Clay Brick Paving: Paver Standards and How Pavers Are Made

Clay brick paving uses fired units held to tougher limits than ordinary walling brick. ASTM C902 Class SX asks for an average compressive strength of 8,000 psi (55.2 MPa) and average cold-water absorption of at most 8% (BIA TN 14, 2017), while EN 1344 grades breaking load, abrasion and slip. Reaching them takes a clean body, dense forming and thorough vitrification.

This guide is for plant owners deciding whether to add pavers to a fired clay brick line. It sets out what each standard measures, then what those limits change in clay, forming, firing and testing. Standard clauses come from the Brick Industry Association’s technical note, public ASTM extracts and a maker’s specification guide to EN 1344. Standards are revised, so check the current edition before you set a plant target.

Clay Brick Paving Standards: Which One Applies

Clay brick paving falls under three main specifications, and the choice depends on traffic and market. ASTM C902 covers pedestrian and light traffic, ASTM C1272 covers heavy vehicular traffic, and EN 1344 covers European and UK-specified projects.

BSI’s record, checked in November 2026, lists BS EN 1344:2013 as current and under review. A paver is also a different product from a masonry brick in specification terms: BSI’s summary says EN 1344 excludes clay masonry units, which fall under EN 771-1. For masonry grades, see our guide to ASTM C62 and C216 brick standards.

ASTM C902 and C1272 Requirements

ASTM paver limits center on compressive strength, absorption and abrasion, and the toughest set applies to flexible-bed heavy-duty units. The Brick Industry Association’s Technical Note 14 (2017), citing the 2016 editions, tabulates them as follows.

Abrasion is a separate limit. TN 14 gives abrasion index and volume abrasion loss of 0.11 and 1.7 cm³/cm² for C902 Type I and for C1272, 0.25 and 2.7 for Type II, and 0.50 and 4.0 for Type III.

Three clauses matter to a producer:

• Defaults. If the specifier names no abrasion type, Type II governs (ASTM C902-09 extract). The same clause sets a default weathering class, which the extract prints as “SC” and we read as SX, so check the current edition. Our advice is to treat SX as the working target, even in a hot market, unless the project clearly allows MX.
• Waiver. In the C902-09 extract, the saturation coefficient limit is waived if average 24-hour absorption is below 6.0%. Freeze-thaw test alternatives also exist. Check the current edition for both.
• Tolerance. For a dimension over 5 to 8 in. (the length of most pavers), TN 14 allows ¼ in. for PS, ⅛ in. for PX and no limit for PA. PX is the grade for tight, consistent joints.

Common sizes in TN 14 are 4 × 8 in. (102 × 203 mm) and 3⅝ × 7⅝ in. (92 × 194 mm). Common thicknesses run from 1¼ to 2¾ in. (32–70 mm). C1272 sets minimum thickness at 2⅝ in. (67 mm) for Type F and 2¼ in. (57 mm) for Type R.

EN 1344 Clay Paver Classes

EN 1344 has no single grade: a producer declares a class for each property, and T4, A3, U3 and FP100 is the top set. Wienerberger’s UK Clay Paving Technical and Specification Guide summarizes the classes of BS EN 1344:2013 as below; the buyer’s specification decides what is needed.

The same guide recommends clay paver thicknesses of 62–65 mm for car parks without heavy traffic, 70 mm with occasional commercial vehicles and 85 mm for regular heavy traffic, with design to the relevant part of BS 7533. Those are one maker’s recommendations, not limits in EN 1344.

The practical difference from ASTM is the test. C902 relies on compressive strength and absorption, while EN 1344 relies on a bending-type breaking load plus abrasion and slip. A plant selling to both markets needs both sets of test equipment, or a third-party lab for each. Results do not convert: C1272 Type F’s 475 lb/in. works out at about 83 N/mm, close to the 80 N/mm of T4, but the test methods differ. See clay brick testing methods for how the ASTM and EN test families compare.

How Paving Bricks Are Made: What Changes in the Plant

Paving bricks follow the same process as other fired clay bricks, but they leave less margin in body preparation, forming and firing. The stages are in our article on the clay brick manufacturing process. The changes below are our production reading of the limits above, not clauses of any standard.

• Raw material. Good brick clays have low carbon and sulfur, usually under 1.5% and 0.2% (Bloodworth, British Geological Survey, 2016). Carbonates and coarse particles deserve extra attention in a unit that will be walked and driven on. Run a brick clay test with fired absorption and strength results before committing.
• Forming. Extrusion, at 10–15% water, is used for about 90% of US brick, while soft-mud molding uses 20–30% water (BIA TN 9, 2006). C902 reflects the difference with its lower strength limit for molded units. As a reference for the lines we source, two-stage vacuum extruders sit in the 4.0 MPa extrusion-pressure class with vacuum to about −0.092 MPa; these are not paver-grade guarantees. In our reading, de-airing is what gives a dense body.
• Shape. Pavers are usually solid, wide units with chamfers or spacers on the die or by repressing. A die change alters the shape, but it does not change how the body dries or fires.
• Drying. Thick solid units release moisture more slowly than thin-webbed perforated units, so drying curves need trial rather than copying.
• Firing. Paving limits are met by vitrification, which BIA TN 9 describes as giving a hard mass with relatively low absorption. It begins at about 900 °C and is complete at about 1,050–1,100 °C (Bloodworth, 2016), and the BIA warns that control must stop short of viscous fusion. US tunnel kilns fire at up to about 1,090 °C (US EPA AP-42, section 11.3). Our reference lines typically fire at 950–1,050 °C, up to 1,150 °C; that is a reference range, and it does not promise a paver grade from any given clay. See clay brick firing temperature.
• Setting. Heavy stacks of solid units change airflow and load on the lower layers, so the position in the setting must be checked for strength and absorption spread.
• Sorting. Size and warpage decide PX or R1 compliance, which turns sorting into a quality gate as well as a packing step.

