Blasting excavation close to fresh Roller Compacted Concrete, in RCC Dam construction sites

RCC dam construction is a long process which takes years to be completed, and requires precise planning and a tight sequence of activities. Due to planning constraints, RCC placement is to start before the completion of the dam foundation blasting excavation. The purpose of this paper is to demonstrate the possibility to perform blast excavation while in the same foundation area RCC is under placing at a distance in the order of 50m or less to the blasting, and compacted by vibrating rollers. The vibrations generated by rollers at different levels into the RCC were measured and compared with vibrations generated by the nearby excavations executed with explosive. It is assumed that controlled blasting excavation is safe in the vicinity of fresh RCC, if the induced vibrations are in the same order as those generated by rollers during the compaction operations. Laboratory tests on fresh RCC that sensed the reduced vibrations compared to those on RCC that did not, confirm that its material properties are not affected by the controlled blasting. The outcome of this work and added value on an RCC dam construction lies in allowing the excavation of a part of the dam foundations to be completed while RCC concrete placement is already in progress in the other part of the foundation.