JRL Group Ltd

S. Lambeth Rd.


JRL Group Ltd




Saving at least half a day on each pour

Concrete framer turns around late project, avoids late-delivery fees, wins more business. “South Lambeth Road went from a 7-day cycle per floor to 5-days, based solely on Converge. The client not only dropped penalties for late delivery – they asked us to tender for another project!”


31 story University accommodation, South Lambeth Road


Converge sensors were embedded into post-tension (PT) slabs, to determine when initial and full tensioning can take place.

Relevance of Strike Times

In tall buildings, the concrete frame is typically on the critical path, as all other work depends on it. At South Lambeth Road, work patterns also meant that floors had to be completed by a specific week-day, so small delays would push the programme into the following week.

Client challenge

From the outset, cube samples cure more slowly than the slabs – building in unnecessary delays. In addition, lab results took up to 4 days to reach site, often after many calls and emails. With fixed working hours preventing overtime, the programme was already 2 weeks late by Level 2 of the building. With further delays expected, the client lost confidence and began discussing financial penalties for lateness.

The Converge Solution

The team installed Converge sensors into the slab, and received email or text alerts as soon as each one reached the correct strength for post-tensioning. That meant they had the right information to get the team started every morning. From the 2nd usage on, information on cure times also meant they were better able to anticipate schedules.

Quick Key Results

Despite being this concrete framer’s first use of Converge, training was completed in 3 hours – including the time taken to deploy the first set of sensors. Cycle times reduced from the first level and continued to improve throughout the program. By Level 10, the program was ahead of schedule.

Variability in concrete performance

As shown in the chart on the right, in-situ strength monitoring highlighted the variability in concrete performance throughout the year. Between colder months and warmer months, there was up to 700% variability in the time it took to reach key strengths. Conventional techniques for determining concrete strengths (ie. cubes cured at 20°C) indicate the same performance all-year-round, leading to unnecessary delays in Summer, and potentially dangerous situations in Winter. Converge’s technology gives accurate strength estimates at all times of year, improving safety and efficiency on-site.

Costs and ROI

The cost of sensors and hire of equipment/software for this type of project is around £35k. Had this project continued as it began, delivery would have been 10 weeks late – a delay which can often translate into LAD’s and prelim costs of £1-2m. That said, the ability to win new client business may prove more valuable still.

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