Paver Block Road Construction: Layers, Block Thickness and Laying Method

Where can you build a paver block road?

IRC:SP:63 lists footpaths, cycle tracks, residential streets, car parks, fuel stations, rural roads through villages, bus depots, intersections, toll plazas, truck parking, container depots and port roads. All of them carry slow traffic. A block surface holds speeds to about 60 km/h, which the guideline counts as an advantage in streets and at junctions.

Clause 1.2 does not recommend blocks for expressways, national highways, state highways or major district roads, except where a state highway or district road passes through a village or town.

On the right road, blocks bring three real gains. There is no curing, so the road opens as soon as the joints are filled. A trench for a water pipe or cable is easy to reinstate, because the same blocks go back down. And the work is labour-based, needing only simple compaction equipment. Against that, the ride is rougher and noisier than machine-laid bitumen or concrete, and water seeps through the sand joints, so drainage needs more care. For a village lane carrying loaded tractors every day, weigh it against a CC road. The types of roads guide shows where village roads, district roads and highways sit.

What are the layers of a paver block road?

Below the blocks, a paver road is built much like any other road; clause 4.1 says the base and sub-base are similar to a conventional pavement. From the bottom up:

• Subgrade: the natural soil, compacted in layers of 100 or 150 mm, with the water table at least 600 mm below. If the soil’s CBR, a measure of the load it can take, is under 5 per cent, it must first be stabilised to 5. The CBR test guide explains the number.
• Granular sub-base (GSB): gravel or crushed material that spreads the load, with a drainable bottom 150 mm.
• Base: WBM (water bound macadam) or WMM (wet mix macadam). Heavy-duty yards, and roads with poor drainage, get lean concrete such as DLC on top.
• Bedding sand, the paver blocks, and fine joint sand brushed into the 2 to 3 mm gaps. The joint sand is what locks the blocks together.

Figure 1: Cross-section of a paver block road for a residential street

A kerb or edge strip stands at each side on the base, so the blocks and sand cannot spread. Figures from IRC:SP:63-2018 Table 1 and clause 8.2. The road construction layers guide covers GSB and WMM in more detail.

How thick should paver blocks be for a road?

Thickness follows the traffic: 60 mm for pedestrians, cars and cycles, 80 mm for medium traffic, and 100 to 120 mm for heavy traffic, with thicker blocks best where vehicles turn a lot (clause 4.3). Traffic is counted in msa, million standard axles: the heavy-axle passes the road is designed to carry, usually over 20 years.

Source: IRC:SP:63-2018 Table 1. M-30, M-40 and M-50 are block compressive strengths in MPa.

The grade is the block’s strength, and the Bureau of Indian Standards sets it in IS 15658:2021, the paving block specification, as revised in 2022.

Source: IS 15658:2021 Table 1 as revised by Amendment No. 1 (April 2022).

Side by side, the BIS table is the stricter one in most bands. For 10 to 20 msa, IRC asks for M-40 blocks 80 to 100 mm thick; BIS asks for M 50 and at least 100 mm. For 2 to 10 msa, IRC allows 60 mm where BIS asks for 80. When the tender names a grade and thickness, supply that. When it names only the traffic, quote the BIS figure, the higher of the two.

Thickness must also be even. IRC:SP:63 holds blocks to ± 2 mm, because mixed thicknesses settle unevenly and leave a wavy road. How block makers hold a grade from batch to batch is covered in the paver block business guide.

What sand goes under paver blocks, and how thick is the sand bed?

Under IRC:SP:63 the bedding sand is 30 mm thick after compaction, give or take 5 mm, which means 30 to 50 mm spread loose. The BIS laying code, IS 16777:2019, allows 20 to 40 mm compacted. Both insist the bed is the same thickness everywhere.

So sand must never fill a dip in the base. Blocks settle until the surface runs parallel to the base, and a hollow in the base comes back as a hollow in the road. Fix the base, then spread the sand.

Bedding sand should be sharp and angular, well graded, with 3 per cent clay and silt at most, and never from a soft stone like limestone, which powders under load. Crushed sand works if it meets the grading; the quarry dust and M-sand guide explains the two crushed products. Joint sand is finer, dry, washed of salts and never mixed with cement, because cemented joints crack into loose pieces.

