Authors:J. Dweck, P. Ferreira da Silva1, R. Silva Aderne, P. Büchler, and F. Cartledge
This paper presents a method to study cement hydration at ambient temperatures by using a micro processed non-conventional
differential thermal analysis (DTA) system, which was used to evaluate the solidification/stabilization process of tannery
wastes produced in the leather industry. The DTA curves of pastes composed by slag cement, Wyoming bentonite and waste are
obtained in real time and used to analyze the heat effects of the reactions during the first 24 h of hydration. By applying
a deconvolution method to separate the overlapped DTA peaks, the energy released in the several hydration stages may be estimated
and consequently, the effects of each component on the solidification process. The highest separated DTA peak occurs during
the several early stages of cement hydration and is due mainly to tricalcium silicate hydration. Very good correlation shows
that the greater is the waste content in the paste composition, the higher is its effect on the rates of reactions occurring
during the induction (dormant) period of cement hydration. The presence of bentonite used as a solidification additive in
the stabilization process has a similar but less dramatic effect on the dormant period.
Authors:Caroline A. Pinto, J. Dweck, J. J. Sansalone, F. K. Cartledge, M. E. Tittlebaum, and P. M. Büchler
Summary This paper presents a study of a cement-based solidification/stabilization process of storm water runoff solid residuals by non-conventional differential thermal analysis (NCDTA). The study was used to investigate the early hydration stages of a type I Portland cement containing the raw residual, two fractions of the residuals (coarse and fine), and two additives (quicklime and sodium bentonite). During these stages the fine fraction of the residuals retards the hydration reactions more than the coarse one, and both fractions have components that are reactive during the hydration process. When sodium bentonite is present in the pastes, the higher the initial cement content of the pastes, the lesser is the reactivity of the residuals. The presence of quicklime, which undergoes simultaneous highly exothermal hydration, accelerates the cement hydration reactions as well as those due to the presence of the residual solids. In these quicklime-containing compositions, the effect of sodium bentonite is similar to that when no quicklime is added, except when the whole residuals are used.
Authors:J. I. Tobón, J. Paya, M. V. Borrachero, L. Soriano, and O. J. Restrepo
have been found very few references. Dweck et al. [ 14 ] present a method to study cement hydration at ambient temperatures by using a micro processes non-conventionalDTA system.
Criado et al. [ 15 ] develop an alternative method applied to
Authors:Maura B. M. Melchert, Marcelo M. Viana, Mariana S. Lemos, Jo Dweck, and Pedro M. Büchler
In order to study the thermal effects of the wastes addition in cement paste by non-conventionalDTA (NCDTA), cement pastes with water/cement ratio equal to 0.5 were used. The samples were composed always by 100 g of cement adding