International Concrete Abstracts Portal

Editors: V. Mohan Malhotra, Pawan R. Gupta, Terence C. Holland

In May 1978, the Canada Center for Mineral and Energy Technology (CANMET), in association with the American Concrete Institute (ACI) sponsored a three-day conference in Ottawa, ON, Canada, on the use of superplasticizers in concrete. Selected papers from the symposium were published as ACI SP-62.

In 1981, CANMET, again in association with the ACI, sponsored a second three-day international conference in Ottawa on the use of superplasticizers in concrete. Proceedings of the conference were published as ACI SP-68.

The purpose of the third international conference in Ottawa in 1989 was to review the progress made since the meetings in 1978 and 1981, and to bring together representatives of the chemical admixtures, cement, and concrete industries to exchange information and delineate new areas of needed research. The scope of this conference was expanded to include chemical admixtures other than superplasticizers. Proceedings of the conference were published as ACI SP-119.

In October 1994, CANMET, in association with the ACI and several other organizations, sponsored the fourth conference in Montreal, QC, Canada. The objective of this conference was to bring attention to new developments in chemical admixtures since the last conference in 1998. Proceedings of the conference were published as ACI SP-148.

In October 1997, the Committee for the Organization of CANMET/ACI International Conferences (ACI Council), in association with the ACI and several cement and concrete organizations in Italy, sponsored the fifth conference in Rome, Italy. The conference was aimed at transferring technology in the fast-moving field of chemical admixtures. Proceedings of the conference were published as ACI SP-173.

In October 2000, the Committee of the Organization of CANMET/ACI International Conferences (ACI Council), in association with several organizations in Canada and France, sponsored the sixth conference in Nice, France. More than 50 papers from more than 20 countries were received and reviewed by the ACI review panel, and 37 were accepted for publication in the proceedings of the conference. The proceedings were published as ACI SP-195.

In October 2003, the Committee for the Organization of CANMET/ACI International Conferences (ACI Council), in association with several organizations in Canada and Germany, sponsored the seventh conference in Berlin, Germany. The conference attracted more than 275 delegates and proceedings of the conference, consisting of 39 papers, were published as ACI SP-217.

In October 2006, the Committee for the Organization of CANMET/ACI International Conferences (ACI) Council), sponsored the eight conference in Sorrento, Italy. More than 60 papers from more than 25 countries were received and peer reviewed by the CANMET/ACI review panel in Budapest, and 36 were accepted for publication as ACI SP-239.

In October 2009, the Committee for the Organization of International Conferences (COIC) (formerly CANMET/ACI International Conferences), sponsored the ninth ACI International Conference in Seville, Spain. More than 50 papers from more than 20 countries were received and peer reviewed, and 35 were accepted for publication in the proceedings of the conference. The proceedings were published as ACI SP-262.

In October 28 to 31, 2012, COIC, sponsored the Tenth International Conference on Superplasticizers and Other Chemical Admixtures in Concrete in Prague, Czech Republic. More than 70 papers from the world over were peer reviewed, and 33 were accepted for publication in the proceedings of the conference. The proceedings were published as ACI SP-288. In July 10-13, 2015, the COIC, in association with ACI, sponsored the Eleventh International Conference on Superplasticizers and Other Chemical Admixtures in Concrete in Ottawa, Canada. More than 60 papers from the world over were peer reviewed, and 28 were accepted for publication in the proceedings of the conference. The proceedings were published by ACI as SP-302. Also, additional papers were presented at the conference that were published in the Supplementary Papers Volume.

Thanks are extended to members of the Technical Paper Review Panel that met in the Bahamas from October 3 to 11, 2014. Without their dedicated effort and hard work, it would not have been possible to publish the proceedings. Cooperation of the authors in accepting the reviewers’ suggestions and in revising the manuscripts accordingly is appreciated greatly. The help and assistance of Dr. Pawan R. Gupta and Prabha Gupta are acknowledged gratefully in the administrative work associated with the conference and processing of the manuscripts for both the conference proceedings (ACI SP-302) and the Supplementary Papers Volume.

Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-302

The impact of clinker grinding aids (GAs) based on amine, glycol, or phenol on static yield stress (t0) of cement pastes is not well understood. Results obtained from this project have shown that GA molecules remain active after the grinding process and provide variations in cement properties, whether in the fresh or hardened states. Flowability improved and t0 decreased when the cement is ground using increased GA concentrations. This was attributed to the adsorption of these molecules onto the cement grains and saturation of surface charges, thus creating repulsive forces between neighboring particles. The decrease in t0 was particularly pronounced when phenol-based GA was used, given the presence of polycarboxylate polymers that help dispersing cement particles upon mixing with water.

The microstructure of MPEG-type polycarboxylate (PCE) copolymers, i.e. the distribution of side chains along the main chain was investigated via 13C NMR spectroscopy and the effect on the interaction with cement was determined. For this purpose, two series of polycarboxylate samples (one series synthesized by radical copolymerization, the other one via grafting/esterification) at molar ratios of –COO– to side chain of 2 to 10 were compared. The 13C NMR spectra suggest that the copolymerized PCEs possess a gradient-like distribution of side chains along the main chain while the grafted PCEs exhibit a statistical (random) repartition. Owed to those microstructural differences the grafted PCE copolymers show a tendency to adsorb in lower amount on cement. The reason is that in the copolymerized PCEs, large blocks of –COO– groups are present which exhibit high affinity to the surface of cement and therefore promote adsorption.

The economic use of chemical admixtures depends on supply chains. Therefore, in most regions ins sub-Saharan Africa (SSA), the use of admixtures is not common practice. This amplifies the unfavorable framework for concrete construction such as fragmentary supply chains, high local cement prices, and unfavorable construction site facilities in this region significantly. The use of superplasticizer (SP) and stabilizing agents (STA) can enhance the concrete technology in SSA, since they can disassociate the concrete quality from external boundary influences. After providing a general overview of the peculiarities of the SSA boundary framework, economic concepts are provided, how existing material solutions can be significantly improved by the use of SPs and STAs based on locally available materials such as lignosulphonates and cassava starch. Finally a three step optimization process is described that helps developing flowable concrete based on materials that can be accessed in most locations in SSA.

The interaction of methoxy-capped poly(ethylene glycol) polymers (MPEG) and a poly(methacrylic acid) anionic polymer (PMA) from water onto sodium Montmorillonite (Na-Mmt) particles untreated or treated by calcium chloride was studied at 20°C. In the absence of Ca2+, MPEGs are able to intercalate by displacing the water molecules present in the interlayer space, as shown by XRD and TGA analyses. In contrast, the adsorbed amount of PMA remains low. The saturation of Mmt with Ca2+ prevents MPEG intercalation through replacing sodium by a stronger water coordinator in the interlayer space, but slightly increases PMA adsorption possibly through a calcium bonding mechanism. This was confirmed with PCE superplasticizers and Na- and Ca-saturated Mmt clays. Whatever the PCE, a larger amount was consumed on Na-Mmt than on Ca-Mmt. This confirms the occurrence of two consumption mechanisms: (i) a superficial adsorption via cation bonding of the carboxylate groups with anionic sites on clay surfaces, (ii) intercalation of ether units of the grafts in the interlayer space by displacement of water molecules coordinated to the exchangeable cations.