You can say that the superplasticizers are an improved version of plasticizers. The workability of concrete can be increased by adding superplasticizers without adding very much water.
The mechanism and properties of superplasticizers are very similar to plasticizers. Researches state that the water content of concrete can be reduced from 15 to 30% without reducing the workability of concrete. So they are also called as high range water reducers.
They are developed in the 1960s in Japan and later in Germany. They can neutralize the surface charges. They can releases water in cement particles and causes dispersion.
Types of SuperPlasticizers.
- Sulphonated Malanie-formaldehyde condensates
- Sulphonated naphthalene formaldehyde condensates
- Modified lignosulphates
- Acrylic polymer
- Carboxylic acrylic ester
- Polycarboxylate ester.
- Cross-linked acrylic polymer.
These are the type of superplasticizers.
What are the effects of superplasticizers? ( Advantages and Disadvantages)
By adding superplasticizer and improved in the slump value is slump test can be improved. But the overdosage of superplasticizer will sometime harm concrete.
There are many compatibility problems happens while adding different types of cement with different superplasticizers. One type of cement may not be suitable for other types of superplasticizers.
The chosen superplasticizer and cement should give an optimum result with the least amount of superplasticizer. These are the advantages and disadvantages of superplasticizers
How to find the optimum amount of superplasticizer to be added to concrete?
There are three tests to find the optimum amount of superplasticizer for concrete. They are
- Marsh cone test
- Mini-slump test
- Flow table test
Marsh cone test is a reliable and simple method to study the rheological properties of mortar and cement.
In marsh cone test, the cement slurry is prepared and its flowability is measured. Out of the above three tests, marsh cone test gives the best value for flowability.
Flow time of cement slurry or mortar though marsh cone is an indicator of viscosity, which depends upon cement super plasticizer compatibility.
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