The main building material of West metro’s stations and railway lines is concrete. Its journey to West metro’s walls, floors, elevator shafts and platforms starts in a mixer.
The concrete truck’s mixer is slowly filling up. From Ruskon betoni’s Kivenlahti factory, concrete is transported to Finnoo metro station for use in constructing vaulted ceilings and floors.
Before that, a cement truck arrives from Finnsementti’s plant in Pargas. In a large concrete mixer, the cement is mixed with aggregate and water, and synthetic and steel fibres are added as needed to prevent cracking.
The concrete factory’s large machines do not have operators. The controls are in an office, which has digital screens for monitoring the processes.
– It may come as a surprise that this work is done indoors and it is not messy. Everything starts with receiving an order. In the West metro project, preliminary information is sent to us the previous week, and the orders are confirmed two days before delivery, says Regional Manager Jukka Tuohino.
The concrete pour rate is agreed in advance. For West metro work sites, concrete trucks often make deliveries every 20 minutes. The digital screens show two mixers preparing concrete. Getting the relative proportion of the aggregate right at the factory is important as it affects the strength of the concrete. For example, elasticity or porousness can be increased with the right materials.
In addition to the office and concrete plants, the factory has a laboratory, where cubes of concrete are ready for the compressive strength test. The laboratory also measures air content and depressions and
monitors fibre content in concrete.
In addition to quality control at the factory, quality is tested at the work site, and Ruskon betoni’s test results are reviewed by an independent third party.
Originally published in West Metro magazine 1/2019.