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With our experience building precast concrete fences and walls in California, we've become pretty comfortable with a good understanding of the concrete and cement business. Generally "concrete" and "cement" are not really the same product. Sidewalks and foundations are constructed from concrete, not cement, although cement is a vital and significant ingredient of concrete. There are other ingredients which may include gravel or crushed stone , sand, water and, other optional additives. The trucks you see that most people call cement mixers are actually concrete mixers.

The cement in concrete is known as Portland cement, because Joseph Aspdin, an English bricklayer who is credited with the invention of its, felt that its color was similar to that of limestone quarried on the Isle of Portland, a peninsula on England's southern coast. Aspdin got a patent for cement as far back as 1824. He used to heat limestone and clay in a kiln until parts of the mixture fused, then he ground the mixture into a fine powder. Adding water to the powder yielded a workable paste and started a complex chemical process, called hydration, in which the water bonded with compounds of calcium, silicon, aluminum and iron, and caused the whole thing to combine into a rigid mass. Wet Portland cement doesn't merely "dry," the way mud does; hydration transforms it into a chemically distinct material, which continues to gain strength over time.

Though concrete is very hard to crush, it's pretty easy to actually pull apart. A way to compensate for this tensile weakness (that means it's easy to break apart) is to add steel reinforcing rods, known as rebar, which hold the concrete in place overall when it cracks.

Another way to reinforce the cement is by adding threadlike fibers made of steel, polypropylene, polyolefin, and other materials-samples. Polypropylene is a good idea for an additional reason - it can provide extra fire protection. So by adding polypropylene fibers to the mix it can reduce the risk of such failures, because in high heat the fibers melt, leaving voids that act like relief valves for steam.