Process
From Slate to Strength.
Precision, innovation, and proven performance behind the world’s finest lightweight aggregate.
Stalite Lightweight Aggregate
Stalite is the world’s only producer of expanded slate lightweight aggregate—a premium material recognized for its exceptional strength, low absorption, and proven durability. For more than 65 years, we’ve refined and advanced our process to ensure the highest performance across structural concrete, geotechnical fills, masonry, stormwater solutions, and specialty applications.
Our technical data, test reports, and project case studies consistently demonstrate the benefits of Stalite LWA: high strength-to-weight ratios, uniformity, and long-term durability even in demanding environments. And with direct access to our experienced engineering and technical support team, customers gain a partner who understands both the science and the field-level application.
Stalite delivers:
- Less weight / lower dead load
- Longer spans and thinner slabs
- Improved fire performance
- Reduced seismic inertia loads
- Lower foundation and structural system costs
- Fewer reinforcement requirements
- Decreased transportation and placement costs
- Overall material and carbon savings
Stalite is more than a lightweight aggregate.
It’s a high-performance material system that helps engineers, designers, and builders do more with less—efficiently, reliably, and sustainably.
Advantages & Benefits
The Benefits of Stalite Aggregate
Stalite’s lightweight aggregate offers a proven balance of strength, durability, and performance across a wide range of construction and environmental applications. Its consistent quality and engineered uniformity make it the preferred choice of architects, engineers, and builders seeking lighter, more efficient, and longer-lasting designs. Whether used in structural concrete, masonry, precast elements, or geotechnical fills, Stalite delivers measurable advantages that translate into real-world savings and superior results.
High Strength
The unique mineral structure of slate produces high-strength, lightweight concrete and masonry with superior performance.
Green Building Applications
Engineered for sustainability, Stalite supports green roofs, aquaponics, and other innovative environmental design systems.
Lower Absorption
With only 6% absorption—versus 15–30% for shale or clay—Stalite improves strength, durability, and long-term structural integrity.
Road Construction
Enhanced skid resistance and greater coverage per ton make it a cost-effective choice for high-performance pavements.
Production Process
Unlike most lightweight aggregates produced from shale or clay, Stalite is made from slate—a metamorphic rock that delivers greater strength and lower absorption. This unique manufacturing process results in superior performance and reliability. Its low weight and sustainable characteristics also make Stalite ideal for green infrastructure applications such as aquaponics, roof gardens, and bioretention systems.
Selective Mining
Advanced geological mapping and core testing identify the highest-quality argillite slate. Only proven, bloatable zones are mined to ensure consistent chemistry and performance.
Primary Crushing
Controlled blasting breaks the slate, which is hauled to primary crushers capable of processing high tonnage while removing oversize and unsuitable material.
Screening & Fractionation
The rock passes through multiple screening and crushing stages. Non-bloatable material is rejected, and kiln-ready fractions are built into uniform stockpiles.
Raw-Feed Conveying
Enclosed conveyors move the screened slate from the processing plant into raw-feed silos positioned above the pre-heaters and kilns, minimizing handling losses.
Pre-Heater Conditioning
Stalite’s patented pre-heaters gradually warm the slate and drive off residual moisture, improving fuel efficiency and ensuring more uniform expansion in the kiln.
Rotary Kiln Firing
Refractory-lined rotary kilns fire the slate to over 2,200 °F using high-BTU, low-sulfur fuels. At peak temperature, the material becomes a lava-like plastic.
Expansion & Cooling
Internal gases form millions of sealed ceramic air cells, creating lightweight “clinker.” Forced-air cooling locks these cells in place for low absorption and high strength.
Clinker Handling
Cooled clinker moves via conveyors to the classification building, where any oversize material is reduced and prepared for final sizing
Final Screening
Precision vibrating screens separate the expanded slate into individual size fractions. Each fraction is stored separately to maintain gradation control.
Automated Blending
Computer-controlled blending recombines selected size fractions into standard or custom gradations and adjusts moisture to predetermined specifications.
Quality Control
Each batch is tested for gradation, moisture content, specific gravity, absorption, and unit weight to verify compliance with ASTM requirements.
Storage & Shipping
Fine grades are stored in silos and coarse grades in managed stockpiles. Clean trucks and railcars are loaded accurately for dependable delivery nationwide and globally.
Featured Video
See Stalite featured on Modern Marvels in this segment highlighting our expanded slate lightweight aggregate production process.
Raising the Standard in Slate Washing
How the Hydro-Clean 1000 Transformed Our Washing Process
Innovation has always been central to Stalite’s success. To elevate material quality, improve efficiency, and reduce our environmental footprint, we invested in the Hydro-Clean 1000 wash plant — a high-pressure cleaning system that has reshaped how we prepare our raw slate. This advanced technology delivers cleaner feedstock, higher throughput, and more sustainable water and energy use across our entire operation.
