Testing & Materials

Material Properties of Steel & Concrete

Materials Testing EngineerCIVL2201, University of SydneyMar 2026

Stress-strain curves for mild and high-strength steel coupons

Project overview

Pulling Steel And Crushing Concrete To Read Their Stress-Strain Curves.

I tested mild and high-strength steel in tension and low- and high-strength concrete in compression, then turned the raw load data into stress-strain curves and material properties.

Load and displacement were logged continuously during each test and converted to stress and strain. From the curves I calculated Young’s modulus, yield stress, ultimate strength, and ductility for all four specimens, then explained the differences through each material’s microstructure.

Key Work & Outcomes

Showed that doubling steel strength halves its ductility without changing its stiffness (≈200 GPa).
Showed that doubling concrete strength also doubles its stiffness, while ductility stays near 0.2%.
Quantified steel as roughly 10× stronger, 5–10× stiffer, and far more ductile than concrete.
Linked the results to microstructure: dislocation movement in crystalline steel versus the heterogeneous cement-aggregate matrix of concrete.

Test setup

Two Machines, Two Australian Standards

Steel coupons were pulled apart in tension; concrete cylinders were crushed in compression.

Steel coupons (≈25 mm × 9.9 mm cross-section, 55 mm gauge length) were gripped in a 300 kN Sintech machine under AS1391-2020. Sulphur-capped 35-day-old concrete cylinders (≈99 mm × 300 mm) were loaded in a 2000 kN DARTEC machine under AS1012.9-2014.

Sketch of the steel tensile coupon test setup with friction grips and 55 mm gauge length — Steel tensile test: friction grips and a 55 mm gauge length

Sketch of the concrete cylinder compression test setup — Concrete compression test: loading ram on a sulphur-capped cylinder

Dimensioned sketch of the high-strength steel coupon — High-strength steel coupon shape and dimensions

Results

What The Curves Show

Steel yields, necks, and stretches; concrete rises non-linearly and then cracks.

Both steels showed a linear-elastic region, a clear yield plateau, and necking before ductile fracture. Both concretes behaved non-linearly with no yield point and failed by brittle vertical and diagonal cracking into a cone.

Material	E (GPa)	f_y (MPa)	f_u (MPa)	Strain at failure
Mild steel	196	399	502	32.5%
High-strength steel	202	820	923	16.5%
Low-strength concrete	19.9	—	24.0	0.222%
High-strength concrete	43.5	—	48.0	0.207%

Full stress-strain curves for mild and high-strength steel

Stress-strain curves for low and high-strength concrete — Stress-strain curves for low- and high-strength concrete

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