1.5m Allegro® Interlocking Concrete Blocks
Flexible, modular precast blocks for storage and fire walls
Why choose 1.5m Allegro® Interlocking Concrete Blocks?
The 1.5m Allegro® range is designed for projects that need fast, flexible walling solutions.
- Smaller and lighter – at 1,270kg, these blocks are easier to handle and allow more per load.
- Modular system – 900mm and 600mm blocks let you stagger joints and form corners, just like traditional brickwork.
- No fixings needed – precast interlocking blocks connect securely through their own weight and interlock, so there’s no need for bolts or reinforcement.
- A1 fire classification – made without steel reinforcement, Allegro® Blocks are non-combustible and rated Class A1, the highest fire classification for construction products.
- Long-lasting – with no reinforcement to corrode, they’re built for a 100-year design life.
- Fire-resistant joints – joints can be sealed with fire-resistant mastic such as Sika® Hybriflex® FR, giving up to 4 hours of fire resistance.
With 1.5m Allegro® Interlocking Concrete Blocks, you’ll get:
Response from the team within 4 working hours
Full technical support, including product datasheets, O&M manuals and CAD files
UK-wide delivery in 2–4 weeks
Retaining walls designed for speed and flexibility
When you need a wall that goes up quickly, can be reconfigured, and doesn’t require fixings, 1.5m Allegro® Interlocking Concrete Blocks are the perfect solution. Each precast block is cast with interlocking round-top nibs and recesses, enabling them to slot neatly together to create strong, stable walls.
The 1.5m range is the smallest and lightest in the Allegro® family. This means more blocks per load, easier handling on site, and quicker installation. As modular interlocking concrete blocks, they’re a practical choice for storage bays, waste and recycling facilities, and fire and blast walls where flexibility is key.
Product Features & Specifications of Interlocking Concrete Blocks
Allegro® Interlocking Concrete Blocks are designed for flexibility, durability, and quick construction. Here’s what makes the 1.5m range a practical choice.
Block sizes: 1,500mm, 900mm, and 600mm lengths
The 1.5m Allegro® range includes three block lengths, each measuring 600mm wide and 600mm high. Smaller units allow you to stagger joints and create 90° corners, resulting in stronger, more stable interlocking block walls without the need for bespoke elements.
Corners: 90° with smaller blocks
Corners are formed using 900mm and 600mm units to stagger and interlock rows, similar to traditional blockwork. This provides flexibility to build neat, strong bays without requiring special corner blocks.
Material density: Up to 18 kN/m³
The system is designed to store a variety of bulk materials, including aggregates, grain, recyclables, and general waste.
Surcharge capacity: Up to 20 kN/m²
Walls constructed from Allegro® Blocks can be engineered to withstand surcharges up to 20 kN/m², depending on height and material density. This makes them suitable for a wide range of storage applications.
Concrete strength: C40 mix
Blocks are cast in a C40 concrete mix, providing the strength and durability needed to withstand daily use in demanding storage and recycling environments.
Connection: Interlocking nibs and recesses
Round-top nibs on each block fit neatly into recesses on the block above, creating a stable wall without the need for bolts or fixings.
Design life: 100 years
Since Allegro® Blocks contain no steel reinforcement, they’re not at risk of corrosion. This allows them to achieve a standard design life of 100 years.
Reinforcement cover: None required
Blocks are unreinforced, so there’s no risk of corrosion that could reduce long-term performance.
Fire resistance: Class A1, up to 120 minutes
Concrete is naturally non-combustible. Allegro® Blocks are rated Class A1 for fire resistance, the highest classification for construction products. When joints are sealed using Sika® Hybriflex® FR, fire performance can extend up to 4 hours.
Edge detail: Chamfered edges
Blocks are cast with chamfered edges to minimise chipping during handling and provide walls with a neat, professional finish.
Finish: Smooth mould finish on the front face
The visible faces of each block are mould-finished for a clean appearance, while the back faces are hand-trowelled for efficiency in production.
Foundation type: RC slab or existing yard slab
Due to their weight, Allegro® Blocks must be installed on a stable foundation such as a reinforced concrete base or existing yard slab. No fixings are required – the mass and interlock of the blocks provide stability.
Interlocking concrete block sizes & product range
The 1.5m Allegro® range includes three block sizes – 1,500mm, 900mm, and 600mm long. The combination allows you to build strong, stable walls with staggered joints and neat 90° corners.
| Height (mm) | Length (mm) | Width (mm) | Weight (kg) |
|---|---|---|---|
| 600 | 1,500 | 600 | 1,300 |
| 600 | 900 | 600 | 780 |
| 600 | 600 | 600 | 520 |
A Partner You Can Trust
We’ve supplied precast retaining walls for over 18 years, delivering more than 1,000 projects across the UK. Contractors, farmers, and engineers come back to us because we’re straight-talking, reliable, and invested in getting projects done right.
Off-site production also means less disruption, less waste, and reduced dust on site – making projects cleaner, safer, and more efficient for everyone involved.
Typical Applications
1.5m Allegro® Interlocking Concrete Blocks are used across a wide range of industries. They’re ideal for fire and blast walls, storage bays, and waste & recycling facilities where modular, fast-build walls are essential.
Fire & blast walls
Storage bays
Waste & Recylcing
Handling & Installation of Interlocking Concrete Blocks
Allegro® interlocking blocks are simple to move, stack, and secure on site.
- Delivered with one or two cast-in lifting pins in the top face.
- Supplied with 2 × 2.5T spherical head lifting clutches for safe handling.
- Offloaded and positioned using a telehandler, forklift, or 360 excavator.
- Placed directly on a reinforced concrete slab or yard base – no fixings required.
Download the full Allegro® Blocks Media Pack
One download with everything you need — brochure, handling guide, and safety data sheets.
Everything you need to plan, specify, and install the product with confidence.
Questions We Get All The Time
A telehandler or 360 excavator is usually sufficient. All lifting loops, shackles, and fixings are supplied with your order.