A concrete contractor in today's building game has only to look back 150 years to realize that, back then, concrete was little more than a novelty and only taken serious by a few forward-thinking people. Limestone, granite, bricks and sandstone blocks were the building materials during the Industrial Revolution and through to the later 1800's. Except for carpenters, stone masons and bricklayers were the most numerous of the trades plying their trades to residential homes, office buildings and factories.
From around the middle of the 1800's a new system of treating limestone quickly gathered popularity in the building trade. The Portland cement process pushed aside the old limestone and clay mixtures due to its ability to harden underwater. By reinforcing the concrete with steel, constructing bridges and buildings using the Portland cement-based concrete became the mainstay.
Today, this process is still being used although the mixtures and reinforcing designs have changed dramatically. Bridges and homes are now being constructed with concrete pieces that have been poured and cured at a different place than the building site. In addition concrete is demonstrating that it is still the material of choice for the world's tallest buildings.
The Concrete Process
Portland cement is the main ingredient in concrete. Joining this material is fly-ash and an aggregate of sand and gravel. Because of a chemical process called hydration the concrete hardens and forms a solid mass. However, this chemical change creates immense pressure that can cause the concrete to split. To combat this compression most structures are reinforced with steel, fiberglass or plastic to both absorb and withstand the forces.
Many concrete products are prepared with differing ingredients for a variety of uses. Accelerators speed up the hardening process while, conversely, retarders slow it down so that it cures evenly. Plasticizers allow the concrete to be more malleable while pigments can be added to color the mixture. So, in all, it is a very versatile material.
Ready Mix Concrete
The ability to manufacture a concrete mixture in controlled conditions and then transport it to the construction site made building large structures easier. Ready-mix concrete is mixed at a batching plant and then transferred to trucks which have rotary mixers to keep the concrete fresh until it can be delivered. This process had an immediate impact on the construction business because having a large area onsite to mix the concrete took up valuable construction space. In addition, it was difficult to get the exact mixture of cement and aggregates because these materials had to be imported to the site in the right quantities at the right time. With ready-mix concrete wastage was kept to a minimum and large labor crews for making concrete were not needed. However, since time is a big factory in the delivery of fresh concrete the plant could not be too far away.
The Tilt-Up Concrete Process
An offshoot of the concrete industry that takes ready-mix to the next step is “tilt-up†technology. Concrete is poured into forms, braced with reinforcing and allowed to dry. Then these pre-cast concrete panels are shipped to the construction site and put into place with cranes. Ornamental façades can also be molded into the panels so that finishing onsite is kept to a minimum.
Buildings constructed with tilt-up technology have proven this technique in natural disasters having withstood hurricane-force winds and earthquakes. And it goes without saying that the concrete walls are impervious to rot and vermin. As well the ability to bring in pre-constructed walls drastically decreases the time that it takes to construct a building. Multiple panels are manufactured at one time and then sent on a constant stream of transport trucks to the site so that there are no delays.
Concrete Driveways and Sidewalks
For the homeowner with a wood-frame building concrete is still the most popular material for sidewalks and driveways. (There is also a very good chance that the foundation of the home is made with concrete) One of the most popular concrete styles is exposed aggregate that highlights the small rocks and gravel in the mix. Usually a special aggregate of colored stones and concrete stain is put in the mix at the plant to make for a dazzling surface. This mixture is made into a concrete slab like it is with ordinary concrete and finished in the same way. Then after a couple of days of curing the installers apply a mild solution of muratic acid which dissolves away the top layers of small, sandy aggregate and cement. When the pad is hosed off with water the tiny particles are drained away leaving 1/2†of small rocks and gravel exposed. The pad is allowed to cure for a few weeks and then a coating of clear epoxy is applied which gives the driveway or sidewalk a beautiful sheen and protects it from salt, oil and other materials which can damage the surface of the driveway.
For more information on concrete projects consult our Contractors Directory or simply post your project online to get several professional opinions.
Posted by: TrustedProsSuggested Reading For You
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