Concrete Aggregates Part 1

Fine Sand / Brick Sand

Fine sand is often sold washed and sterilized as "play sand" or sand intended for childrens sandboxes. This is a sand that is free of debris and larger aggregates and has been tumbled to remove all the sharp edges from the sand. This essentially makes the individual sand granules round instead of random shaped which is great for making a smooth and comfortable texture to the touch. In a concrete mix this undermines the strength of the concrete vastly. Other than using dirty sand, using play sand is the next worst thing you can do to undermine the finished strength of your concrete.

Plaster Sand

Plaster sand in an incredibly dense sand, commonly dolomite, that is rated according to size. A size of 00, or double zero, refers to an extremely fine sand that when mixed with concrete makes an incredibly smooth and dense finished concrete. This type of sand is difficult to locate for the average consumer and is most commonly used by swimming pool finishers and stucco plasterers.

Limestone Screening

Limestone screening is 3/8" and smaller pieces of limestone. This material is most commonly used in the preparations for concrete or paving stone as it accepts compression well and holds its shape due to the random and jagged shape of the limestone. Limestone can be added to concrete mixes in part or in whole however in whole the concrete would be weakened due to a lack of very small aggregate such as sand in the mix. Though limestone screening does have some sand sized limestone mixed in, it is mostly somewhat larger pieces of limestone.

Crush And Run

Crush and run, or crusher run, is a mixture of sand, limestone screening and 1/2" sized limestone gravel in one. This would be a good gravel choice for large areas where a lot of gravel is needed. It compacts down extremely well and is sometimes used as a concrete alternative for this reason. It is also one of the primary substrates that concrete is installed overtop of. You can make concrete out of crush and run but would do so only in places where finishing detail is of little overall importance.

Gravel

Gravel refers to essentially any stones, though often it is dolomite or limestone, that are graded according to size. The size rating for gravel indicates the maximum size of the aggregate you will find in the product, not the consistent size. Gravel is an integral part of all concrete mixes that are designed to fill large areas for a low cost. Gravel is most commonly random in shape with sharp edges that make it incredibly strong when inset into concrete.

River Stone

River stone or river rock is the generic name given to all forms of round flat rock most commonly used for landscaping purposes. This style of aggregate is not ideal for making concrete, but can be used as a huge aggregate for decorative concrete projects.

Proceed to the section on Lightweight Concrete Aggregates