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

Journal Article · Tue Nov 15 04:00:00 EST 2016 · Cement and Concrete Research

DOI:https://doi.org/10.1016/J.CEMCONRES.2016.09.002· OSTI ID:22697083

Cincotto, Maria A.; Figueiredo, Antonio D. de ^[1]

---

1. Department of Civil Construction Engineering, Polytechnic School of University of São Paulo, Professor Almeida Prado, Trav 2, 83, 05424-970 São Paulo (Brazil)

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 C{sub 3}A/SO{sub 3} ratio (between 0.67 and 0.90) remains after accelerator addition and if limestone filler is employed, because undersulfated C{sub 3}A 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.

• OSTI ID: 22697083
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Vol. 89; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ACCELERATORS
BIOMEDICAL RADIOGRAPHY
CEMENTS
CHEMICAL PROPERTIES
HYDRATION
SCANNING ELECTRON MICROSCOPY
SULFATES
SULFITES
X-RAY DIFFRACTION