Steel Abrasives for Construction & Infrastructure
Bridge decks, structural steel, and reinforced concrete demand surface preparation that lasts decades. Our steel shot and grit deliver the anchor profile and cleanliness required by the most demanding civil engineering standards.
Why Surface Preparation Defines Infrastructure Longevity
Infrastructure projects — bridges, flyovers, highway gantries, marine structures — operate under relentless mechanical stress, moisture ingress, and thermal cycling. Protective coatings are the last line of defense against corrosion, but they are only as good as the surface they adhere to.
Studies by major coating manufacturers consistently show that surface preparation accounts for more than 80% of coating failure root causes. A poorly prepared surface — residual mill scale, inadequate anchor profile, or contamination — can reduce coating life from 25 years to under 5.
Macloid Metalix steel abrasives are engineered to produce consistent cleanliness levels and anchor profiles on structural steel and concrete, enabling contractors to meet project specifications with confidence on first blast.
Sa 2.5
Minimum standard for bridge coatings
50–75 μm
Typical anchor profile for zinc-rich primers
2000+
Abrasive reuse cycles per batch
ISO 8501
International standard compliance
Bridge & Structural Steel Preparation
Bridges are among the most demanding applications for protective coatings. Salt spray, humidity, traffic vibration, and freeze-thaw cycles all attack the coating system simultaneously.
Cleanliness Requirements
Bridge standards typically mandate Sa 2.5 (Near-White Blast Clean) or Sa 3 (White Metal) per ISO 8501-1. This means removal of all mill scale, rust, and contaminants, with only trace shadows or streaks permitted (Sa 2.5). Steel grit G16–G25 achieves these levels efficiently in wheel blast and pressure blast applications.
Coating System Compatibility
Modern bridge coating systems use a three-coat approach: zinc-rich epoxy primer (sacrificial protection), intermediate epoxy barrier coat, and an aliphatic polyurethane topcoat for UV resistance. Each layer demands a specific anchor profile — too shallow and adhesion fails; too deep and the primer cannot fill the valleys. Angular steel grit creates the sharp profile these systems require.
Anchor Profile Control
Abrasive hardness, particle size, and shape collectively determine the anchor profile. Our steel grit G16 produces profiles of 50–75 μm, while G25 delivers 40–60 μm — measured per ISO 8503-2 or ASTM D4417. Consistent hardness (55–65 HRC) ensures predictable profiles across the full blasting run.
Concrete Surface Preparation
Steel shot blasting on concrete surfaces serves multiple purposes in construction: removing laitance (the weak surface layer of cement paste), creating a mechanical key for overlays and coatings, decontaminating bridge decks of chloride-laden concrete, and producing anti-slip textures in parking structures and industrial floors.
The Concrete Surface Profile (CSP) scale, defined by ICRI Technical Guideline 310.2R, classifies surface texture from CSP 1 (light brush-off) to CSP 10 (heavy scarification). Shot blasting typically produces CSP 2–6 depending on shot size, velocity, and passes — making it the most controllable method for overlay preparation.
Unlike scarifiers or planers, shot blasting removes only the surface layer without damaging the aggregate matrix, preserving structural integrity while creating the bond surface needed for epoxy, polyurea, or cementitious overlays.
Bridge Deck Decontamination
Chloride ions from de-icing salts penetrate bridge decks and accelerate rebar corrosion. Shot blasting removes the contaminated surface layer and creates a clean profile for waterproofing membrane application.
Anti-Slip Surface Texturing
Parking ramps, loading docks, and pedestrian walkways require controlled surface roughness for traction. Shot blasting with S280–S390 produces consistent CSP 3–4 profiles without chemical etching.
Removal of Laitance
New concrete slabs develop a weak surface layer (laitance) during curing. This must be removed before any coating or overlay — shot blasting is the fastest and most complete method, far superior to acid etching.
Overlay Bond Preparation
Polymer concrete overlays, epoxy terrazzo, and resin-bound aggregates all require a mechanically roughened, contaminant-free base. Shot blasting achieves the pull-off strength values required by overlay manufacturers.
Application Reference Guide
Recommended products and surface standards for common construction applications
| Application | Recommended Product | Surface Standard | Typical Profile |
|---|---|---|---|
| Structural steel beams | Steel Grit G16–G25 | Sa 2.5 (ISO 8501-1) | 50–75 μm |
| Bridge deck preparation | Steel Shot S330–S460 | Sa 2.5 (ISO 8501-1) | 40–70 μm |
| Reinforcement bar cleaning | Steel Shot S230–S330 | Sa 2 (ISO 8501-1) | 30–50 μm |
| Concrete texturing | Steel Shot S280–S390 | N/A (concrete) | CSP 3–5 |
| Parking structure floors | Steel Shot S230–S330 | N/A (concrete) | CSP 2–4 |
Products for Construction Applications
Two core abrasive types — each optimised for specific construction tasks
Steel Grit
Angular steel grit (G16–G80) produces sharp, well-defined anchor profiles ideal for structural steel, bridge components, and any substrate where maximum coating adhesion is required. Hard particles (55–65 HRC) cut aggressively through mill scale and rust.
Steel Shot
Spherical steel shot (S110–S780) produces smoother, peened profiles suited to bridge deck blasting, concrete surface preparation, and rebar cleaning. Higher recyclability than grit, with consistent size distribution throughout the working mix.
Standards Compliance
Macloid Metalix abrasives support compliance with all major international and industry standards for surface preparation in construction
Visual Cleanliness Assessment
Defines rust grades (A–D) and blast cleanliness grades (Sa 1, Sa 2, Sa 2.5, Sa 3) with photographic reference comparators.
Near-White Blast Cleaning
At least 95% of each unit area free of all visible residues. Staining allowed only in the form of light shadows, slight streaks, or minor discolorations.
Surface Profile Measurement
Defines the method for measuring surface roughness using stylus instruments and comparators, ensuring the anchor profile meets coating manufacturer requirements.
Need Abrasives for Your Construction Project?
Our technical team can recommend the right abrasive grade for your surface preparation standard, substrate type, and blasting equipment. Reach out for product samples or a detailed specification sheet.
Contact Our Technical Team