The present study is based on the influence of the addition of a pozzolanic material as a result of the activation of an industrial
waste coming from the Spanish paper industry on the heating as well as hydration heat of the cement mortars made with 10 or
20% of active addition.
Once the sludge has been calcined at different temperatures (700–800°C) and stays in furnace (2 and 5 h), the calcined products
showed high pozzolanic activity. The maximum activity corresponded to the paper sludge calcined at 700°C for 2 h (S1). Besides,
it can be proved that there was an increase both of the heating and also of the hydration heat in the first 23–25 h for both
additions (10 and 20% of S1) regarding the reference cement mortar. This behaviour would be related to the influence of different
effects: filler and pozzolanic during the first hours of reaction, and by the dilution effect for longer hydration times,
mainly when 20% of S1 was added.
The heats of hydration reactions for MgCl2⋅4H2O and MgCl2⋅2H2O include two parts, reaction enthalpy and adsorption heat of aqueous vapor on the surfaces of magnesium chloride hydrates.
The hydration heat for the reactions MgCl2⋅4H2O+2H2O→MgCl2⋅6H2O and MgCl2⋅2H2O+2H2O→MgCl2⋅4H2O, measured by DSC-111, is –30.36 and –133.94 kJ mol–1,respectively. The adsorption heat of these hydration processes, measured by head-on chromatography method, is –13.06 and
–16.11 kJ mol–1, respectively. The molar enthalpy change for the above two reactions is –16.64 and –118.09 kJ mol–1, respectively. The comparison between the experimental data and the theoretical values for these hydration processes indicates
that the results obtained in this study are quite reliable.
Thermal phenomena at the hydration of calcium sulphate hemihydrate (CaSO4·0.5H2O) are investigated in the paper. Time development of hydration heat of β-calcium sulphate hemihydrate prepared from flue
gas desulphurization (FGD) gypsum is determined using two different types of calorimeter, namely the differential calorimeter
DIK 04 and the isothermal heat flow calorimeter KC 01, and the differences in measured data analyzed. Then, the effects of
plasticizers and hydrophobizers on the hydration process of analyzed gypsum mixtures are studied.
Authors:Yan Yao, Dao-Wu Yang, Ju-Lan Zeng, Li-Xian Sun, and Wen-Jian Li
, researchers have rarely investigated the hydrationheat of fly ash and fluorgypsum co-doped cement.
The hydration of cement is an exothermic reaction, which can result in serious problem for mass concrete: The interior of the concrete could reach very
The calorimetric data of binders containing
pure Portland cement, 20% fly ash, 20% slag and 10% silica fume respectively
are determined at different initial casting temperatures using an adiabatic
calorimeter to measure the adiabatic temperature rising of concrete. The calorimetric
data of binders with different dosages of fly ash at two water binder ratios
are determined, too. Elevation of initial casting temperature decreases the
heat evolution of binder, enhances the heat evolution rate of binder and increases
the heat evolution rate of binder at early age. The dosage of fly ash in concrete
has different effects on the heat evolution of binder with different w/b. At high w/b ratio the
heat evolution of binder decreases when dosage of fly ash increases. At low w/b ratio the
heat evolution of binders increases when dosage of fly ash increases from
0 to 40% of total binder quantity. The heat evolution of binder decreases
after the dosage of fly ash over 40%. An appropriate dosage of fly ash in
binder benefits the performance of concrete at low w/b ratio.
Authors:M. García de Lomas, M. Sánchez de Rojas, and M. Frías
This work presents the relation between the pozzolanic activity, the hydration heat and the compressive strength developed
by blended mortars containing 10 and 35% of a spent fluid catalytic cracking catalyst (FCC).
The results show that, in comparison with 100% Portland cement mortar, a mortar with 10% FCC increases the hydration heat
all over the period of testing. This hydration heat increasing is due to the pozzolanic effect, therefore the resulting compressive
strength is higher than the reference mortar. Whereas, in a mortar with 35% of FCC, the hydration heat is higher than 100%
PC mortar, until 10 h of testing. After this age, the substitution degree predominates over the pozzolanic activity, showing
in this case, lower hydration heat and developing lower compressive strength than 100% PC mortar.
Authors:Vratislav Tydlitát, Igor Medveď, and Robert Černý
evolution of the hydrationheat. This occurs almost immediately after adding water according to the equation
The hydration of β-anhydrite III is completed within several minutes and, subsequently, the hydration of β-hemihydrate to dihydrate begins,
Authors:Vratislav Tydlitát, Jan Zákoutský, and Robert Černý
which are measured in physical and chemical laboratories using calorimetric techniques. In engineering laboratories, hydrationheat of cementitious systems belongs to the class of most extensively studied parameters. Isothermal [ 10 ], isoperibolic [ 11
Authors:Shengxing Wu, Donghui Huang, Feng-Bao Lin, Haitao Zhao, and Panxiu Wang
In this part, the calibrated FE model is used to perform parametric studies to evaluate the effect of hydrationheat, ambient temperature and casting temperature on temperature variations, and crack behavior of early age concrete