Les effets des caractéristiques du réseau de bulles d'air, du type de mûrissement, du truellage de surface et de la fumée de silice sur la résistance à l'écaillage d'un béton à haute performance

1996 ◽  
Vol 23 (6) ◽  
pp. 1260-1271
Author(s):  
Richard Gagné ◽  
Yvon Latreille ◽  
Jacques Marchand
Keyword(s):  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Surface Finishing ◽  
Air Bubbles ◽  
Concrete Durability ◽  
Freeze Thaw ◽  
Spacing Factor ◽  
Entrained Air ◽  
Scaling Resistance

In Canada, high-performance concretes (HPCs) are increasingly used in construction and repair, particularly for its durability, which is distinctly superior compared with ordinary concrete. The current tendency is to provide for a spacing factor of air bubbles lower than 230 μm in all HPCs that are subjected to freeze–thaw cycles. This choice is basically the outcome of an ongoing controversy as to the necessity of providing a good network of entrained air bubbles to protect HPCs against freeze–thaw cycles. In the future, the optimal use of HPC will depend, among other factors, on a better understanding of minimal requirements regarding the characteristics of air voids to ensure a good behavior of HPCs under freeze–thaw cycles. The results of the investigation reported herein show that a spacing factor lower than approximately 500 μm can be sufficient to ensure a good resistance of HPCs to scaling. It is also shown that surface trawling, slump, and set-retarding agents have only secondary effects on the scaling resistance of HPCs. Silica fume and membrane curing have allowed to improve significantly the scaling resistance of the HPCs under investigation. Key words: high-performance concrete, durability, scaling, set-retarding agent, silica fume, surface finishing, curing, pumping, entrained air, spacing factor.

La durabilité au gel des bétons à haute performance

1992 ◽  
Vol 19 (6) ◽  
pp. 975-980 ◽  
Author(s):  
Michel Pigeon ◽  
Richard Gagné ◽  
Pierre-Claude Aitcin ◽  
Marcel Langlois
Keyword(s):  
Silica Fume ◽  
Standard Procedure ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Freeze Thaw ◽  
Spacing Factor ◽  
Thaw Cycle ◽  
Entrained Air ◽  
Air Void ◽  
Limiting Value

Frost resistance of high-strength concrete (80–100 MPa) was studied by subjecting 44 concrete mixes to freeze–thaw cycles in water (ASTM C666, standard procedure A) and to scaling tests in the presence of deicer salts (ASTM C672, standard). The test programme was designed to analyze the effects of the water/cement ratio, the type of cement, the type of coarse aggregate, the duration of curing, and the air-void spacing factor. Results demonstrate that the water/cement ratio limiting value, below which entrained air is no longer necessary to protect concrete against freeze–thaw cycles, is sometimes higher than 0.30 but is more often below 0.25. This limiting value is affected most by cement characteristics: type 30 cement yielded much more durable concretes. Laboratory scaling tests demonstrated that when water/cement ratios are less than 0.30, the resistance deicer salt is generally very good, no matter what are the type of cement, the silica fume content, or the air-void spacing factor of the concrete. Key words: durability, freeze–thaw cycle, silica fume, scaling, curing, spacing factor, water/cement ratio, compressive strength, cement type, entrained air, aggregate. [Journal translation]

Bétons à haute performance pour fabriquer des panneaux destinés à réparer des structures submergées

1993 ◽  
Vol 20 (4) ◽  
pp. 650-659 ◽  
Author(s):  
M. Sonebi ◽  
K. H. Khayat
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
High Performance ◽  
Steel Fibre ◽  
Concrete Durability ◽  
Freeze Thaw ◽  
Limestone Aggregate ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Economic Worth

