How to correctly add water reducing agent and coagulant to mixed concrete

I plan to do an experiment on fast-hardening concrete. If I add water-reducing agent and retardant, how should I add them? I looked up the literature and it said that they should be mixed with water. It is said that the two should be added separately for the best effect. How should it be added, when should it be added, and how should it be added separately. Please ask professionals to answer.

For laboratory testing, the water-reducing agent and retarder are generally mixed with the mixing water first, and then added to the concrete mixture.

In concrete production, retarder is usually compounded with water-reducing agent (a job done by admixture supply companies) and added directly to the concrete mixture. This can ensure the metering accuracy of the retarder (the dosage of the retarder is smaller), and also simplify the types of additives added in production. It is unreliable to say that adding retarder separately is effective. Unless it is some special or new retarder that needs to be added separately, I have not seen it yet.

First add the two admixtures into the water and disperse them evenly, then introduce the aggregate and glue materials into the mixer, turn it on to pre-mix, and then turn it on to stir. , add while stirring, at a constant speed, and do not pour it on the shaft of the mixer, otherwise the admixture will stick to the top and cannot be stirred, resulting in a certain error. Rapid hardening and retarded setting are two completely opposite effects. For fast hardening, early strength agent or quick setting agent should be used.

When making fast-hardening concrete, you don’t need to add a retardant. You can add an early strengthening agent and a water-reducing agent. If the admixture is a powder, you can add it with the adhesive and mix well. Then add water and stir. If it is a liquid admixture, it can be added and stirred together with water after the aggregate and rubber materials are mixed. When making concrete, you don’t have to think about what to add first and what to add last. The water-reducing agent delivered by the manufacturer has already been mixed. You only need to add it according to your dosage. There are two types of water-reducing agent: 1. Standard type 2. Retarding property</p