Sand Cone Test Equipment: A Complete Guide [Updated 2024]

Sand cone test equipment offers a budget-friendly option compared to nuclear gauge testing. It checks the soil’s density at construction sites against project specifications. This test determines if corrective measures are necessary before construction starts. Performing this test is crucial. Improper soil density can lead to increased settlement after construction, compromising structural support and potentially endangering lives. While you won’t get results as quickly as with the nuclear gauge method, the sand cone test is still a relatively simple test that doesn’t take long to perform, outside of drying your samples.

Sand Cone Test Equipment Needed for the Test

While dry and wet sieving follow many of the same principles, there are certain supplies designed specifically for wet sieving that you will need to have in your lab in order to perform the procedure accurately and efficiently.

• Trowel: Used for digging the test hole at the job site and extracting your soil sample.
• ASTM Sand: Used to find the volume of your test hole — standardized for ASTM specifications.
• Plastic Sand Bags: Used to collect the soil sample and retain moisture until the test can be performed.
• Scale: Needed to weigh your sand cone test equipment, as well as sand and soil samples.
• Compaction Mold: Also known as a Proctor mold. It is used at the start of the sand cone test to determine the weight of dry sand.
• Field Density Plate: Use it as a guide to dig your test hole. Then, fill it with the right amount of sand.
• Sand Cone Density Apparatus: A jar features a detachable cone fitting with threads to control sand flow. It has a brass valve that halts when fully open or closed for precise testing. The apparatus also includes a 1-gallon threaded plastic jar, easily replaceable and attachable to the cone fitting.
• Evaporating Dish: Used to weigh and dry moist soil samples.
• Vacuum Oven: Needed to dry your soil sample over a 24-hour period.

Step 1: Find the Dry Unit Weight of Sand

You’ve gathered the necessary equipment. The sand cone test can now be performed in simple steps using easy equations.The sand cone density test is a reliable method for density testing, ensuring accurate measurements of in-place soil density.

In order to perform the first portion of the sand cone test, you will need to gather your scale, compaction mold and sand. First, record the weight and volume of your compaction mold. Then, note the weight after filling it with dry sand. Obtain these values, subtract the weight of the sand and mold from the initial mold weight, and divide by the mold’s volume. This is your dry unit weight of sand.

(Weight of Mold & Sand – Weight of Mold) ÷ Volume of Mold = Dry Unit Weight of Sand

Step 2: Determine the Weight of a Coneful of Sand

Take out your sand cone density apparatus and weigh it. Check that the cylindrical valve is fully closed before flipping the apparatus. Open the cone thread. Carefully pour dry sand from the compaction mold into the density apparatus. Record the weight of the apparatus now that it has been filled with sand. After weighing, close the cone and flip the entire apparatus upside down, placing the mouth of the cone on the table. Open the thread and let the sand pour out on the table until it stops. Close the cone and put your device back in its spot, leaving the sand out. Weigh the device with the sand left in it. To find a cone’s worth of sand weight, subtract the second measurement (device and less sand) from the first (device and sand). Also, deduct the device’s weight to get the sand’s true weight.

Weight of Apparatus & Sand – Weight of Apparatus & Sand2 – Weight of Apparatus = Weight of a Coneful of Sand

Step 3: Prepare the Test Hole & Collect Your Soil Sample

Now that you have your initial values, it’s time to dig. First, secure your field density plate to the soil. Use your trowel to dig a hole 10cm deep, using the circular cutout in the center of the plate as your guide. As you dig, place your soil in a plastic sand bag to ensure it doesn’t lose moisture before it is weighed in the following steps.

Step 4: Determine the Volume of the Test Hole

Prepare the test hole for volume calculation. Standard volumes for the sand cone density test are around 0.1 cubic feet (2.8 liters). Fill your sand cone density apparatus with sand, making sure to close the thread. Position the apparatus over the hole on the base plate, then open the thread to let sand pour out. Fill the hole until the sand stops flowing, close the thread, and remove the apparatus. Record the weight of the apparatus again.

To calculate the hole’s volume, do the following: First, subtract the weight of the full apparatus from its weight after filling the hole. Next, subtract the weight of a coneful of sand to account for the sand in both the cone and the hole. Also, account for the space between the base plate and the hole surface, which slightly increases the volume. This adjustment is the cone correction factor. Finally, add the weight of the sand in the cone and the thickness of the base plate to simplify the calculation.

Weight of Apparatus & Sand – Weight of Apparatus & Sand3 – Cone Correction Factor ÷ Dry Unit Weight of Sand = Volume of Test Hole

Step 5: Determine the Moist Unit Weight of the Soil Sample

First, weigh your evaporating dish. Next, add the soil sample to the dish and weigh it again. Subtract the weight of the evaporating dish from the weight of the dish with the wet soil to calculate the soil’s moist unit weight. Then, divide this difference by the volume of the test hole. This gives you the moist unit weight of the soil.

Weight of Evaporating Dish & Wet Soil – Weight of Wet Soil ÷ Volume of Test Hole = Moist Unit Weight of Soil

Sand Cone Test Equipment Step 6: Determine the Water Content of the Soil

Calculate the moist unit weight of your soil sample. Then, place the dish and soil in a vacuum oven. Let the soil dry until it reaches a constant weight. Dry your sample at about 221°F for 24 hours. Add more time if necessary. Once dry, use the following equation to calculate the soil’s water content, expressed as a percentage:

Weight of Wet Soil – Weight of Dry Soil ÷ Weight of Dry Soil – Weight of Evaporating Dish = Water Content of Soil

The moist unit weight and water content of soil are critical before construction. Moisture can change soil density, reduce strength, and affect how a structure settles. This can lead to damage and instability.

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