Zeolite & Concrete

A pozzolan is a "siliceous or siliceous and aluminous material, which in itself possesses little or no c ementitious valve but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties" (ASTM)

1) Limestone (CaCO 3) 2) Aluminum silicate (clay or shale) 3) Inert materials such as sand and gravel.

The limestone and clay are fired together in a rotary kiln. The limestone decomposes to lime (CaO) which reacts with the clay or shale to form "clinker". Clinker consists of tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetra calcium aluminate ferrite. The clinker is finely ground generally in a ball mill to make "cement". In Portland-pozzolan cement, 15% to 40% of the cement can be replaced by a Zeolite pozzolan.The definition of cation exchange capacity (CEC) of pozzolans for the concrete business is as follows: Typically pozzolans CEC range from 19.1 meq/100g to 63 meq/100g while Zeocan Zeolite CEC is 160 to 180 meq's/100g.

Zeolites are naturally-occurring porous aluminosilicate minerals that impart improved hydraulic cementing properties when added to cement and concrete, giving them improved strength.Natural zeolite can be used to prepare lightweight concrete for construction. Its porous silicate structure makes zeolite much lighter than sand and provides increased volume per tonne with similar hardness and strength. Zeolite is free from clay (clay reduces overall strength of concrete) and zeolites' porous structure holds moisture thus facilitating more rapid curing of the concrete.