Asphalt inspection involves:
- Assessing its condition
- Identifying any damages or issues
- Determining the necessary repairs or maintenance
Asphalt Inspection Process
Start by visually examining the asphalt surface. Look for signs of cracking, potholes, raveling (loose aggregate materials), rutting, or any other visible damage. Then, walk or drive around the area to get a comprehensive view.
Evaluate the overall condition of the asphalt surface. Check for signs of oxidation, discoloration, or fading. Also, assess the smoothness and texture of the pavement.
Identify and categorize different types of cracks, such as:
- Longitudinal cracks (parallel to the direction of traffic)
- Transverse cracks (perpendicular to the direction of traffic)
- Block cracks (interconnected rectangular cracks).
Measure the width and length of the cracks using a ruler or crack gauge.
Look for potholes or depressions in the asphalt paving. Measure their size and depth. Assess the severity of the damage and its impact on the pavement’s usability.
Check for proper drainage. Look for standing water or areas where water accumulates on the surface. Poor drainage can lead to accelerated pavement deterioration.
Evaluate the condition of asphalt pavement markings, such as lane lines, arrows, and symbols. Note any fading, missing markings, or signs of wear.
If necessary, conduct a structural assessment. This will help determine the integrity of the asphalt pavement layers. This may involve coring, where samples are taken from the asphalt to evaluate its thickness and composition.
Assess the condition of the subbase or underlying layers. Uneven or sinking areas in the asphalt mixes may show subbase issues that need attention.
To create a comprehensive inspection report, record your findings, including photographs and measurements. This report can be used to plan repairs or maintenance.
It’s worth noting that a professional asphalt inspector or civil engineer may be required. They will give more detailed assessments or complex projects.
Asphalt inspection in a laboratory involves conducting tests and analyses. This will evaluate its properties and quality. Here are some standard methods used to examine asphalt in a laboratory:
Obtain representative samples of the asphalt to be tested. Collect cores from the pavement or obtain bulk samples from construction sites.
Perform a sieve analysis to determine the asphalt mixture’s gradation or particle size distribution. This testing involves passing the sample through a series of sieves with different mesh sizes. This is to separate the particles into various fractions.
Extraction and Binder Content:
Determine the asphalt binder content in the mixture using an extraction test. This involves extracting the binder from the sample using a suitable solvent. Then weigh the extracted binder to calculate its percentage in the mixture.
Analyze the composition of the asphalt binder using techniques such as:
- Thin-layer chromatography (TLC)
- Gas chromatography (GC).
These methods can help identify the types of binders and their properties, including:
Marshall Stability and Flow:
Conduct Marshall tests to evaluate the stability and flow of the asphalt mixture. This testing involves compacting cylindrical samples of the mix and subjecting them to loading and deformation. This is to measure their resistance to deformation and flow.
Density and Void Analysis:
Determine the density and void characteristics of the asphalt mixture. Use methods like bulk specific gravity (Gmb) and percent air voids. The testing provides insights into the compactness and durability of the asphalt mix.
Assess the moisture susceptibility or resistance of the asphalt mix. Conduct tests such as the AASHTO T283 or AASHTO T324. These tests evaluate the mixture’s ability to resist damage caused by moisture infiltration.
Perform additional performance-related testing depending on the specific requirements and objectives. These tests can include:
These assess the asphalt’s ability to withstand traffic loads and environmental conditions.
Compliance with Standards:
Compare the laboratory test results with established specifications. These are provided by transportation agencies or industry standards. Verify if the asphalt mix meets the required criteria.
It’s important to note that asphalt testing procedures may vary depending on the:
- Specific laboratory equipment
- Testing standards
- Project requirements
PMET-trained technicians or engineers with expertise in asphalt testing should perform these laboratory inspections.