ACI Global Home Middle East Region Portal Western Europe Region Portal
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
Topics In Concrete
Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 31 Abstracts search results
Document:
SP262-29
Date:
October 1, 2009
Author(s):
D. Platel
Publication:
Symposium Papers
Volume:
262
Abstract:
The implementation of cement materials is improved by the addition of a polymer called a superplasticizer. In this presentation, we look for the impact of the polymer architecture on the physico-chemistry properties of cement slurries. Initially, we focus on the adsorption of sodium polymethacrylate grafted by poly(ethylene oxide) chains on different types of cement using macroscopic and microscopic techniques. Finally, we measure the fluidity of different cement slurries with the use of new tools such as helicoidal ribbon geometry to explain how polymer architecture controls the performance concrete formulations.
DOI:
10.14359/51663247
SP262-30
Z. Zhibin, X. Lingling, and T. Minshu
In order to improve dimensional stability of cementitious materials, synergistic effect of shrinkage reducing admixtures (mixture of glycol ethers and siloxane, SRA) and MgO-based expansive agent (MEA) burned at 850, 950, 1050 and 1200°C (1560, 1740, 1920, and 2190°F) for 1 h on the deformation of cement paste cured in water and sealed by polyethylene sheet at 20, 40 and 60°C (68, 104, and 140°F) was investigated. The results illustrated that combined use of MEA(850~950) and SRA could compensate the shrinkage of cement paste effectively, MEA also could make up for the shortage of SRA whose shrinkage-reducing ratio decreased at later age. Then hydration of MEA in the present of SRA was examined by DSC/TG and gravimetry. The results indicated that the presence of SRA retarded the hydration of MEA because SRA decreased the polarity of solvent and adsorbed on the surface of MEA, but with prolonged curing, the hydration degree of MEA with or without SRA tended to be the same.
10.14359/51663248
SP262-26
E. Maruya, R. Ichinose, and E. Sakai
Increasing the aluminate phase content in cement clinker is an effective measure to expand use of various industrial wastes and by-products. Wit h such clinker, it is important to control the fluidity of cement. In this study, we investigated the influence of mineral admixtures on the paste fluidity of cement containing high aluminate phase content. Cement pastes were prepared adding polycarboxylatetype superplasticizer at a 0.32 w/c. Apparent viscosities of the cement pastes were measured with a concentric-cylinder type rotational viscometer. The fluidity of the cement paste containing aluminate phase of 12 mass% was improved by adding 10 mass% of limestone powder, and this improvement was much higher than with other admixtures. The rate of initial heat liberation decreased with the addition of limestone powder, as did the apparent viscosity.
10.14359/51663244
SP262-27
I. Goc-Maciejewska, B. Chun, P.J. Sandberg, and P. Krzyżanowski
Polyethylene glycol (PEG)-comb branched polyphosphonate copolymer was prepared to study the effect of complete replacing the carboxylic acid groups in PEG polycarboxylate copolymer by phosphonic acid groups on the cement dispersion property. The purpose of the present study was to determine if the phosphonate group renders less so-called "cement sensitivity" sometimes observed with the carboxylate polymers. A series of phosphonate and carboxylate comb-polymers were synthesized and their dispersion ability was examined by the mini slump method using four commercially available normal portland cements (CEM I) with differences mainly in water-soluble alkali and clinker composition. Although the polyphosphonate comb-polymer exhibited comparable dispersing ability to the polycarboxylate counterpart, the phosphonate substitution did not reduce the cement sensitivity.
10.14359/51663245
SP262-28
M. Ohno, T. Sugiyama, T. Sugamata, and A. Ohta
Lignosulfonate-based air-entraining (AE) water-reducing agents have been used in various concrete structures for over 50 years. Polycarboxylate-based superplasticizers, which are the main superplasticizers in use today, have been on the market for 20 years and have recently been applied to various kinds of concrete structures. Therefore, it is important to know the difference that these three dispersants (lignosulfonate-based (LG), B-naphthalenesulfonate-based (BNS), and polycarboxylate-based (PC)) have on concrete durability. The authors, using superplasticizers containing each dispersant, studied the properties of concrete at a w/c of 0.50 up to the age of 20 years. This paper discusses the experimental results up to the age of 3 years following standard curing and artificial sea water curing, and under normal external exposure and exposure in a splash zone. As a result, no major difference has been observed in the effect on properties of the hardened concrete between PC and BNS, dispersants in superplasticizers. In addition, the authors consider that concrete incorporating PC-based superplasticizer or BNS-based superplasticizer has equal durability to that of concrete incorporating an AE waterreducing agent, most of which is in service over the long term.
10.14359/51663246
Results Per Page 5 10 15 20 25 50 100
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.
Edit Module Settings to define Page Content Reviewer