Ready Mixed Concrete or RMC is delivered to job sites in a ready-to-use manner. Traditionally, concrete is prepared at job sites. It requires a lot of labor and raises the possibility of human error. An adequately mixed batch of concrete is essential for the integrity of structures. Preparing concrete mixture at job sites cannot ensure every batch has the right proportion of cement, water, and aggregates. As a result, RMC was introduced in the construction industry as advanced technology, involving a high degree of mechanization and automation. Hence, every concrete batch has the exact proportions of ingredients certifying the best outcome.
Cement is the primary ingredient of concrete. So, concrete inhabits the properties of cement. Cement starts a hydration reaction after coming into contact with water. It is responsible for the hardening process of cement. Therefore, it is crucial to know the setting time of ready mixed concrete to work effectively. The setting time of concrete will determine how to schedule the task list in order to achieve the best results.
As mentioned earlier, concrete mainly consists of cement. Cement starts the hardening process when water is added to it. RMC is a mixture of cement, water, and aggregates. RMC is produced at batching plants where water is added to the dry mix of cement and aggregates. Hence, the cement is activated and starts the hardening process.
After a certain amount of time, the concrete will lose its effectiveness if not placed before it is hardened. The setting of RMC indicates its hardened state. The concrete batch will be considered waste if it gets hardened before being used on a job site. So, it is decisive to know when the concrete will be set.
However, RMC has a particular setting time compared to site mixed concrete. There are many differences between site mix concrete and Ready-Mix Concrete. The setting time can vary depending on the mixture type.
The setting time of RMC can be divided into two categories. These are 1) Initial Setting Time and 2) Final Setting Time. The concrete starts the hardening process as soon as the water is added to the cement mixture. RMC is transported via cement trucks. These trucks have rotating drums or vessels that carry the RMC. The RMC requires continual agitation and mixing while it is transported from the batch plant to the job site.
The initial setting time of concrete is around 210 minutes. So, the RMC must be used within 210 minutes after preparing in batching plants. It becomes a race against the clock to transport the RMC in due time. Sometimes admixtures are added to the concrete mix to delay its setting time to travel further distances. That is why local Ready Mix Concrete suppliers are crucial. The concrete trucks should be able to deliver within standard time, or the concrete will lose its effectiveness. Too much delay might make it completely useless.
Technically, concrete never stops the hardening process. Concrete continually hardens forever. However, it reaches a point where further hardening becomes incredibly slow and unnoticeable after a specific time. In standard industrial cases, full-strength concrete is accepted at 28 days. After a week, concrete gains 70% of full strength when appropriately cured. After the final setting time, the concrete mixture completely loses its plasticity. The concrete hardens and takes the shape in which it is cast. Any form or scaffolding can be removed after the final setting time. Concrete’s final setting time is generally 24 to 48 hours, depending on the conditions. At this point, it is safe to walk over the concrete without worrying about footprints. However, it would help if you kept it clear of heavy equipment during this time.
Source: Power Blanket
There are some factors you should take notice of that can influence the setting time of ready-mix concrete. These are:
Here is a list of essential aspects regarding concrete setting time:
The popularity of ready-mix concrete is gaining due to its many advantages. There are many advantages of using Ready Mix Concrete in Bangladesh as well. Big construction sites rely on the accuracy and consistency of concrete mixtures to build robust structures. However, if the workers are not educated about the setting time of concrete mix, your job site will experience a lot of waste and inefficiency. Hence, consult with your contractor to inform the workers how to deal with the concrete mixture. RMC is delivered via trucks, and your job site must expedite the delivery process. It will guarantee a safer workplace and scheduled construction work.
Ans: Typically, it takes 24 to 48 hours to dry enough for you to walk on it.
Ans: Ready Mix Concrete should be used under 210 minutes after leaving the batching plant.
Ans: Ask your contractor to order from local RMC suppliers. Otherwise, a long delivery duration might weaken the integrity of the concrete.
Ans: A good rule of thumb is that concrete takes approximately 30 days to dry for every inch of poured concrete.
Ans: Ready Mix Concrete gains around 65% – 70% strength in a week.