The field of repair of submerged hydraulic structures (dams, stilling basins, lock chambers, and so forth) is becoming more and more important given the economic worth of such structures. Damage caused by abrasion can make it difficult to maintain such structures in service. The purpose of the study described in this paper was to develop durable high-performance concretes that can be used for manufacture of board for repair of abrasion-damaged surfaces. The board might also be placed on surfaces already repaired with colloidal concrete poured underwater. Two types of cement (Type 30 and Type 10) and two high-performance coarse aggregates (granite and dolomitic limestone) were used. The eight concrete mixes developed included a variety of additives and admixtures such as silica fume, steel fibre, latex, and superplasticizer. For precise characterization of the mixes, hydraulic abrasion tests, compressive strength tests, and freeze–thaw cycle resistance tests were performed. In addition, shrinkage, thermal expansion coefficient, and permeability of the concretes were measured; in some cases, the board might be subject to freeze–thaw cycles in structures partially emptied for repair or maintenance. Results show that high-performance concretes with very low water: cement ratio, good workability, and improved freeze–thaw cycle resistance can be manufactured. Concretes made with Type-30 cement, silica fume, and granite or limestone aggregate offer excellent hydraulic abrasion resistance (depth of erosion on the order of 1 mm after 72 h), compressive strength greater than 115 MPa after 91 days, and a freeze–thaw durability factor of more than 100%. Key words: abrasion, concrete, durability, steel fibre, silica fume, freeze–thaw cycle, latex, board, underwater repair.

Development and field applications of silica fume concrete in Canada: a retrospective

1998 ◽  
Vol 25 (3) ◽  
pp. 391-400 ◽  
Author(s):  
MDA Thomas ◽  
K Cail ◽  
R D Hooton
Keyword(s):  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Blended Cement ◽  
High Strength ◽  
Hardened Concrete ◽  
Selling Price ◽  
Concrete Durability ◽  
Wide Range ◽  
Strength And Durability

The effects of silica fume on the properties of plastic and hardened concrete are now fairly well-established. If properly used, silica fume imparts significant improvement to the strength and durability of concrete; and the availability of this material together with high-range water reducers (superplasticizers) has been largely responsible for the development of high-strength and high-performance concretes. Silica fume has been used in the Canadian cement and concrete industry for over 15 years. Early use was driven by economy, since concrete of a given strength grade could be produced at lower cementitious material content (and cost) if silica fume was incorporated in the mix due to the initial low selling price of the material. The construction boom of the mid to late 1980s saw the exploitation of high-strength silica fume concrete for high-rise construction. By the 1990s, concerns over the deteriorating infrastructure had shifted the focus to concrete durability and silica fume was finding applications in high-performance concrete. Today, silica fume is perhaps the material of choice for engineers designing concrete to withstand aggressive exposure conditions. This paper documents the major developments in the use of silica fume in Canada and discusses the wide range of applications for which the product may be used to beneficial effect.Key words: blended cement, Canada, concrete, high-performance, silica fume.

Effect of Copper Slag as a Fine Aggregate on the Durability Characteristics of High-Performance Concrete (HPC) Containing Silica Fume

2020 ◽  
Vol 07 (02) ◽  
pp. 1-10
Author(s):  
Rizwan Ahmad Khan ◽  
Keyword(s):  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Copper Slag ◽  
Chloride Penetration ◽  
Interfacial Transition Zone ◽  
Fine Aggregate ◽  
Fresh Properties ◽  
Fine Aggregates ◽  
Effect Of Copper

This paper investigates the fresh and durability properties of the high-performance concrete by replacing cement with 15% Silica fume and simultaneously replacing fine aggregates with 25%, 50%, 75% and 100% copper slag at w/b ratio of 0.23. Five mixes were analysed and compared with the standard concrete mix. Fresh properties show an increase in the slump with the increase in the quantity of copper slag to the mix. Sorptivity, chloride penetration, UPV and carbonation results were very encouraging at 50% copper slag replacement levels. Microstructure analysis of these mixes shows the emergence of C-S-H gel for nearly all mixes indicating densification of the interfacial transition zone of the concrete.

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