Category: Structure & materials
Prepared by Eng. Ahmed Fathy, Projects Manager ·
Definition
A compaction test measures the in-place density of a soil or fill layer and compares it with the maximum density from the lab test; the result is a percentage, usually required at 95% or more.
Why it matters on a project
Uncompacted fill settles under slabs and paving within months, cracking floors and breaking buried pipes.
Measurement and pricing
Carried out for each fill layer at the number of points set in the specification.
Worked example
Lab maximum dry density 2.10 g/cm³ and field density 2.02: compaction = 2.02 ÷ 2.10 = 96.2%, acceptable where 95% is required.
Common mistake
Placing thick layers of fill at once and compacting only the surface.
Frequently asked questions
What is the Proctor test?
A lab test that finds the maximum dry density and optimum moisture of a soil; field results are compared with it.
How thick is each fill layer before compaction?
The specification sets it by equipment, often 20 to 30 cm.
Related terms
- BackfillRefilling excavations around foundations with suitable soil in compacted layers.
- Soil investigation reportThe borehole study on which the foundations are designed.
- Blinding concreteA thin layer of plain concrete under footings and ground beams.
- Inspection request (IR)A formal request from the contractor to the consultant to inspect work before the next stage.
Does your project need structural design and reinforcement drawings? Send the drawings or a short description and we reply within one working day.
Service detailsRequest a quote