Experimental study on electro-thermal and compaction properties of electrically conductive roller-compacted concrete overwintering layer in high RCC dams

Abstract

To solve the thermal crack problem of overwintering layer of roller-compacted concrete (RCC) dams. A new type of intelligent hydraulic concrete, namely electrically conductive roller-compacted concrete (ERCC), was designed. ERCC layer could provide a new way to control the temperature distribution and reduce the cracking likelihood of RCC dams by its electro-thermal properties, closely related to the variation of resistivity of ERCC. Thus, the relationships between design factors and the resistivity were investigated to obtain the real resistivity of ERCC layer of RCC dams. Then the temperature increase of ERCC layer with the size of 3000 × 700 × 200 mm was measured under 30 V direct current voltage. The temperature rises 14 ~ 16 ℃ within 235 min. It means that the electro-thermal properties of ERCC are enough to resist cold waves in winter. On the other hand, the mechanical and compaction properties of ERCC were investigated through experiments to evaluate whether the roller compaction method can overcome the poor fluidity and improve the construction quality of ERCC. So the density and strength of roller compacted device formed ERCC were compared with those of vibration formed ERCC, which shows the superiority of rolling construction method. According to unit compaction energy and parameters of the roller machines, the onsite compaction passes NS are calculated, which provides guidance for the construction of overwintering layer. In summary, selecting ERCC as the overwintering material instead of traditional thermal insulation materials could provide a more flexible and intelligent temperature control way for RCC dams in the severe cold areas, signifying ERCC is a promising material in hydraulic engineering.