Comprehensive Hardscape Education
for over
40 Years
Comprehensive Hardscape Education
for over 40 Years
UTEC – 102 - Driveway Base Fundamentals - 01
Instructions:
1.
Read the contents of each slide.
2.
Listen/watch to all multimedia content.
3.
Click on the link on the last slide and take the
online quiz.
4.
Take the next course segment (if applicable).
5.
Once you have completed a course or all the
segments of a course, print off a Certificate of
Completion
I
Comprehensive Hardscape Education
for over 40 Years
UTEC – 102 - Driveway Base Fundamentals - 01
Welcome to Part 1 of 3. (All 3 parts must be
completed before certificate can be obtained.)
•
Driveway Load Requirements
•
Site Soil Assessment
•
Drainage Considerations
Part 2 of 3
•
Base Options
Part 3 of 3
2
•
Compaction Equipment and Testing
•
Bedding Course Materials
Comprehensive Hardscape Education
for over 40 Years
UTEC – 102 - Driveway Base Fundamentals - 01
Driveway Load Requirements
The longevity of a solid driveway base will depend on:
1. Load/Usage/Drainage - The amount of base required in an area with light vehicle traffic/parking is much less
than what is required for an area that will have heavy vehicular traffic/parking. i.e. small compact cars vs large
SUV’s and trucks. The frequency of this load is important as well as the slope and drainage of the area.
2. Subsoil Type – Depending on the subsoil types, both the load bearing properties and drainage properties are
affected. Gravel subsoils for example, will support heavier loads and will not be affected by frost. Clay subsoils
on the other hand hold water and rut more easily.
3. Subsoil density/compaction – If the subsoil is loose and has recently been disturbed (new developments are
prone to this), settlement may occur if the subsoil has not been properly re-compacted.
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Comprehensive Hardscape Education
for over 40 Years
UTEC – 102 - Driveway Base Fundamentals - 01
Driveway Load Requirements
Depth (inches)
Driveway Load Requirements
Subsoil Types
4
Comprehensive Hardscape Education
for over 40 Years
A driveway base serves
TWO main purposes:
1. Load bearing/weight
dispersion. – to
prevent settling under
the pressure of a
wheel load.
2. Drainage – to prevent
frost movement.
Video:
Understanding
the chart.
UTEC – 102 - Driveway Base Fundamentals - 01
Site Subsoil Assessment
Assessing the subsoil type is important. Why?
Excavation - the poorer the subsoil the deeper the excavation. The deeper the excavation, the greater the expense of
excavation and gravel and compaction
Excavation Equipment - e.g. wet/buttery silt clay subsoil may require backhoe instead of skid steer. You may need to
rent these machines or hire a subcontractor
Excavation Timing - When is it feasible to excavate? You may have to wait for dryer period before excavating subsoils
that hold on to water longer than subsoils that drain better.
Drainage Properties - if the subsoil is poor, a thicker base may be required which will add to the cost
Load Bearing Capabilities - silt/sands and clays do not support loads as well, which means that your driveway will
require more base to prevent rutting.
Filter Fabric Requirements - certain silty subsoils can easily migrate over time into the base downgrading its structural
and drainage properties. Using filter fabric or geogrid between the gravel and subsoil can prevent this.
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Comprehensive Hardscape Education
for over 40 Years
1
4
2
5
UTEC – 102 - Driveway Base Fundamentals - 01
Adhoc Site Subsoil Assessment Using the Patty, Shake and Snake Test
Patty Test
1.
Take 1 cup of soil in your hand.
2.
Add enough water to make it into a “putty-like” consistency.
3.
Form the soil into a ball about the size of an egg. (Easy to do
most clay and silt soils.)
4.
Flatten out a sample into a patty (about 3/8” (10 mm) thick) and
let it dry in the sun. You will find that sandy soils will fall apart
while drying which indicates that the soil type is “well drained”.
5.
If it is difficult to break, it has high clay content. If it breaks
easily, it has a predominance of sand and silt in it.
