Geosynthetics in roads and pavements

Placement of the Aggregate 

Place the aggregate over firm subgrades by back 

dumping aggregate onto the geosynthetic and 

then spreading it with a motor grader.  For 

weaker subgrades, dump onto previously placed 

aggregate and then spread the aggregate onto 

the geosynthetic with a bulldozer.  On weaker 

subgrades, a sufficient layer of aggregate must 

be maintained beneath all equipment while 

dumping and spreading to minimize the 

potential of localized subgrade failure. 

 

Avoid traffic directly on the geosynthetic. 

 

When using construction equipment on the 

aggregate, try to avoid any sudden stops, starts 

or sharp turns. 

 

Maintain a minimum lift thickness of 6-inches 

(15 cm) except in cases of low volume roads.  

Compact the aggregate to the specified density 

using a drum roller.  Fill any ruts with additional 

aggregate and compact as specified. 

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                                                      GEOSYNTHETICS IN ROADS AND PAVEMENTS:                                                       17 

Subgrade Separation and Stabilization, Base Reinforcement, Overlay Stress Absorption and Reinforcement 

For more information please contact the Geosynthetic Materials Association at www.gmanow.com. 

 

 

Fabric Rolled Out and Overlapped (or seamed) 

 

 

If the subgrade is firm and free of debris, run and dump 

placement of aggregate may be used 

 

 

When constructing over weak subgrades, back-dumping 

of the aggregate is required 

 

Normal construction activities, including 

aggregate spreading and compaction are used. 

Caution should be used when selecting 

compaction equipment.  When thin lifts are 

used, vibratory compaction is not recommended 

until a minimum 12-in (30 cm) compacted 

thickness is achieved.  Use of such equipment 

may result in damage to the geosynthetic.