WATERPROOFING ADMIXTURES FOR CONCRETE

Waterproofing admixture for concrete is also called as water resisting admixture and permeability reducing admixture. These admixtures prevent the passage of water through hardened concrete under a pressure head.Water is an essential part of concrete construction from the mixing of concrete to the curing of concrete. But once the...

CONCRETE ADMIXTURES – SELECTION AND APPLICATIONS

Concrete admixtures are used to enhance the properties of concrete for applications in concrete works with special requirements. Concrete admixtures are used to modify the properties of concrete to achieve desired workability in case of low water cement ratio, and to enhance setting time of concrete for long distance transportation...

CONCRETE CHEMICALS AND APPLICATIONS

Concrete Chemicals (Admixtures) and ApplicationsAdmixtures are materials other than cement, aggregate and water that are added to concrete either before or during its mixing to alter its properties, such as workability, curing temperature range, set time or color. Some admixtures have been in use for a very long time...

FACTORS AFFECTING CONCRETE ADMIXTURES PERFORMANCE

The various factors which affect the performance of concrete admixtures are: 1. Type of super-plasticizer: The admixture will be more effective if molecular weight of the super-plasticizer is high. 2. Dosage: The quantity of admixture should be optimum. Excess of admixture may cause segregation or...


ADVERSE EFFECT OF CONCRETE ADMIXTURE

Adverse effects due to improper application :Admixtures are used extensively to produce high workable, high strength high performance and highly durable concrete with minimum cost. However, these admixtures are not used judiciously and with the poor knowledge of admixture among engineers at site results in the following adverse effect...

STANDARD CODES FOR CONCRETE ADMIXTURES

Standard Codes for concrete admixtures: Admixtures used should conform to the following relevant  standard codes. In reinforced concrete, the chloride ion of any admixture used should not exceed 2% by weight  of the admixture as determined in accordance with IS:6925 and the total chloride ion in...

PROPERTIES AND USES OF CONCRETE ADMIXTURES

What are Concrete Admixtures? Ingredients other than cement, water, and aggregates that impart a specific quality to either plastic (fresh) mix or the hardened concrete (ASTM C496) is called concrete admixture. Why use Concrete Admixtures?1. Reduce cost of concrete construction2. Achieve specific concrete properties more effectively3. Ensure quality...

FUNCTIONS OF CONCRETE ADMIXTURES

Concrete admixtures are added to change the properties of concrete to make it function as required. Admixtures are used to modify properties of both fresh and hardened concrete as discussed below: Functions of admixtures to modify fresh concrete properties: a) To increase workability without increasing water content...

ACCELERATING WATER-REDUCING CONCRETE ADMIXTURES

Accelerators increase the initial rate of chemical reaction between the cement and the water so that the concrete stiffens, hardens, and develops strength more quickly. They have a negligible effect on consistence, and 28-day strengths are seldom affected. Accelerating admixtures have been used mainly during cold weather when...

RETARDING WATER-REDUCING CONCRETE ADMIXTURE

Retarding water-reducing admixtures are chemicals that slow down the initial reaction between cement and water by reducing the rate of water penetration to the cement and slowing down the growth of the hydration products. The concrete therefore stays workable longer than it would otherwise. The length...

SHRINKAGE REDUCING CONCRETE ADMIXTURE

Shrinkage-reducing concrete admixture promote expansion of the concrete at about the same volume that normal drying shrinkage is contracting it. The net change in length of the hardened concrete is small enough to prevent shrinkage cracks. The typical materials used for shrinkage compensation in concrete are based on calcium...

CORROSION INHIBITING ADMIXTURES

Corrosion-inhibiting admixtures are not currently covered by EN 934 but are effective after the concrete has hardened and give a long-term increase in the passivation state of steel reinforcement and other embedded steel in concrete structures. The three most common generic types of corrosion inhibiting admixture are: ...

VISCOSITY MODIFYING ADMIXTURES IN CONCRETE

VISCOSITY MODIFYING CONCRETE ADMIXTURES Viscosity modifying concrete admixtures (VMAs) is a family of admixtures designed for specific applications. The European Federation for Specialist Construction Chemicals and Concrete Systems cites the following uses: Reduce segregation in highly flowable/self compacting concrete. Reduce...

HIGH RANGE WATER REDUCING ADMIXTURE

HIGH RANGE WATER REDUCING ADMIXTURE FOR CONCRETE High range water reducing admixture (ASTM C494 types F and G) decreases the water/cement ratio and provides high-performance, particularly at early ages. Matching the chemical admixture to the cementitious materials, both in type and dosage rate is important. Slump loss characteristics...