Reasons For Compaction; Compaction Speci Cation - Altrad Belle PCX 450 Manual Del Operador

Soil, which has been disturbed or new in ll, subbase and blacktop, will have small voids or air pockets which, if not compacted, will
lead to one or more problems occurring.
1. As traf c crosses the surface of an uncompacted area, the material is compressed. This leads to subsidence of the top
surface as the material lls the voids.
2. A similar situation occurs with static loads on uncompacted ground. The load (e.g. a building) will sink.
3. Materials with voids are more susceptible to water seepage, leading to erosion. Water ingress may also cause the soil
to expand during freezing temperatures and contract during dry spells. Expansion and contraction is a major cause of
damage to building foundations and normally leads to the structure requiring underpinning.
Compaction increases the density of the material and therefore increases its load bearing capacity. Reduces air voids
and therefore reduces the risk of subsidence, expansion and contraction, due to ingress of water.
Various methods have been employed in the past to specify the compaction required for various applications. The factors to
consider are, material properties, layer thickness, pressure applied, vibration and number of passess. Greater understanding of how
compaction works has lead to new compaction speci cations being introduced.
The most up to date speci cation is part of the U.K.'s NRSWA (New Roads & Street Works Act). Civil Engineers are now adopting
these speci cations to ensure good compaction for all site work.
NRSWA (HAUC speci cation).
The speci cation was compiled by HAUC (Highways Authorities & Utilities Committee).
The 'New Roads and Street Works Act 1991, set a new standard for road repairs and reinstatements in the UK. It covers materials,
methods, equipment and safety when carrying out reinstatements on roads and footways.
The reason for the act is to ensure repairs and reinstatements are carried out to a higher standard and ultimately last longer. This in
turn will reduce the need for costly remedial work and reduce traf c delays.
There are two categories speci ed for plate compactors.
1. 1400 to 1800kg/m²
These gures relate to the static pressure applied by the machine
NOTE: No standard single direction plate compactors comply with this minimum speci cation. For highways work always use a 'Dual
Force' plate compactor.
DUAL FORCE
Altrad Belle studied the act then developed and patented equipment to enable contractors to comply with the act's requirements.
The NRSWA legislation requires that compaction equipment meets the minimum speci cation. By purchasing an Altrad Belle 'Dual
Force' plate, you are immediately complying with this part of the act. To comply with the speci cation and maintain surface tolerance,
Altrad Belle 'Dual Force' base plates are divided into two areas providing two stages of compaction.
Stage 1: The full base area compacts the material like a standard machine.
Stage 2: The base rises onto the 'Dual Force' section to give 3 to 4 times the compaction force of standard plates.

Reasons For Compaction

Compaction Speci cation

2. Over 1800kg/m²
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