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Comprehensive Hardscape Education
for over 40 Years
3
Difficult to break? = clay
Some coarse fines? = silt
Easy to break/falls apart
= sandy subsoil
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4
UTEC – 102 - Driveway Base Fundamentals - 01
Adhoc Site Subsoil Assessment Using the Patty, Shake and Snake Test
Shake Test
Little or no moisture = clay/silt
1.
Take 1 cup of soil in your hand
2.
Add enough water to make it into a “putty-like” consistency.
3.
Form the soil into a ball about the size of an egg. (Sandy soils may not
2
5
3
6
form immediately indicating its soil type – well drained.)
4.
Cup the ball of soil in two hands and shake vigorously for about 30
seconds.
5.
If small drops of water are released to the surface and hands, there is
some sand in the soil.
6.
7
If no water is released, the soil is clay or at least contains some silt.
Comprehensive Hardscape Education
for over 40 Years
1
4
UTEC – 102 - Driveway Base Fundamentals - 01
Adhoc Site Subsoil Assessment Using the Patty, Shake and Snake Test
Snake Test
1.
Take 1 cup of soil of soil in your hand
2.
Add enough water to make it into a “putty-like” consistency.
3.
Form the soil into a ball about the size of an egg.
4.
Begin rolling the sample into a few moistened “snakes” about 3/8” (10 mm) in
2
5
diameter.
5.
Roll into a snake up to 6 inches long. If the snake remains “rubbery”, this
indicates a clay soil type. Sandy soils will not form a “snake” beyond 2 inches
in length and easily break off indicating the soil type –”well drained”.
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Comprehensive Hardscape Education
for over 40 Years
3
If the snake will not
break off at (around the
2” mark) indicates “clay
soil” type.
UTEC – 102 - Driveway Base Fundamentals - 01
Field Test for Subsoil Drainage Assessment
Percolation Test
This is an ad-hoc field percolation test to establish site suitability for a permeable paver
installation without tertiary drains (weeper drains). Over time, the subsoil must be able to drain
the captured rainwater adequately.
Waterhole Test Procedure:
1.
Excavate 6 random holes /1000 sq.ft. of driveway area.
Each hole should be 16” x 16” wide x 16” deep.
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2.
Fill with water to top.
3.
Drive in stake with waterline marked.
4.
Observe hourly for 18 hours.
5.
Note the amount of percolation that has occurred.
Comprehensive Hardscape Education
for over 40 Years
UTEC – 102 - Driveway Base Fundamentals - 01
Percolation Test Results
Field Test for Subsoil Drainage Assessment
I0
Best Subsoil Conditions
Average Subsoil Conditions
Poor Subsoil Conditions
Gravel Subsoil
Sandy Subsoil
Clay/silt Subsoil
½” per hour
¼” per hour
Less than 1/8” per hour
Comprehensive Hardscape Education
for over 40 Years
UTEC – 102 - Driveway Base Fundamentals - 01
Drainage Considerations
A water saturated base of any depth can be a problem resulting in settlement under load or frost
heaving. In some cases it can also cause moss or efflorescence (white salty deposits on the
surface of the paver).An installation that is not properly sloped and is almost level can possibly
trap and hold water in the base. For this reason, measures must be taken to drain the driveway
surface appropriately by sloping to a lower area, or to a proper storm drain. Re-routing
downspouts (see photo) is also important to keep water out of a base.
Beware of the “Tub Effect”
The tub effect occurs where there is no hydrostatic relief or drainage of the
base material. This generally only happens when the soil is heavy clay and
where there is no outlet allowing the base material to drain. Proper
excavation below the curb at the street goes a long way to solve this
problem. (see diagram) Making a “connection” between the driveway base
and the road base should help to drain the driveway.
Il
Comprehensive Hardscape Education
for over 40 Years
Road base
UTEC – 102 - Driveway Base Fundamentals - 01
Congratulations!
You have just completed UTEC – 102-01, Driveway Base Fundamentals Part 1
If you feel that you have a good understanding of the information presented,
please click here to take the Part 1 Quiz. (If you would like, feel free to review
the information a second time before taking the quiz.)
Once you have completed and passed Part 3, you can print out an official
certificate of completion for Driveway Base Fundamentals 102.
Take the Quiz now
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Comprehensive Hardscape Education
for over 40 Years