Paving

• AS 3727 Guide to residential pavements
• Where doubt exists as to the acceptability of the fine content of base material or sand, it shall be tested in accordance with AS 1141.33, a summary of which follows.

Summary Extract From AS 1141.33-1997 Methods For Sampling And Testing Aggregates Method 33: Clay And Fine Silt (Settling Method) This settling test may be used as a guide to determine the amount of fine silt, clay and similar materials in fine aggregates. Test portion of material to yield 100mL of fine aggregate from sample. Make a salt solution by dissolving 10 g of common or table salt in 1.0 L of water. Place approximately 50 mL of salt solution in a 250 mL stoppered measuring cylinder. Add 100 mL of aggregate to solution. Make volume up to 150 mL by adding more salt solution. Stopper cylinder. Shake for 30 s. Tap cylinder until aggregate surface is level. Stand for three hours. Note the volume of sand (S) and settled clay and fine silt (F).The percentage of clay and fine silt can be calculated from: C = ( F/S ) x 100

Rutting of Segmental, Asphalt or Bituminous Pavements

If constructed poorly on uncompacted subgrade or base course, segmental pavements, asphalt pavements and bituminous spray-sealed pavements can progressively develop ruts under the vehicle loading.
Ensure that the correct thickness of base course is constructed and compacted, using a plate vibrator or compactor. If small areas are involved, it may be economical to use a layer of blinding concrete.
To repair small areas of rutted pavement:

• Remove the surface layer and the affected base.
• Check for drainage problems.
• Reinstate the base, using cement stabilised road base or lean-mix concrete.
• Re-lay and re-compact the surfacing layer.

Creep of Segmental Pavements

When segmental pavements are constructed on a sloping site, the braking and acceleration forces applied by vehicles may cause the joint spaces to progressively close.
To avoid this problem, the following actions are possible:

• Use pavers with spacer nibs, tightly butting adjacent units.
• If units without spacer nibs are to be used, a gap of approximately 3 mm should be left between adjacent units to enable jointing sand to be forced into the space. Otherwise fretting of the top surface can occur. Use dry sand of the correct grading, ensuring that the joints are correctly filled.
• On steeply sloping pavements, construct false beams across the pavement, usually associated with a soldier course, to arrest any downhill creep.

Cracking of Segmental Pavements

Cracked units in residential segmental pavements usually result from and inadequate base (associated with rutting) or using units with insufficient breaking strength.
Breaking strength of a paver depends, not only on the quality of the material, but also on the relationship between length, width and thickness.
Ensure that the correct thickness of base course is constructed and compacted, using a plate vibrator or compactor.

Cracking of Concrete Pavements

Shrinkage of the concrete is the principal cause of cracking in concrete pavements. This will be exacerbated by excessive thickness of concrete, failure to cure the concrete, and by the use of light reinforcement. AS 3727 permits the use of SL 62 fabric for light duty applications and SL82 for medium duty applications. SL62 fabric is not considered to be adequate to minimise shrinkage cracking.
The inadequate thickness of the concrete, light reinforcement and the poor compaction of the sub-grade may lead to structural cracking.
The designer should consider carefully the possibility of shrinkage and structural cracking with light fabric. Unless stated otherwise in the drawings, reinforcement should be SL82 fabric.
To avoid cracking:

• Ensure that the sub-grade, including any fill material, is properly compacted.
• Place the correct quantity of reinforcement in the top half of the slab.
• Construct control joints at the required spacing and located at any points of weakness and re-entrant corners. Avoid T-junctions of control joints.

To repair cracked pavement:

• Saw cut new control joints in strategic locations to arrest further cracking
• Remove and reinstate the cracked concrete, or saw cut the cracked area and patch with epoxy. Both solutions result in a loss of aesthetics.

Efflorescence of Concrete and Segmental Pavements

Efflorescence is the white discolouration, which appears on the pavement surface. It can result from several varied sources, the most common of which is evaporation of moisture from the surface of the pavement. This draws salts (often calcium hydroxide) to the surface where it is deposited (often carbonating to deposit insoluble calcium carbonate).
To avoid efflorescence problems:

• Use products with a low potential to effloresce
• Use clean sands and bedding materials

To remove efflorescence:

• Allow the pavement to stand for several months to ensure that the full extent of the efflorescence is known.
• Saturate the pavement, use proprietary cleaners in accordance with the manufacturer’s recommendations and thorough wash off all material. Observe all recommended safety precautions.

Slip Resistance

AS/NZS 4586 defines the method of classifying slip resistance of new pedestrian surface materials. Standards Australia Handbook HB 197 provides background and guidance to slip resistance, but does not give mandatory requirements.
The following tables are provided for the assistance of designer for external applications, but do not constitute recommendations. They are derived from HB 197 Table 3, together with a proposed amendment to HB 197 Table 3. Items which have been struck out struck out are considered to be too liberal by the authors of this sample specification, and more conservative values have been substituted in italic print.
The designer must take full responsibility for the selection of the appropriate values. This must be done giving full consideration to slope, lighting, volume of traffic, age of pedestrians, gait, maintenance of surface and any other factor likely to affect the probability of slip occurring. The designer should refer to HB 197 and AS/NZS 4586 for full details.
Suggested amendments to HB 197 Table 3