How high is the load bearing and shear strength of the pathway?

Natural pathways come in all shapes, sizes and colors. The first thing to consider is the traffic placed upon the pathway. A very crowded botanical garden path or a maintenance vehicle access road will require different support from the surface than a lightly used foot trail. A pathway must be designed to provide (in engineering terms) the correct amount of load bearing and shear strength to support the traffic placed upon the surface. This load bearing and shear strength requirement can be met naturally. Soil particle structure, depth and slope of the pathway layer, construction of the base layer, and strength of the natural binder can all increase load bearing and shear strength. When these elements are incorrect in a pathway the result will be reduced longevity, rutting, erosion from traffic, dust, and reduced accessibility for users.

What does weather do to the pathway?

Natural pathways can be appealing because of porosity- the path permeates moisture. This can allow the path to manage some stormwater and also cools the surface, reducing the heat island effect. The soil structure of the aggregate, depth and slope of the pathway layer, construction of the base layer, and strength of the natural binder will change how the path responds to water. When these elements are incorrect the result will be reduced longevity, rutting, erosion from water, and mud.

How much time to maintain the pathway surface?

All natural materials will develop loose surface rock particles. This provides the natural look and crunch. It reminds users that the path is not concrete or asphalt. This loose rock layer should lay on the surface at a quarter of an inch thickness. Below the loose surface rock, the pathway should be stable to support traffic. Many natural materials can appear to be very stable after the initial installation, but will continually produce greater amounts of loose rock too quickly. To maintain a path, the loose rock should be evenly distributed across the path. If there is too much loose rock, this will create much more maintenance and result in a renovation too quickly.

Aggregates such as decomposed granite, crushed granite, limestone, or other types of crushed stone are considered “soils.” These aggregates contain the soil particles sand, silt and clay, along with gravel or rock particles. Soil particles are like the DNA of the pathway. They decide how your pathway will perform. Soil structure is the composition and arrangement of particles and pores, the open voids that occur between and within soil particles. If base and slope conditions are constructed properly, then soil structure will determine the load bearing and shear strength, or traffic resistance of the pathway.

Clay is the only soil particle that has cohesion without water, a critical component. Clay particles give us cohesion for load bearing and shear strength, but when the concentration of clay particles becomes too high, moisture can destabilize the clay particles and they become muddy. We must balance clay content with the correct percentages of silt and varying sizes of sand and rock particles. The wrong percentages of these other particles can cause additional problems. Rock particles provide structure. The amount and size of rock particles, angularity and hardness will change the load bearing strength of the pathway.

Performance Testing and Soil Particle Engineering

Our experience and understanding of soil structure helps us evaluate aggregates for long term pathway traffic. Each sample submitted to our lab goes through a rigorous testing protocol. Proprietary test methods help determine the longevity of an aggregate. In some areas, we can even use this science to engineer aggregates to have the right composition of soil particles.

Color Selection - largest selection of tested and approved colors

Stabilized Decomposed Granite and Crushed Stone colors are derived from the natural weathering from soil and rock particles in various regions. Stabilizer does not change the color. StaLok will darken the natural colors. We have the largest network of tested and approved aggregate colors in the world.

Moisture retention in a pathway can actually be a good thing, but too much can be devastating. Porosity helps manage some stormwater runoff, reduce the Heat Island Effect and can provide cohesion. In this process, gravity forces water molecules downward into the soil. Water molecules are attracted to soil particles. While being held by the soil particles, water molecules are also attracted to other water molecules. These forces give us cohesion without destabilizing the surface when moisture is present. To take advantage of the benefits from natural porosity without suffering instability, we must maintain a moisture content between 4%-12%, or a damp soil consistency.

In a very wet soil, above our ideal 12% moisture content, most of the water is retained in large pores or thick films around soil particles. Water molecules are not very close to a soil particle surface, therefore are not held very tightly by the soil solids. In this scenario, water has freedom to go where it wants. The water molecules separate soil particle bonds, destabilizing the pathway, reducing our load bearing strength, and creating mud.

