Discuss plasticizers and superplasticizers, indicating their purpose. Name some products and their dosage for use as plasticizers and superplasticizers.
PLASTICIZER :- Plasticizers is used mainly to fluidity the mix and improve the workability of concrete, mortar or grout. Plasticizers are high range water – reducers. When plasticizers are used they get absorbed on the cement particles and form a thin sheath. This thin sheath inhibits the surface hydration reaction between water and cement.
SUPERPLASTICIZERS:- They are high range water reducers used for producing self compacting self strength and high performance concrete.
What are flaky and elongated aggregates? How can the shape of aggregate influence strength of concrete? Following is the result of a sieve analysis of 500 gm aggregate:
| IS sieve size | 10 mm | 4.75 mm | 2·36 mm | 1·18 mm | 600 micron | 300 micron | 150 micron | lower than 150 micron |
| Weight retained in gm | 0 | 10 | 50 | 50 | 95 | 175 | 85 | 35 |
Find out the 'Fineness Modulus' of the sample
How standard consistency test is done on cement? Explain the procedure briefly.
Short notes on :
Differentiate between creep and shrinkage of concrete.
Give the physical characteristics of 53 grade OPC.
Write notes on Mixing and Mixer machines of concrete.
