The use of concrete strength sensors on Allies and Morrison’s King’s Cross apartment building enabled contractor Laing O’Rourke to increase the proportion of GGBS and cut 34 tonnes of embodied carbon
Allies and Morrison’s Capella is one of the last building residential buildings to complete in the 20-year King's Cross regeneration programme. Facing onto Lewis Cubitt Park, the 14-storey tower contains 120 market and 56 socially rented flats in a range of studios, duplexes and split-level units. On the 12th floor, five two-storey homes with private rooftop gardens animate the skyline.
The architect describes the facades of the L-shaped building as “intentionally picturesque”, diffusing the backdrop to the park. A simple palette of materials includes pale brick, white precast balconies and pale green wave-like concrete panels.
Because of the busy and congested location, deadlines were tight. To improve efficiency on site, SmartRock sensors from concrete supplier Heidelberg Materials were attached to the reinforcement of the concrete frame, to generate real-time data on the curing process. Assessing in-situ strengths, as opposed to testing cubes poured onsite at the same time, accelerated the striking time and shutter turnaround, so the construction team could move on to the next stage more quickly.
The data also enabled a change to the concrete mix design so that a greater proportion of the cement was replaced with GGBS. This lowered the embodied carbon content of the concrete by 10kg/m3, saving more than 34 tonnes of CO2e.
Overall embodied carbon was measured at a Stage 3 environmental compliance audit as 774kgCO2e/m2.