caa a22 4500 463224221 CHVBK 20180405153221.0 cr unu---uuuuu 170326e20070501xx s 000 0 eng 10.1007/s10853-006-0565-y doi (NATIONALLICENCE)springer-10.1007/s10853-006-0565-y Alkali activation of metakaolins: parameters affecting mechanical, structural and microstructural properties [Elektronische Daten] [M. Granizo, M. Blanco-Varela, S. Martínez-Ramírez] The composition, structure and properties of the reaction product resulting from the alkali activation of metakaolin (MK) are directly impacted by the specific surface and composition of the initial kaolin and the type, concentration and relative amount of alkali activator used. This study aimed to analyze the effect of these parameters on the flexural strength, degree of reaction, porosity and chemical and mineralogical composition of alkali-activated metakaolin pastes. Two types of metakaolin with different specific surfaces were activated under hydrothermal conditions (85°C, 2h) using solutions consisting of waterglass and Na(OH) as activators (Na concentrations=6, 8, 10, 12, 15, 18, 20M) and two metakaolin/solution ratios. Regression analysis was used to quantify the effect of the parameters tested (activator concentration and MK/solution ratio) on flexural strength. Mathematical models were likewise built to relate the degree of reaction and amount of sodium fixed in the polymer structure to the synthesis parameters. According to 29Si and 27Al MAS NMR, XRD, FTIR, DTA/TG data and chemical analysis, the material obtained by activating two MKs with waterglass plus NaOH was an amorphous hydrated sodium aluminosilicate in which a Q4 Si (3Al) type three-dimensional structure predominated, i.e., a structure where three Al atoms are connected to SiO4 tetrahedra. The alkaline ions in the structure maintain the electrical balance. The general formula obtained for this inorganic polymer was Na2O·3SiO2·Al2O3·3H2O. Springer Science+Business Media, LLC, 2007 Granizo M. SIKA S.A., Ctra Fuencarral 72, 28108, Alcobendas, Madrid, Spain aut Blanco-Varela M. Instituto de Ciencias de la Construcción Eduardo Torroja (CSIC), c/ Serrano Galvache 4, 28033, Madrid, Spain aut Martínez-Ramírez S. Instituto de Ciencias de la Construcción Eduardo Torroja (CSIC), c/ Serrano Galvache 4, 28033, Madrid, Spain aut Journal of Materials Science Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 42/9(2007-05-01), 2934-2943 0022-2461 42:9<2934 2007 42 10853 https://doi.org/10.1007/s10853-006-0565-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10853-006-0565-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Granizo M. SIKA S.A., Ctra Fuencarral 72, 28108, Alcobendas, Madrid, Spain aut NATIONALLICENCE 700 1- Blanco-Varela M. Instituto de Ciencias de la Construcción Eduardo Torroja (CSIC), c/ Serrano Galvache 4, 28033, Madrid, Spain aut NATIONALLICENCE 700 1- Martínez-Ramírez S. Instituto de Ciencias de la Construcción Eduardo Torroja (CSIC), c/ Serrano Galvache 4, 28033, Madrid, Spain aut NATIONALLICENCE 773 0- Journal of Materials Science Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 42/9(2007-05-01), 2934-2943 0022-2461 42:9<2934 2007 42 10853 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer