Sika® Retarder-21

Sika® Retarder-21 follows the requirements of ASTM C494; Type B and EN 934-2

Selected phosphates

12 months from date of production if stored properly

Store in undamaged, unopened, original sealed packaging in dry conditions at temperatures between +5 °C and +45 °C. Protect from direct sunlight and frost.

~1.09 kg/l (+25 °C)

The standard rules of good concreting practice for production and placing must be observed when using Sika® Retarder-21 in concrete. Refer to relevant standards.
Fresh concrete must be cured properly especially at high temperatures in order to prevent plastic and drying shrinkage. Use Sika® Antisol® products as a curing agent or apply wet hessian.

Sika® Retarder-21 may be combined with all types of Portland cement (OPC and SRC), concretes containing pozzolanic materials such as GGBS, PFA, micro-silica and the following Sika products:
Sika® ViscoCrete®, SikaPlast® and Sikament® ranges;
SikaPump®, Sika® FerroGard®-901, SikaFume®, SikaFiber®, Sika Aer®, Sika® Stabilizer, Sika®-1 WT, Sika® WT-10
We recommend to perform trial mixes to establish the required performance when combining Sika® Retarder-21 with the above products or other admixtures. Please consult our Sika Technical Department.

Sika® Retarder-21 is added to the gauging water or simultaneously poured with it into the concrete mixer at the batching plant.
Do not add Sika® Retarder-21 directly to the dry mix.
For optimum utilization of its high water reduction property we recommend thorough mixing at a minimal wet mixing time of 60 seconds.The addition of the remaining gauging water (to fine tune concrete consistency) may only be started after two-thirds of the wet mixing time to avoid surplus water in the concrete.

0.2 - 1.5 % by weight of binder.
Higher dosages by weight of binder can be used depending on the mix design, raw materials, climatic conditions and concrete requirements.
Trial mixes must be performed to establish the exact dosage rate required.