Moisture Management

This is where soil structure and the binder technology really determine whether a pathway succeeds or not. Stabilizer Water Binding Technology absorbs water and maintains stability between soil particles. StaLok Waterless Technology coats soil particles making them hydrophobic, completely repelling moisture penetration.

Freeze/Thaw

In colder climates, when water is present the freeze/thaw cycle is a concern. On properly constructed stabilized pathways the effects of freeze/thaw are limited. It is common to see cracking with concrete or other rigid pavements because they resist the movement of the cycle. Stabilized pathways flex with the freeze/thaw cycle. This means that no expansion joints are needed.

Around Plants and Trees

Stabilizer Water Binding Technology poses no threat to plants and trees. It is non-toxic and can be used at lower rates to allow for increased moisture infiltration in planting areas. StaLok Technologies are designed to resist water infiltration and should not be used around planting areas.

Leadership in Energy & Environmental Design (LEED) by The US Green Building Council is a third party verification of Green building practices. Natural pathways, specifically Stabilized Decomposed Granite and Crushed Stone and StaLok Paving Material can potentially help earn LEED points towards certification.

Reduced Heat Island Effect/Solar Reflectance

When surfaces such as asphalt and concrete retain heat in an urban environment it is called the Heat Island Effect. Lighter colored Stabilized Decomposed Granite and Crushed Stone aggregates can reflect solar rays reducing the heat retained in the pathway surface. This is measured by the Solar Reflectance Index. LEED Code- SS 7.1 Heat Island Non-Roof.

Rapidly Renewable Resources

Stabilizer is made from rapidly renewable plant material. LEED Code- MR 6 Rapidly Renewable.

Stormwater Management

Stabilized Decomposed Granite and Crushed Stone is considered permeable pavement. Permeability can reduce stormwater runoff that collects pollutants into our natural bodies of water. LEED Code- SS 6.1 Stormwater Quantity and SS 6.2 Stormwater Quality.

Use of Regional Materials

Aggregates from within 500 miles of the construction project are considered regional materials and can earn points for a reduced carbon footprint. LEED Code- MR 5 Regional Materials.

Recycled Content

Stabilizer itself contains pre-consumer recycled content. Furthermore it can be used to stabilize recycled materials such as asphalt or concrete grindings, glass, and even metal scoria. LEED Code- MR 4 Recycled Content.

Recyclable Pathways

While not a LEED Category, Stabilized Decomposed Granite is non toxic and can be reused in many other areas when its service as a pathway has run its course.

Natural pathway materials may not be suitable for every scenario, but neither are concrete and asphalt. Stabilized Decomposed Granite and Crushed Stone and StaLok Paving Material can meet performance standards required of concrete and asphalt.

Accessibility

To comply with the Americans with Disabilities Act (ADA), pathways must meet standards for firm, non-slip surfaces. While The National Center on Accessibility (NCA) does not officially approve any product, Stabilized Decomposed Granite and Crushed Stone and StaLok Paving Materials are recommended natural surfaces when used in proper design. Our products meet testing requirements for slip friction.

Longevity

Natural aggregates vary in durability, but tend to be composed of harder rock particles that can make pathways last over decades with proper design. The amount of loose surface material will increase over time, this can be maintained easily by adding a new surface layer every 5-10 years.

Trail Potential

Wilderness trails pose unique requirements on designers and trail builders. Site conditions, including water flow and limited access to water for installation, along with heavy traffic, make these paths a challenge. Stabilized Decomposed Granite and Crushed Stone can be pre-hydrated with moisture prior to transportation to the site. It can be combined with StaLok Concentrate in challenging waterflow areas. StaLok Paving Material can also be used which requires no water at all for installation.

Driveways and Parking

With proper design, Stabilized Decomposed Granite and Crushed Stone and StaLok Paving Material meet most municipal requirements for driveway and parking surfaces.

Firelane Support

With proper design, Stabilized Decomposed Granite and Crushed Stone and StaLok Paving Material can meet load bearing requirements needed to support firetruck and other rescue vehicles.

Download CAD details and CSI specifications

Stabilizer | Original Stabilized Decomposed Granite and Crushed Stone | StaLok Paving Material | StaLok Concentrate