Effect of HEMC on the early hydration of Portland cement highlighted by isothermal calorimetry

In the paper, the results of investigation concerning the influence of 0.3% addition of hydroxypropyl methylcellulose (MC) of 40 and 70 Pa s viscosity on the hydration process of main clinker phases C 3 S and C 3 A are presented. The course of hydration is documented using microcalorimetry, and formed phases were identified by XRD. The research indicated that methylcellulose inhibited the hydration process of clinker phases, analysed both, separately and in their mixture. Moreover, it was found that the presence of MC admixture also led to the reduction in calcium sulphate dihydrate reactivity in the system.

Section: Introductionmentioning

confidence: 99%

Microcalorimetric analysis of methylcellulose influence on the hydration process of tricalcium aluminate, alite and their mixture

Pichniarczyk

Malata²

2016

“…the acceleration period from 70 min to 9 h, IV. the deceleration period from 9 to 36 h and V. the stable period after 36 h, as mentioned in our previous research [22].…”

Section: Isothermal Calorimetrymentioning

confidence: 51%

“…The complete hydration heat Q max of the used Portland cement is 479.1 J g -1 , according to our previous study [22]. At the same hydration time, the hydration degree of cement paste with E/VC/VL is lower than that of the reference paste, and the higher the E/VC/VL dosage is, the lower the hydration degree is, indicating the retardation effect of E/VC/VL on cement hydration.…”

Section: Isothermal Calorimetrymentioning

confidence: 54%

See 1 more Smart Citation

Calorimetric study on the influence of redispersible E/VC/VL terpolymer on the early hydration of Portland cement

Zhang

Wang

et al. 2016

Self Cite

The effects of redispersible ethylene-vinyl chloride-vinyl laurate terpolymer (E/VC/VL) on the early hydration evolution of Portland cement were quantitatively investigated by isothermal calorimetry, setting time testing, thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction analysis and environmental scanning electron microscope analysis. The results show that the E/VC/VL definitely affects the early hydration process of cement paste, increases the initial exothermic peak value, decreases the heat evolution rate of the acceleration period and the second hydration exothermic peak, but increases the heat evolution rate during the deceleration period. And the E/VC/VL has little effects on the length of these different hydration periods. The E/VC/VL decreases hydration heat and hydration degree within 72 h, and the bigger the E/VC/VL dosage is, the less hydration heat and hydration degree are. The E/VC/VL retards the formation of hydrates, decreases the content of Ca(OH) 2 and CSH gels, affects the morphology evolution of hydrates and declines the crystalline degree and crystal size of Ca(OH) 2 . Besides, the E/VC/VL retards the formation of AFt and inhibits the conversion of AFt to AFm, accordingly keeping AFt content higher at later hydration time. In addition, no new phases are formed in cement paste with the E/VC/ VL. The retardation of E/VC/VL is also evidenced by the setting time of cement pastes. But with hydration time prolonging, the retardation of E/VC/VL on cement hydration gradually weakens.

“…Different from the isothermal (Zhang et al [9]) or the semi-adiabatic (Eddhahak et al [10]) concrete calorimetry, a more direct approach known as adiabatic calorimetry was chosen in this study so that the ATR could be directly measured. Using the concept described by Gibbon et al [11], an adiabatic calorimeter for concrete materials was developed during this study.…”

Section: Introductionmentioning

confidence: 99%

Thermal analysis and adiabatic calorimetry for early-age concrete members

Lin

Chen

2015

This paper describes a procedure for thermal analysis on early-age concrete structures with experimentally obtained concrete adiabatic temperature rise and interface conductance between steel formwork and concrete. During hydration, concrete is considered in the analysis as non-homogeneous and the degree of hydration is dependent on both thermal loading and thermal properties development. A thermal convection model was implemented to simulate the external heat loss. Experimentally, two 1.2-m concrete cubes were constructed with embedded temperature sensors. The measured temperature time histories correlate well with the calculated values using a finite element model developed for this study. The modeling method and the experimental procedures developed are able to accurately predict the temperature evolution within an early-age concrete structure.