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The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

Showing 1-5 of 51 Abstracts search results

Document: 

SP320

Date: 

September 1, 2017

Author(s):

Arezki Tagnit-Hamou

Publication:

Symposium Papers

Volume:

320

Abstract:

The purpose of this international conference is to present the latest scientific and technical information in the field of supplementary cementitious materials and novel binders for use in concrete. The new aspect of this conference is to highlight advances in the field of alternative and sustainable binders and supplementary cementitious materials, which are receiving increasing attention from the research community. The conference was held in Montréal, Canada from October 2 to 4, 2017. The conference proceedings, containing 50 refereed papers from more than 33 countries, were published as ACI SP-320.

DOI:

10.14359/51701166

Document: 

SP-320_42

Date: 

August 1, 2017

Author(s):

Théau Conte and Mohend Chaouche

Publication:

Symposium Papers

Volume:

320

Abstract:

Cement pastes exhibit virtually all the rheological features of complex fluids. Thus, several rheological methods and setups have been used in the literature to characterize these materials. In the present investigation Large Amplitude Oscillatory Shear (LAOS) is for the first time exploited for cement pastes. LAOS can be used to characterize all the rheological properties within a single procedure. This technique is tested in the case of three different cement mixes: a Portland cement paste, nanoclay blended cement paste and a cement paste containing a hydro-soluble polymer. These mixes were selected in order to get rheological properties that are different both quantitatively and qualitatively. Indeed, addition of a low amount of nanoclay increased significantly the yield stress and the shear-thinning/thixotropic aspects of the cement paste, whereas addition of cellulose ether led to the decrease of yield stress and thixotropy. These non-linear rheological properties are discussed within the framework of LAOS.

DOI:

10.14359/51701080

Document: 

SP-320_04

Date: 

August 1, 2017

Author(s):

M.I. Sánchez de Rojas1*, M. Frías1, E. Sabador1, C. Medina2, E. Asensio1, J. Rivera1

Publication:

Symposium Papers

Volume:

320

Abstract:

Waste management initiatives have arisen around the world in recent years, attendant upon increasingly strict regulations that favour alternative solutions such as diminution and recycling. The sludge generated in ceramic industry glazing and milling, for instance, may be a source of alternative raw materials. The chemical, physical, morphological and mineralogical characterisation of such sludge conducted in this study aimed to determine whether it is appropriate for using in the manufacture of the cement. The kinetics of the pozzolanic reaction in a ceramic sludge/lime system were also assessed. The hydration products ensuing from that reaction induced a steeper rise in flexural strength than compressive strength in the ceramic sludge-bearing material, rendering the end product more flexible and elastic than portland cement.

DOI:

10.14359/51701042

Document: 

SP-320_05

Date: 

August 1, 2017

Author(s):

Dulani P. A. Kodippili, Ehsan Rezabeigi, Michelle R. Nokken, and Robin Drew

Publication:

Symposium Papers

Volume:

320

Abstract:

One challenge of the use of nanoparticles in concrete has been agglomeration and dispersion. In this study, silica nanoparticles were synthesized via sol-gel using tetraethylorthosilicate (TEOS) as the precursor and ammonium hydroxide (NH4OH) as the gelation catalyst. The composition and particle size distribution of the resulting powder were examined by energy-dispersive X-ray spectroscopy (EDS) and particle size analysis (PSA), respectively. It was found that ammonium hydroxide delayed the setting time of cement, thus the suspension was thoroughly rinsed with a solution of Ca(OH)2 in distilled water. The suspension of nanoparticles in Ca(OH)2 solution was directly incorporated into the cement and water mixture to make the cement paste. Setting time and heat of hydration of cement were compared for cement pastes with the nanoparticles as suspension, as dried particles and control specimens. Results indicate that direct incorporation of nano-silica as an aqueous suspension has potential benefits.

DOI:

10.14359/51701043

Document: 

SP-320_14

Date: 

August 1, 2017

Author(s):

E. Pustovgar, M. Palacios, J.-B. d’Espinose de Lacaillerie, T. Matschei, N. Ruffray, R. Verel, and R.J. Flatt

Publication:

Symposium Papers

Volume:

320

Abstract:

Clinker replacement by supplementary cementitious materials (SCMs) is one of the most effective routes to reduce the environmental impact of Portland cement. However, increasing amounts of alumina-rich SCMs can reduce the reactivity and early mechanical strength of concrete. The reason of the lower strength includes a lower reactivity of the SCMs, but possibly also a passivation induced by the aluminates released from the SCMs on the silicates hydration. In this study, we have investigated the effect of the aluminate ions on the hydration of tricalcium silicate (C3S) by using a combination of several analytical techniques such as isothermal calorimetry, nuclear magnetic resonance (NMR) and scanning electron microscopy. It has been revealed that the initial and total dosages of aluminates play an important role on the length of the induction period and the time of the main peak position. Results are consistent with C3S dissolution being rate limiting. Finally, the influence of Na2SO4 on the passivation induced by the aluminates has been studied.

DOI:

10.14359/51701052

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