Why Concrete Pumps May Clog


Several factors can make a concrete mix difficult to pump. Construction project managers need to account for these elements when they are selecting a concrete mix and the pump that will deliver that concrete to the desired pour site. This article discusses some of those variables that can affect concrete pumping.

Aggregate Quantity

Different concrete mixes are suitable for various applications. For example, the concrete that will be poured at a site which is prone to flooding may have a greater quantity of aggregates than concrete that will be used for an upper floor of a building. Too many rocks (aggregates) in a concrete mix reduces the plasticity (the ability to change shape and flow freely) of the concrete. Select a concrete pump with more power so that this thick mix can be forced to flow without causing clogs in the pumping system.

Aggregate Size

Concrete mixes that have large aggregates are more likely to cause clogs than mixes with smaller aggregate particles. This is because the larger particles are more likely to form clumps that will fail to move through the delivery lines. One way to avoid this problem is by selecting pump hoses based on the size of the largest aggregates. A simple rule of thumb to follow is that the diameter of the hose should be at least thrice the size of the largest aggregate in the concrete mix. This large hose will be less likely to be clogged by those larger aggregates.


Concrete will rarely clog a pumping system if that concrete has a good mix of solids of different sizes. This is because those solids will hardly have gaps through which the liquids in the mix can flow and leave solid clumps. Proper gradation also gives concrete added strength after curing because that concrete will not crack since the different aggregate sizes hold it together and prevent excessive changes in its dimensions during expansion and contraction. Always ensure that the solids in the concrete mix you use are properly graded/mixed so that you will not have any flow problems as that concrete is being pumped.

Type of Aggregates or Sand

Manufactured sand and aggregates are more likely to clog a pump system than river sand can. This is because river sand has smooth edges that will allow the particles to slide against each other during the pumping process. Manufactured sand/aggregates clump together due to the sharp edges that make it hard for the particles to slide against one another as they move through the hoses of the pumps. Manufactured sand and aggregates should be used in a concrete mix that has fly ash so that more water can be retained by the mix during the pumping process. The water acts as a lubricant and prevents the concrete pump from clogging.


15 January 2018

Drainage, Reinforcement, Tamping and Other Concrete Essentials

Pouring concrete isn't necessarily as straightforward as it looks. Depending on the land, you have to make multiple adjustments ranging from laying a layer of gravel to putting in moisture barriers. Then, depending on the size of the concrete pad, you may need to add steel reinforcements. After the concrete has dried and cured, you may decide to add sealants, do an acid wash or play with other finishes. Then, of course, there are differences between pouring concrete inside or outside. In this blog, I hope to cover all those issues and more. If you're looking for tips and ideas, take a look at these posts. Whether you plan to hire a concrete contractor or do the work yourself, it can help to know this information.