Parameters controlling early age hydration of cement pastes containing accelerators for sprayed concrete

The objective of this work is to parametrize the early age hydration behavior of accelerated cement pastes based on the chemical properties of cement and accelerators. Eight cements, three alkali-free and one alkaline accelerators were evaluated. Isothermal calorimetry, in situ XRD and SEM imaging w...

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Bibliographic Details
Published inCement and concrete research Vol. 89; pp. 230 - 248
Main Authors Salvador, Renan P., Cavalaro, Sergio H.P., Cincotto, Maria A., Figueiredo, Antonio D. de
Format Journal Article Publication
LanguageEnglish
Published Elmsford Elsevier Ltd 01.11.2016
Elsevier BV
Subjects
Accelerator
ACCELERATORS
Alkalies
Aluminum
BIOMEDICAL RADIOGRAPHY
Cement hydration
Cement paste
CEMENTS
CHEMICAL PROPERTIES
Differential scanning calorimetry
Enginyeria civil
Formigó gunitat
Heat measurement
HYDRATION
Kinetics
Limestone
Materials i estructures
Materials i estructures de formigó
MATERIALS SCIENCE
Mechanical properties
Reaction kinetics
SCANNING ELECTRON MICROSCOPY
Shotcrete
Sprayed concrete
Studies
SULFATES
SULFITES
Tricalcium aluminum ferrite
Tricalcium silicate
X-RAY DIFFRACTION
Àrees temàtiques de la UPC
Kinetics
Hydration
Cement paste
Sprayed concrete
Accelerator
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Summary:The objective of this work is to parametrize the early age hydration behavior of accelerated cement pastes based on the chemical properties of cement and accelerators. Eight cements, three alkali-free and one alkaline accelerators were evaluated. Isothermal calorimetry, in situ XRD and SEM imaging were performed to characterize kinetics and mechanisms of hydration and the microstructure development. The reactivity of all accelerators is directly proportional to their aluminum and sulfate concentrations and to the amount and solubility of the setting regulator contained in cement. Alite hydration is enhanced if a proper C3A/SO3 ratio (between 0.67 and 0.90) remains after accelerator addition and if limestone filler is employed, because undersulfated C3A reactions are avoided. Combinations of compatible materials are recommended to enhance the performance of the matrix and to prevent an undesirable hydration behavior and its consequences in mechanical strength development.
ISSN:0008-8846
1873-3948
DOI:10.1016/j.cemconres.2016.09.002