Tests for Fresh Concrete | Building Construction

Tests for Concrete to be performed on site

Tests are held at 28 days, 7 days and 3 days. Constituent of mix should be such that concrete can be transported, placed and finished easily without segregation.

  • Workability – it is a property of fresh concrete and affects the finished product as it affects compaction.
  • Need for workability – Imparted by the amount of useful internal work necessary to provide full compaction.
Tests for Fresh Concrete
Tests for Fresh Concrete

Optimum water varies for different methods of compaction

  • i.e., more water – hand compaction – lower density
  • less water – mechanized compaction – higher density

If we add more water, the workability may increase may increase but core has more voids

  • 5% of more voids – reduces strength by 30%
  • 2% of more voids – reduces strength by 10%

The voids result due to –

The entrapped air voids are caused by grading of fine aggregate.

Excess water evaporating later excess – (water) voids are due to increase in workability

Aim should be to have maximum density – therefore for maximum compaction, you will have to have optimum water cement ratio, at which both the type voids are at minimum.

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