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International Concrete Abstracts Portal

Showing 1-3 of 3 Abstracts search results

Document: 

SP172-24

Date: 

December 1, 1999

Author(s):

Kamal Gad Sharobim

Publication:

Symposium Papers

Volume:

172

Abstract:

This paper deals with the design and testing of high performance concrete mixtures capable of being cast under water and resisting the sulphates and chlorides existing in soil and ground water. Such concrete shall have high workability, self compactibility, high strength, and high durability. Fourteen concrete mixtures were proportioned to give compressive strength of 56 Mpa after 28 days using high slag blast furnace cement and natural gravel and sand. Five types of admixtures were used to obtain a slump from 200 mm to 250 mm. These concretes were specified to cast the diaphragm walls and 600 piles comprising the foundation of the new Alexandria library, by using a tremie pipe to a depth of 34 meter under water. The properties of fresh concrete such as slump, slump loss, air content, compaction factor, unit weight, and setting time were measured for each mixture. For hardened concrete, characteristics such as compressive strength at different ages, tensile strength, flexural strength, water absorption, coefficient of permeability, drying shrinkage and wetting expansion were determined. A concrete block model and full scale trial panel were cast by tremie pipe to investigate the flowability and self compactibility of concrete mixture. Cores were drilled from both the block model and trial panel at different depths and examined to check the compactibility of concrete without vibrating. In addition, temperature development of concrete used for casting of the trial panel due to the heat of hydration was measured.

DOI:

10.14359/6146


Document: 

SP153-38

Date: 

June 1, 1995

Author(s):

Q. Chu, S. Bonnamy, and H. Van Damme

Publication:

Symposium Papers

Volume:

153

Abstract:

To better understand the behavior of silica fumes (SF) in fresh mortar and concrete, four French silica fumes, with different chemical and textural properties, were characterized with respect to their surface properties and their behavior in aqueous dispersion. Zeta potential measurements were performed as a function of pH and ionic strength. Below about pH=4, all materials behave similarly, whereas at higher pH, the electrochemical potential was found to be related to the Ca content. In suspension, the decrease of the average particle size (bimodal distribution) is directly related to the power input (ultrasonic treatment) and to the intragranular compactness, mass-fractal dimension, and densification treatment. With Ca-rich SF, sedimentation volumes and velocities were found to increase as dispersion proceeds, which suggests that the elementary sub-micrometric silica spheres re- agglomerate after the dispersion treatment, probably due to bridging by calcium silicate hydrates.

DOI:

10.14359/1094


Document: 

SP35-07

Date: 

January 1, 1973

Author(s):

B.S. Taranath and B. Stafford Smith

Publication:

Symposium Papers

Volume:

35

Abstract:

A study is made of open-section core supported structures subjected to torsional loads. Vlasov's theory relating rotations, bimoments, and warping stresses, in cores is reviewed briefly.

DOI:

10.14359/17482


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