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In this study, normal concrete (NC) and four types of self-compacting concrete (SCC), in which cement was partially replaced by 5%, 10%, 15%, and 20% of silica fume (SF), were used to evaluate the effect of SF content on the bond strength of tension lap-spliced bars embedded in NC and SCC specimens. Therefore, 15 full-scale beam specimens (2000 Â 300 Â 200 mm 3 ) were tested and 20 mm reinforcing bars were used with a 300-mm splice length as tension reinforcement. Each beam was designed with bars spliced in a constant moment region at midspan. It was found that the bond strength of the reinforcement embedded in SCC beams was higher than that of the reinforcement in NC beams, whilst the bond strength increased with increase in the replacement of cement by SF from 5% to 10%. Moreover, the beam specimens produced from SCC containing 5% SF had the highest normalized bond strength of 1.07 followed by SCC beams with 10% SF, 15% SF, NC beams, and 20% SF.Résumé : Dans la présente étude, du béton normal et quatre types de béton autoplaçant (BAP) dans lesquels le ciment a été substitué en partie par quatre proportions de fumée de silice (5, 10, 15 et 20 %) ont été utilisés pour évaluer l'effet des fumée de silice sur la résistance du liage des tiges en tension collées par chevauchement dans les échantillons de béton normal et de béton autoplaçant. Ainsi, 15 échantillons de poutre à pleine échelle (2000 x 300 x 200 mm) ont été mis à l'épreuve et des tiges d'armature de 20 mm ont été utilisées avec une longueur de chevauchement de 300 mm servant de renforcement en tension. Chaque poutre incorporait des tiges chevauchant dans une zone à moment constant au milieu de la portée. Il a été découvert que la résistance du liage du renforcement dans les poutres en béton autoplaçant était supé-rieure à celle du renforcement dans les poutres en béton normal alors que la résistance de liage était supérieure avec un accroissement du pourcentage de remplacement du ciment par la fumée de silice de 5 à 10 %. De plus, les échantillons de poutre fabriqués en béton autoplaçant contenant 5 % de fumée de silice présentaient la plus forte résistance de liage normalisée avec 1,07 suivis des poutres en béton autoplaçant comportant 10 % de fumée de silice, puis 15 % de fumée de silice, les poutres en béton normal et, finalement, le béton autoplaçant comportant 20 % de fumée de silice.Mots-clés : lien, chevauchement, béton autoplaçant, fumée de silice, poutre à pleine échelle.[Traduit par la Rédaction]

Aggregate is an important ingredient of concrete that affects both fresh and hardened properties of concrete. The properties of concrete can be enhanced or worsened by changing properties of aggregate, especially particle size distribution of aggregate. However, in the literature, the effects of particle size distribution of aggregate on the properties of concrete have been neglected for particularly Steel-Fiber Reinforced Concrete (SFRC) although packing is a very important aspect for SFRC quality. Thus, this study investigates the effects of changing particle size distribution and maximum size (Dmax) of aggregate on the workability and mechanical properties of SFRC. With this aim, three gradations and two Dmax were used to produce SFRC mixtures with constant cement dosages and water/cement ratios. Totally, nine different concrete series were tested. To observe the properties of fresh concrete, Slump and Ve-Be tests were performed. The compressive, splitting tensile and flexural strengths of concretes were also evaluated, and the toughness of the SFRC specimens was calculated. Based on the test results , it can be concluded that the ratio of fine-to-coarse aggregate, the void content between the aggregate particles and Dmax have remarkable effects on the properties of both fresh and hardened SFRC. In addition, the toughness of the SFRC specimens which has constant cement dosage, and water/cement ratios were influenced by those aspects of the aggregates.