ABSTRACT
Abstract High strength and low strength hydrophilic polyurethane chemical grouting materials (HW & LW) can be easily dispersed, emulsified and gelated when meeting water. The solidified mass of HW & LW possess different strength and water-swell properties. They have been used on stop seepage, strengthening crack and consolidating foundation of concrete structures, particularly on the treatment of deformation crack, contraction joint etc. This paper presents the gel time, swell data and strength when mixing HW & LW in different proportion and the application on roller compacted concrete (RCC) dam. Keywords: anti-seepage, chemical grout, hydrophilic polyurethanes, RCC dam
1 Introduction
Roller compacted concrete technology is the significant innovation in hydraulic structures, with the advantage of quick construction, and lower costs, which develops very fast domestically and internationally. The seepage of RCC dam is the critical problem which will increase uplift, decrease safety, consume large amount of water and cause erosion to the internal concrete structure. Therefore, the design and construction organization always make great efforts to take suitable measures to reduce or avoid large seepage. Generally, the methods to solve the seepage problem are accepted by using “Internal method” and ccExtemal method”. “Internal method” indicates to take the measures to control the separation between placement layers, such as adopting high dosage of cementitious materials; adjust the exposed concrete time and place time; and control the temperature. “External method” implies depending on the upstream facilities to prevent seepage, such as adopting conventional concrete; set up the independent anti-seepage on upstream face, like asphalt mortar, precast concrete facing; and combine with the concrete facing and plastics. Although careful consideration is made for the seepage during the design and construction of RCC dam, seepage will occur with the large possibility due to the inferior combination around dam body and foundation, crack of anti-seepage facing itself, and the crack in dambody caused by the
rapid weather variation during construction or other structural problems when the dam is being built without longitudinal and transversal joints on the whole area, and the quality problems induced by the mechanical equipment, site condition, quality and responsibility of the construction operators. Therefore, a series of anti-seepage and reinforcement measures are needed to be taken for the RCC dam.
