Structural Guide

Structural loads, structural analysis and structural design are simply explained with the worked example for easiness of understanding. Element designs with notes and discussions have added to get comprehensive knowledge. Also, construction materials, shoring system design, water retaining structures, crack width calculations, etc. have discussed in addition to other aspects. 

Concrete Curing Time | When to Start | How Long

Concrete curing time is very like the method of curing concrete. Selecting the right time for curing concrete and carrying out the suitable curing method for the required duration is very important.

What is the Curing of Concrete?

Curing is the process of supplying adequate moisture to the surface of concrete once it is poured and levelled. It will enable to completion of the hydration process.

In addition, we do curing to control the rise of the temperature in large concrete pours due to the heat of hydration.

When concrete is done in a cold environment, it is required to increase the temperature of the concrete to complete the hydration process.

When to Start Curing?

The start of the concrete curing time depends on several factors. Once the concrete is poured, we can start the concrete curing and also, there are some limitations related to the curing method.

Some curing methods such as laying covering over the concrete cannot be done till the concrete surface gets hardened up to a certain level.

Water curing can be started immediately after concrete starts getting hard. Therefore, concrete curing time depends on many factors. There are a few factors to decide how long concrete takes to dry the concrete.

  • Moisture in the concrete 

When there is higher moisture content, concrete gets delayed to harden. Lesser the moisture, the faster the hardening process.

We shall be careful with the moisture level. If the concrete gets dry also, the moisture level in the concrete surface drops. When the high wind is there, the concrete cold gets dry fast and as a result of that drying shrinkage cracks could occur.

  • Temperature

Temperature is an indication of how fast concrete gets dry. When the ambient temperature is high, concrete gets dry fast.  This shall be monitored and attention shall be made to decide to cure starting time.

  • Mix Design

Mix design significantly affects the starting point curing of concrete. Curing time can be assessed at the site and judgement shall be by the site engineer.

How long it will take as Concrete Curing Time 

The following figure taken from the internet indicates the strength gained against the curing period.

concrete curing time

The summary of this study is as follows.

  • If we do the curing, the strength of the concrete does not increase after a certain level.
  • There is a considerable difference between 7 days curing and 28 days curing. However, the difference is constant and it is not significant.
  • Carrying out curing for a year, there is a very high increase in strength.

Practically, extending concrete curing time for a year is not possible. Therefore, we have to agree on selecting the most suitable period for curing.

In general, concrete gains most of the strength, 70-80% of characteristic strength, within 7 days of concreting. In this background, usually, curing is done for 7 days.

However, for larger concrete-like very high volume concretes, the curing period shall be determined based on the data obtained from a mockup test. We can obtain the variation of the temperature with the time from this test. If there is no considerable drop in the temperature after 7 days, the curing period shall be extended.

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