What does load bearing mean?

Q: What are the CDM Regulations?

The Construction (Design and Management) Regulations 2015 (CDM) are the main set of regulations for managing the health, safety, and welfare of construction projects in the UK. MPS Concrete acts as a competent contractor under CDM, producing Risk Assessments and Method Statements (RAMS) and coordinating with the Principal Designer/Contractor to ensure all repair works are planned and executed safely.

Q: What is concrete spalling and why does it happen?

Concrete spalling, often referred to as 'blown' concrete, occurs when the surface of the concrete cracks, breaks, or flakes off, exposing the aggregate or reinforcement steel underneath. The primary cause is the corrosion of the embedded steel rebar. As steel rusts, it expands up to seven times its original volume, creating immense internal pressure that forces the surrounding concrete to break away. Other causes include freeze-thaw cycles, where water enters capillary pores, freezes, and expands, as well as 'concrete cancer' (Alkali-Silica Reaction). Ignoring spalling can lead to severe structural weakness and falling debris hazards.

Q: How do you repair a spalled concrete surface?

Repairing spalled concrete involves a strictly regulated process, typically governed by BS EN 1504 standards. First, the damaged concrete is broken out back to a sound substrate, ensuring the reinforcement is fully exposed and cleaned (often via grit blasting) to remove rust. A primer or bonding bridge is applied to the steel to prevent future corrosion. We then reinstate the profile using a polymer-modified repair mortar, which offers superior adhesion and waterproofing properties compared to standard concrete. Finally, a fairing coat or anti-carbonation coating is applied to protect the entire surface from future moisture and CO2 ingress.

Q: What is the difference between structural and non-structural concrete repair?

Structural repair (BS EN 1504-3 Class R3 or R4) restores the load-bearing capacity of the concrete element. It uses high-strength materials and possibly additional reinforcement to ensure the structure can safely carry its design loads. Non-structural repair (Class R1 or R2) is cosmetic or protective, focusing on restoring the geometry, aesthetics, or durability of the surface without adding structural strength. For example, filling surface blowholes is non-structural, whereas injecting epoxy resin into a deep crack in a load-bearing column is structural.

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