The science to mixing concrete seems simple enough to the layman. It would, however, be a folly to think there is nothing to it. In fact, there is much that goes on as soon as water, aggregates and concrete are combined. Through this process, the malleable wet mix that hardens to a strong and durable surface is used to build everything from sidewalks to skyscrapers.
What’s the Difference?
Despite a generally interchangeable use of the terms concrete and cement, concrete is mixed using cement along with water and then adding an aggregate of sand and gravel or crushed stone. Portland cement is the fine powder that mixes with water to form a paste, which is used to cover and fill the voids existing within the coarse aggregate. A typical concrete mix consists of 15 to 20 percent water, to 60 to 75 percent aggregate material to about 10 to 15 percent cement powder.
The Chemical Reaction
Through the process of hydration, the treatment of adding the proper ratio of water to cement, a chemical reaction occurs. The transition from powder to paste causes the cement to gain its strength. Depending upon the ratio, the quality of concrete is determined. Without the workability of fresh concrete suffering for it, the water content may be lowered to produce a higher quality concrete. Ultimately, proper placement, consolidation and curing will determine the outcome.
The quality of the water and aggregate play a significant role as well. Water possessing excessive impurities affects both the time it takes to set-up and the strength of the concrete. While aggregates need to be clean and free of matter that may negatively affect the outcome, properties such as solids, sulfates, chlorides and alkali content in the water may be responsible for staining, reduced durability and volume instability. In addition, reinforcement materials risk corrosion and finished surfaces could suffer efflorescence evidenced by the powder incrustation as it dries.
Curing and Hardening
The chemical reaction or hydration process continues to occur beyond the curing time of concrete. In the early stage of pouring and placement, concrete is transforming from sludge to a solid. There is a period of time where it is possible to draw lines as is done by famous Hollywood stars who set their hands or footprints and signatures in the cement squares on TCL Chinese Theatre on Hollywood Boulevard in Los Angeles. Other lines and marks are made in construction concrete while it is curing for structural purposes, such as expansion and contraction.
What many people may not realize is that the hardening process of concrete is a constant one. The apparent stage of hydration and strength gain occurring within the first month makes it seem as though the work is done. Though the rate of hydration slows, realistically, it continues for years, and the concrete continues to gain in strength the older it gets.
Concrete finishers take into consideration the volume of material especially when it involves epoxy joints, for example. The stress applied to the material must not come before sufficient curing to avoid the potential for hairline fractures that can undermine the integrity of the joint, which can lead to structural failure. You can see why it is so important to understand the basics of concrete and how it works.
This article was written together with Billy Dunham, a home improvement expert who looks forward to helping you have an even better home. He writes this on behalf of Allied Outdoor Solutions, your number one choice when looking for concrete coating in Houston. Check out their website today and see how they can help you!