Coring of Pavement for the Determination of Average Depth

Introduction

Coring is technique for mining a sample of the earth, mineral, or rock. We remove a cylindrical shaped sample of the roadway using coring rig. The use of coring machine allows us to analyze the layers of strata. Coring helps us to judge the strength of the road in relation to the weight and amount of traffic travelling over it. This involves the determination of the thickness of the pavement.
Samples of asphalt concrete collected using the coring method may be used to evaluate various characteristics of an asphalt concrete pavement for construction quality control testing, quality assurance testing and product acceptance testing. The sample can be used in the determination of bitumen content and samples may also be used for research testing purposes (Stp204-5 Saskatchewan Highways and Transportation, 1994).

Objective(s) of the Experiment

The test is carried out to remove a cylindrical sample of a layed pavement material

Equipments and Materials Needed

Portable Drilling Equipment – mounted on a trailer, truck or other similar equipment for transportation purposes. The drill shall be equipped with a source of power suitable for driving the core barrel.
A source of water supply to cool the core barrel during drilling operations and to lubricate the contact between the drill and the pavement.
Core Retrieval Tool – to extricate cores from the pavement when coring is completed, without causing damage to the cores.
Marshall handheld compaction hammer.
A container in which cores can be placed and maintained at a cold temperature.
Towels – To clean the cores to avoid swelling
Hot asphalt mix will be used to backfill core holes.

Sample to be tested

The material to be sampled will be an asphalt concrete pavement. Sampling locations will be determined by methods as directed by the Engineer.

Procedures

Mark the core sample locations before positioning the coring equipment.
Position the core drill with the core barrel perpendicular to the asphalt concrete surface at the specified sampling location.
Turn on the coring machine.
When the core barrel projects through the asphalt concrete, stop the barrel rotation and turn off the equipment.
Raise the core barrel and remove the core from the hole using core retrieval equipment.
Wipe the cores immediately with a dry towel to minimize water absorption into the core.
Identify the core by sample number. All other sample documentation as described in section 3.3.6 should be recorded and submitted with the core samples.
Backfill the core holes with hot asphalt mix and compact with hand held Marshall Compaction hammer. Core holes shall be dry and clean prior to backfilling.

Results and Calculations

Data Required

Data to be submitted with each core sample includes the following;