Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
The effect of activators Na2SO4 and CaCl2 on early microstructure development of lime-fly ash pastes was examined. The control lime-fly ash pastes did not show a significant strength up to 28 days. The addition of 4 % Na2SO4 increased both the early and later strengths of lime-fly ash pastes significantly. (CaCl2)(2H2O) (4 %) was less effective at 3 and 7 days, but more effective at 28 days than Na2SO4. Scanning electron microscope observation and X-ray diffraction analysis indicated that very limited amount of CaO-SiO2-H2O, ettringite (AFt) and monosulphoaluminate (AFm) formed in the control pastes even at 28 days. CaO-SiO2-H2O and AFt filled most spaces between fly ash particles in the Na2SO4 activated pastes at 3 days, and the structure became denser with time. CaCl2 activated pastes also exhibited a dense structure at 3 days, in which most voids between fly ash particles were filled with CaO-SiO2-H2O and the solid solution of Ca4Al2((SO4(2-))(x)(Cl(-))(y)(OH(-))(2-2x-y))((z)H2O) (x<1 and y<2). The amount of the solid solution increased drastically from 7 to 28 days, which resulted in a denser structure and a higher strength than Na2SO4 activated pastes.
The effect of activators Na2SO4 and CaCl2 on early microstructure development of lime-fly ash pastes was examined. The control lime-fly ash pastes did not show a significant strength up to 28 days. The addition of 4 % Na2SO4 increased both the early and later strengths of lime-fly ash pastes significantly. (CaCl2)(2H2O) (4 %) was less effective at 3 and 7 days, but more effective at 28 days than Na2SO4. Scanning electron microscope observation and X-ray diffraction analysis indicated that very limited amount of CaO-SiO2-H2O, ettringite (AFt) and monosulphoaluminate (AFm) formed in the control pastes even at 28 days. CaO-SiO2-H2O and AFt filled most spaces between fly ash particles in the Na2SO4 activated pastes at 3 days, and the structure became denser with time. CaCl2 activated pastes also exhibited a dense structure at 3 days, in which most voids between fly ash particles were filled with CaO-SiO2-H2O and the solid solution of Ca4Al2((SO4(2-))(x)(Cl(-))(y)(OH(-))(2-2x-y))((z)H2O) (x<1 and y<2). The amount of the solid solution increased drastically from 7 to 28 days, which resulted in a denser structure and a higher strength than Na2SO4 activated pastes.
Early microstructure development of activated lime-fly ash pastes
Gefügeentwicklung von aktivierten Kalk-Flugasche-Pasten in frühen Abbindestadien
Shi, C. (Autor:in)
Cement and Concrete Research ; 26 ; 1351-1359
1996
9 Seiten, 5 Bilder, 2 Tabellen, 16 Quellen
Aufsatz (Zeitschrift)
Englisch
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