‘Automated Concrete Removal’ (ACR) saves the day in Salt Lake City

Published 24/11, 2021 at 16:36

To support expected economic growth, experts predict that massive global infrastructure investment will be needed between 2017 and 2035. The question arises however if the labour market will be able to support any investment.

Clearly, there is a need for automation that can maximise productivity, particularly when it comes to infrastructure construction projects. Fortunately, innovative equipment manufacturers, such as Conjet AB, and its customers, are working hard to solve these challenges. An ongoing car parking deck rehabilitation project in Salt Lake City, Utah, provides an excellent case study on this subject.


High profile renovation project 

In December 2019, the Church of Jesus Christ of the Latter-Day Saints (the ‘Church’) began a large renovation project in the heart of downtown Salt Lake City, Utah. The plaza sits between the Church’s administrative buildings and consists of an impressive landscape of fountains, flower gardens, grass and other vegetation. The Church hired Jacobsen Construction to serve as general contractor in charge of the overall renovation of the Salt Lake Temple and Temple Square, with Paul Shingleton as project manager on the project. 

Below the plaza sits an underground, three story carpark built in 1962. This had been experiencing some leakage from the water circulation system and landscape directly above. To clear the landscape area for renovation and address the leakage, the entire plaza of landscaping and concrete architecture would have to be removed along with the waterproofing layer on the carpark’s concrete roof. Complicating matters, the water proofing layer contains asbestos from the original construction. As structural engineers developed the scope of work and renovation timeline for the plaza, they estimated that excavation would reveal 2% to 5% delamination of the concrete roof.

In March 2020, renovation work began and the site was excavated, where it was discovered that there was in fact a 70% to 90% delamination across the entire 200,000m2 roof area. This unknown, unanticipated condition presented a major risk of significant project delays. Jacobsen quickly called in a demolition subcontractor to start removing the top layer of damaged concrete, totalling between 13,000m2 to 16,722m2. The subcontractor immediately got to work with a crew of 12 operating six large jackhammers. However, it became clear that the project would be delayed by an additional two years, minimum, due to the massive amount of concrete to be removed. At this point, Jacobsen’s culture of resourceful creativity came into play as it searched for innovative technologies that could automate and increase efficiency compared to the manual jackhammer removal process. Fortunately, it did not take them long to discover the ACRTM robots manufactured by Conjet AB.


Increased efficiency

Conjet, headquartered just outside of Stockholm, Sweden, with additional offices in Charlotte, North Carolina, is a leading manufacturer of ACRTM robots. Conjet was established in 1990 by a small group that had developed hydrodemolition technology as a division of a larger company in the mid-eighties. Since then Conjet has been focused exclusively on making the hydrodemolition process easier, more precise and more productive. Collectively, years of technology development is embedded into every Conjet robot.

After discovering the ACRTM robots through online searches, Shingleton contacted Conjet’s North American team to investigate its potential utility on the plaza renovation. Shingleton and the Conjet team had a detailed meeting where Conjet explained the efficiency, safety, and quality advantages of ACRTM and hydrodemolition. Shingleton then connected Conjet with one of its most capable subcontractors, TID Demolition, which could further investigate the application and advantages of ACRTM for the renovation. TID Demolition, based in North Salt Lake, has over 25 years of experience in retail spaces, office towers, medical facilities, government projects, manufacturing and residential work. Through a combination of experienced, skilled personnel and specialised equipment, TID is able to successfully execute complex and challenging demolition projects while providing a safe, clean and productive job for its customers.

Although TID had no prior experience of hydrodemolition, Conjet’s team was able to explain the process and answer all of TID’s questions, such as the key factors to consider when performing hydrodemolition, the ACRTM robots’ operation, productivity capabilities as well as how to handle water containment and treatment. In addition to the clear productivity advantages of ACRTM, Conjet was also able to educate both Jacobsen and TID on its other benefits. For example, worker safety is improved due to the elimination of silica dust and vibrations, along with drastically reduced noise. Also, the useful life of the structure is extended significantly because the hydrodemolition process results in a 2,5 times stronger bond between residual concrete and the new overlay. After multiple meetings with Conjet, Jacobsen and TID decided to try out the ACRTM technology. In June 2021, TID purchased a Conjet ACRTM Robot 557 standard model and began work on the Temple Square renovation.


