Ca6 vs Ca7 Gravel

Gravel is a loose aggregation of rock particles that occurs naturally worldwide due to sedimentary and erosive geologic processes. It is also industrially produced in large quantities as crushed rock. Gravels are graded into fine, medium, and coarse by ISO 14688, but here we want to consider the Ca6 and Ca7 gravel, which are coarse gravels to see how they compare. 

Ca6, otherwise known as grade 8 and commonly referred to as road gravel, is frequently used for driveways and as a base for sidewalks, terraces, and retaining walls.

While Ca7, also known as ¾ inch or sometimes 1-inch limestone, is an angular stone that self-compacts. It is popularly referred to as bedding stone and appears white/gray.

Their major difference is that Ca7 is more coarse than Ca6 because it has more coarse aggregates. However, both gravels are useful and are required in different construction projects.


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Comparison between Ca6 and Ca7 Gravel.   

Popular namesRoad gravel, grade 8, compactable 14Bedding stone, ¾ inch limestone, binder
Coarse aggregate67
SizeCrushed limestone mixtures vary in size from ¾ inch to fine particlesCrushed limestone, ranges from ¾ to  1¼ inch in size, with no fine particles
Weight1 cubic yard weighs 2,400 to 2,900 pounds1 cubic yard weighs 2,400 to 2,900 pounds
CoverageOne cubic yard provides enough material that can cover an area measuring 100-square-foot with 3 inches of gravelOne cubic yard provides enough material that can cover an area measuring 100-square-foot with 3 inches of gravel
Appearance Irregular, and Light grayAngular, irregular, white or gray
UsesUsed for temporary and permanent roads, and as a base for walkways, driveways, bike trails, and pavementsSuitable for sewer and pipe bedding, drainage, wall backfill, used as a binder

Differences between Ca6 and Ca7 gravel

The differences between Ca6 and Ca7 gravel can be seen in their appearance and uses, and cost


Looking at both gravels, you will observe that Ca7 is more coarse than Ca6, and it is bigger in size, measuring from ¾ inch to 1-¼ inch, than Ca6, which measures from ¾ inch to ½ inch. You will also notice that Ca6 has fine particles, unlike Ca7. Ca7 has an angular and more irregular shape than Ca6, and it appears white or gray, while Ca6 has a light gray color.


It is important to understand the uses of both gravels and where they can be applied. This will help in your decision-making and for effective construction or building. Let’s look at some of the cases where each gravel is more suitable. 

Road construction

Ca6 is 100 percent recycled limestone that varies in size ranging from ¾ inch to fine particles. Therefore, it is suitable for constructing roads, parking lots, pavements, bike trails, patios, and many others like this. This is because these types of constructions require a smooth concrete surface, and the nature of Ca6 matches that requirement better than the Ca7, which is more coarse, so Ca6 is the winner here. 


Bedding is the material used to surround a pipe to protect it from load coming from the topsoil and to prevent distortion of the pipe. The best material for this type of construction is a granular material with high compact ability. Therefore, the self-compact ability of Ca7 gravel gives it an edge over the Ca6 gravel, making it the winner in this case. 

Drainage construction

Drainage construction requires gravels that are highly coarse and lacks fine particles. This is because gravels with tiny particles are more likely to clog the drain pipe holes. Also, smooth stones will settle together and won’t move as much water as coarse rock. Therefore Ca7 is a better option here because it is more coarse than Ca6 and has no fine particles. Ca6 contains particles smaller than 1/2 inch; therefore, it is less suitable for drainage construction when compared to Ca7.


When backfilling, you need to use a material that is sure to compact properly in other to provide support, and stone or gravel is the easiest material to use. For instance, a home with a basement will need at least 8 to 9 feet of fill up if the garage is connected to the foundation. So for better compaction, Ca7 is the go-to gravel. 

Asphalt binding

Here, Ca7 is better preferred to Ca6 during the production of asphalt binding coat because of its special ability to allow water drainage.


There are lots of factors that influence the cost of purchasing each gravel. Factors like location, the company you are buying from, and the quantity you want to buy. Generally, Ca7 is always slightly more expensive than Ca6. In some places, a ton of Ca6 is about $27.50, while Ca7 is about $31.75 if you are buying from 23 tons and above. The cost of one ton might increase if you order fewer tons. These prices are subject to change but should give you an idea of the cost when you want to buy.

Similarities between Ca6 and Ca7 gravels

Ca6 and Ca7 share some similarities, which can be seen in their grade, weight, and the distance they cover per ton.


From the Udden-Wentworth scale, gravels are graded into fine, medium, and coarse. Both the Ca6 and Ca7 belong to the coarse gravels. 


1 cubic yard of Ca6 and Ca7 gravel weighs from 2,400 to 2,900 pounds. 


One cubic yard of Ca6 and Ca7 will provide enough material to cover an area measuring 100-square-foot with 3 inches of gravel.


From the details above, you should know which gravel will work best for the job you plan to execute and seek experts’ help to know how many tons you need to execute the project.  Generally, Ca6 and Ca7 gravels are useful in several construction projects ranging from road constructions to backfill and drainage systems. Ca6 will make a fine road, pavements, walking paths, and parking lots. While Ca7 is better suited for bedding, backfill, and drainage construction because of the absence of fine limestone particles.

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