We’ve talked extensively before about how much the characteristics of concrete are influenced by the ratio of water used in the mixture. Reducing the amount of water creates a higher density, and higher quality, cement paste. Water content can’t simply be reduced without taking any other measures. Higher water content is needed so that the concrete can remain workable. If you simply reduce the amount of water, without taking any additional measures, you might end up with a stiffer mixture that you can’t work with very well and that may result in placement problems. This is where water reducers come in.
Water reducers are admixtures for concrete. This means that they are actually added into the concrete mixture to reduce the water content. This allows the concrete to retain its flowing properties so that it’s easy to work with. The water reducer doesn’t evaporate; it helps increase the slump or flow without adding water. It also allows you to maintain the desired strength that you need in the concrete.
This admixture will reduce the amount of water used while increasing or maintaining the compressive strength of the concrete mix. This occurs because you are not adding water to increase slump and therefore your water cement ratio is kept at a lower level. For every inch of slump where you use water reducer admix versus actual water you can save around 200 to 300 psi. This can be critical with certain concrete structures. Other benefits of using water reducers include: improved workability, lower permeability, increased resistance to weathering, reduced shrinkage cracking and more.
The National Precast Concrete Association (NPCA) explains how water reducers work:
When cement comes in contact with water, dissimilar electrical charges at the surface of the cement particles attract one another, which results in flocculation or grouping of the particles. A good portion of the water is absorbed in this process, thereby leading to a cohesive mix and reduced slump.
Water-reducing admixtures essentially neutralize surface charges on solid particles and cause all surfaces to carry like charges. Since particles with like charges repel each other, they reduce flocculation of the cement particles and allow for better dispersion. They also reduce the viscosity of the paste, resulting in a greater slump.
We offer a full range of water reducers, from low range (e.g. Pozzolith), mid-range (e.g. Polyheed 997) and high range (e.g. Glenium). Each type of water reducer offers specific properties depending on what you are trying to achieve with your concrete mix whether it be early strength requirements, slump retention or general workability.
Contact us to answer any questions or to get started today!