High Slump Concrete

High-slump or “flowing” concrete mixes are economical ready mix products that allow maximum flowability without sacrificing strength by adding water at the job site. These high-slump, high-strength properties are attained through the use of high-range water-reducing admixtures.

The higher the slump of the concrete, the more workable it is. High-slump concrete is easy to place, mold, and smooth out. However, if the slump is too high, the gravel, sand, and cement may segregate. To avoid compromising concrete quality, admixtures should be used instead of water to achieve high slumps. The use of high-range water reducers allows practically to achieve high slump concrete with less water than traditional mixes with low-slump, reducing issues of shrinkage, difficulty finishing, and bleed water. Polycarboxylate- based polymers in conjunction with viscosity-modifying admixtures are generally used in the production of high-slump concrete without segregation. Concrete can be placed with minimal vibrations, even at low-water cement ratios. Benefits include a reduction in surface defects and improved aesthetic appearance.

To avoid cement lumps appearing in high slump concrete mixes, the batching protocol should include guidelines, which specify load size, discharge rates, number of mixing revolutions, and initial water content.