Performance evaluation and structural applications of tensile strain-hardening-type high toughness cementitious composites

点击翻译按钮获取中文摘要

(1) Tensile behavior of DFRCC members with reinforcementThe tensile load-bearing capacity of steel reinforced DFRCC (Ductile fiber reinforced cement composites) members was the superposition of those of steel reinforcement and DFRCC, even with a low reinforcement content. Even if DFRCC had a low tensile deformability, the tensile deformability of the member increased due to steel reinforcement.(2) Cracking behavior of DFRCC under bending momentBending tests were carried out on DFRCC beams each having different specimen length. The area under the load-displacement curves up to the peak load point was proportional to the specimen length. Therefore, the dissipated energy per unit volume can be used as a parameter to indicate multiple cracks.(3) Behavior of DFRCC under cyclic loadingAfter an introduction of several bending cracks on RC beams by a static loading, DFRCC was placed by spraying on the beams. Fatigue tests of 17 million cycles were conducted on them. For beams with DFRCC layer on the surface, the crack width was kept to be narrow after fatigue tests.(4) Behavior of steel tubes covered with DFRCCBending tests were carried out on steel tube specimens covered with DRFCC. The crack width in DFRCC with spiral and axial rebars welded to the tubes was smaller,(less than 0.15m), and the number of cracks greater, than in steel fiber-reinforced or plain concretes for steel tube covering.(5) Development of lightweight DFRCC by adding bubblesDuctile lightweight mortars were developed by adding pre-foamed bubbles to DFRCC. Multiple fine cracks were observed on specimens in flexure. As the air content increased, the loads at the first crack and the peak decreased and the number of cracks increased.