improved by replacing the -OH group with the hydrophobic organic functional group, O-Si-(CH 3 ) 3 . For this purpose, the most employed precursors in the sol-gel synthetic route are methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES) and vinyltriethoxysilane (VTES) [8][9][10][11][12][13][14][15][16][17][18][19]. Guilong et al, fabricated a superhydrophobic SiO 2 film with TEOS and MTES as precursors by the sol-gel method, and then, the SiO 2 particles obtained were modified by dodecyltrimethoxysilane (DTMS) [20].…”