Email Address is required Invalid Email Address
In today’s market, it is imperative to be knowledgeable and have an edge over the competition. ACI members have it…they are engaged, informed, and stay up to date by taking advantage of benefits that ACI membership provides them.
Read more about membership
Learn More
Become an ACI Member
Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
Staff Directory
ACI World Headquarters 38800 Country Club Dr. Farmington Hills, MI 48331-3439 USA Phone: 1.248.848.3800 Fax: 1.248.848.3701
ACI Middle East Regional Office Second Floor, Office #207 The Offices 2 Building, One Central Dubai World Trade Center Complex Dubai, UAE Phone: +971.4.516.3208 & 3209
ACI Resource Center Southern California Midwest Mid Atlantic
Feedback via Email Phone: 1.248.848.3800
ACI Global Home Middle East Region Portal Western Europe Region Portal
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 34 Abstracts search results
Document:
SP288
Date:
October 1, 2012
Author(s):
Editor: V.M. Malhotra
Publication:
Symposium Papers
Volume:
288
Abstract:
This CD contains 33 papers presented at the Tenth International Conference of Superplasticizers and Other Chemical Admixtures in Concrete held in Prague, Czech Republic, in October 2012. Topics include Synthesis, Characterization, and Dispersing Performance of a Novel Cycloaliphatic Superplasticizer; Compatibility between Polycarboxylate and Viscosity-Modifying Admixtures in Cement Pastes; Aspects of Gypsum-Free Portland Cement; A Novel Type of PCE Possessing Silyl Functionalities; and much more. 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-288
DOI:
10.14359/51684135
SP288-03
September 14, 2012
Harald Justnes
Calcium sulphate (e.g. gypsum) is the common set regulator in portland cement. It has been shown that ground calcium sulphate (e.g. gypsum) is the common set regulator in portland cement. It has been shown that ground clinker can be set regulated by other calcium salts than gypsum, in particular calcium acetate, formate, and nitrate. Rheology of paste is improved when gypsum is replaced by the other salts, probably due to less water binding and less needle shaped surface hydration products than ettringite. For in particular calcium nitrate the cumulative hydration temperature is reduced, which opens up for low-energy cement without changing clinker chemistry. Removing calcium sulphate all together may also allow heat curing or evolution of hydration heat in massive structures to exceed 70°C (158°F) without risking delayed ettringite formation (DEF). These aspects have been elucidated by experiments in the present paper.
10.14359/51684219
SP288-02
Marta Palacios, Robert J. Flatt, Francisca Puertas, and A. Sanchez-Herencia
Superplasticizers and viscosity-modifying admixtures (VMA) are often combined in the production of self-compacting concrete. The former provide high flow¬ability and the latter are being increasingly used to enhance its stability. A deep knowledge of the mechanisms of action of both admixtures is needed for optimizing concrete design and for reducing possible technological problems on site. The aim of the present study is to provide a scientific understanding of the compatibility between a PCE and two different VMA admixtures, starch and welan gum-based. For this, the interaction of both types of admixtures with cement was first studied by determining adsorption isotherms. Rheological tests were also performed and showed that the studied VMAs do not modify notably the plastic viscosity, but they control the stability of cement pastes by increasing the yield stress (up to 100%). Moreover, it was found that the increase of yield stress depends on the mode of VMA addition, reaching higher values when the VMA is added after the PCE.
10.14359/51684218
SP288-01
Lei Lei, Johanna de Reese, and Johann Plank
A novel superplasticizer made from cyclohexanone, formaldehyde and pyrosul¬fite utilizing a polycondensation reaction is presented. The new CFS polymer possesses a molecular weight of ~57 kDa and medium anionic charge density of ~1100 μeq/g. It disperses cements of diverse compositions (CEM I, CEM II, CEM III) effectively and does not retard cement hydration. In the presence of clay (montmorillonite), its dispersing perfor¬mance is only slightly affected whereas that of a commercial polycarboxylate is severely perturbed. The reason behind is low adsorption of CFS on clay (~40 mg/g clay) while PCE sorbs in large quantity (~290 mg/g clay) and thus is deprived of cement. Adsorption and zeta potential measurements show that anionic CFS works by occupying positively charged surface sites on cement and achieves its dispersion effectiveness by instigating electrostatic repulsion between the cement particles.
10.14359/51684217
SP288-06
Karel Lesage, Ozlem Cizer, Geert De Schutter, Bram Desmet, John Vantomme, and Lucie Vandewalle
Calcium nitrate (CN) has been used as a cement hydration accelerator in varying dosages in order to explore its potential to compensate hydration retardation caused by a polycarboxylic ether (PCE) superplasticizer. The initial setting time, obtained from Vicat needle penetration tests, was found to decrease for increasing CN dosage until 4 percent of the cement mass was added. For dosages beyond this amount, the initial setting time slightly increased. The detected alite and aluminate hydration products appeared to have an influence on the structure evolution during setting. It is assumed that the AFt needles destruct the C-S-H network, which could lead to lower needle penetration resistance.
10.14359/51684222
Results Per Page 5 10 15 20 25 50 100