Concrete Defect Repairs Rules For AGC London : The 90%/70% Matrix We Use on Site

Most defects we see on London projects fall into a small number of repeatable patterns. The table above is our field template—designed from our method statements and repair schedules—and it reliably covers ~90% of residential issues and ~70% of commercial ones. It’s the framework our team follows, refined by live site experience.

How to use this table:

1. Identify the defect class and confirm location.
2. Check depth/area thresholds.
3. Apply the remedy and product class. Always follow manufacturer data sheets and our method statement steps (roughen → soak/SSD → slurry where required → place/compact → cure → QC).

Tailored to us

This matrix is not generic—it’s the way we Amtaargc deliver watertight, durable repairs with speed and consistency across live jobs. If your project needs a variant (e.g., different concrete grade, exposure class, or a specified brand system), we’ll adapt the rows and lock it into the site QA pack.

Never Mistaken This to Be Simple

1) Assess and mark the repair zone

We start with a targeted inspection and a quick sketch of the repair limits, so everyone agrees what’s in scope before tools come out.

2) Remove loose or weak material (without harming reinforcement)

Trained operatives chip back only the unsound concrete—using hand chisels or a 5–7 kg pneumatic chipping hammer as needed—so we expose solid substrate and avoid nicking the bars.

3) Fix the kicker and waterstop geometry

Defects around kickers are common and critical. We trim the kicker to restore a clean arris and ensure the waterstop has the required 100 mm stick-up, fixed firmly to prevent bending during the next pour. Getting this right is essential for watertight joints.

4) Prepare the construction joint for bond

Both sides of the joint are roughened to create mechanical key, then soaked overnight and primed with a cement slurry immediately before placing concrete. This combination—texture, moisture conditioning, and slurry—promotes a strong, continuous bond.

5) Reset concrete cover (if needed)

If inspection shows inadequate cover, we increase wall thickness locally to recover the specified cover. That means roughening the kicker side and forming a proper splay so the thickening integrates structurally and aesthetically.

6) Place a dense, workable mix for the next lift

We pour using a dense mix (max aggregate 3/8″ down) at around 6–7″ slump—workable enough for good consolidation, dense enough to minimise voids at the repaired joint and around the waterstop. Vibration and placement are controlled to avoid disturbing the reset waterstop.

7) Seal porous surfaces before waterproofing

On basement slabs and wall upstands, we apply a cementitious lining across the slab and 500 mm up surrounding walls to close surface pores before the specified coating goes on. We use reputable systems (e.g., Fosroc, Sika or equivalent) to match the project spec.

8) Quality control that clients can trust

Every repair goes through our QC gateways: approved method, approved materials, recorded weather conditions, daily site reports, RFIs, and site instructions. This documentation protects the asset—and the client—long after handover.

9) Safety throughout

From hand tools to compressed-air equipment, we maintain exclusion zones, PPE, and dust/noise controls while keeping rebar and waterstops intact.

The outcome

By sequencing assessment, substrate prep, joint priming, and controlled re-pour with a pre-seal lining, we restore both performance and durability—so the repair doesn’t just look right on day one but keeps water out and strength in for decades