Preserving the project timeline

As the Robot 557 was delivered to TID, Conjet provided start-up training using the Conjet University (‘ConjetU’) curriculum. Tim Best, Conjet’s customer success manager for North America, led the training. He has over 20 years’ experience operating hydrodemolition equipment in the field, as well as planning, estimating, and managing the execution of complex and challenging projects all across the U.S. and Canada. 

Conjet’s ACRTM robots have been designed with ease of use, precision and productivity as the primary objectives, and the 557 lived up to its design intentions on this project: Within a couple of days, Best had trained TID’s primary operator on how to properly use the Robot 557, the accompanying Hammelmann high pressure pump and manage waste water runoff. In the first week of operations, TID’s main operator became comfortable using the Robot 557. By the second week, the productivity advantages of ACRTM became clear. The Robot 557, along with two TID employees, was removing on average each hour the same amount of concrete that required the previous contractor to spend three full days with 12 employees using jackhammers. 

TID’s early productivity results caused project engineers to re-evaluate the timeline once again. The initial phase of work involved a 6,000m2 removal area. Using jackhammers, it was estimated to take until February 2022 to complete this initial phase. However, with the ACRTM Robot 557 TID finished this removal in September 2021. In fact, due to sequencing conflicts with the garage below, TID has begun moving the 557 for work on other jobsites in between work sprints on the plaza project. In addition to the productivity gains experienced with ACRTM compared to jackhammers, there have been other, more qualitative benefits. Because the plaza is surrounded by offices, Jacobsen was receiving many complaints about the loud noise created by jackhammering. In contrast, the Robot 557 and pump are relatively quiet and have drastically reduced the number of noise complaints from surrounding office workers.

Travis Keenan, TID’s project manager overseeing the Temple Square work, stated, “We have been extremely impressed with both the ease of use and the productivity of the 557. With the ‘Conjet One’ operating system and just a couple days of training from Mr. Best, our field employees were able to quickly become comfortable and adept at the ACRTM process. And the productivity has absolutely blown us away. When we first were brought into the Temple Square project, the general contractor set what we thought was an aggressive target for concrete removal per day. However, with Conjet’s ACRTM technology we have been able to actually exceed that target. We could not be more pleased with our decision to bring the ACRTM Robot 557 into our arsenal of tools at TID Demolition.” Paul Shingleton also commented: “The amount of time that will be saved based on the jackhammer process will completely save the project. This was my first experience with Conjet’s ACRTM technology and hydrodemolition. In the future when we have jobs with concrete removal required, we will most definitely be consulting with TID and Conjet to find the most efficient, effective ACRTM solution.”


Bridging the gaps

When the unexpected bad news was first heard by Jacobsen that the amount of delaminated concrete in the plaza was way higher than the original estimates, the timeline for completion was pushed back two years to July 2023. However, after TID brought in the Conjet ACRTM Robot 557 and quickly learned how to utilise the innovative technology for performing hydrodemolition, the completion date for removal of all delaminated concrete was moved up to July 2022. This is a full year earlier than would have been possible using the manual jackhammer process. In addition, TID estimates that the automation and productivity of the 557 has reduced the amount of labour needed by 30,000 to 40,000 man hours. 

The plaza renovation project is a microcosm of both the infrastructure challenges that face our planet, as well as the power of innovation to solve these challenges. There is a massive inventory of aging concrete infrastructure in need of repair, coupled with the aggravating factor of a declining construction work force. Yet, innovative technologies such as Conjet’s ACRTM robots provide a viable path forward that is more sustainable, safe and efficient than the old ways of doing things.

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