Think concrete, go precast

Although precast concrete walls have a tough exterior, they hold up to all kinds of weather. But making this structural wall panels is an inside job. Production starts with a mix of crust rock and sand. This collection is limestone based. The mineral can be altered for different strengths and finishes. A conveyer delivers the collection of minerals to a huge mixer merging all the ingredients into a fit ready mix. Before the casting of the wall, a release agent is sprayed on the casting form. High strength steel cables are strung throughout the form. With a hydraulic device they pull each cable to a specific tension. Than rebar is bent into loops that will be linked to create long cages. One cage will be placed at the top of the form and one at the bottom. A sheet of welded wire mesh, pre-cut to fit the size of the form is being laid.

The mould is ready now for concrete pour. A truck dispenses the concrete directly into the form. The concrete flows around the steel reinforcement. The steel will keep the wall strong when the concrete expands and contracts as the weather changes. The team spreads the concrete and levels it with a tool called screed. This first layer of the panel is essentially the first layer of the sandwich. Rigid firm insulation studded with protrusions (to secure to the concrete) is placed at the center of the sandwich.

More steel reinforced concrete completes the wall sandwich. After about 14 hours the wall is solid enough to be handled. After a 3 days cure, the precast concrete wall is ready for the construction site.