2026-04-17T07:39:12Zhttps://recercat.cat/oai/request

oai:recercat.cat:2445/2102232025-12-04T20:53:23Zcom_2072_1057col_2072_478796col_2072_478917

00925njm 22002777a 4500 dc Alvarez-Coscojuela, Adrian author Mañosa Bover, Jofre author Formosa Mitjans, Joan author Chimenos Ribera, Josep Ma. author 2024-04-19T16:03:45Z 2024-04-19T16:03:45Z 2024-03-13 2024-04-19T16:03:50Z This study examines the structural evaluation of differently activated kaolins for potential use as supplementary cementitious materials (SCM) or as precursor for alternative cementitious materials (ACM). Chemical activation involved amorphizing the kaolinite structure using varying phosphoric acid concentrations, reaction times, and temperatures. Metakaolin obtained via thermal activation served as a comparison. Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES) characterization of the activating solutions revealed phosphoric acid activation leading to dealumination in kaolinite structures, with temperature emerging as the most significant parameter. X-ray diffraction (XRD) confirmed amorphization, attributed to the dealumination process causing Al loss and creating new Si–O–Si interlayered bonds, as monitored by 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR) tracking the change from Q3 to Q4 environments. Furthermore, pozzolanic activity was assessed through Ca(OH)2 consumption and reaction heat release via modified Chapelle and R3 tests, respectively. Kaolinite subjected to intensive chemical activation exhibited high reactivity and increased specific surface area, indicating its potential as a pozzolanic material. Keywords: Kaolin; Chemical activation; Supplementary cementitious materials; Alternative cementitious materials; Dealumination; Pozzolanic reactivity. Àcid fosfòric Materials de construcció Ciment Phosphoric acid Building materials Cement Structural characterisation and reactivity measurement of chemically activated kaolinite