How to Make Aggregate Concrete

Aggregate concrete is a polymer concrete that is made of aggregates such as limestone, granite, silica, quartz, or a combination of these minerals. Aggregate concrete differs from cement in that it contains many different mineral rocks that protrude from its surface, while a cement surface is smooth. While cement is simply mixed together and applied to a surface, aggregate concrete must be properly prepared and applied so that the aggregates bond to the polymer. Because of this, the aggregates must be dry, clean, and made of a strong material. When properly prepared, aggregate concrete is very rough and can be used to make shapes or patterns by using different colored minerals.

How is Aggregate Concrete Made?
Aggregate concrete itself is simply made of a polymer based binding paste that is mixed with an assortment of mineral rocks. In a typical concrete patch, boards are set up to provide a space for the aggregate concrete to be poured into. The concrete is generally poured to a 3 ¼ or 3 ½ inch level, although more can be used. The concrete is then smoothed out and allowed to dry. Surface retarder is often used to slow the cure time so that the top layer of concrete can be scrubbed and washed off. The aggregates are then exposed.

Applications
Aggregate concrete has many purposes, most notably decorative. In addition to being an asphalt replacement, aggregate concrete can be used to make driveways. When making a driveway, concrete should always be applied at a slope with a 1 inch drop for every 1 foot of concrete so that rain water is directed away from the house. Aggregate concrete can also be used to repair existing concrete walls (whether made of aggregate or cement) and to construct new buildings.

Advantages
Aggregate concrete has several advantages that make it the preferred type. For example, aggregate concrete is highly resistant to most chemicals and corrosion. It also bonds well with most surfaces and does not break apart in water. It can therefore be used under water as well as in any system that involves liquids. Aggregate concrete is also very lightweight and can last for many years, despite freeze and thaw cycles. When dry, aggregate concrete’s  rough surface provides traction for both vehicles and pedestrians.

Disadvantages
Aggregate concrete’s biggest disadvantage is that it costs significantly more than cement. Aggregate concrete has to be mixed more thoroughly and properly prepared in order to bond correctly. While, technically, any type of rock can be used as an aggregate, the rocks used must be smooth, dry, and free of foreign debris. In most cases, pebbles are used as an aggregate.