Though in our business we rarely ever use it, concrete sand is still a mainstay in the hardscape industry in a traditional installation. Since opting primarily for open graded bases where we use High Performance Bedding, concrete sand has less and less of a use in our installations. That being said, ASTM C33 sand is the recommended bedding layer of the Interlocking Concrete Pavement Institute.
What is Concrete Sand
Concrete sand or ASTM C33 sand is a small coarse granular from the natural disintegration or crushing of rock. It is a fine sand that is more coarse than masonry sand. The reason why a coarser material is used for the bedding layer of interlock is for the drainage characteristics that come with a larger granule. Finer material becomes suspended in water creating a slurry that will lubricate the bedding layer and also congregate to clog drainage areas. This larger granule allows that water to drain at a higher rate. Additionally, granules that do not pass the hardness test will degrade over time as the bedding layer is the most susceptible to degradation due to the proximity of traffic to it. An easy hardness test that you can do in the field is to use a swiss army knife to put pressure on a granule. It should not break under this pressure. Additionally, the gradation of the granules is important. ICPI concludes that granules that are predominantly subangular (partial angularity) or subrounded (partial roundedness) perform best. Concrete sand as a bedding layer will compact approximately 1/4 inch when screeded at a uniform 1 inch depth. This compaction beds the interlock and initializes interlocking.
What is Concrete Sand Used For
- Bedding Layer
- Concrete Overlay
- Levelling Over Paver Base Panels
ASTM C33 sand is a traditional bedding layer in paver installation. It is used as no more than a 1″ on top of a specified amount of a dense graded material for the base. It is not used on top of clean stone, as it would migrate into the voids of the clean stone base material. However, we have opted for an alternative bedding layer in all of our applications (except concrete overlays) in the form of High Performance Bedding. This is because of its ease of use and performance in comparison to concrete sand.
Concrete sand is the ideal choice for most concrete overlay solutions as a bedding layer to allow for the drainage of any water that enters the system. This is because with most concrete overlays there is minimal height difference to allow for a suitable layer of High Performance Bedding. However, if for any reason there is the tolerance for a suitable layer of High Performance Bedding, we would opt for it instead of concrete sand.
Though concrete sand can be used for the bedding layer below paver base panels, we opt for High Performance Bedding because of its ease of installation. However, on top of paver base panels when there are any inconsistencies in the paving surface, concrete sand is specified to be used to allow for this minimal levelling.
Concrete Sand Calculator
There are three measurements that you need in order to calculate how much concrete sand you need in your installation. You need measurements for the length in feet, the width in feet, and the depth that you will need to cover with the sand for your project. You can use these measurements to complete the formula below and to calculate the total cubic yards of product that your project requires.
[Length (in feet) x Width (in feet) x Depth (in inches)] x 0.003 = Total Cubic Yards
For concrete sand, you really only need at most a one inch depth for your bedding layer. So ultimately it is a calculation of square footage multiplied by 0.003 in order to provide you with the total cubic yards that you would need for your project.