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Home > Publications > International Concrete Abstracts Portal
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 37 Abstracts search results
Document:
SP329
Date:
October 2, 2018
Author(s):
Jiaping Liu, Ziming Wang, Terence C. Holland, Jing Huang, Johann Plank
Publication:
Symposium Papers
Volume:
329
Abstract:
On October 28-31, 2018, the Chinese Ceramic Society and the China Academy of Building Research (CABR), Beijing China, in association with ACI, sponsored the Twelfth International Conference on Superplasticizers and other Chemical Admixtures in Concrete in Beijing China. More than 80 papers from all over the world were received and peer reviewed. A total of 36 refereed papers were accepted for publication in the proceedings of the conference. The proceedings were published by the ACI as SP 329. Also, 54 additional papers were presented at the conference, and were published in the Supplementary Papers Volume. The organizers of the conference were the Chinese Ceramic Society, Beijing and the Committee for the Organization of International Conferences (formerly CANMET/ACI Conferences).
DOI:
10.14359/51712247
SP-329-24
September 26, 2018
Min Qiao, Jian Chen, Nanxiao Gao, Qianping Ran, and Jiaping Liu
The development of high performance air entraining agents for concrete is of great importance. In this work, gemini surfactants (a new class of surfactants) have been utilized as high performance air entraining agents. Gemini surfactants modified with sulfonic groups were designed and successfully synthesized. The surface tensions and foam heights of their solutions were tested. Using them as the air entraining agents, the air contents and air-void parameters of the cement mortars were also tested. The study results clearly show that the gemini surfactants have higher surface activity, foamability, foam stability and air entraining performance compared with their single-chained cousins. The gemini surfactants had more concentrated arrangement than their single-chained cousins in gas-liquid interface, which enhanced the stability of the bubble film. The foam generated by gemini surfactants had fine bubble and high stability. So the gemini surfactants were considered as novel competent air entraining agents for concrete.
10.14359/51711222
SP-329-20
P. Gronchi, S. Bianchi, L. Brambilla, and M. Goisis
Graphene, graphite nanoplatelets and graphene oxide are emerging nanomaterials for future technologies. Despite the conservative nature of the building industry, nanomaterials are already making their way into some construction applications and nanotechnologies have the potential to open a new season in this field. Recent studies reported mechanical improvements in cement-graphene oxide composites. The interaction between the carbon nanoadditives and C-S-H is not clear yet. In this paper, we investigate whether and how graphite nanoplatelets and graphene oxide affect morphology and kinetics of C-S-H formation, studying the simple reaction between calcium oxide and silica. Influence on hydration by two different types of silica having different specific surfaces was considered. Instrumental analyses of the products were performed through Infrared and Raman spectroscopy, TG and SEM analysis up to four weeks. Results indicate that GO interacts with C-S-H phase and hinders its formation while GNPs remain only dispersed in the matrix.
10.14359/51711218
SP-329-17
Harald Justnes
Other compounds than gypsum to regulate the setting of Portland cement clinker have been investigated. This will potentially improve particle packing of such a cement since elongated ettringite needles should NOT form on the surface of the cement grains in the fresh state as with gypsum as set regulator. It has been demonstrated that small dosages of citric acid (0.2%), lignosulphonate (0.3%) and tannic acid (0.05%) can be viable alternative set regulating admixtures to 3.5% gypsum in Portland cement clinker. It has been proven for paste specimen cured for 90 days that the porosity of clinker paste with w/c = 0.45 using 0.05% tannic acid has more than 20% reduced porosity compared to paste made with the normal 3.5% gypsum dosage of clinker mass at the same w/c. In addition to reduced total porosity, the pore openings were also finer.
Other compounds than gypsum to regulate the setting of Portland cement clinker have been investigated. This will potentially improve particle packing of such a cement since elongated ettringite needles should NOT form on the surface of the cement grains in the fresh state as with gypsum as set regulator.
It has been demonstrated that small dosages of citric acid (0.2%), lignosulphonate (0.3%) and tannic acid (0.05%) can be viable alternative set regulating admixtures to 3.5% gypsum in Portland cement clinker.
It has been proven for paste specimen cured for 90 days that the porosity of clinker paste with w/c = 0.45 using 0.05% tannic acid has more than 20% reduced porosity compared to paste made with the normal 3.5% gypsum dosage of clinker mass at the same w/c. In addition to reduced total porosity, the pore openings were also finer.
10.14359/51711215
SP-329-14
Y. Chen, S. Wang, P. Juilland, L. Frunz, and J. Zhu
In this article we investigate the effect of precipitation of ettringite on the dispersion effect of four PCE with different structures. We first developed a simple method to qualify commercial cements with respect to early ettringite precipitation. The difference in flow between a paste prepared with the PCE in the mixing water (direct mode) and a paste prepared by adding the PCE after 3 minutes of hydration (indirect mode) can be correlated to amount of ettringite forming for a specific cement. A similar test setup was used to assess the effect of the precipitating ettringite on the flow properties of the different PCE. We found that all tested PCE were impacted by ettringite precipitation but to a very different extent. This suggests that, for concrete applications, the selection of a PCE more robust against variations in ettringite precipitation due to fluctuations in the used raw materials is feasible.
10.14359/51711212
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