abstract
Despite the steady progress of research on the alkali activation of wastes or subproducts from established industrial processes, the brittleness of the hardened alkali-activated materials frequently results in questionable mechanical reliability, particularly in industrial applications beyond construction materials. This work used a 3(3) factorial Design of Experiments to examine the effect of three different particle size distributions on the compressive strength and mechanical reliability (Weibull modulus) of a sodium silicate-activated blast-furnace slag under the same processing conditions. As expected, curing temperature and time were strongly correlated, and the corresponding response surfaces showed that, for all studied particle sizes, compressive strengths above 60 MPa with mechanical reliability above 5.0 could be obtained by curing at similar to 60 degrees C for similar to 40 h. The particle size differences caused no significant changes in the extent of alkali activation, as seen in the infrared-spectroscopy results. However, the intersection of the response surfaces showed that a coarser and narrower particle size distribution extended the working area (time x temperature) and favored mechanical reliability. Thus, the precursor's particle size distribution, which governs particle packing and viscosity during processing, also determines the permeability of the set binder, which affects water removal during drying and the dried binder's mechanical performance.
keywords
BLAST-FURNACE SLAG; SHRINKAGE; HYDRATION
subject category
Chemistry; Materials Science; Metallurgy & Metallurgical Engineering; Physics
authors
Camargo, WF; Segadaes, AM; Cruz, RCD
our authors
Ana Maria B C Segadães
Retired Professoracknowledgements
W.F. Camargo acknowledges the MAI/DAI innovation grant (PhD in industry program, process n. 155435/2019-1) awarded by CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, Brazil). The authors gratefully appreciate the assistance provided by the technical support team at Fras-Le Mobility and the Materials Laboratory at the University of Caxias do Sul, in Caxias do Sul, Brazil.