Properties of GFRC

The final properties of GFRC depend greatly on the mix formulation, the processing method and the overall quality of workmanship incorporated. Early (28 day) properties are typically used to determine appropriate design parameters and to monitor quality control throughout manufacturing.

The values of these properties for GFRC made with spray and premix processes are presented below:

Stress Strain Relationship

The stress strain relationship is important for the design and analysis of GFRC elements. The stress-strain curve of GFRC tested in compression is similar to the curve which would be obtained from testing the matrix alone. The compressive strength is several times the tensile strength, it is normally the tensile characteristics that control the flexural behaviour of GFRC elements. General shape of the stress-strain curves both in tension and bending for a typical spray-up GFRC material containing 5% glass fiber is shown in the table above.

Strength Classification
The International Glassfiber Reinforced Concrete Association (IGFRCA) classifies GFRC into 3 grades of material based on the 28 day flexural strength. These are Grade 18, Grade 10 and Grade 5 and there are significant differences between them as illustrated by the nominal stress strain curve in the table above.