Making the most of concrete pumps
Concrete pumping is the most efficient and cost-effective method for concrete placement we have in today’s time.
It is widely acknowledged by construction experts that concrete pumping wins over traditional techniques in almost every way that matters. It is the most accurate and quality way of pouring concrete exactly where it is needed. With speed being an important factor for all construction projects, pumps greatly speed up the pouring process. It reduces site congestion, as less labour is required. And concrete pumps require less amount of water compared to other concrete pouring techniques, making the final output stronger.
According to a report by Research and Markets, the global construction industry is expected to record a CAGR of 6.5% to reach US$ 10,835.6 billion by 2023. Naturally this means increased demand for concrete and concrete pumping. However, there are several factors which must be taken into consideration to ensure quality and safety of concrete pumping.
Matt Smith, associate head, School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University Dubai, outlines the ways by which productivity and efficiency of pumped concrete can be maximized.
Construction is time-consuming and an expensive affair. One of the ways by which positive outcomes can be ensured is by putting in place a thorough pre-pour inspection. This will also bring safety hazards to light, especially if initial assembly was undertaken by a third party. A pre-pour checklist would include meetings with crew foreman and the project superintendent to discuss factors like required equipment, labour needs, rebar pulling/chairing, mix design and more. All measurements such as footprint, wall openings and lintels must be verified along with proper placement of reinforcing steel. The form system should be closely inspected for irregularities such as weak spots and irregular joints.
Concrete mixes today call for complex analysis and adjustment in order to address the need for strength, durability as well as environmental sustainability standards. Add to this the need for moving concrete through pump lines with the efficiency demanded by construction schedules and it is obvious then that the concrete mix itself plays an important role. The ideal concrete mix for pumping typically contains air-entraining agents, some extra sand, fly ash, and a well-graded aggregate blend. Water-reducing admixtures or superplasticizers are often added to make the pumping process easier. Concrete mix in the hose can stiffen if there are delays. This can be avoided by coordinating timings correctly to result in a steady supply of concrete. Finally, grout slurry should be run through the hose to slick it before starting to pump. Once pumping is complete, any remaining concrete in the hose can be dumped back into a ready-mix truck.
The role of weather
Cold weather can make the process of pumping much harder than it actually is. The most obvious issue of course is the danger of the concrete freezing and restricting the flow. When frozen, standing water in the pump can increase in volume by up to 9%, which can crack equipment. Ways to combat this include insulating the pipes and drums of the pump system, using very hot water at the mixing stage, avoiding sharp bends in the hose and paying extra attention to pump bearings. Despite these measures, if the mix does freeze during pumping, it’s best to turn off machinery and allow it to thaw before restarting. Pumping with frozen concrete in the boom could seriously damage equipment.
Like extreme cold weather, extreme hot weather could also pose several challenges to pumping concrete. Some of these are formation of shrinkage-related cracks, reduced strength and durability, increased potential for dry shrinkage after hardening that can hamper quality of the finish and more. Some solutions include pumping during the morning hours, using protective covers for equipment as well as an evaporative retarder to prevent the mix from drying out upon application.
Like any industrial process, concrete pumping comes with its share of hazards which can be eliminated through the use of the correct safety procedures. All equipment must be regularly checked for wear and tear. Worn couplings, valves or gaskets can pose a serious risk if undetected. Powerlines are another aspect of safety. They can cause the most fatal accidents while pumping concrete. If there is a power line in the vicinity, it should be clearly marked and identified as a danger zone. It is also a good idea to use a spotter who can warn an operator when the boom comes close to the danger zone. The American Concrete Pumping Association (ACPA) mandates that booms should never be used within 20 feet of powerlines. Additionally, adequate cribbing is essential to distribute the weight of the cement load, close attention must be paid to outrigging procedures and all operators should receive safety certification to prevent accidents and operate machinery safely.
Using the right equipment
Construction requirements and the type of work being performed will help decide which kind of concrete pump should be used. Factors to be considered include the concrete mix design, size of aggregate, volume of concrete to be pumped and the distance. Use of the right equipment will go a long way in securing good results. For example – wood or aluminum forms tolerate concrete pressures better than polystyrene foam forms and a 2-inch diameter hose is ideal for full speed pumping while offering better control and minimizing the danger of a blowout.
The future of concrete pumping
The global concrete pump market is projected to grow significantly in the next few years. A report by Zion Market Research states the global concrete pump market is expected to reach USD 5.9 billion by 2025, at a CAGR of 6% between 2019 and 2025. This is being driven by several innovations in concrete pump technology. One of these is hydraulics, which provide the load-holding strength, precision and predictability to keep complex concrete pumps operating smoothly. With hydraulics, pumps can safely reach distances even in tight surroundings, as well as pump at low boom angles that a crane cannot. Another is boom pumps – used for high-volume pumping with flexible and accurate delivery. Its design allows maneuvering over and around objects, thereby improving accessibility. The 360-degree continuous swing boom reaches to virtually any spot, making these pumps suitable for almost any kind of construction job. And finally, remote controls used to control concrete pumps are a technology advancement which permit operators to move around freely, eliminates safety risks and increases speed of operations, leading to greater profitability.