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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 22 Abstracts search results
Document:
SP261-08
Date:
October 1, 2009
Author(s):
J. Kwasny, M. Sonebi, and P.A.M. Basheer
Publication:
Symposium Papers
Volume:
261
Abstract:
The performance of self-consolidating pastes was optimized by studying the effect of three mix composition parameters, limestone powder (LSP) content, dosage of superplasticizer (SP), and that of viscosity-modifying admixture (VMA), in a statistically designed experiment. Four properties of the pastes were measured: fluidity (mini-slump flow), Vicat setting times, volume change in the fresh state, and 28-day compressive strength. The optimization was preceded by the evaluation of the response surfaces of all chosen properties in the specified ranges of the three variables. The response surface results emphasized the primary and secondary effects on the properties of cement paste. The optimization indicated that pastes with properties acceptable for self-consolidating applications could be obtained with a moderate LSP content (for example, 19.5% by mass of total powder) and low dosage of the chemical admixtures (for example, 0.64% of SP and 0.01% of VMA by mass of total powder).
DOI:
10.14359/51663205
SP261-16
I. Moundoungou, D. Bulteel, E. Garcia-Diaz, and P. Dégrugilliers
Alkali-silica reaction (ASR) concrete expansion tests at 60°C (140°F) and 100 % relative humidity showed that siliceous limestone aggregates could have pessimum behavior similar to that of flint aggregate. For a given content of alkalis, a concrete made with fine and coarse reactive aggregates expands less than concrete made with reactive fine aggregate and no reactive coarse aggregate. The higher the reactivity of the aggregate, the higher is the observed expansion reduction. This expansion reduction effect could be used to make concrete that would have a low level expansion.
10.14359/51663213
SP261-18
J. Staerke Clausen and A. Knudsen
The appearance of cracks and spalling in concrete columns in a new eight-story office building brought about concerns that the injection of the ducts in the columns was poor quality. The cracks were mainly present at one floor, and trial drillings into the ducts on columns with severe cracks disclosed the presence of water and loose gravel and aggregates. Opening a duct revealed that the duct was either partially empty, filled with compacted gravel, or fully grouted. It was decided to use the impact-echo (IE) method to investigate the columns and ducts. Each column contains four ducts with a 25 mm (1 in.) diameter reinforcing bar for distribution of the shear stress at the lower and upper 1.0 m (3 ft) to each floor. Testing was performed for each 0.1 m (4 in.) elevation in these areas. The criterion to approve the injection was that at least 0.7 m (2 ft) of the column at the floor or the ceiling was fully injected. After testing the columns on 3 floors, it was decided to investigate the ducts in the walls of the three stairwells of the building, as they were vital for transferring the stresses of the reinforcement down through the building. Verification of the IE-system by drilling cores showed that is possible to distinguish between empty ducts, fully injected ducts, and ducts with compacted gravel. More than 35,000 measurements were made. The examination of the ducts showed that approximately 63% of tests at the top and approximately 86% at the bottom of the columns and walls indicated full injection.
10.14359/51663215
SP261-13
M. Bianchi, F. Canonico, L. Capelli, M.L. Pace, A. Telesca, and G.L. Valenti
The X-ray diffraction analysis and mercury intrusion porosimetry were employed to investigate the hydration process of calcium sulfoaluminate (CSA)- portland cement blends with C4A3S mass concentration, C3S/C4A3S, and CS/C4A3S mass ratios ranging from 7.7 to 22.0%, 1.0 to 6.5, and 0.5 to 1.2, respectively. Owing to the hydration of adequate C4A3S contents and the generation of sufficient quantities of expansive ettringite, blends with C4A3S amounts as well as C3S/C4A3S and CS/C4A3S values comprised between 17.6 and 22.0%, 1.0 and 1.7, 0.5 and 1.0, respectively, showed high-early strengths and low drying-shrinkage when compared to normal portland cements. The formation of expansive ettringite was associated with concentrated pore distributions and most preferred pore radii ranging from either 47 to 225 or 367 to 896 nanometers, depending on both C3S/C4A3S and CS/C4A3S ratios.
10.14359/51663210
SP261-21
G.Y. Kim, Y.S. Kim, and T.G. Lee
In this study, the effects of high temperature on mechanical properties of high strength concrete were experimentally investigated. The effect of elevated temperatures ranging from 20 to 700 °C (68 to 1292 °F) on the material mechanical properties of normal-weight and lightweight aggregate high-strength concrete of 60 MPa grade was evaluated. Tests were conducted on Ø100 × 200 mm (3.94 × 7.87 in.) cylinder specimens. The specimens were tested under both stressed and unstressed conditions. The specimens were preloaded to 20 and 40% of their ultimate compressive strength at room temperature and subjected to temperatures ranging from 100 to 700 °C (212 to 1292 °F), and the compressive strength compared to that observed at 20 °C (68 °F).
10.14359/51663218
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