Crushed Glass in Concrete: What is the Effect on Concrete Workability?

Dear reader we have already had few idea about application of glass in concrete production. In the last post, we have discussed about contamination in crushed glass. We know waste glass can be recycled, but this contaminants and foreign materials define whether it can be recycled or be used as other purposes like concrete production. We will discuss about separation of contaminants and foreign materials for glass, in details, in our upcoming posts.

Here our concern is workability of concrete; we are not considering glass to be used in concrete as coarse aggregate. The usual fine aggregate that is very frequently used in concrete industry is sand. This sand can be classified further as fine and coarse sand.

The workability of concrete is significantly impaired when natural sand is replaced with crushed glass in mix proportioning. The detrimental effect on workability is due to several factors as follows:

a. Interlocking nature of glass particles which are angular in shape.

b. Glass particles are coated with water which results surface tension.

c. When water is added suction is developed between large glass particles.

But the workability of fresh concrete remain constant for long period as the glass particles are less absorbent in compare to normal sand concrete. This property is not only always good, as sometimes we have expectation to set concrete rapidly due to different unfavorable site conditions.