Admixtures for caissons
The giant concrete caissons for the Los Mármoles harbour in Lanzarote's capital, Arrecife, were constructed during July and August 2016 using the slip-form technique. The concrete was manufactured in two production plants installed outside the harbour. The client – the joint venture Acciona-Lanzagrava – required a concrete offer-ing low viscosity, good robustness, easy pumpability, adequate setting times and, not least, high resistance to sea-water. MC Spain was awarded the task of optimising the concrete formulation in a contract that included the provision of con-sultancy support for the duration of the project.
The company suggested a combination of the PCE superplasticiser MC-PowerFlow 3210 and a concrete plasticiser from the Centrament BV product family especially designed in order to provide the desired blend of properties. MC Spain has extensive experience in the manufacture of caissons and floating docks, having already handled 60 orders of this kind involving 20 port authorities in Spain, corresponding to a market share of more than 50 percent.
Each box caisson is about 66.5 m long, 19.5 m wide and 23.5 m deep – and took just seven days or less to build. In all, a total of 35,000 m³ of concrete was used – a supreme technical and logistical achievement that required a high level of communication and cooperation between all participants and in which secured continuous supplies of concrete were of paramount importance. Following the hardening of the concrete, the huge box structures were towed out onto the water, ballasted and sunk at the exact locations required for extending the harbour dock . Thus land was reclaimed from the sea, with the harbour being extended by 430 metres to increase its handling capacity.