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Quality assurance of concrete for pre-construction Verkkosaari district


GRK Infra Oy


30,000 cubic meter of concrete

30,000 cubic metres of concrete needed for the pre-construction of the new Verkkosaari district

The construction of the northern part of Verkkosaari is the largest piece-work contract with a total price in the history of main contractor GRK Infra. About 30,000 cubic metres of concrete are needed for the pile slabs and the different engineering structures. The quality of the concrete is assured in Sweco’s laboratory with hundreds of compression strength tests.

The City of Helsinki has commissioned the construction of a new residential area into the northern part of Verkkosaari, to where about 3,600 residents are expected to move in 2024. GRK Infra acts as the main pre-construction contractor of the 70-million-euro project. The size of the area is 13 hectares. 

“In addition to streets and municipal technology, a massive shore wall will be built into the area, as residential construction spreads out onto the sea,” says GRK Infra Oy’s construction site manager Risto Laakkonen. The pre-construction also includes the removal of contaminated soil and sea dredging. ”We expect to be ready by autumn 2022.” 

The construction of Verkkosaari is the largest piece-work infrastructure contract with a total price in the history of GRK. About 30,000 cubic metres of concrete is needed, two thirds of which are used for cast pile slabs supported by drilled steel piles. In addition, concrete is needed for different engineered structures such as shore and retaining walls. ”There will definitely be hundreds of concrete compression strength tests!” Laakkonen says. 

Ruskon Betoni manufactures the test pieces of concrete and delivers them to Sweco’s laboratory. The compression strength of the concrete is tested within 28 days from the manufacturing of the test piece, and the result is sent to the customer the same day. 

”Hardened pieces of concrete will be subjected to an accredited compression strength test according to the SFS-EN 12390-3 standard, which ensures the concrete’s compliance with the specified structural strength,” says Tuomo Rimpiläinen of Sweco. 

Unwavering cooperation in concrete quality monitoring

The construction of Verkkosaari has been preceded by long-term cooperation between GRK and Sweco in the metropolitan area’s infrastructure projects. 

”During the last five years, we have needed concrete quality monitoring for example in the City of Helsinki’s contract at Pasila railway yard and in large infrastructure contracts of the Finnish Transport Infrastructure Agency,” Laakkonen reports. “With the smaller contracts included, the number of tested concrete pieces rises to the hundreds.” 

Laakkonen appreciates his long-term cooperation partner for independent concrete quality monitoring and smooth services. “The testing of concrete is based on infrastructure construction guidelines and quality assurance requirements. I always receive clear, timely and appropriate documentation from Sweco.”