Recently a group of U.S. scientists put forth a solution for “What makes concrete creep?” that was published in the latest issue of The Journal of Chemical Physics. To study the problem, researcher used a combination of experimental and theoretical methods.
Typically concrete mixes are made up of water, aggregate (rock, sand, or gravel) and Portland cement. The curing process starts immediately once the concrete is placed. To ensure it cures properly, which increases strength and decreases permeability, concrete contractors protect the concrete from loss of moisture by keeping it in a reasonable temperature range. While it is curing, concrete shrinks, and that can cause cracks.
As the cement paste in the concrete reacts with the water, the pressure or stress on concrete known as “creep” can cause it to slowly deform or change shape. This generally occurs in the same direction as the force applied on the concrete. The amount of cement paste and its quality influences creep, however, it does not cause concrete to fail or break apart.
Until now the cause of creep has been a mystery. This new study by researchers from UCLA suggests that they have found the exact mechanisms that cause concrete creep and its “origin is in the calcium–silicate–hydrates (C-S-H) that form once water is added to cement.” The scientists add that, “It’s all seemingly down to a process called dissolution-precipitation, so-called because the sticky C-S-H compounds dissolve in some areas of the concrete, while they are precipitated (or deposited) in other areas.”
Since concrete is the most widely used construction material in the world, a better understanding of creep will give researchers an opportunity to create concrete that minimizes creep. A more durable concrete is good for the industry as well as the environment.
At The Conco Companies, we are one of the leading concrete contractors in the Western U.S. and offer a wide range of quality services and products. Our experience includes providing services for commercial, educational, parking and other construction development as well as public works projects. We serve California, Washington State, Oregon, Colorado and Nevada.