Performance of impregnation of Concrete Structures - Results from a 5-year field study at Rv40, Borås

Abstract

BSTRACT Concrete is the most widely used construction material in the world. It is one of the most durable building materials and possesses properties such as high compressive strength and low permeability. Hydrophobic impregnations often referred to as water repellent agents, today mainly consisting of alkylalkoxysilanes, are often used on concrete to prolong the service life of the structure. This is accomplished by protecting the reinforcement bars from chlorides or by changing the moisture content inside. When the concrete is treated with a water repellent agent the properties of the surface layer becomes hydrophobic and thereby water droplets are stopped from entering, still allowing water vapour to pass through. On behalf of the Swedish Transport Administration (TRV), the Swedish Cement and Concrete Research Institute (CBI) was consulted to investigate the effects of two commercial impregnation agents, applied on four different types of concrete and exposed during 5 years in the vicinity of Swedish national road RV40 between Gothenburg and Borås. Results from the master thesis indicate reduced chloride content in concrete after hydrophobic surface treatment. No carbonation was detected on any sample. Moreover one of the two hydrophobic agents was consistently more efficient, most likely due to the gel based consistency.