What is PC mortar?
PC mortar (polymer concrete/mortar) is a repair mortar in which the binder is entirely synthetic resin — epoxy, polyester or methacrylate — mixed with graded sand. It contains no cement and no gauging water: it hardens through a chemical reaction between two components.
In the European concrete repair standard EN 1504-3, PC is one of three binder systems. The other two are CC (purely cement-bound) and PCC (cement-bound with a polymer addition).
Properties
- Very fast strength development. Depending on the resin system and the temperature, the repair can carry load within hours instead of days.
- High bond and compressive strength, with very low water absorption.
- Good chemical resistance to acids, salts and oils.
- Vapour tight. Moisture behind the repair cannot escape, which is a risk on a damp or damp-penetrating substrate.
- Different coefficient of thermal expansion from concrete. In thick layers and under temperature swings this creates stresses in the bond line.
Application
PC mortar suits small, shallow repairs where speed or chemical exposure is decisive: broken-out corners and arrises, anchor holes and threaded rods, loading dock edges, industrial floors and concrete in wastewater plants or silos. For large break-outs, where tens of centimetres of concrete are removed, a cement-bound mortar is almost always the better choice.
Four points matter during application:
- Dry, dust-free and grease-free substrate. Resin will not bond to a wet or dusty surface.
- Application temperature. Most systems require a substrate temperature above roughly 8 to 10 °C; always check the technical data sheet.
- Mix thoroughly until the colour is even and streak-free — a poorly mixed portion will not cure.
- Pot life. Working time is often only a few minutes to half an hour. Mix small batches.
Per kilogram, PC mortar costs considerably more than cement-bound repair mortar. For small repairs that difference is minor compared with the labour.
Related terms
- PCC mortar
- Mortar
- Concrete rot
- Cement
- Permeability
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