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Cemairin® Block R20

Integral water repellent admixture for blocks and concrete masonry units

Cemairin Block R20 is a water-based, ready to use integral concrete waterproofing admixture specially designed for use in concrete masonry units and provides easy to use product that imparts water-repellency.

Cemairin Block R20 also provides manufactured low slump concrete with improved compressive strength and absorption properties, as well as improved “machinability” or ease of manufacturing units.

Cemairin Block R20_TDS_1.pdf
Cemairin Block R20_SDS.pdf
  • Reduces capillary water absorption.
  • Minimizes the risk of efflorescence and dirt pick-up.
  • Provides a better color intensity and uniformity.
  • Reduces the growth of algae and fungi on concrete surfaces.
  • Enhances physical properties such as compressive, flexural and tensile strength.
  • Improves the colour shades and thus reduces the needed pigment dosages.
  • Highly alkaline resistant.
  • Provides a better demolding and sharper edges.
  • Reduces chloride diffusion.
  • Improves workability.

Cemairin Block R20 is used to provide water repellent concrete masonry units (CMU). The product is used in conjunction with Cemairin Block M to provide a system of water repelling CMU and mortar offering long lasting resistance to water penetration.


Cemairin Block R20 is available in 5 gal (19 litre) containers as well as 275 gal (1,041 litre) IBC totes. Bulk supply in tanker trucks is also available upon request.


Cemairin Block R20 should be stored under cover at a minimum ambient temperature of 41°F (5°C).
Cemairin Block R20 has a minimum shelf life of 12 months from date of manufacture if stored in good conditions and sealed drums.


The recommended dosage of Cemairin Block R20 is 5 - 25 fl oz/100 Ib (325 - 1,600 ml/100 kg) of cement or cementitious materials in the mix including GGBFS, PFA or micro-silica.

Cemairin Block R20 should be added after adding the final needed amount of water to the system. And allow for 2 minutes mixing time.