Pages Navigation Menu

3 Benefits Of Using Preplaced Aggregated Concrete In Bridge And Dam Repair

The use of preplaced aggregate concrete, also known as PAC, is a well-known concept. It is a method of placing concrete that has been around for many years. However, using PAC to repair underwater bridges and dams has only recently become commonplace. There are a variety of advantages to using PAC in bridge and dam repair:

Less Cracking

When placing PAC, a higher ratio of aggregate to cement is achieved due to the process in which it is placed into the formwork. The aggregate is put into the form, and then the grout is injected in increments. This can significantly reduce the amount of shrinkage that would normally occur in traditional repair methods. The reduced shrinkage leads to a higher bond with the concrete surfaces that are already present in the structure. This higher bendability and reduced shrinkage results in a structure that will be less likely to crack.

Stronger Repair

When a formwork is submerged in water, whether it is a partial submersion or full, PAC prevents the materials from becoming separated. After the aggregate is placed, the process of grout injection starts at the bottom of the form. It then progresses upward at different injection points. Water that is trapped in the formwork is forced out and is replaced with the grout. This process will result in fewer open spaces between the aggregate. This will ultimately result in a much stronger repair to the bridge or dam columns.

No Heavy Equipment Required

There is no heavy equipment needed to place preplaced aggregate concrete. This is a significant advantage, largely due to the cost of equipment and labor. Instead, the aggregate is washed into place by using a sluice pipe. A grout pump is used to place the grout. In addition to a cost savings, the lack of heavy equipment allows for easier access when repairing small bridges, piers, or dams. The minuscule amount of equipment used for PAC placement can be left on the banks or shore of the area that is being worked on while the grout and aggregate is funneled through the pipe and grout hose.

Typical concrete is placed as a cement and grout mixture, while PAC and grout are placed separately. Preplaced aggregate concrete is placed in separate steps, leading to a stronger build and repair to dams and bridges. If you will be working on a very old structure or one that is small in size, consider the benefits of using preplaced aggregate concrete, as it is an ideal option for many projects.

For more information about bridge and dam repair, visit websites like