Source: IRC:SP:63-2018 Annexure I and IS 16777:2019 Tables 1 and 2, which give the same gradings.

Keep the sand slightly moist and under a tarpaulin. Spread it with screed boards carrying nails 2 to 3 m apart; dragged along, they leave the bed at nail depth plus a little for settlement. Nobody walks on the screeded bed.

Why does a paver block road need edge restraint?

Every vehicle that brakes or turns pushes the blocks forward and sideways. In the middle, neighbouring blocks push back. At the edge, only an edge restraint can: a kerb, an edge block or a concrete edge strip.

Clause 4.6 asks for edge members of at least 30 MPa compressive or 3.8 MPa flexural strength at 28 days, with a vertical face towards the blocks. IS 16777 adds that the base should run about 60 cm beyond the edge line so the kerb sits on firm ground, and that heavy-traffic roads can take a 150 mm × 150 mm strip of M-25 concrete over dry lean concrete for extra hold.

Order matters. The edge restraints go in after the base and before the sand. A kerb cast after the blocks lets the edge rows move before anything holds them.

Which laying pattern suits a road: herringbone or stretcher bond?

The codes name three common patterns. Stretcher or running bond lays rows like a brick wall, with continuous joints in one direction. Herringbone sets blocks at right angles in a zig-zag, at 45° or 90° to the traffic. Basket weave lays pairs side by side, each pair turned 90° to the next.

IS 16777 defines herringbone as a pattern in which no joint runs longer than one and a half blocks. That explains why it suits roads: there is no long straight joint for a row of blocks to slide along under braking wheels.

Block shape decides what is possible. IRC:SP:63 sorts toothed-edge (dentated) blocks into three categories. Category A blocks key in on all four sides, resist joints opening, and can generally go in herringbone. Category B, toothed on two sides, and Category C, plain, can usually go only in stretcher bond. If the drawing says herringbone, check the category before ordering. Herringbone also solves awkward spots: a curve can be laid in herringbone with straight approaches in stretcher bond, and herringbone turns through a junction without a construction joint.

How is a paver block road laid, step by step?

IS 16777 clause 8.1 sets the order, and IRC:SP:63 clause 8 fills in the detail:

1. Lay sub-surface drains, usually 80 mm perforated pipes in filter material, before compacting the subgrade.
2. Build subgrade, sub-base and base to level, with a crossfall of about 2.5 per cent for rainwater. The field density test checks the compaction.
3. Fix kerbs or edge strips on the finished base.
4. Spread and screed the bedding sand to an even depth.
5. Lay blocks from the edge strip, working in one direction across the full width. On a slope, start at the lowest point and work uphill. Chalked string lines every 5 m keep the pattern straight. Never hammer blocks into the sand while laying.
6. Cut edge blocks with a block splitter or power saw. Pieces under 50 mm are not used; fill such gaps with concrete or sand-cement mortar.
7. Compact, fill the joints and compact again (next section).
8. Sweep clean and fill any gaps beside the edge restraints with concrete.

A trained pavior, the skilled block layer, with one helper lays 50 to 75 m² a day. Around a manhole, lay along both sides at once and close the pattern beyond it, so small errors do not pile up at one point.

Which compactor is used for a paver block road?

A vibratory plate compactor does the main work. Clause 8.8.3 asks for at least two passes over the laid blocks, until every block sits level with its neighbours. Stay 1 m back from the laying face, and never leave compaction to the end of the day: loose blocks shift under site traffic overnight, joints widen and corners chip.

A standard plate weighs about 90 kg, with about 0.3 m² of plate and about 15 kN of vibrating force. A heavy-duty plate weighs 300 to 600 kg, with 0.5 to 0.6 m² and 30 to 65 kN, and is the one to use where the sand bed was compacted before laying and on heavy-traffic roads. The plate compactor guide explains why a rubber pad under the plate protects block faces.

After the plate, both codes allow 2 to 6 passes of a small vibratory roller. It needs rubber-coated drums, or a static weight under 4 tonnes and a nominal amplitude, the up-and-down travel of the vibrating drum, of not more than 0.4 mm under IRC:SP:63 or 0.6 mm under IS 16777. That means the small tandem rollers often called baby rollers. Full-size tandem rollers are far above the limit: the twelve listed on DesiMachines weigh 8,700 to 10,060 kg.

