AAC Products
AAC U-Blocks
AAC U-blocks are channel-shaped AAC units used to coordinate reinforced courses, bond beams, and opening details while keeping the wall system within the AAC product family. MHE Group is a global AAC producer producing and delivering AAC building systems at its associated AERCON plant, backed by 40+ years of AAC engineering, factory development, installation, and project delivery expertise.
When to choose U-Blocks
Choose U-blocks when a beam has to be formed inside the AAC wall. The channel is filled with reinforcement and grout on site to create a continuous bond beam or a cast-in-place lintel over an opening. For standard openings that can be bridged by a ready-made element, factory-reinforced AAC lintels avoid on-site grouting and curing time.
Applications
- Bond beam coordination
- Reinforced wall courses
- Opening headers and transitions
- Integrated AAC wall-system detailing
Technical data (ICC-ES ESR-4740)
The AERCON plant in Haines City, Florida, which produces the AAC products MHE Group supplies in the United States, holds ICC-ES Evaluation Report ESR-4740 for AERCON AAC blocks and lintels (reissued May 2026, valid through May 2027). The values below are quoted from Table 2 of that report. They are material design values for strength categories AC-4 and AC-6, not whole-wall or whole-assembly ratings; the final design is confirmed by the project engineer.
| Property | AC-4 | AC-6 |
|---|---|---|
| Nominal dry density | 31 pcf (500 kg/m³) | 40 pcf (600 kg/m³) |
| Minimum compressive strength of masonry, f′m | 570 psi | 855 psi |
| Allowable compressive strength of masonry | 140 psi | 210 psi |
| Allowable flexural compressive strength | 190 psi | 285 psi |
| Allowable flexural tensile strength | 24 psi | 24 psi |
| Allowable shear strength | 15 psi | 22 psi |
| Modulus of elasticity, E | 260,000 psi | 360,000 psi |
| Thermal conductivity, k≈ 0.14 and 0.18 W/m·K | 0.97 Btu·in/(ft²·h·°F) | 1.25 Btu·in/(ft²·h·°F) |
| Thermal resistance per inch, R/in (computed as 1 ÷ k)Material value, not a whole-wall R-value. Example: an 8 in AC-4 wall ≈ R-8.2 | ≈ 1.03 | ≈ 0.80 |
| Design dead weight of masonry | 37 pcf | 47 pcf |
Fire resistance
- Standard Blocks at least 6 in (150 mm) thick: 4-hour fire-resistance rating for both bearing and nonbearing walls (ASTM E119), with block density between 25 and 43 pcf (400–650 kg/m³), laid in running bond with AERCON thin-bed mortar.
- For bearing walls the load is limited to 11,560 lbf/ft (168.7 kN/m) at a height of ten feet.
- The material is noncombustible per ASTM E136.
Further reading: AAC fire safety and what AAC is, and how AAC blocks compare with concrete blocks. For wider comparisons, see fire-resistant wall systems, building materials for hurricane-prone areas and lightweight vs traditional concrete construction.
Product sizes listed in ESR-4740
| Product | Length | Height | Thickness |
|---|---|---|---|
| U-Block | 24 in | 8 in | 8, 10, 12 in |
- Dimensional tolerance 1/16 in (1.5 mm) for all dimensions.
Source: ICC-ES ESR-4740 (PDF), Tables 1 and 2, held by AERCON Florida, LLC, Haines City, Florida. Compliance basis: ASTM C1386, C1693 and C1694 (material and reinforcement), ASTM E119 (fire tests), ASTM E136 (noncombustibility), for the IBC and IRC. Report status can be checked at icc-es.org; values on this page are updated when the report is reissued.
Technical Considerations
- Reinforcement and grout details must follow project engineering requirements.
- U-block dimensions should be coordinated with standard blocks, cored blocks, and lintels.
- Installation sequencing should account for temporary support where required by the design.
Design and Installation Notes
- Confirm compatible block dimensions before ordering.
- Coordinate U-block courses with structural drawings and shop drawings.
- Avoid publishing load or span values without current product tables and engineer review.
Completed projects
For completed load-bearing AAC block projects, see AAC blocks.
More projects are listed in the North American AAC project reference list.
Related AAC Product Paths
- AAC Standard Blocks
- AAC Cored Blocks
- AAC Reinforced Lintels
- AAC blocks overview
- View the complete AAC product catalog
- Request global supply and export planning
Request a quote for U-Blocks
Request a quote, product documentation, supply information and technical review support for aac u-blocks from MHE Group.
Request a QuoteFrequently Asked Questions
What are AAC U-blocks used for?
AAC U-blocks are commonly used for bond beams, reinforced wall courses, and opening details within engineered AAC wall systems.
Do U-blocks require reinforcement?
They are typically used where reinforcement or grout is part of the design, but exact requirements must be confirmed by the project engineer.
Can U-blocks be supplied with other AAC products?
Yes. MHE can help coordinate U-blocks with standard blocks, cored blocks, lintels, slab panels, roof panels, vertical wall panels, and horizontal cladding panels.
Should I use AAC U-blocks or reinforced lintels over openings?
Reinforced lintels are factory-made and set directly on the wall, which is faster for standard openings. U-blocks are filled with reinforcement and grout on site, which suits continuous bond beams and non-standard openings. The project engineer confirms which applies.