If you have a large concrete pad that you want to install before you build a garage, shed, barn, or house, then you may want to consider renting a portable concrete pump for the job. A line pump or a trailer-mounted device is ideal for residential and non-professional use. These pumps can help you to place large volumes of liquid concrete by spraying it instead of pouring it. If you have never used a concrete pump before, you may make a mistake while using the device. One of these mistakes involves using the wrong type of concrete with the pump. Keep reading to understand why this is an issue and how you can make sure you use the right mixture. 

Problems With Using The Wrong Kind Of Concrete

Concrete pumps work by forcing concrete out through a large pipe and a spray nozzle. The concrete is mixed and then added to a collection tank called a hopper. This hopper has a large opening on the bottom that allows concrete to move through the hose. The concrete is forced through the hose with the help of pistons and two separate cylinders. A piston in the first cylinder chamber will move backward and pull concrete into the cylinder from the hopper. A discharge tube will be shifted in front of the cylinder and the piston will move forward to force the concrete through the tube and out of the attached pipe. As the concrete is forced out of the first cylinder, the second one will fill with concrete. The discharge tube moves over to the second cylinder once it is filled. The tube alternates back and forth between the two cylinders, and this helps to ensure continual concrete flow.

Continuous concrete flow is important when placing large volumes of concrete. This allows the concrete to collect faster so the materials can bond and cure properly. This flow is dependent on the ability of the concrete to move into each holding cylinder. If the concrete is too thick, then the pistons may not be strong enough to pull the material into the chamber. This can result in a slow flow of concrete, too much air mixed into the liquid, and possible clogs in the pipeline. 

Mixing The Concrete

Unfortunately, the concrete you would normally create with an electric mixer is too thick to use with a concrete pump. You can use less water when mixing concrete this way and end up with a concrete slab that is more dense and durable. To help increase the flow of concrete, you will need to add more water to the mixture. However, you do not want to add too much water that you substantially reduce the strength of the finished concrete slab. Also, too much water can cause pumping issues. Specifically, the concrete can move through the pump too fast. You may not be able to add concrete to the hopper fast enough to keep up with the pumping speed.

To make sure that your concrete is suitable for the pump, you will want to work with a material that has a large slump. The slump is the amount that the concrete will fall when it is released from a form, and you should add enough water so that the water to concrete ratio is relatively high. Water to cement ratios are typically between .45 and .6. A ratio at around .55 or .6 will work well. This means that you should mix about one-half pound of water or more for every pound of concrete. One pound of water is equal to 15.34 fluid ounces of water, so add about 7.7 ounces of water for every pound of concrete. For example, if you end up placing 100 pounds of concrete mix in the hopper at one time, then you will need to add about 77 fluid ounces of water. 

For more information or if you feel you cannot do this on your own, talk with a local concrete pumping company, such as Masterlink Concrete Pumping.