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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-329-07
September 26, 2018
Manuel Ilg and Johann Plank
Concretes formulated at low water-cement ratios exhibit good material properties. Nevertheless, such concretes exhibit a honey-like consistency with a low speed of flow (“creeping behavior”) which is highly undesirable. In this paper it is shown that non-ionic small molecules can help to improve the fluidity at low water-cement ratios significantly and eliminate the “stickiness” when combined with ordinary PCE superplasticizers. For this purpose, different non-ionic glycol derivatives were screened via mini-slump testing. It was found that especially less polar species behave as very powerful co-dispersants. To gain a more profound understanding of the working mechanism, heat flow calorimetry was carried out. Additionally, concrete lab tests were performed to ascertain the impact of the non-ionic molecules on the V-funnel empty time of SCCs. Based on adsorption measurements it is inferred that the co-dispersants act as osmotic spacers which keep the cement particles apart and prevent them from agglomeration.
10.14359/51711205
SP-329-25
Yanwei Wang, Xin Shu, Yong Yang, Qianping Ran, and Jiaping Liu
Conformational properties of comb-shaped copolymer polyelectrolytes such as polycarboxylate ether-based superplasticizers (PCEs) in aqueous solutions and at liquid/solid interfaces are fundamental to their performances as polymeric dispersants. Pioneering studies of Flatt and coworkers have demonstrated the great relevance of polymer theory to the PCE community. The present work revisits this topic with an emphasis on the semi-flexible characteristics of the anionic backbone decorated with flexible side chains. A simple physical picture, where the backbone adopts a "train-like" conformation on the surface, effectively as a two-dimensional worm-like chain, with the side chains mimicking surface-tethered chains, is presented for PCEs in the strongly adsorbed state.
10.14359/51711223
SP-329-21
Yunhui Fang, Yuliang Ke, Xiaofang Zhang, and Geli Li
The water-reducing typed PCE (KZJ-1) has a short branched chain and a long main chain structure, while the structure of early strength typed PCE (KZJ-2 and KZJ-3) with a long branched chain and a short main chain. A detailed investigation on the chemical structure of different typed PCEs was characterized by GPC and particle charge density test. The effects of superplasticizer on dispersion, retarding stability and strength development are studied at the same time by paste and concrete. The superplasticizer was placed into different concentration to test the surface tension. The amount of adsorption and hydration heat were carried by TOC and TAM AIR. The molecular chain of KZJ-2 and KZJ-3 stretches more than KZJ-1 in the alkaline environment of concrete. The KZJ-2 and KZJ-3 can accelerate cement early hydration, shorten the induction period significantly, promote the hydration of C3A, and accelerate the formation of AFt.
10.14359/51711219
SP-329-19
Angela Rozzoni and Michael Dolci
Admixtures for concrete offer a wide range of water reducers that are mostly based on polycarboxylate polymers (PCE) bearing polyethylene oxide nonionic side chains. It is possible to increase PCE effectiveness mixing them with a special workability retention agent (WRA). We focused on ester-based PCE, synthesized from methoxypolyethylene glycol (Mpeg) and acrylic or methacrylic acid, and allylic-type PCE, synthesized from TPeg (polyethyleneglycol isopentenyl ether) or Ipeg (polyethylenglycol methallyl ether) and acrylic or methacrylic acid. By modifyng the composition of the backbone, the kind of repeating units and the molecular weight of polyethylene oxide side chains of PCE it is possible to optimize the properties of the mixture of PCE and WRA. The structures of the most interesting polymers we prepared are described in terms of their conformations (worms or stars). WRA is a particular acrylic polymer that can hydrolyze in alkaline environment; to work properly it must have a certain molecular weight and a low polydispersibility index. If it is used alone it is an ineffective water reducer. To investigate the reason behind this behavior slump test and rheological measured were carried out on mortar.
10.14359/51711217
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