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Raising the Environmental Bar on Concrete Pumping

The Conco Companies have been busy working on the new Wilshire Grand Center in Los Angeles, which is slated to become one of the tallest buildings west of the Mississippi. Before the start of the project, we were asked how we will pump concrete 650 feet horizontally and then 1,125 feet vertically to reach the upper levels of the skyscraper? Additionally, since we would be pumping concrete higher than was ever pumped in Los Angeles, could this be done without generating air pollution or creating too much noise for the adjacent office buildings?

Conco’s unique solution was to purchase and use a new state-of-the art electric pump. This high pressure, high powered pump is the only electric pump of this size being used on the West Coast by the concrete pumping industry. Since it is electric, this pump allows both the project owner and the contractor to meet the guidelines imposed by the Southern California Air Quality Management District (SCAQMD) for reduced emissions.

Another benefit of the electric pump is that it generates much less noise than a traditional diesel powered pump. This is important as the pump must sit less than 30 feet from an occupied office building, which makes it less disruptive to the neighboring businesses.

The new pump will be the primary workhorse in pumping concrete throughout the course of the project and it will be used to pump concrete all the way to the top of the skyscraper. We are anticipating that we will pump more than 100,000 yards of concrete through our electric pump to complete the Wilshire Grand project.

Conco is a leading supplier of concrete services for the Western United States. We have built our reputation with superior concrete formwork, reinforcing, place and finish, shotcrete and other ancillary services that benefit from our vast experience. Our concrete projects include commercial, educational, parking and other construction development as well as public works projects and highways.

A job in the construction industry is a great career choice for young men and women and an ironworker is one of those highly-skilled positions. To get started, an interested candidate should contact their local iron workers union about apprenticeship training programs available in the area. You may not be aware that the Iron Workers Union actively seeks to encourage and recruit women into the field and report that they have almost 2,000 active members.

An apprenticeship is done on-the-job so you have the opportunity to work alongside journeymen ironworkers. There is also a classroom component where an apprentice must attend approximately 160 hours of classes per year over a period of four years. During the apprenticeship period, an ironworker’s salary starts at about half of that as a journeyman’s wage and increases with experience. Once an apprentice successfully completes the four year program, they become a journeyman ironworker and receive full pay.

Like other construction work, ironworkers must be physically able to perform all the duties of the job. The work can be challenging and the Iron Workers Union states that applicants must be willing to work in high places, have a good sense of balance, and be alert for potential danger to themselves and others. Comprehensive safety training is included in the classroom portion of the program. In addition an apprentice must be able to follow directions and work well with others.

Ironworkers are involved in many aspects of a construction project. At Conco, workers perform all reinforcing work in connection with field fabrication, including but not limited to the pre-assembly of reinforcing cages, loading and unloading, handling, racking, sorting, cutting, bending, hoisting, and the intermittent use of forklifts.

For more information on joining the Conco team take a look at our career page.

For over 50 years, Conco has been providing premium concrete services and is one of the most trusted concrete contractors in Seattle. We partner with clients on every project from the pre-construction stage right through to final completion to maximize efficiency and ensure goals and budgets are met. Our concrete services include commercial, educational, parking and other construction development as well as public works projects.

Cement masons and concrete finishers are the group of construction workers that place and finish the concrete. Interested persons can enter the field through a comprehensive apprenticeship program which includes technical training as well as on-the-job experience. Apprenticeship programs are usually sponsored by unions and contractor associations and provide participants the opportunity for advancement and higher pay.

A typical cement mason apprenticeship is a three-year program and consists of 4,200 on-the-job hours and over 430 related classroom hours. An applicant must be in good health and physically able to perform all phases of the work. The technical training that an apprentice receives includes understanding the basics of concrete, concrete form work, concrete finishing as well as construction related math skills and blueprint reading. The on-the-job training allows him/her to learn the tools of the trade with plenty of practical experience in finishing sidewalks, curb and gutter, floor slabs, and architectural concrete.

On large commercial concrete projects, cement masons and concrete finishers need to be able to follow directions from their supervisors and work well with the rest of the team on the jobsite. Concrete finishers are often responsible for pouring the concrete into forms and constructing the foundations, slabs, sidewalks, roads, and other ground-level tasks. The cement masons work with the finished forms and construct walls and other above-ground structures. These jobs demand a high level of skill as well as understanding and using jobsite safety procedures.

