skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Effects of setting regulators on the efficiency of an inorganic acid based alkali-free accelerator reacting with a Portland cement

Abstract

Today, in the field of underground constructions, alkali-free accelerators are commonly employed, during tunnel excavation, to allow flash concrete setting. In this way, the cementitious sprayed material can firmly bond to the tunnel walls, controlling the convergence (the tendency of the section to squeeze). Their efficiency may be related to many parameters like: cement type, setting regulator, concrete composition, working temperature. Nevertheless, the influence of such factors on the accelerator performance has not been clarified yet. The accelerator efficacy is evaluated by real spraying test in job site or, when only laboratory equipment are available, by measuring the final setting times of cement systems admixed with the accelerator. Several alkali-free flash setting admixtures are available on the market. They can be divided into two main categories both containing aluminium sulphate complexes stabilized either by inorganic acids or by organic acids. In this paper, the influence of different setting regulators on the performances of an inorganic acid based alkali-free accelerator was analysed. Portland cement samples were obtained by mixing clinker with gypsum, {alpha}-hemihydrate, {beta}-hemihydrate or anhydrite. The setting regulator instantaneous dissolution rates were evaluated through conductivity measurements. The setting time of cement pastes with and without the accelerator was measured. Itmore » was found that the shorter the final setting time (therefore the more efficient is the accelerator) the lower the setting regulator instantaneous dissolution rate. In order to understand this phenomenon, a comparison was performed between accelerated cement paste samples containing the setting regulator with the highest ({beta}-hemihydrate) and the lowest instantaneous dissolution rate (anhydrite). The analytical work included morphological (Environmental Scanning Electron Microscopy-Field Emission Gun - ESEM-FEG), crystal-chemical (X-Ray Powder Diffraction - XRD), physical-chemical (hydration temperature profile) and chemical (Induced Coupled Plasma-Atomic Emission Spectroscopy - ICP/AES) evaluations. The results revealed significant morphological differences among the investigated samples.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1]
  1. Mapei S.p.A. - Via Cafiero, 22-20158 Milan (Italy)
Publication Date:
OSTI Identifier:
20995376
Resource Type:
Journal Article
Journal Name:
Cement and Concrete Research
Additional Journal Information:
Journal Volume: 37; Journal Issue: 4; Other Information: DOI: 10.1016/j.cemconres.2007.01.002; PII: S0008-8846(07)00014-2; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0008-8846
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM SULFATES; ANHYDRITE; AUGER ELECTRON SPECTROSCOPY; DISSOLUTION; EFFICIENCY; EMISSION SPECTROSCOPY; EXCAVATION; GYPSUM; HYDRATION; INORGANIC ACIDS; PERFORMANCE; PORTLAND CEMENT; SCANNING ELECTRON MICROSCOPY; X-RAY DIFFRACTION

Citation Formats

Maltese, C, Pistolesi, C, Bravo, A, Cella, F, Cerulli, T, and Salvioni, D. Effects of setting regulators on the efficiency of an inorganic acid based alkali-free accelerator reacting with a Portland cement. United States: N. p., 2007. Web. doi:10.1016/j.cemconres.2007.01.002.
Maltese, C, Pistolesi, C, Bravo, A, Cella, F, Cerulli, T, & Salvioni, D. Effects of setting regulators on the efficiency of an inorganic acid based alkali-free accelerator reacting with a Portland cement. United States. https://doi.org/10.1016/j.cemconres.2007.01.002
Maltese, C, Pistolesi, C, Bravo, A, Cella, F, Cerulli, T, and Salvioni, D. 2007. "Effects of setting regulators on the efficiency of an inorganic acid based alkali-free accelerator reacting with a Portland cement". United States. https://doi.org/10.1016/j.cemconres.2007.01.002.
@article{osti_20995376,
title = {Effects of setting regulators on the efficiency of an inorganic acid based alkali-free accelerator reacting with a Portland cement},
author = {Maltese, C and Pistolesi, C and Bravo, A and Cella, F and Cerulli, T and Salvioni, D},
abstractNote = {Today, in the field of underground constructions, alkali-free accelerators are commonly employed, during tunnel excavation, to allow flash concrete setting. In this way, the cementitious sprayed material can firmly bond to the tunnel walls, controlling the convergence (the tendency of the section to squeeze). Their efficiency may be related to many parameters like: cement type, setting regulator, concrete composition, working temperature. Nevertheless, the influence of such factors on the accelerator performance has not been clarified yet. The accelerator efficacy is evaluated by real spraying test in job site or, when only laboratory equipment are available, by measuring the final setting times of cement systems admixed with the accelerator. Several alkali-free flash setting admixtures are available on the market. They can be divided into two main categories both containing aluminium sulphate complexes stabilized either by inorganic acids or by organic acids. In this paper, the influence of different setting regulators on the performances of an inorganic acid based alkali-free accelerator was analysed. Portland cement samples were obtained by mixing clinker with gypsum, {alpha}-hemihydrate, {beta}-hemihydrate or anhydrite. The setting regulator instantaneous dissolution rates were evaluated through conductivity measurements. The setting time of cement pastes with and without the accelerator was measured. It was found that the shorter the final setting time (therefore the more efficient is the accelerator) the lower the setting regulator instantaneous dissolution rate. In order to understand this phenomenon, a comparison was performed between accelerated cement paste samples containing the setting regulator with the highest ({beta}-hemihydrate) and the lowest instantaneous dissolution rate (anhydrite). The analytical work included morphological (Environmental Scanning Electron Microscopy-Field Emission Gun - ESEM-FEG), crystal-chemical (X-Ray Powder Diffraction - XRD), physical-chemical (hydration temperature profile) and chemical (Induced Coupled Plasma-Atomic Emission Spectroscopy - ICP/AES) evaluations. The results revealed significant morphological differences among the investigated samples.},
doi = {10.1016/j.cemconres.2007.01.002},
url = {https://www.osti.gov/biblio/20995376}, journal = {Cement and Concrete Research},
issn = {0008-8846},
number = 4,
volume = 37,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}