RESILIENCENIST Engineers Design 5 New Ways to Connect Concrete Pieces for More Resilient Buildings
Precast concrete is an efficient and cost-effective building material made in a factory instead of at a construction site. One of the biggest challenges with precast concrete is connecting the concrete pieces at a job site. Working with industry, NIST has designed five new connections for precast concrete buildings that will make them more resilient.
People have been using concrete for thousands of years, but scientists and engineers are still finding ways to improve this versatile material. Now, researchers at the National Institute of Standards and Technology (NIST) have developed five new ways to securely connect large concrete pieces. These connection methods are intended for a type of material called “precast concrete,” in which parts such as beams and columns are made in a factory and assembled later at a construction site.
“Connections are usually the weakest points in this type of construction,” explained NIST structural engineer Malcolm Ammons, who led the project. “These new connections are designed to make precast concrete buildings more resilient and less likely to collapse after sudden damage such as from a flood, earthquake or explosion.”
What Is Precast Concrete?
Pouring wet concrete at a construction site is expensive and time-consuming. Builders must transport wet concrete to the construction site before it hardens. They must pour the concrete into molds that are often used only once and then thrown away. Even getting wet concrete into the molds can be tricky, requiring long hoses and pumps. On top of all those concerns, workers must worry about the weather.
“Heat, humidity and precipitation all have an effect on the strength of the final concrete,” said Ammons. “Quality control is simpler and overall construction costs are often less expensive if the concrete can be cured indoors.”
That’s where precast concrete comes in. Factory workers pour large pieces of concrete that harden before they are transported to the job site. Construction workers then connect these pieces like Swedish furniture. Precast concrete can greatly reduce the cost of construction and improve quality and consistency because it can be mass-produced in a climate-controlled factory with reusable molds.
One drawback to precast concrete is that it tends to have more connection points than concrete that is cast on-site. These connections need special attention to ensure that the overall structure is strong.
