Understanding Concrete Construction

How Concrete Is Made

Concrete is a mixture of several materials combined to create one composite building material stronger than all the individual materials alone.  Most concrete mixtures is made up of three ingredients; cement, water, and aggregate.  Depending on the load requirements or the strength needed, steel reinforcing bars can be added to the mixture.  Cement is used as the binder that sets, hardens, and adheres other materials together, such as the aggregate.  The aggregate that is set, hardened, and adhered is typically made up of sand and gravel or crushed stone.  During the production of concrete all of the ingredients are batched and the cement, aggregate, and water are added together and loaded into concrete trucks.  The concrete trucks are equipped with revolving mixer that allows the truck to keep the concrete agitated while it's being transported.  Without the mixer, the concrete would begin to cure and harden while it's being transported.

Concrete Over The Years

Forms of concrete date all the way back to the Pyramids of Giza, where ancient Egyptians used a concoction of mud, water, and straw to produce the building material.  Later, in the 1st century BC, the Romans began using concrete to build many of their icon structures such as the Pantheon and the Colosseum.  After the fall of the Roman empire, the use of concrete in any meaningful way decreased significantly until the 18th century when hydraulic cement was created and used during the construction of most sea walls and bridges.  Then, in 19th century, Portland Cement was created, which is a combination of different limestones and additives, such as trass and pozzolanas.  Portland cement is the most common type of cement used in concrete mixtures today.  From then, the strong and workable material began to grow in the number of uses across the construction industry.  Everything from sewer systems to skyscrapers would eventually see concrete as their primary building material.  Lastly came the innovation of reinforced concrete.  Using steel bars laid properly in the concrete can significantly increase the structural capacity of the concrete.  This is what most modern roads, bridges, and buildings are made of today.

How to Pour Concrete Properly

First, it's important to properly clear the surface where you are about to pour concrete.  Remove any grass, trees, rocks, or old concrete and get the surface as level as you can.  Once your surface is prepared, you can lay your subbase which is typically open-grade stone.  Then you need to tamp the subbase to make sure the subbase as well as the surface is compact tightly to prevent movement or craters occurring over the concrete.  Next, you will lay out your perimeter using wood pieces fixed to the ground with stakes.  Be sure your perimeter forms have a slight slope to them so water can properly grade off the surface.  Depending on what the concrete surface is for, at this point you can install rebar to reinforce the concrete if you're building a driveway or anything else that needs to bear a heavy weight.  If you're just pouring concrete for a back patio, the reinforcement is not necessary.  Once the site is prepared, you will need to begin mixing your concrete, but combining the ingredients; cement, sand, & aggregate.  Be sure to check what ratios you want to mixture to be based on what you're using the concrete for.  Once the concrete is mixed you can begin pouring it into the site that you've prepared.  While the concrete is still wet, you can begin flattening it using a screeting tool until it's mostly level with your perimeter form.  While the concrete is still curing, you will want to use a bull float to begin floating the surface making it even smoother.  Then, depending on how large your site is, you might want to add control expansion joints every 6 feet or so.  As the concrete begins to dry and cure more, you will use a broom to create some traction and grip on the concrete surface so it is not too slippery when it is wet.  Lastly, you need to seal the concrete to help it cure fast, and prevent cracks and discoloration.  Then your concrete pad is ready to enjoy.