GRP or concrete? Choosing a delineator material
The two materials do not do the same job. The difference shows most clearly at the moment of impact. One flexes and returns, the other breaks and damages the vehicle that struck it.
| GRP (glass reinforced polymer) | Concrete post | |
|---|---|---|
| Impact behaviour | Flexes and returns to position in typical grazing contacts; the flexibility lowers the damage risk to the vehicle. Behaviour depends on impact speed and angle. | A rigid body can break on impact; vehicle damage and injury risk are higher. |
| Flexural tensile strength | min. 500 MPa | Does not bend; breaks on impact. |
| Colour | Pigment is in the compound. Does not fade, rub off, or discolour when scratched. | Surface paint. Fades in sunlight, chips on scratches and impact. |
| Thermal behaviour | −30 / +80 °C. Resistant to UV and thermal cycling. | Paint peels with temperature change. |
| Cleaning | Exhaust soot and mud clean off with detergent or chemicals; the colour is unaffected. | Difficult, because the concrete surface is porous. |
| Installation | Driven in with a sleeve tool, quickly. No excavation or concrete. | Needs excavation and concrete; result varies with the installer. |
| Transport | Light, cheap and easy to move. | Heavy; difficult and expensive to transport. |
| Barrier mounting | Rivets or bolts to an existing steel barrier; if bolted it can be removed and reused. | Not possible. |
| Applications | Road edge, buried fibre, gas and oil route marking, urban and rural road dividers. | Road edge only. |
| Service life | Long service life is a documentation-backed design target; the commitment is stated in writing with the quotation. | Spalling and body damage outdoors; the life is generally shorter. |
| Theft and scrap value | Cannot be recycled or stolen. | Same. |
Why is concrete still used at all?
The honest answer: habit and local supply tradition. The cost table puts concrete ahead on no line: the product costs more, the freight is heavy, installation is laborious work of excavation and formwork, it breaks on impact and leaves rubble when removed. On a live road edge a broken post is a safety problem on top.
White or yellow?
On high-altitude, foggy and snowy routes the yellow body is preferred. In fog it is markedly easier for a driver to pick out. Reflectors sit on both faces: the concave front face toward the driver is red and the rear face white — the driver sees red in the row on their right and white on their left.
Source: the manufacturer’s comparison table (GRP–concrete), 2026. Figures are consistent with the product technical document.
Roadside delineator posts