Concrete is one of the most ubiquitous construction materials on the planet – and for good reason. It is incredibly durable and versatile, and is composed of materials that are readily available and often local. The production of concrete is a relatively simple process: the ingredients are mixed together and, through the ensuing chemical reaction, solidify.
Concrete is formed when hydraulic cement reacts chemically with water and binds with a blend of aggregates. This reaction, called hydration, causes the concrete mixture to harden and continues as long as there is free moisture to react with the cement.
This hydration stage is called “curing”. Curing can continue on a minute level for months, even years, but most concrete substantially cures in 28 days. During this time concrete gains the bulk of its strength and loses most of its moisture content to the chemical reaction and to evaporation.
For aesthetic concrete (such as fire pits, mantels and tiles), the initial 28-day cure is of particular importance as this is when the concrete will undergo a change in appearance – from a darker, wet-looking surface to a lighter, dry one.
This is also the time when the concrete’s true color, with all of its nuances, reveals itself. Concrete cured for at least 28 days is not only stronger than younger or “greener” concrete, but it is more aesthetically stable.
Proper curing depends on the application of consistent and appropriate temperature and humidity and is crucial to the performance of the final, hardened product.
Keep in mind that proper cure time is essential to the creation of a quality hand cast concrete product. Your patience is part of the recipe for a lifetime of function and enjoyment from your hand cast concrete fire feature.