Materials Performance

APR 2017

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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39 NACE INTERNATIONAL: VOL. 56, NO. 4 MATERIALS PERFORMANCE APRIL 2017 T This article assesses the behavior of concrete coated with a silicone-based material. Studies were conducted to evaluate the rate of carbonation, resis- tance to chloride penetration, and wa- ter permeability of concrete when treated with silicone coatings. The re- sults indicate that the water absorp- tion, chloride ion, and carbonation resistance of concrete with a silane coating were greatly improved when compared to concrete coated with the acrylic coating used in this study and uncoated concrete. The results also show that the silane coating adheres well to the concrete surface. Scanning electron microscopy was employed to investigate the interface. Th e pro c e ss of c on cret e degradation draws considerable attention to the proper maintenance and preservation of concrete structures. The cost of repair may some- times be more than the original invest- ment. 1 Attempts have been made by several investigators 2-4 to improve concrete, and several materials have been tried in order to increase concrete durability. A promi- nent way to enhance the durability of con- crete is to apply a surface treatment, which is done to reduce water permeability and chloride penetration from both seawater and deicing salts. Surface treatments play an important role in protecting structures from the ingress of deleterious substances. To date, numerous surface coatings are used to help prevent the degradation of concrete structures. 5-7 Some of them are organic coatings with volatile organic sol- vents; however, such organic coatings can have the decisive shortcoming of generat- ing air pollutants during manufacturing and application . 8 In fact, th eir use i s restricted in some jurisdictions. Silane surface treatments include water emul sion c o atin gs that av oi d v o l ati l e organic solvents, but may produce volatile alcohols. This study presents behavior find- ings for both alkyl alkoxy silane (AAS) and acrylic concrete surface treatments. Con- crete specimens were used to assess the coatings' resistance to carbonation, chlo- ride dif fusion , and water permeability. Scanning electron microscopy (SEM) was employed to inve sti gat e th e int er fac e between the concrete and these coatings. Experimental Procedure Materials Surface Coating The main component of the silane coat- ing investigated is an AAS compound. It is a low viscosity, colorless, pH neutral water- based material, which is used for water- repellent impregnation of exterior cementi- tious bui l din g mat eri al s. Th e sp e cif ic gravity and solids content of the AAS solu- tion were 1.03 g/cm 3 and 10 wt%, respec- tively. A commercial acrylic coating was also used in the study. The specific gravity and solids content of the acrylic solution was 1.53 g/cm 3 and 10 wt%, respectively. Concrete Substrate The Portland cement used for sample specimens was produced by the Huaxin Cement Co., Ltd. The fine aggregate was a Silane Treatment Effective for Concrete Durability l iu j ies H eng, l i Faping, He Xiang, l iu Xiao F an, and z H ang Rongtang, School of Civil Engineering and Architecture, Wuhan Polytechnic University, Wuhan, China COATINGS & LININGS

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