Pumpability of non-sand concrete with anti-segregative additives

Non-sand concrete contains only normal portland cement, water and course ag gregate. The use of non-sand concrete has expanded into many ureas such as drainage pipes, wells, small retaining walls, and pavement (for local roads and parking lots). One of the disadvantages of non-sand concrete is the di fficulty of mixing and placing due to the stiff consistency of the mix caus ed by the low water-cement ratio required to prevent segregation. This prob lem could be reduced or eliminated if methods of placing could be developed using conventional concrete placement methods. The investigation reported in this paper explored one such method in which the concrete was made pumpable by adding several admixtures. Pumping charac teristics are based on the mix's ability to provide good slump and excellen t cohesiveness. The rest results include compressive and flexural strengths , permeability, unit weight, and the potential for the mix to be pumped suc cessfully. The purpose of this research was to obtain a pumpable non-sand c oncrete mix within the specified design parameters that exhibits excellent pumping characteristics and yields equal or higher strength values than mix es made without admixtures. The results indicated good performance of mires containing silica fume concurrently with the hydroxyethyl cellulose admixt ure. This holds true for non-sand concrete mixes containing 12.7 mm and 6.3 5 mm maximum size aggregates.