If too much concrete retarder is used, can accelerating agent be used?

Mainly for night construction of building construction

I found on the Internet: "Construction units can also use Retarders and accelerators are used to adjust the setting time of concrete to avoid disturbing the noise of night application. The use of these two agents has no impact on the quality of concrete."

How are these two things added to concrete to adjust the concrete setting time?

For example, the construction unit said they would do construction at night because the concrete company (which uses commercial concrete instead of self-mixing here) arranged for them to be at night, and if they The construction site is in an environmentally sensitive area. Can these two chemicals be used to adjust the pouring construction time to daytime? Is there anything unfeasible in the process?

When the concrete company delivers the concrete by truck after 10pm, can the retarder be added to the truck and wait until after 6am the next morning? Formal pouring construction?

Or the construction unit will start pouring during the day and it is estimated that it will be around 12 o'clock at night. Can an accelerating agent be used to speed up the construction so that it can be done before 10 o'clock at night? End of construction?

Then how do I estimate the time required for pouring based on the area of the floor that needs to be poured? I saw a timetable in the concrete pouring construction process standard,

"The time from when the concrete is unloaded from the mixer to the completion of pouring (MIN)"

Concrete strength grade air temperature (℃)

Below 25 Above 25

<C30 120 90

>C30 90 60

For example, I don’t know how many cubic meters (or other units) the time is calculated in per unit. For example, if the strength level is less than C30, when the temperature is lower than 25 degrees, how much concrete is needed to pour in 120 minutes? time?

First of all, regardless of the effect of the retarder, the commercial concrete you mentioned at 10 o'clock in the evening will not be poured on the floor during the day the next day. aspect doesn't work. Concrete pouring is usually transported to the floor by pumping or tower crane. If the cubic volume is small (less than 10 cubic meters), it can be manually transported twice and leveled. The cost will increase, but it is also difficult for you to store concrete on site.

In addition, the retarder can generally extend the time by 2-3 hours. If the concrete is left in the open for too long, it will lose moisture and affect the quality of the concrete. If too much retardant is added and the concrete cannot solidify, or the time exceeds 6 hours, it will be counted as a quality accident.

The above pouring time is the time before the initial setting, and it has nothing to do with the amount. After 120 minutes, the concrete will reach the initial setting time. After entering the initial setting time, the concrete will Disturbance is prohibited. Adding a retarder can delay the initial setting time.

Retarders can generally extend the time by 2-3 hours. If the concrete is left in the open for too long, it will lose moisture and affect the quality of the concrete. If too much retardant is added and the concrete cannot solidify, or the time exceeds 6 hours, it will be counted as a quality accident.

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