Protective coatings with hydrophobic agents as durability building material

• 作 者: Cao Weiqun Ba Guangzhong Zhao Tiejun
• 机 构: Qingdao Technological University,Qingdao,China;Xi'an University of Architecture and Technology,Xi'
• 出 处: 2010年建筑环境科学与技术国际学术会议
• 发表日期: 2010年7期
• 关键词: hydrophobic agents durability permeability concrete.

　　In many cases, service life of reinforced concrete structures is severely limited by chloride penetration until the steel reinforcement.Today, concrete with high resistance with respect to chloride penetration can be produced by internal hydrophobic treatment.Hydrophobic agents are surface protection materials capable of increasing the angle of contact between the water and the concrete surface.For this reason, hydrophobic agents reduce water(in liquid form) penetration in concrete.Therefore, many European construction regulating agencies recommend this treatment in their maintenance policy.Nonetheless, there continues to be a gap in the understanding about which transport mechanisms of the concrete are modified by the hydrophobic agents.The aim of this study was to fill this gap in regards to reinforced concrete structures inserted in a marine environment.To this end, certain tests were used: Two involving permeability mechanism, one determining capillary absorption, and the other, a migration test used to estimate the chloride diffusion coefficient in saturated condition.Results indicated the efficacy of the hydrophobic agents in cases where capillary suction is the mechanism of water penetration.However, when the transport mechanism is permeability this product is not advisable.Moreover, it was demonstrated that the chloride diffusion coefficient is reduced by the hydrophobic agents, and the steel bar could be well protected in the treated concrete with hydrophobic agents of silane.The durability of reinforced structures can be considerably increased and can be accurately designed by the application of an appropriate and optimized protective layer.