Centuries ago, builders used buckets, barrels, and wheelbarrows to help erect the pyramids. Oddly, many contractors are still using that back-breaking, outdated technology for concrete and mortar jobs. A better choice for many jobs is to pump. Concrete pumps simplify the process, not to mention saving on labor, improving speed of placement and accessibility, reducing safety hazards, adding versatility, and boosting the bottom line.
A concrete pump allows contractors to complete a wide range of jobs, above, below, and at ground level. If speed is important, the answer is pumping, where material can be moved faster than 150 cubic yards an hour.
Contractors need to consider many factors before proceeding, among them:
- how fast does the job have to be completed?
- what is the mix design of the concrete?
- how far is the material being pumped?
- what are the limitations of the pump?
When concrete has to be pumped far and fast, a high-capacity/high-pressure concrete pump should be used. Keep in mind that roughly a half-inch of slump will be lost for every 200 feet the concrete is pumped.
Equally crucial is the mix design of the concrete, paramount in determining pumpability. Choosing an incorrect mix is one of the most common mistakes made by contractors. Good concrete requires a well-graded, dense, homogenous mix. Modern concrete pumps will pump most standard mixes, according to the American Concrete Pumping Association. If a mix must be changed, it generally will not require additional cement or cost more.
Mix designs vary greatly based on location and engineering specifications. Every concrete mix contains different amounts of rock, sand, cement, and frequently admixtures. The more rock, the stronger, and, in most cases, the cheaper the concrete mix. The larger the diameter of rock, the larger the pump and hose required to pump the concrete. Industry standard pump hoses are available with interior diameters of 2, 2½, 3, 4, and 5 inches. Contractors should choose a hose that is at least three times as large as the biggest diameter rock in the pump mix to minimize the risk of clogging in the pump, hose, and steel pipe.
The application also plays an important role in the type of pump you will need. Do you plan to pump high slump mixes for jobs such as block grouting or solidifying voids under concrete slabs? Are you going to use the pump for shotcrete or for structural concrete? These are questions to review with your dealer before deciding on a pump.
Another common mishap is failing to properly “shoot the line.” Before pumping, contractors must pump primer (a watery cement slurry) through the concrete pump to coat the inside of the hoses. Then add concrete to begin pumping.
The volume of concrete being pumped is important in pump and hose selection. Individual applications require different amounts of material. Other factors to consider include the time of day the concrete is needed, where to set up the pump, and how to clean out the pump and hoses at the end of the job.
Of course, using the tried and tested buggy, bucket, or wheelbarrow methods don't require most of these considerations, but contractors will quickly realize the improved accessibility, easier workload, and the ability to complete many jobs in less time by using a concrete pump. It is well worth the effort.