Introducing: Glass Powder - The Superior SCM
Recycled glass powder is the single best solution for a fly ash substitute and partial cement powder replacement.
How is Ground Glass Processed?
Recycled glass is collected from various means, including by direct receipt from businesses and recycling centers. Once the glass is received, it is sorted via optical sorting that separates glass colors, as well as removing contaminants such as ceramic, metals and stone. Various types of magnets and vacuum systems further clean up the glass to remove any small trace of metals and light materials such as paper and other organic material.
Once the glass is properly sorted and cleaned, it is crushed and screened to size the material down to certain fines. For use as a partial cement replacement, ACS requires that our glass powder to be of a very specific sieve size to properly undergo pozzolanic features.
What Is an Ideal Pozzolan?
The purpose of a pozzolan or SCM is to increase strength, increase impermeability, create sulfate resistance, decrease ASR (alkali-silica reaction), reduce bleeding and, reduce maximum rise in temperature.
Below is a chart showing the most common SCMs used in a concrete mix – fly ash, metakaolin, slag and silica fume.
Compressive Strength Testing
After the recycled glass is processed down to the required fine size, it can now be used as a fly ash substitute in the concrete mix.
ACS’ initial testing has proved that you can achieve desired mix workability qualities and strength in concrete by using a 30% replacement of glass powder. At 28 days, our cylinders achieved their required strength.
Since standard mix designs typically have a 20-25% replacement using fly ash, this is a great benefit to further reduce the OPC (Ordinary Portland Cement) content while not diminishing compressive strength.
ASR (alkali-silica reaction) is caused between the alkaline pore of concrete and a silica aggregate reaction. The silica structure around an aggregate is dissolved through reaction of OH- ions, which creates a gel-like structure that cross-links, coagulates and swells the concrete.
It has been proven that the finer glass powder as cement replacement actually mitigates ASR. At a 30% replacement using glass powder, our expansion percentage falls below the threshold required per ASTM and is improved compared with fly ash.
Reduced Chloride Permeability
Concrete containing 30% Type GS ground glass as a partial cement
replacement has less chloride permeability long-term than a slag or
fly ash mixture. Having this feature creates a more durable concrete.