Sustainable Concrete Through Curing

Sustainable is defined as "capable of being continued with minimal long-term effect on the environment." Concrete has been used as a building material for over 3000 years and is one of the world's most sustainable building materials. It is continually undergoing postmodern developments due to its versatility and lack of limitations.

A primary building block toward sustainable concrete is proper curing technique. Curing's influence on the properties of hardened concrete include durability, strength, water-tightness, abrasion resistance, volume stability and resistance to freeze/thaw.

There is a chemical reaction that occurs when you mix water and cement. It is a two stage process:

1.The first stage happens quickly when concrete forms a liquid to a solid state, usually within four hours.

2.The second stage begins as reaction slows down, but crystals continue to grow and the concrete gets stronger. This is where curing comes in; for this reaction to continue (and concrete to continue gaining strength), concrete needs optimal water retention.

There are several ways to stop water from leaving freshly poured concrete. We frequently see tarps covering slabs, often secured by duct tape and concrete chunks. These tarps will often blow loose during a strong wind gust. While this may seem to be an easy and economical solution, it is important to focus on the life-cycle costs of maintaining the structures we have worked hard to design.

One of the simplest and most effective methods to cure concrete is by using a curing compound. Curing compounds are typically made from waxes, acrylics and various resins. These cures form a watertight film that prevents water from evaporating from the concrete. The key is to apply the curing compound when the concrete product is damp but without standing bleed water.

Dissipating resins are among the most popular cure because they chemically break down over time when exposed to traffic, weather and ultraviolet light. These cures allow easy removal before a subsequent floor coating or covering is installed. Some curing compounds contain a white pigment to reflect sunlight and keep outdoor concrete cooler. The pigment also allows for a visual inspection of coverage.

Generally, curing compounds do not provide any long-term protection or enhanced appearance to concrete. "Cure & Seals" are used in the same ways as curing compounds, but have the added benefit of imparting a lasting seal on the concrete surface. These products can be reapplied when traffic or weather wear away the protective seal and diminish its effectiveness.