Concrete is by definition is the composite material composed of cement, aggregates, and water that are bonded together with a fluid cement that hardens overtime. Concrete holds everything in place like the water for the dams and soil stack for retaining walls. Several mixtures are now widely accepted depending on the strength requirements of the structure.
Generally, slab on grades may be designed with strength lower compared to suspended slabs. Also, the concrete constituents are the bars to be raised or lowered depending on the budget. There are various techniques available and widely accepted to attain certain design strength by merely getting proper water, cement and aggregates ratio. And to obtain the output of quality and good concrete to be used on
Thus, it is important to understand what the concrete constituents are.
The heart of concrete lies in the cement. The calcium silicate which is the main component of cement reacts with the water that forms hydrates. This is the primary cause of concrete setting. Several tests should be performed to determine the characteristics of cement and its compatibility with other materials in the concrete mix design.
Read Also: Concrete Concepts and Its Importance
May be fine (sand) and coarse (gravel). Depending on the availability, it is preferable that the aggregates come from only one source for the concrete to be homogenous. There are certain ratios that are followed on the mixture of aggregates to cement to attain certain strengths and meet budget. For course aggregates, common sizes are 20mm ( ¾”), 10mm (½") and 5mm (⅛") and 1mm sand usually used for the structures such as beams, slabs, column, and girders while G-1 gravel with sizes up to 1-1/2” are used for gravel beds.
The dihydrogen oxide is necessary for the chemical reaction needed to make the concrete harden. This is also used for the viscosity and workability of the concrete. It has to be clean and free from excessive oil, acid, alkali or any organic material so as not to add any impurities to the reaction with the cement. The water needed is potable.
These are additional substance that may or may not be added to concrete. They are just used to maximize concrete workability, control setting and provide additional cementing properties. The most commonly used are the retarder and accelerator. Retarder and accelerator are used for controlling the setting time of concrete. This is relevant so one can estimate and regulate how much time needed to get the concrete placed and finished. It also able to increase the strength of concrete.
Read Also: Concrete Curing: How It Is Done?
There are cases that you need to replace an optimal percent of Cement. Like for the purpose of enhancing permeability and absorption of concrete. So, in this case, you will replace that percentage with Microsilica or Ground Granulated Blast-furnace Slag (GGBS) whichever is adaptable.
Concrete has to attain certain design strength depending on the design specifications. It is usually achieved through the process of curing to promote further adhesive bond to get the target design strength at the perceived time. Liquid curing is by far the most common type of curing. This is done by spraying the casted concrete with clean water at certain time interval. For vertical structures like column, sheet material or burlap cloth are also used to cover the structures to cover the surface of the concrete to inhibit moisture loss.
Preformed expansion joint. This is used for roads and bridges concrete terminations. Expansion joint filler materials should be bituminous fiber type. Materials such as expansion joints are used so concrete may safely expand or shrink as temperature varies. This also absorbs vibration for movements and or earthquakes.
Waterstops. For underground tanks such as sewage treatment tanks to prevent liquid leakage.
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| Concrete Cube 150mm |
Generally, slab on grades may be designed with strength lower compared to suspended slabs. Also, the concrete constituents are the bars to be raised or lowered depending on the budget. There are various techniques available and widely accepted to attain certain design strength by merely getting proper water, cement and aggregates ratio. And to obtain the output of quality and good concrete to be used on
Thus, it is important to understand what the concrete constituents are.
1. Cement
The heart of concrete lies in the cement. The calcium silicate which is the main component of cement reacts with the water that forms hydrates. This is the primary cause of concrete setting. Several tests should be performed to determine the characteristics of cement and its compatibility with other materials in the concrete mix design.
Read Also: Concrete Concepts and Its Importance
2. Aggregates
May be fine (sand) and coarse (gravel). Depending on the availability, it is preferable that the aggregates come from only one source for the concrete to be homogenous. There are certain ratios that are followed on the mixture of aggregates to cement to attain certain strengths and meet budget. For course aggregates, common sizes are 20mm ( ¾”), 10mm (½") and 5mm (⅛") and 1mm sand usually used for the structures such as beams, slabs, column, and girders while G-1 gravel with sizes up to 1-1/2” are used for gravel beds.
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| Course Aggregate 20mm (3/4") |
3. Water
The dihydrogen oxide is necessary for the chemical reaction needed to make the concrete harden. This is also used for the viscosity and workability of the concrete. It has to be clean and free from excessive oil, acid, alkali or any organic material so as not to add any impurities to the reaction with the cement. The water needed is potable.
4. Admixtures
These are additional substance that may or may not be added to concrete. They are just used to maximize concrete workability, control setting and provide additional cementing properties. The most commonly used are the retarder and accelerator. Retarder and accelerator are used for controlling the setting time of concrete. This is relevant so one can estimate and regulate how much time needed to get the concrete placed and finished. It also able to increase the strength of concrete.
Read Also: Concrete Curing: How It Is Done?
5. Cement Replacement
There are cases that you need to replace an optimal percent of Cement. Like for the purpose of enhancing permeability and absorption of concrete. So, in this case, you will replace that percentage with Microsilica or Ground Granulated Blast-furnace Slag (GGBS) whichever is adaptable.
6. Curing Materials
Concrete has to attain certain design strength depending on the design specifications. It is usually achieved through the process of curing to promote further adhesive bond to get the target design strength at the perceived time. Liquid curing is by far the most common type of curing. This is done by spraying the casted concrete with clean water at certain time interval. For vertical structures like column, sheet material or burlap cloth are also used to cover the structures to cover the surface of the concrete to inhibit moisture loss.
7. Other Concreting Materials
Preformed expansion joint. This is used for roads and bridges concrete terminations. Expansion joint filler materials should be bituminous fiber type. Materials such as expansion joints are used so concrete may safely expand or shrink as temperature varies. This also absorbs vibration for movements and or earthquakes.
Waterstops. For underground tanks such as sewage treatment tanks to prevent liquid leakage.
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