Waterproof sprayed concrete with improved sustainability performance

Abstract

Sprayed concrete in combination with rock bolts has successfully been used for permanent rock support in tunnels for decades. The main shortcoming is that sprayed concrete alone is unable to function as permanent waterproofing in tunnels that requires a dry interior tunnel surface. Therefore, the trend is final inner linings of cast-in-place concrete or waterproof pre-cast segmental lining. In hard rock conditions such concrete linings often represent an excessive structural design, resulting in unnecessary costs, excavated volume, construction time and CO2 emissions. The research project SUPERCON, aims to develop a waterproof sprayed concrete, as an alternative to the currently used linings. The research results indicate the feasibility of a waterproof sprayed concrete. The concept is presented and discussed. To emphasize the effect of the concept, a comparison is made on CO2 emissions from cement and excavated volume of rock for four different lining types used in road and railroad tunnels.