Concrete is a material made from cement, aggregates (rock and sand), water, and admixtures (chemicals that enhance or modify the properties of concrete). Concrete is one of the most widely used and versatile building products known to man.
Cement, or Portland cement , is a dry powder made from limestone and other materials. It is burned in a kiln and then ground finely. Cement reacts chemically with water to cause concrete to harden. There are several different types of Portland cement, designated as Type I, Type II, etc.
Ready mix, also known as ready mixed concrete, is a type of concrete that is delivered in trucks that agitate and/or mix the concrete on the way to the job or at the job site. The concrete is delivered in a plastic, unhardened state.
Cement is an ingredient in concrete. It is the ingredient that forms a paste with the water, sand, and admixtures and fills the space between the coarse aggregates (rock) and binds the rocks together. The term "cement" is commonly misused to refer to concrete.
Flyash is a byproduct of coal-burning power plants. When used properly in concrete, it improves the quality of the mix and saves money. Concrete with flyash will typically have a higher ultimate strength, although early strength will be lower than with straight cement. Sometimes users will complain about "too much flyash in the mix." That is rarely the problem. More often the problem is not enough cement in the mix.
First of all, you do everything you can to prevent that from happening. If it happens anyway, then you get inside the mixer drum with an air hammer and break it out. It is a difficult job and nobody likes to do it.
Normal weight concrete weighs about 4000 lb. per cubic yard. Lightweight concrete weighs about 3000 lb. per cubic yard.
If a truck is carrying 10 cubic yards, then the weight of the concrete is 40,000 lb. The truck will weigh approximately 26,000 lb. for a total of 66,000 lb.
Finishing is the process used to create the surface texture of the completed concrete pour. Finishing involves several different steps. Depending on the type of surface desired, it can involve striking off, floating, edging, jointing, troweling, texturing, and curing.
It depends. Concrete will not set when the concrete temperature is below about 35F. Many times specifications will say something like "Concrete may not be poured when the temperature is 37F and falling." With heated water and aggregates, accelerating admixtures, and other methods, jobs can be poured below freezing, but it is more expensive. In most southern states there are so few freezing days that it is not worth it to try to pour when the temperature is below freezing.
It depends. High temperatures (90F and above) cause concrete to set faster. High temperatures also reduce the strength of concrete. Strong winds and low humidity can also cause problems with plastic shrinkage and drying shrinkage cracks, even at moderate temperatures. To avoid these problems, planning, timing of the finishing operations, proper use of retarding admixtures, and proper curing are necessary.
