Vol. 1, No 3, 1996 pp.
240 - 248
UDC
543 : 547.21
INFLUENCE OF MINERAL ADDITIONS ON CEMENT HYDRATION INVESTIGATED BY NMR AND SEM METHODS
V. Manić, Lj. Miljković, P. Dimitrijević
Department of Physics, University of Niš, P.O.Box 91, 18001 Niš, Yugoslavia
Abstract.
In order to explore new cement type materials two mineral additions, kaolinite and mica, were used to replace a fraction of Portland cement in a small amounts. The hydration properties of obtained cement pastes were studied by means of 1H T1 pulse NMR (Nuclear Magnetic Resonance) technique, with multicomponent analysis of spin-lattice relaxation. The values and evolution dynamics of T1 (spin-lattice relaxation time) and M0 (fraction in total magnetization) show that both kaolinite and mica accelerate the initial hydration of Portland cement to the extent depending on percentage of addition. The lowering of pastes fluidity in dormant caused by both additions is more apparent in the case of kaolinite. In advanced stages of hydration the retarding influence of kaolinite as well as mica is observed yielding to a higher final porosity of samples, where the effect is more pronounced for mica additions. The results of SEM (Scanning Electron Microscopy) investigation indicate the pozzolanic activity of kaolinite, not evidenced for mica, as a mechanism of slowly filling of pores in a hardened pastes.
NMR I SEM ISPITIVANJE UTICAJA MINERALNIH DODATAKA NA HIDRATACIJU PORTLAND CEMENTA
U cilju ispitivanja novih materijala cementnog tipa, mali iznosi dva mineralna dodatka, kaolinita i liskuna, korišćeni su kao zamena dela Portland cementa. Osobine hidratacije dobijenih cementnih pasti proučavane su korišćenjem 1H T1 pulsne NMR tehnike, uz primenu multikomponentne analize spin-rešetka relaksacije. Vrednosti i dinamika evolucije T1 (spin-rešetka vreme relaksacije) i M0 (frakcija totalne magnetizacije) pokazuju da oba dodatka ubrzavaju inicijalnu hidrataciju Portland cementa u stepenu koji zavisi od njihovog procenta. Sniženje fluidnosti pasti u dormantu izraženije je u slučaju dodatka kaolinita. U kasnijim stadijumima hidratacije opaža se usporavajući uticaj kaolinita i liskuna, kao i veća finalna poroznost hidratisanih uzoraka, sa nešto izrazitijim uticajem liskuna. Rezultati SEM istraživanja ukazuju na pucolansku aktivnost kaolinita (koja nije evidentirana u slučaju liskuna) kao mehanizam sporog popunjavanja pora u hidratisanim pastama.