Testing Plan for a Paver Trial

A paver trial should test the full list of properties on fired samples from known kiln positions, because the weakest position, not the mean, decides whether a batch passes individual limits.

Clay Brick Pavers vs Concrete Pavers

Clay brick pavers and concrete pavers can meet similar compressive limits, but they are different plants: clay pavers need a kiln and suit a clay deposit, while concrete pavers need cement, aggregate and curing. The comparison below uses clay paver limits from BIA TN 14 (2017) and concrete paver limits from ASTM C936/C936M-23; check the current edition of each.

Absorption limits measure different materials and do not rank durability directly. For an investor, the deciding factors are local clay or local aggregate, fuel supply, the market’s habit and specification, and whether the plant also sells walling units. A clay plant can make bricks and pavers from the same kiln, subject to trials. In process terms, a concrete paver press is closer to hollow block machines and brick making machinery than to a kiln line.

FAQ

What makes clay brick for paving different from walling brick?

Clay brick for paving needs higher strength, lower absorption and more abrasion resistance than most walling brick. ASTM C902 Class SX sets 8,000 psi average compressive strength and 8% maximum cold-water absorption (BIA TN 14, 2017). Ordinary bricks can also meet some of those limits, but only tested abrasion and freeze-thaw results show a unit suits paving.

Which is better, clay brick pavers or concrete pavers?

Neither wins on every point. ASTM limits for strength are similar: 8,000 psi average for C902 SX and for C936-23 concrete units. Clay color comes from the fired body, and concrete has tighter length and width tolerances in its standard. A plant decision usually depends on local raw material, fuel and the specification in the target market.

What do T4, A3, U3 and FP100 mean on a clay paver?

They are the top declared classes under BS EN 1344:2013. As summarized in Wienerberger UK’s paving guide, T4 means a mean breaking load of 80 N/mm with 64 N/mm minimum, A3 means under 450 mm³ abraded volume, U3 means a mean slip value of 55, and FP100 means freeze-thaw resistance over 100 cycles. Check the current edition.

Can ASTM C902 pavers be used for heavy vehicles?

No. ASTM C902 covers pedestrian and light traffic such as residential driveways and commercial drop-offs, and states that its units are not intended for heavy vehicular traffic. Heavy-duty applications fall under ASTM C1272, which asks for stronger units: 8,000 psi average for Type R and 10,000 psi for Type F on a sand bed (BIA TN 14, 2017).

Can an existing fired brick line make clay pavers?

Often, but only trials can confirm it. A die change gives the shape, but the clay body must still reach the target strength and absorption without distorting, and the thicker solid unit needs its own drying and firing curve. Test the clay and fire samples from several kiln positions before promising a paver grade to customers.

Planning to Add Clay Pavers?

A paver trial starts from the same core equipment as a fired clay brick production line: vacuum extrusion and a tunnel kiln. Send clay samples and your target paver standard. Only trial results can show whether your deposit reaches that grade and whether a paver scope suits the line.

Sources

• Brick Industry Association, Technical Note 14: Paving Systems Using Clay Pavers (May 2017): https://gobrick.com/media/file/14-paving-systems-using-clay-pavers.pdf
• Brick Industry Association, Technical Note 9: Manufacturing of Brick (December 2006): https://gobrick.com/media/file/9-manufacturing-of-brick.pdf
• ASTM C902-09, Pedestrian and Light Traffic Paving Brick (public extract): https://cdn.standards.iteh.ai/samples/66167/a07bf1ec12f440b890bd858e894eef27/ASTM-C902-09.pdf
• ASTM C936/C936M-23, Solid Concrete Interlocking Paving Units (public extract): https://cdn.standards.iteh.ai/samples/115599/6e32e9bb128f4e0d849b902e76b1f42f/ASTM-C936-C936M-23.pdf
• BSI, BS EN 1344:2013, Clay pavers. Requirements and test methods (record): https://knowledge.bsigroup.com/products/clay-pavers-requirements-and-test-methods
• Wienerberger UK, Clay Paving Technical and Specification Guide (brochure, undated): https://www.wienerberger.co.uk/content/dam/wienerberger/united-kingdom/marketing/documents-magazines/commercial/UK_MKT_PAV_PEN_DOC_Paver_Technical_Brochure_001.pdf
• A. Bloodworth (British Geological Survey), The influence of geology on English brickmaking, IHBC Context 143 (March 2016): https://www.designingbuildings.co.uk/wiki/The_influence_of_geology_on_English_brickmaking
• US EPA, AP-42 Section 11.3: Brick and Structural Clay Product Manufacturing: https://www.epa.gov/sites/default/files/2020-10/documents/c11s03.pdf