Our company has compiled relevant road construction data.Before proceeding to the next level of construction,the base layer must undergo multiple tests to ensure its strength,stability,and overall quality meet requirements.Specific test items may vary depending on engineering specifications,but the following are the most common and critical inspection items:

1.Compaction Test(Field Density Test):

·Purpose:Verify that the subbase is adequately compacted to the specified density(typically

95-100%of maximum dry density as per Modified Proctor Test,ASTM D1557 or equivalent)

·Method:

·Oven-Drying Method(ASTMD2216)

·Speedy Moisture Tester(ASTM D4944)

Requirement:Moisture content should align with project specifications.

3.California Bearing Ratio(CBR)Test:

Purpose:Assess the subbase's strength and load-bearing capacity

Method:Conducted in the lab(ASTM D1883)or in-situ(if specified).Samples are tested at the compacted density and moisture content achieved in the field

Requirement:CBR value must meet the design requirement(e.g.,20-80%for subbase,depending on road type)

4.Gradation Test(Sieve Analysis):

·Purpose:Confirm that the subbase material's particle size distribution complies with the project's gradation requirements

·Method:

Sieve analysis(ASTM C136).

Requirement:Material must fall within the specified gradation envelope.

5.Atterberg Limits Test(if applicable):

Purpose:For fine-grained materials,check plasticity to ensure the subbase isn't overly plastic or susceptible to deformation

Method:Liquid Limit and Plastic Limit(ASTM D4318).

·Requirement:Plasticity Index(PI)should be within allowable limits(typically low for subbase materials).

6.Plate Load Test(optional):

·Purpose:Evaluate the subbase's stiffness and load-bearing capacity in-situ.

·Method:Apply load via a plate and measure settlement(ASTM D1196).

·Requirement:Modulus of subgrade reaction(k-value)or deflection should meet design criteria.

7.Proof Rolling Test:

Purpose:Identify weak or soft spots in the subbase by observing deformation under heavy loads.

·Method:Use a loaded truck or roller to pass over the subbase and check for rutting or pumping.

·Requirement:No significant deformation or instability should be observed.

8.Thickness Verification:

·Purpose:Ensure the subbase layer meets the specified thickness.

·Method:Direct measurement(e.g.,probing or coring)or survey methods.

·Requirement:Thickness should be within allowable tolerances(e.g.,10 mm)