Is it possible to used two types of admixture in a concrete mix? example; adding retarder+superplasticizer admixture during hot weather concreting.

Hi Lloyd Milla, Sorry for late reply.

Super-plasticizers: The admixtures are used in concrete mix to reduce water/cement ratio and improve workability of concrete mix.

Retarders: These admixtures are used to retard the hydration process of cement in the concrete mix. The cement hydration process depends on the content (amount) of C3A in cement. The higher the C3A content of cement the more the heat of hydration which makes the hydration process faster, so if you want to retard it, either you use type of cement which has lower C3A content OR use retarder in the cement mix.

YOU can use both these admixtures at one time since their reactions in concrete mix do not over-lap each other. The best thing would be to ask the manufacturer of these admixtures like BASF, SIKA, GRACE etc., of the percentage (amount) of each admixture to be added and any further information on the use of these admixtures.

Also check the Standards (ASTM, EU Norms or BS) you are using for this combination.

Regards

according to astm c-494 already the classification of admixtures contains super  plasticizer and retarder , piasticizer and retarder , plasticizer and accelerator,......etc. .so all the range is covered and all the companies which produce these products have this range , so you can use both in one batch but you should return to the company which supply this material to get an accurate mix design and also accurate timing of addition  

Yes dear absolutely no problem but you need to confirm the effects on concrete by doing trial mixes to check compatability of the admixtures

sure, it can be used but compatibility of admixtures should be checked thoroughly by trial mixes