Drawing No. EH–MT–009 // Engineering Materials
Concrete Properties
Reviewed September 2026
Normal-weight concrete with compressive strength around 30 MPa is used as a reference point. Unlike a homogeneous metal, concrete properties depend strongly on aggregate, mixture, moisture, curing, age and test method.
Representative properties
Switch units without changing the underlying material reference.
What changes these properties?
Engineering variability
- Elastic modulus depends on density, aggregate stiffness and compressive strength; 25.7 GPa is an approximate normal-weight reference for f′c≈30 MPa.
- Direct/splitting/flexural tensile measures are not interchangeable; the 2–4 MPa range is only a scale reference.
- Thermal conductivity and heat capacity are especially sensitive to aggregate and moisture.
- Concrete does not simply melt as one substance; dehydration, cracking, spalling and constituent transformations occur during heating.
Selection note
Use actual mix test data and the governing concrete code for structural design. The overview values are useful for preliminary thermal/mechanical estimates only.
Do not combine strength from one grade/condition with modulus, thermal data or temperature limits from another without checking compatibility. Where the overview shows a range, it is intended to expose variability—not establish allowable bounds.
Concrete in practice
The most-used material on earth by mass, specified by performance rather than by composition, and defined as much by its curing as by its mix.
Where it is specified
Foundations, frames, slabs, walls, dams, pavements, tunnel linings, marine structures. It is chosen for compressive strength at very low cost per unit volume, mouldability into any shape, inherent fire resistance, thermal mass, and durability measured in decades.
Specification is by exposure class and strength class, not by mix proportions: EN 206 defines classes such as XC (carbonation), XD (chlorides), XS (seawater), XF (freeze-thaw) and XA (chemical attack), and each imposes minimum cover, maximum water-cement ratio and minimum cement content. The mix is the contractor's means of meeting that requirement.
Chosen over what
Against structural steel: far cheaper per unit of compressive capacity, inherently fire resistant without protection, and better at damping vibration. Against that, it is heavy, slow to build, weak in tension, and requires formwork and curing time.
Against timber: far more durable and fire resistant, with no moisture movement problem, but with vastly higher embodied carbon — cement production accounts for roughly 7–8% of global CO&sub2; emissions, which is now a first-order design consideration.
How it fails
Reinforcement corrosion is the dominant durability failure, and it is what governs design life. Concrete's alkalinity (pH around 13) passivates embedded steel; that protection is lost either by carbonation (atmospheric CO&sub2; lowering pH from the surface inward) or by chloride ingress from de-icing salt or seawater. Corroding steel expands two to six times in volume, spalling the cover off and accelerating the process. Cover depth and concrete permeability, not strength, are what control it.
Freeze-thaw damage where saturated concrete freezes; air entrainment provides expansion space and is essential in cold climates.
Alkali-silica reaction — reactive aggregate and alkaline pore solution forming an expansive gel, cracking the concrete from within over years. Aggregate testing and low-alkali cement address it.
Sulphate attack from groundwater, and delayed ettringite formation where early-age temperature was too high.
Plastic and drying shrinkage cracking, largely a curing and detailing failure rather than a material one.
Fabrication notes
Water-cement ratio governs almost everything. Lower w/c means higher strength and, more importantly, lower permeability and better durability. Adding water on site to improve workability is the single most damaging thing that can be done to a mix, and is why superplasticisers exist.
Curing is not optional. Strength development requires moisture and temperature; concrete that dries early never reaches its design strength and has a permeable surface layer precisely where durability is needed.
Concrete is weak in tension, roughly a tenth of its compressive strength, which is why it is reinforced or prestressed. Design assumes cracked sections in tension and relies on the steel.
Supplementary cementitious materials — fly ash, ground granulated blast-furnace slag, silica fume — reduce permeability, lower heat of hydration and substantially cut embodied carbon, at the cost of slower early strength gain.
Specifications and standards
EN 206 and EN 1992 (Eurocode 2) for specification and design; BS 8500 for the UK complement to EN 206; ACI 318 for structural design and ACI 301 for specifications in North America; ASTM C39 (compressive strength), C1202 (chloride permeability), C1260 (ASR); EN 12390 for hardened concrete testing.
References
Neville, Properties of Concrete — the standard reference; ACI 201.2R on durability; fib Model Code for service life design.
Property interpretation
Stiffness vs strength
Young’s modulus controls elastic deformation. Yield or fracture strength controls how far the material can be stressed. These are separate material characteristics.
Thermal response
Thermal conductivity controls temperature gradients, specific heat contributes to thermal inertia, and expansion controls thermally induced strain when movement is restrained.
Temperature transition
The final property card is deliberately labeled “melting / transition.” Metals often have a solidus–liquidus range; amorphous polymers and glass use softening or glass-transition concepts; concrete and wood decompose instead of exhibiting one clean melt point.
Technical sources
Source hierarchy favors manufacturers, industry associations, standards bodies and government engineering references. Strength data must still be reconciled with the exact procurement specification.