Our Spacer Standards

The reinforced concrete durability is merely achieved by protecting the steel reinforcement from environmental attacks. The level of that protection depends not only upon the quality of the concrete spacers but also upon the type and quality of concrete spacers that are utilized. The concentration of standards and specifications on improving concrete quality and durability has not been matched by improved spacer requirements.

BS, EN and DIN standards have clearly specified the spacer strengths and dimensional tolerances and their adoption improves concrete performance. Reflecting the recognition of how spacers can affect concrete durability, standards and specifications are now also including spacer durability properties that require them to match or exceed those of the host concrete.


Additional Characteristics

Due to environmental factors and application requirements, concrete spacers may need to meet quality requirements that exceed current spacer standards. To ensure that you always have the correct spacer, we can create special spacers to meet your requirements. These spacers are usually not stock items, they are produced based on your project requirements.


In many countries any products that come in contact with potable or drinking water require independent certifications of their suitability for use. Essentially materials in contact with the water must not deteriorate the microbiological condition of the water. ASTRO produces a range of approved spacers for such applications.

Drinking Water Applications


Fire resistance of structures and all structural elements is considered of core importance. Although small in size any burn out of the concrete spacer during a fire event is to be avoided. Every ASTRO made fiber concrete spacers are fire resistant to the highest requirements.

Fire Resistance


In most applications the water absorption of the concrete has a significant impact on the life and performance of the structure, particularly for those in contact with water. Spacers in such structures also need to be resistant to water absorption. ASTRO can produce concrete spacers with varying resistance to water absorption to meet your project needs and requirements.

Water Absorption


Chloride attack is very prevalent in marine environments and also in the presence of de-icing salts. Reinforcement not protected by concrete spacers of a suitable quality will cause premature structural failure. ASTRO produces spacers with chloride ingress values to match or surpass those of the host concrete, thus ensuring maximum structural durability.

Chloride Resistance


Structures exposed to chemical attack from sulfates, require special highly sulfate resisting spacers. In accordance with EN206-1 these spacers may be used for Exposure Classes XA2 ASTRO produces concrete spacers made from special mixes that fulfil the requirements of these exposure classes.

Sulfate Resistance


Fair faced concrete to the specified standards can be hard to achieve and can be negative influenced by the use of the wrong spacers and sealing cones. The range of concrete spacers includes different shapes to help minimize visibility of the spacer on the finished surface. Sealing cones for sealing tie bar holes are also available in different colours and finishes to help ensure that you get good quality exposed concrete to the highest standards.

Fair Faced concrete applications

Drawing for various sizes of Fiber Reinforced

Concrete Cover Blocks


20 X 25 MM

Multicover Block 

20 MM Thickness

35 X 40 X 45 X 50 MM Multicover Block 

30 MM Thickness

30 X 40 MM

Multicover Block 

25 MM Thickness

75 MM Single Cover Block 

30 MM Thickness

50 MM Single Cover Block 

30 MM Thickness


The numbers and maximum permissible distance between two neighboring ASTRO fiber concrete spacers.


The under mentioned recommendations in the table are made on the basis of our study and analysis on various construction sites. They provide guidelines for a proper cover provision and helps site engineers to order the spacers based on project requirements.


ASTRO Standards & Dimensioning