* is a construction material composed of cement and other cementitious materials such as fly ash and slag cement, aggregate, water, and chemical admixtures.
* Solidifies and hardens after mixing with water and placement due to a chemical process known as hydration. The water reacts with the cement, which bonds the other components together, eventually creating a stone-like material.
Concrete is used to make:
* Architectural Structures
* Parking Structures
* Brick Wall
* Block Wall
There are many types of concrete available, created by varying the proportions of the main ingredients below. By varying the proportions of materials, or by substitution for the cementitious and aggregate phases. The finished ...view middle of the document...
Aggregates – Fine and coarse aggregates make up the bulk of a concrete mixture. (slate, stone, gravel, rocks, boulders and sand)
Various Test Conducted
1. Slump Test – this method requires a fabricated metal with shape and dimensions.
2. Compression Test – is the process applied in determining the strength of concrete.
The process of mixing concrete for building construction is done in two different ways. It is either mixing on the job site or by ready mixed concrete.
Centralized Ready-Mix Plant
* Concrete of any desirable proportions and quality for numerous special purposes can be ordered directly from the ready-mix concrete dealers. The desired type and quality of concrete is delivered to the project site very rapidly.
* A ready-mix concrete is mixed by either:
a) In mobile mixers
b) In stationary mixers
* Mobile Mixing. Cement and aggregates are loaded in a mobile mixer at the batching plant and then mixing operation is done on its way to the job site.
* Stationary Mixing. The concrete is mixed before it is loaded inside the truck mixer where the concrete is only agitated.
* Hand Mixing. A good concrete can be produced also by hand mixing, provided that the fine and coarse aggregates are clean and well graded.
Depositing Of Concrete
* Concrete mixing requires adequate preparation of the steel reinforcement, various embedment thereat, strong forms, equipment and the materials required for the activities.
Segregation of Particles
* Segregation means the seperation of sand and stone from the matrix or paste resulting to an inferior quality of concrete.
* The hardening of concrete depends upon the chemical reaction between the cement and water. Hardening of concrete will continue as long as moisture is present under favorable temperature condition. The initial setting of concrete will start at about two or three hours after the concrete has been mixed.