No matter what type of construction project you’re working on, it won’t be successful without a strong foundation. One of the most important aspects of understanding your site stabilization needs is to identify the existing soil’s proctor. Which is the measurement to identify your soil type’s optimum moisture content to help achieve its maximum dry density.
Dry density refers to the mass of soil without any water content. This is a critical component when it comes to understanding the shear strength, permeability, and compressibility of the ground. Site developers, construction and engineering firms need to pay close attention to this, as it can have a serious impact on the cost of your soil stabilization project. The importance of optimum moisture content and dry density for the strength of a substrate cannot be ignored, or else projects may not succeed.
Smart Testing to Determine Your Project’s Soil Maximum Dry Density
Proper soil moisture measurement and testing is a critical component of managing your projects stabilization costs. You should always have a soil engineer perform a proctor soil compaction test of your jobsite’s existing soil prior to soliciting bids. This process includes collecting samples of the existing soils onsite and performing a standard proctor or modified proctor test in a laboratory. The results will yield a value that represents the maximum density of the soil at its optimum moisture. This value should be shared with your soil stabilization subcontractors so they can use it to calculate the spread rate of the material best suited to dry and or strengthen your existing soils. This way, you will better ensure you’ll receive quotes that provide the same treatment rates for your project that will be successful with the existing soil type.
In addition to proctor tests, there are other methods commonly used to determine dry density for soil. These include the sand cone test, which starts with excavating a portion of the soil. The excavated material is collected and saved for analysis. A cone filled with sand is placed over the cavity and the sand fills the space. The amount of sand remaining in the cone is used to determine precisely how much sand fills the excavated space. The weight of the soil sample is divided by the volume of sand filling the cavity to find the soil’s set weight. From there, the dry density is calculated by dividing the weight of the soil sample by the percentage of water it contains.
Another commonly employed technique is the nuclear gauge testing process. This involves inserting a retractable rod into a hole dug into the soil. Radiation is emitted through the rod, and the denser the soil is the more of the radiation will be redirected back to the gauge. The amount of radiation that bounces back is measured and the results are used to determine the density and moisture content of the ground.
Cost Benefits of Determining Your Maximum Soil Dry Density
Ensuring you understand your site’s existing soil’s maximum dry density before you begin to compare estimates can save you thousands of dollars in change orders. If contractor A is bidding using a maximum dry density of X, and contractor B is bidding using a maximum dry density of Y. You can have pricing that appears to be consistent by description, but is not apples to apples, and possibly not even representative of your site’s existing soil conditions.
For instance, if both contractors quote 5% Cement Stabilization at a depth of 12” but use different maximum dry densities to calculate their spread rate you could have the following scenario:
Contractor A uses a Dry Density of 110 p/cf:
- 5% – 12” Cement Stabilization = $5.00 per SY
- (@ a Dry Density of 110 p/cf this treatment rate would need 50 lb/ SY)
Contractor B uses a Dry Density of 100 p/cf:
- 5% – 12” Cement Stabilization = $4.50 per SY
- (@ a Dry Density of 100 p/cf this treatment rate would need 45 lb/ SY)
You may choose to go with contractor B and save the $.50 per SY, then use your remaining discretionary budget elsewhere only to find out when they get onsite that your project soil’s maximum dry density is 110 p/cf and 45 lb/ SY will not be enough material to generate the results you need to properly build your project.
Common Misconceptions About Soil Dry Density
- The higher the dry density is, the stronger the soil will be. Although it’s tempting to think of a higher dry density as automatically better for stability, that’s not always the case. The strength of soil depends on its optimum soil moisture content, which can vary based on the type of soil and other conditions.
- All soils are the same. Different soils have different densities, which means they will offer unique performance profiles under heavy use. For example, soils that contain a lot of sand will be denser than soils that have a lot of clay.
You Can Trust Rock Solid to Put You on Solid Ground
As a leader in soil stabilization, Rock Solid can be your ideal partner for ensuring proper maximum dry densities are used to evaluate your soil stabilization & modification quotes. All estimates and project consultations are free. Let us help you protect your next project from unnecessary change orders. We offer a wide range of services to give your jobsite the stability it needs. To learn more about everything we have to offer, reach out and speak with us today.