Why is water added to concrete at the construction site?
Concrete is an essential building material that we often take for granted. One crucial aspect of working with concrete is something called “jobsite addition of water.” It may seem like a simple concept in the concrete industry, but it plays an important role in ensuring concrete is poured, placed, and finished correctly to maintain the desired quality and performance of the concrete.
Jobsite addition of water is exactly what it sounds like – it involves adding water to the ready- mixed concrete in a truck mixer upon arrival at the job site, rather than pre-mixing it with the exact amount of water at the concrete plant. This process allows concrete professionals to adjust the water-cement ratio right at the location where the concrete will be utilized.
The primary reason for adding water at the job site is to adjust the consistency of the concrete. The ideal consistency depends on the specific project and the conditions at the construction site. Sometimes, factors like weather, transportation time, or unforeseen delays can cause the concrete mix to become stiffer than desired. Adding a bit of water on-site helps to bring it back to the right consistency for pouring and finishing. Environmental conditions, like temperature and humidity, can vary from one construction site to another. These conditions can affect how quickly the concrete sets and hardens. In hot and dry climates water might evaporate from the mix faster, making it necessary to add water onsite to prevent premature drying and cracking.
Additionally, concrete is a naturally time-sensitive material. Once concrete is mixed, there is a limited window of time during which it remains workable. If there are unexpected delays in transporting or placing the concrete, it can start to set before it is properly positioned.
As you will soon discover, adding water to concrete on the job site is a delicate process that requires careful consideration to maintain the desired strength and durability. When adding water at the job site in the concrete industry, it involves assessing the need, measuring water carefully, mixing it gradually while testing consistency, and keeping a record of the amount added for quality control. By understanding why and how water is added on-site, we can appreciate the careful considerations that go into the process of getting the mix just right.
To learn more about this crucial step in construction and how to properly add water to concrete at the job site, please see NRMCA’s Concrete in Practice 26 – Jobsite Addition of Water.
PDF courtesy of the National Ready Mixed Concrete Association, Silver Spring, Maryland. USA
Additional PDFs can be found on the NRMCA site for a variety of topics.