Manufacture of Vapor-Hardened Bodies from Natural Zeolite and Lime

Abstract

Uniaxial compressive strength of vapor-hardened bodies from natural zeolite and lime was studied. The zeolite occurs at Arita-machi, Nishimatsuura-gun, Saga, and contains about 34wt% of mordenite crystal and about 11vol% of small pore whose size is in the range from 0.01μm to 10.0μm. The chemical components of zeolite are: SiO₂=69%, Al₂O₃=13%, Fe₂O₃=0.8%, Na₂O=2.0%, K₂O=5.6% and ig. loss=9.2%. The hardened bodies made at 80°C were stronger than those from perlite-lime and quartz-lime. The chemical components of perlite are as same as those of zeolite, but the perlite contains only 3.6vol% of small pore. In the preparation, alkalline ions were easily dissolved from the zeolite with calcium ions by ion exchange and it is known that the alkaline ions promote the dissolution of pozzolanas. Then, the vapor hardened bodies from perlite-lime with Na₂CO₃ solution were investigated. These strength were not so large as those of zeolite-lime. It seems that the high reactivity of zeolite depends on its porous structure. The maximum uniaxial compressive strength of vapor-hardened bodies from zeolite-lime was 250kg/cm²⋅g in the range of zeolite/lime ratio from 4/1 to 2/3. Its curing conditions were at 20°C for 24h and at 80°C for 20h. The vapor cured bodies from zeolite-lime at 20°C for 3 months also had the compressive strength in the range from 160kg/cm²⋅g to 170kg/cm²⋅g.
With increase in reaction between zeolite and lime, the strength of zeolite-lime bodies decreased. By XMA of the cross section of zeolite-lime body, the cracks were found between pozzolanas and products. It seems that these cracks decreases the strength of body.