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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 53 Abstracts search results
Document:
SP172
Date:
December 1, 1999
Author(s):
Editor: V.M. Malhotra
Publication:
Symposium Papers
Volume:
172
Abstract:
SP-172 The theme of the Third ACI International Conference in Malaysia in 1997 was "High-Performance Design and Materials and Recent Advances in Concrete Technology". Over 90 papers were submitted and reviewed, and 52 were accepted for this publication.
DOI:
10.14359/14170
SP172-04
Abdullah M. Alshamsi
The effect of silica fume and curing temperatures on the strength of High Strength Concrete (HSC) was investigated. Two concrete mixtures were prepared. The first mixture contained normal portland cement whereas 10% of the cement was replaced by silica fume in the other mixture. W/CM of 0.27 and slump of 40-60 mm were kept constant for both mixtures with the aid of a superplasticizer. Three curing temperatures were maintained throughout the testing age by means of water tanks. They were 20°C 35°C and 50°C. Testing was carried out at 1, 3, 7 , 2 8, 56 and of 90 days of age. The results indicate that while high curing temperatures accelerate strength development at early age, the strength at later ages is adversely affected. Furthermore, the adverse effect was greater in the case of silica fume concrete. The results also show that at 2OC, silica fume concrete produced similar results to other mixture from 7 days onwards. At the other two temperatures, silica fume concrete exhibited (in . general) lower results.
10.14359/6126
SP172-05
M. H. Zhang, N. Bouzoubaa and V. M. Malhotra
The state-of-the-art relating to the resistance of silica-fume concrete to de-incing salt scaling is reviewed. The performance of silica-fume concrete to de-icing salt scaling is compared with that of the ocntrol portland-cement concrete. The efects of the silica-fume content, air content, air-void spacing factor, water-to-cementitious materials ratio, placement considerations, and curing conditions are discussed.
10.14359/6127
SP172-06
Richard Gagne, Danielle Martin, Francine A. Blais, Alain Prezeau and Salsutio Guzman
The ore enrichment process used by QIT Fer et Titane of Sorel, Quebec, Canada generates a mining by-product referred to as OPP fmes (Ore Pretreatment Plant Fines). It is a fine dark powder, composed mainly of ilmenite, hematite, magnetite, and quartz, with a particle-size distribution similar to ASTM Type I I cement. The aim of this research project was to assess the potential use of OPP fines as a filler material in RCC for dam construction. A three-variable factorial plan of experiment was used to analyze the effects of the total dosage of fine particles (cement + OPP fines), the OPP fines replacement ratio (OPP fines/[ OPP fmes+cement]) and the water/fines (W/[OPP fines+cement]) on the fresh and hardened properties of RCC. The properties evaluated were: Vebe time, compressive strength, modulus of elasticity, water permeability, and heat of hydration. The research program also included a full-scale field test where approximately 140 m3 of RCC were produced to build an 8 m x 8 m x 2 m slab to evaluate the in situ properties of an RCC containing the OPP fines. This RCC was designed to meet Hydro-Quebec’s typical specifications for dams. The results show that OPP fines is a very effective filler in RCC because its particle-size distribution is very similar to that of the cement. Therefore, a large proportion of the total fines content (cement or fly ash) can be replaced by OPP fines without significantly changing the workability of the RCC. A simple mathematical model, based on the results of the factorial analysis, is proposed to select the total fines content, the OPP fines replacement ratio, and the water/fines ratio of an RCC mixture as a function of the required Vebe time (5 s to 60 s) and 91-d compressive strength (5 to 25 MPa). The results of the in situ testing program show that it is possible to produce an optimized RCC with a 91-d compressive strength of 23 MPa and very low heat generation, when using 120 kg/m3 of cement (ASTM Type II) and 80 kg/m3 of OPP fines (40% OPP fines and 60% cement).
10.14359/6128
SP172-07
Richard H. Scott
An investigation of moment redistribution effects in high strength concrete beams is described. Results from a test programme involving six two-span beams are presented. Three beams contained strain gauged reinforcing bars for making detailed measurements of reinforcement strain distributions. Results are compared with those from previous tests on similar beams made with normal strength concrete. Design implications are assessed.
10.14359/6129
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