The Customer decided to take a leap in production efficiency and ordered a facility to enable it. Later on, the Customer also invested in a hollow core line in order to introduce long span floors.
By now, as a Business Director of a global leading supplier of concrete connections, I have seen construction here and there and discussed with dozens of people about precast. I have formed an understanding of why builders see precast as a scary thing – here the major 3 beliefs and my response to them:
1. Designing in precast is difficult.
Well, design always needs thinking and consideration, whatever you try to plan. It is always easier to do first, see what the outcome is and then change. Anyhow, even cast-in-situ structures have to be designed before the concreting works. In precast, the prefix “pre” stands for design. The project must be predesigned as complete as possible before planning the precast scheduling, element sizes, etc. Cultural beliefs stick strong and changing habits and traditions is a demanding task, but not impossible. With modern 3D-based BIM software, colliding structures and dimensional mishaps can be found already in the virtual building. The Cloud Server working model has improved collaboration, such as construction design, and taken it to the next level. When all parties of the design process are working within one virtual building, problems are noticed before any concreting work is done.
2. Precast structure can’t be as strong as cast-in-situ.
Well, it can, but many times it is not necessary. It is again a matter of design. There are certain basic things in structural design, starting from statics of the building, transferring the loads from the top to foundations, stiffening the building and the size of the cross-sections. In-depth studies usually find that the structural design could be much lighter than originally thought and therefore much more suitable for the precast method.
3. Precast construction has too tight tolerances to achieve.
Construction is still quite a labor-intensive work. People transfer dimensions of the building from the drawings to the construction site, and it is a question of professional skills how successful this transfer is. Modern site measuring electronics help in this process to an amazing degree. The precast can adapt to whatever tolerances the site follows. Well-designed mold equipment can reach an accuracy of ±5 mm in precast component dimensions, so there’s plenty of space for normal ±20 mm site tolerances; precast does not limit it.
Environmental issues and climate change require CO2 reduction and recycling of raw materials. The cement and concrete industry is currently developing new concrete types with lower CO2 emissions and recycled or easily available raw materials. Instead of natural sand, in the future aggregates could be waste from some other processes. Concrete structures can be demolished after use, steel can be reused, and crushed concrete can be delivered for land filling.
Precast has one advantage compared to cast-in-situ: with modern connection technology, a building can also be disassembled and transferred to a new location and maybe even for a new purpose. Good connections can indeed bring a lot more out of precast structures and lead to a faster, safer, and more efficient way to design and build.