Alkali activated clay of moderate kaolin content

Abstract

Metakaolin clay of 30% reactive silica was alkali activated by blends of sodium silicate and sodium hydroxide using Na2O/Al2O3 = 1.2 to 1.7 and H2O/Na2O = 10 to 6. at room temperature. The geopolymer pastes obtained was investigated for durations up to one year. In spite of the relatively low SiO2/Al2O3 ratio of 2.06, 3 days and one year strength of 39 and 80 MPa are obtained at Na2O/Al2O3 = 1.4 and H2O/Na2O ~ 8. A successful prototype of geopolymer concrete building was realized to introduce the geopolymer application in Egypt. A geopolymer concrete foundation with 3-days and 28-days strength of 11 and 35 MPa was achieved with lower ratios than those used in the pastes and an with increased amount of water to insure the workability. The results are good reference for the achievement of geopolymer construction of better properties in the future, in Egypt.