Low compaction energy concrete for improved slipform casting of concrete pavements

The current practice in concrete pavement construction is to use low-slump concrete, which is processed by a slipform paving machine. Extensive vibration, introduced by equally spaced internal vibrators, is required for the concrete to reach proper consolidation. It has frequently been reported that malfunctioning internal vibrators cause over-consolidation of the concrete pavement and lead to premature cracking and durability problems. The research presented in this paper is focused on optimizing the consolidation properties and shape stability of fresh concrete mixtures so that the internal vibration may he eliminated during the slipform paving process. The experimental results have shown that it is possible to design a concrete mixture that can be consolidated without internal or external vibration and at the same time can maintain its slab shape at the end of a slipform paving process. This was achieved by selectively manipulating flowability, consolidation properties, and green strength of fresh concrete through the use of chemical admixtures or the addition of small amounts of fine materials.