Accelerated Cube Test and benefits

What is Accelerated cured concrete test?

An Accelerated Cured concrete test is a process of checking the specimen cube within 28 hours and determining the quality of the concrete. Structural consultants can get guidelines for this test on the IS 9013-1978.?

IS 9013 provides the guidelines for making, curing & testing in compression specimens of concrete stored under conditions intended to accelerate the development of strength.

Traditionally, the concrete quality is calculated after 28 days by compressive strength test. However, multiple specimens must be cast and cured in water for 28 days. CTM machine (Concrete Cube Testing Machine ) gives compressive strength. The tests on the 7th day are 60% greater than the target strength on the 28th.?

A disadvantage of this test is that by the 28th day, the concrete would have hardened. Another disadvantage is the concrete could also be under subsequent construction. It makes any rectification and rehabilitation difficult and impractical. On the other hand, concrete of excessive strength increases expenses due to the increase in cement. These reasons make the traditional 28th-day testing too late and not feasible for any corrective action.?

Benefits of ACT?

1. The ACT helps to achieve an early compressive strength of the concrete.?
2. It helps to provide faster project delivery.?
3. ACT helps in cost control by using optimum cement content.
4. Additionally, ACT also helps in deciding how to rectify bad quality work.?
5. In actual site conditions, accelerated curing reduces cost by reducing formwork removal time.?

Thus, the structure is functional at an early stage.

Methods of Accelerated Curing?

The standards provide for two methods:

1. For Quality-control purpose
2. For prediction of normal strength of concrete at later stages: Warm-water method?and Boiling-water method?

The boiling-water method is the most common method for accelerated curing.

How to Predict 28-Day Compressive Strength (R28) using Accelerated Compressive Strength (Ra)?

The predicted 28 days compressive strength?R28 = 8.09 + 1.64 Ra. Ra?is accelerated compressive strength, and?R28?is predicted compressive strength at 28 days.?