How to Determine Hollow Block Wall Thickness
Learn how hollow block face shell and web thickness relate to product geometry, intended use and applicable standards, and what to specify when ordering a mould.
What Are Face Shells and Webs?
In a hollow concrete block, the face shells are the outer concrete walls surrounding the cavities. Webs are the internal sections that separate the cavities and connect the outer walls.
Hollow block wall thickness should not be confused with the overall block width. Blocks with identical external dimensions can have different cavity arrangements, face shell thicknesses and web thicknesses.
Is There a Universal Minimum Wall Thickness?
There is no single minimum thickness that applies to every hollow concrete block. The intended loadbearing or non-loadbearing use, product dimensions and applicable requirements in the destination market must be considered together.
For example, ASTM C90 includes requirements relating to face shells and webs for products within its scope. Requirements from a particular standard should not be applied automatically to every block type or market. The applicable standard and edition should be identified before the product drawing is finalised.
The approved geometry must therefore reflect the relevant product specification rather than a general thickness value taken from an unrelated block design.
How Thickness Affects Material Consumption
When external dimensions remain unchanged, thicker face shells and webs increase the concrete volume within each block. With the same mix and compaction conditions, this increases product weight and material consumption per block.
Reducing thickness solely to save material is not a sufficient design approach. The block must meet its required performance and be suitable for consistent forming, handling and production.
Wall thickness alone does not establish product strength. Mix properties, compaction and curing must also be considered when evaluating the finished block.
What Should Be Defined in the Hollow Block Mould Drawing?
A hollow block mould drawing should define the external dimensions, product height, cavity count and shape, face shell thicknesses and web thicknesses. Where cavities are tapered, the drawing should clearly identify the sections at which dimensions are measured.
The mould cores and tamper shoes are developed around the agreed product geometry. Aggregate characteristics, filling of narrow sections and the machine’s compaction conditions should also be considered during the technical review.
When reproducing an existing hollow block, external dimensions alone are insufficient. Photographs of the top and bottom faces, cavity measurements and cross-sectional details help establish the geometry that must be retained.
Technical Approval and Mould Quotation
Block Mould manufactures hollow concrete block moulds according to the product drawing and machine configuration. Before manufacturing, product dimensions, cavity geometry, wall and web thicknesses and the mould cavity arrangement are submitted for technical approval.
To request a quotation, send your machine brand and exact model, production board dimensions, required product height and dimensioned block drawing. Include the applicable product standard or customer specification where available.
For an existing installation, photographs of the block, current mould, tamper assembly and machine connections help clarify the production requirements.
Contact us to discuss your project and request a quotation.