Concrete vs. Plastic PBT GF30

Compare Concrete vs. Plastic PBT GF30 strength, stiffness, weight and thermal properties.

Plastic PBT GF30Bulk polymer (molded or machined)

Mechanical	Concrete	Plastic PBT GF30
Yield strength	none (brittle)	not given (tensile used)
Ultimate tensile strength	not sourced	stress at break140MPa1
Compressive strength	27.6MPa2	not sourced
Flexural strength	not sourced	210MPa1
Elongation at break	none (brittle)	strain at break3%1
Young's modulus (stiffness)	design value25.1GPa3	9.8GPa1
Density	2,240–2,400kg/m³4	1,530kg/m³1
Strength to weight	not sourced	91.5kN·m/kg
Stiffness to weight	10.8MN·m/kg1.69x higher	6.41MN·m/kg
Poisson's ratio	0.15–0.25	not sourced
Shear modulus	10.7GPa	not sourced
Bulk modulus	12.9GPa	not sourced
Speed of sound	3,289m/s30% faster	2,531m/s

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Concrete	Plastic PBT GF30
Thermal conductivity	0.9W/m·K63.33x more heat through a fin	0.27W/m·K1
Thermal expansion	8–12µm/m·K7	longitudinal25µm/m·K1
100 mm part over a 50 °C swing	50µm growth2.5x less	125µm growth
Specific heat	900J/kg·K8	1,050J/kg·K117% higher
Heats up and cools (diffusivity)	0.431mm²/s2.56x faster	0.168mm²/s
Thermal shock resistance	not sourced	not sourced
Melting point	not sourced	DSC223°C1
Max service temperature	65°C5	HDT 1.8 MPa205°C1

Thermal conductivity against densityHigher and further left: spreads more heat for its weight

Thermal expansion against thermal conductivityLower and further right: warps less when heated

Try it on a partA sample part to run stress or thermal on, free in your browser	Open in LessCAD	Open in LessCAD

Sources8 documents: BASF, National Ready Mixed Concrete Association, Federal Highway Administration, Oak Ridge National Laboratory, USDA Forest Products Laboratory, National Institute of Standards and Technology

Concrete: Normal-weight portland cement concrete, strength class f'c = 4000 psi (28 MPa) per NRMCA CIP 35; density NRMCA CIP 36; thermal conductivity USDA FPL Wood Handbook; service temperature ORNL/NRC review
Plastic PBT GF30: BASF Ultradur B 4300 G6 (PBT, 30% glass fibre), injection moulding grade; product information sheet 09/2026, typical values for uncoloured product at 23 °C.

1
Ultradur B 4300 G6 Product InformationBASFPlastic PBT GF30 · Ultimate tensile strength: stress at break, 23 °CPlastic PBT GF30 · Flexural strength: typical, 23 °CPlastic PBT GF30 · Elongation at break: strain at break, 23 °CPlastic PBT GF30 · Young's modulus (stiffness): typical, 23 °CPlastic PBT GF30 · Density: typicalPlastic PBT GF30 · Thermal conductivity: typical (DIN 52612-1)Plastic PBT GF30 · Thermal expansion: longitudinal (flow), mean 23-55 °CPlastic PBT GF30 · Specific heat: typical, 23 °CPlastic PBT GF30 · Melting point: DSC (ISO 11357)Plastic PBT GF30 · Max service temperature: HDT 1.8 MPa
2
CIP 35: Testing Compressive Strength of ConcreteNational Ready Mixed Concrete Associationarchived copyConcrete · Compressive strength: specified compressive strength class (f'c), not a measured typical
3
LRFD Steel Girder Superstructure Bridge Design Example, Design Step 2: Concrete Deck DesignFederal Highway AdministrationConcrete · Young's modulus (stiffness): design value: AASHTO LRFD 5.4.2.4 applied by FHWA to f'c = 4.0 ksi normal-weight concrete
4
CIP 36: Structural Lightweight ConcreteNational Ready Mixed Concrete Associationarchived copyConcrete · Density: range for normalweight concrete
5
The Effect of Elevated Temperature on Concrete Materials and Structures: A Literature Review (ORNL/TM-2005/553)Oak Ridge National Laboratoryarchived copyConcrete · Poisson's ratio: general range at normal ambient conditions (overall 0.11-0.32)Concrete · Max service temperature: code long-term temperature limit (ASME Code, concrete containments)
6
Wood Handbook (FPL-GTR-282), Chapter 4: Moisture Relations and Physical Properties of WoodUSDA Forest Products LaboratoryConcrete · Thermal conductivity: typical (comparative value)
7
Thermal Coefficient of Portland Cement ConcreteFederal Highway AdministrationConcrete · Thermal expansion: typical range for portland cement concrete (aggregate dependent)
8
Best Practice Guidelines for Structural Fire Resistance Design of Concrete and Steel Buildings (TN 1681)National Institute of Standards and Technologyarchived copyConcrete · Specific heat: typical (NIST guidance for thermal analysis)

Each number points to the document that states it, with the exact basis. Values without a number are computed from the sourced ones. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.

Questions

Mechanical

Which is lighter, Concrete or Plastic PBT GF30?

Plastic PBT GF30 is lighter: 1,530 kg/m³ against 2,320 kg/m³ for Concrete.

Which is stiffer, Concrete or Plastic PBT GF30?

Concrete is stiffer: Young's modulus 25.1 GPa against 9.8 GPa for Plastic PBT GF30, so the same part in Concrete deflects less under the same load.

Which is lighter for the same job, Concrete or Plastic PBT GF30?

For the same stiffness or strength: Concrete is lighter for a stiff rod or tie (tension), stiff beam (bending); Plastic PBT GF30 is lighter for a stiff panel or plate.

Part that must be	Concrete	Plastic PBT GF30
Stiff rod or tie (tension)	lighter	1.69x heavier
Stiff beam (bending)	lighter	6% heavier
Stiff panel or plate	11% heavier	lighter

For the same stiffness or strength, mass scales with density over stiffness (or strength) raised to a power set by how the part is loaded: 1 for a rod in tension, 1/2 for a beam in bending, 1/3 for a panel (the standard material-selection indices).

Thermal

Which conducts heat better, Concrete or Plastic PBT GF30?

Concrete conducts heat better: 0.9 W/m·K against 0.27 W/m·K for Plastic PBT GF30.

Which expands less with temperature?

Concrete expands less: 10 µm/m·K against 25 µm/m·K for Plastic PBT GF30.