Figure 2: A small tandem roller of the class both codes allow over laid blocks

The Dynapac CC800 weighs 1,575 kg with a 0.4 mm nominal amplitude, inside the stricter IRC limit.

Weights, amplitudes and drum widths are each machine’s published specification at the time of writing. The two right-hand columns are our own reading of the code limits.

Every small tandem roller here fits the BIS laying code; only the lightest fits the road guideline’s tighter amplitude limit. If the contract follows IRC:SP:63 to the letter, ask which code the engineer will apply before a heavier baby roller goes onto laid blocks. The CASE 450NX and Dynapac CC800 comparison sets the two lightest side by side, and the tandem roller guide covers their other uses. Compare listed tandem rollers by weight, amplitude and drum width, and connect with a dealer near your site.

Joint filling comes straight after. Spread a thin layer of dry joint sand, brush it into every joint, and run a few more plate passes with a little sand left on top. Dry sand and dry blocks matter: damp sand sticks at the top of a joint and only looks full, and the next rain shows it hollow. In wet weather, wash the sand in with a light spray and repeat the sand, water and plate cycle until the joints are full. Finish the joints the same day.

When can traffic use a new paver block road?

As soon as every joint is full, because the blocks need no curing. The exception is a treated layer underneath: IRC:SP:63 asks for at least 7 days of curing for a cement-treated layer and 14 days for a lime-treated one before traffic.

About a week after laying, walk the road and top up any joint where the sand has dropped. Repeat for two to three months, until road dust tightens the joints; after that, check once a year. Keep 1 to 3 per cent of the original blocks in store, as the guideline suggests for important projects, because a matching block can be hard to find after the first trench is dug.

Why do paver block roads sink, rock or open up?

Almost every failure traces back to a step above:

• A wavy surface: the base was out of level, or sand filled its dips.
• Single blocks standing proud or sunk: blocks of mixed thickness.
• Blocks rocking, with chipped edges: joints never completely filled.
• Rows opening near the edge: edge restraint missing, weak or cast after the blocks.
• Patches sinking after rain: water through the joints has no way out through the sub-base or drains.
• Cracked or spalled blocks: blocks butted tight with no joint gap.
• Small pieces knocked out at the edges: cut pieces under 50 mm used instead of concrete infill.

Trenching is a common cause in towns. IRC:SP:63 Annexure I notes that the WMM and GSB under a block road are often disturbed when utilities are laid and rarely rebuilt well, and suggests DLC or controlled low-strength material, a self-compacting flowable fill, over the base along utility strips. Failures on bitumen and concrete roads are covered in the types of pavement failure guide.

What should you check before signing off a paver block road?

The tolerances a site engineer checks most often, from IRC:SP:63 clause 8.8.6:

• Finished surface within 3 mm under a 3 m straight edge.
• Adjacent blocks no more than 5 mm above or below each other.
• Joints 2 to 3 mm wide, with no more than 10 per cent outside that range along any 10 m line.
• The block surface at least 5 mm above manhole covers, gully gratings and side drains, so water runs into them.
• Every joint full to the top, and the edge restraints solid.

How rollers and other machines are planned across a whole road package is set out in the guide to machinery required for road construction, and more on how roads are built is in the road construction guides. Browse the full range of road rollers and compactors to find a roller for the job.

Where the figures in this guide come from. Layer thicknesses, laying and compaction rules, tolerances and road-type limits are from IRC:SP:63-2018, Guidelines for the Use of Interlocking Concrete Block Pavement (first revision), read in full, with Tables checked against the printed pages. The laying sequence, sand bed range, edge-strip detail and 0.6 mm roller limit are from IS 16777:2019, Laying of Paver Blocks: Code of Practice. Block grades are from IS 15658:2021 with Amendment No. 1 of April 2022. Roller specifications are as published for each machine at the time of writing. The 540 to 610 mm total is our own arithmetic from IRC Table 1.

Prices, specifications and features are indicative, vary by variant, location and date, and should always be confirmed with the official OEM or authorised dealer before any purchase decision. DesiMachines is not liable for decisions taken on the basis of information that may have changed after publication.