Ordinarily, concrete mixtures are not ideal for pumping. The pressure used to pump these mixtures often forces water out of the cement, leaving some portions dry and others wet. The friction caused by fine particles in the mixture is also a concern; concrete pumps must operate at higher pressures to offset this friction.
Modifying the mix by adding more sand, cement, or water to achieve better pumping performance often leads to undesirable physical properties and increased costs. Admixtures called pumping aids are commonly used to improve the pumpability of concrete and reduce the overall cost of placement.
What is a Pumping Aid?
Simply put, a pumping aid is an admixture that makes concrete mixtures easier to pump through a line. It acts as a lubricant for the mix and ultimately reduces the pumping pressure necessary to place concrete without altering the sand, cement, water, and aggregate content.
POLYOX™ WSR 301 is a high–molecular weight polyethylene oxide polymer that improves concrete pumpability by thickening the water in the mix, reducing friction, and providing pseudoplastic (shear-thinning) rheology. To test the performance of POLYOX™ WSR 301, two typical concrete mixes were compared side by side.
POLYOX™ WSR 301 was included in Formulation A at 25 ppm and reduced the pumping pressure of the mix by 16% without impacting the compressive strength or causing shrinkage upon drying. In addition, POLYOX™ WSR 301 stabilized air content, allowing for a 20%–30% reduction of air-entraining agents without any detriment to the workability of the concrete. POLYOX™ WSR 301 also has film formation properties that efficiently encapsulate mineral powders and aggregates.
Benefits of POLYOX™ WSR-301 in Concrete
Improved water retention and distribution with highly porous and harsh aggregate
Pump longer distances at lower pressures
Prevents aggregate segregation
Stabilizes sprayed concrete
"Waterproofs" underwater concrete to improve setting qualities
Stabilizes foam in concrete
Summary
Concrete made with small concentrations of POLYOX™ WSR 301 pumping aids is easier to pump, shows reduced rebound, and is easily workable at most temperatures. POLYOX™ WSR 301 effectively achieves this through its thickening and lubricating properties. These properties reduce the energy required for concrete pumps to operate and eliminate the need to change the cement, water, or aggregate composition of concrete mixes to achieve optimal pumping performance. Click below to request a sample of POLYOX™ for your concrete mix.
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