3. Wearing course

This chapter is a special chapter in the eLearning package as it will focus on the “pavement” of a gravel road and forest road. The contents will overlap and reinforce information in the other Chapters of the eLearning, ie some material will be repeated. The reason for this is that many readers most likely will review only this chapter when trying to find information what to do with the wearing course.

3.1 General

General information regarding the functions of wearing courses in gravel roads and forest roads. There are some differences between these two types of roads and these will be presented.

3.2 Wearing course material

3.2.1 Material types specifications

Introduction of grading, especially max grain size, amount of fines and fines content. The basic rules of thermodynamic and suction forces will be also presented. Also how increase salt increase compaction level. Discussion also about material types , crushed gravel, hard rock, moraine and added clay.

3.2.2 Material testing methods

Grading (fines content. clay content), plasticity index, water adsorption test, tube suction test). These techniques will be “copied” from other eLearning packages.

3.2.3 Wearing course thickness

Guidelines of wearing course thickness specifications, when it is too thin and when too thick. Also discussion about longitudinal geometry and wearing course thickness, ie. why thickness is small on the top of hill and thick in the valleys and what is the importance of that.

3.2.4. Dust binding additives

The function of dust binders. Summarizing different types of dust binders (salts), alternative dust binders and their usage.

3.2.5. Grading control

How to control grading in the wearing course.

3.3. Wearing course maintenance in different seasons

3.3.1. Spring maintenance

Spring thaw maintenance operations to ensure good quality wearing course over summer

3.3.2. Summer maintenance

Summer maintenance, when wearing course should be graded dragged and when not…

3.3.3. Autumn maintenance

What is needed to do with wearing course before winter.

3.3.4. Winter maintenance

Wearing course management during the winter time, when and how to do compacted snow wearing course and how and when to remove it.

3.4. Monitoring wearing course condition

3.4.1. Monitoring wearing course thickness

Techniques how to measure/ monitor wearing course thickness, manual method, GPR, other techniques

3.4.2. Monitoring roughness

Description of different roughness issues, washboarding, potholes, bumps, settlement. Presenting different roughness monitoring techniques, visual inspection, accelerometers, cell phone techniques, video/photos, GPR antenna bouncing method.

3.4.3. Plasticity monitoring

Description GPR dielectric value survey method in plasticity monitoring

3.4.4. Monitoring dusting

Presenting different methods to monitor dusting, visual method, video/ still images, laser scanner method

3.4.5. Monitoring crossfall

Why cross fall should be measured, flattening of gravel road crossfall
Presenting visual methods, laser scanners method, 3D accelerometer technique. Examples how to present crossfall

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