Job opportunities for cement masons and concrete finishers increase dramatically during growth in building activity, and right now the outlook is extremely positive for steady employment. The Bureau of Labor Statistics predicts a 29% increase for cement masons and concrete finishers between the years of 2012 to 2022, which is a total of about 41,700 new jobs.

For more information on joining the Conco team take a look at our career page.

Conco is one of the leading concrete contractors in San Francisco offering a range of innovative, quality services. We have been honored to work on many high-profile projects and were recently awarded the concrete contract for the San Francisco 49ers Stadium. Our concrete services include commercial, educational, parking and other construction development as well as public works projects.

While Conco is justifiably proud of breaking the World record for the largest continuous mat pour, we are even more proud of doing it safely. Our commitment to safety began with the vision from Conco’s Southern California General Manager, Rick Parker. Five months prior to the pour, he invited John Messing, Conco’s Safety Director, to participate in the planning meetings for the Grand Pour. Rick has learned from his years of experience that projects go more smoothly when the safety department is involved early-on to ensure that safety is built into the overall work plan.

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*Photos provided by Gary Leonard

Rick also made the prudent decision to devote the first-quarterly company safety meeting in January entirely to the safety of the pour. During the meeting, Rick Parker and Pumping Manager, Doug Marquis, provided an overview of the Wilshire Grand jobsite along with the challenges, unique project features, and logistical considerations of the job. John Messing spent the balance of the time devoted to discussing the importance of pre-task plans. He assigned three sub-groups to develop such plans regarding the work that they would perform. At the conclusion of the safety meeting, the pumping crew, place and finish crew, and street-level supervisors all had a unique, customized pre-task plan that was used as the basis to ensure their workers understood the hazards of the work and how to mitigate them.

The end result of the successful well-thought out plan was a highly professional team effort from all Conco employees. The entire team—at all levels—executed the plan to perfection, which resulted in zero injuries for this world record continuous concrete pour.

Among the many unique features of the Wilshire Grand mat foundation pour was the thermal control plan. Occasionally we need to make provisions for the heat that is generated in mat foundations. In mass concrete structures there are two thermal properties that must be considered: the maximum temperature and the temperature difference between the center of the structure and surface.

There are multiple ways to control the overall thermal properties of mass concrete. For the Wilshire Grand pour, one of the first things Conco addressed was the concrete mix design. There are a few common adjustments that can be made to the actual mix, but they all have some impact on the production rate when the concrete is being batched. In this case, working with our supplier Catalina Pacific, we increased the proportion of fly-ash which normally results in reduced maximum temperatures.

The next step was to mechanically control the temperatures. Pre-chilling the concrete was not an option due to the rate that we needed to batch and place the concrete. Nor was there a way to feasibly pre-chill 21,200 cubic yards of material ahead of time so we had to consider post-chilling by means of cooling pipes to mechanically remove heat.

For this, we turned to John Gajda of the CTL Group. CTL developed a thermal control plan specific to the mix design, the geometry of the foundation, and the configuration of the rebar. With help from Couts Heating and Cooling, we implemented CTL’s thermal control plan. Ultimately the system we installed to post-chill the concrete was composed of 18 miles of cooling pipes, over 660 tons of chiller capacity, 40,000 gallons of chilled water, multiple pumps, 3 x 500kva generators, and over 2,200 valves. This includes a large amount of contingency and redundancy for reacting to unanticipated thermal phenomena and providing backup during the critical early stages of the thermal control plan.

Subsequently we installed 24 thermal couplers to digitally monitor the thermal properties of the concrete. For assistance, we teamed up with Twining Laboratories who were able to provide hourly readings of the foundation utilizing Intelirock equipment. By monitoring temperatures closely, we could respond by increasing chiller capacity and/or adding insulation if required. Furthermore, monitoring allowed us to determine when the thermal control system could be removed and the concrete core started.

In the end the thermal control system was a success. The maximum temperature was kept below ACI limits and the temperature difference was well within the ranges required to avoid thermal cracking.

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