To explore a new structure form of fiber reinforced concrete, namely, the layered steel fiber and layered hybrid fiber reinforced concrete （LSFRC and LHFRC）, the mechanical properties of LSFRC and LHFRC, such as com...To explore a new structure form of fiber reinforced concrete, namely, the layered steel fiber and layered hybrid fiber reinforced concrete （LSFRC and LHFRC）, the mechanical properties of LSFRC and LHFRC, such as compressive strength, tensile strength, flexural strength, fatigue and durability were focused on. The experimental results show that LSFRC and LHFRC can improve the flexural strength of concrete by 20%-50%. In the aspect of improving the flexural strength of concrete, adulterant rate has more obvious effect than length/diameter ratio. Double logarithmic fatigue equation considered liveability was founded. The impermeability of LHFRC is superior to LSFRC and plain concrete （C）. However, the porosity of LHFRC is lower than LSFRC and C. The shrinkage of LHFRC at every age is obviously lower than C. The antifreeze durability of LHFRC is also better than C.展开更多
The tensile strength of a corroded rebar in a 53-year-old concrete structure was studied. The microstructure of the metallic substrate, the fracture surface, and the corrosion product layers were investigated. Metallo...The tensile strength of a corroded rebar in a 53-year-old concrete structure was studied. The microstructure of the metallic substrate, the fracture surface, and the corrosion product layers were investigated. Metallographic observation results showed that the carbon steel was constituted of ferrite and some pearlite. The tensile test results indicated that the corroded rebar presented low strength and elongation. In addition, the fracture surface of the rebar in the tensile test displayed dimple fracture behavior. The Raman spectroscopy results indicated that corrosion products at the general corrosion zone were obviously different from those at the localized corrosion zone. The rust layer at the general corrosion zone was composed of goethite （α-FeOOH）, magnetite （Fe304）, and hematite （α-Fe203）, while that of the pitting zone was made of feroxyhyte （δ-FeOOH）, goethite （α-FeOOH）, and hematite （α-Fe203）. However, the general tendencies that the corrosion products were constituted of a mix of oxides and hydroxides, the oxides mainly existed in the internal part and the hydroxides more presented in the external layer were observed.展开更多
基金the Technical Specification for Fiber Reinforced ConcreteStructure (No. CECS:2004 2000jb15)
文摘To explore a new structure form of fiber reinforced concrete, namely, the layered steel fiber and layered hybrid fiber reinforced concrete （LSFRC and LHFRC）, the mechanical properties of LSFRC and LHFRC, such as compressive strength, tensile strength, flexural strength, fatigue and durability were focused on. The experimental results show that LSFRC and LHFRC can improve the flexural strength of concrete by 20%-50%. In the aspect of improving the flexural strength of concrete, adulterant rate has more obvious effect than length/diameter ratio. Double logarithmic fatigue equation considered liveability was founded. The impermeability of LHFRC is superior to LSFRC and plain concrete （C）. However, the porosity of LHFRC is lower than LSFRC and C. The shrinkage of LHFRC at every age is obviously lower than C. The antifreeze durability of LHFRC is also better than C.
基金Funded by the National Natural Science Foundation of China(51301060,51210001)the 111 Project(B12032)+1 种基金the Key Laboratory of Advanced Civil Engineering Materials(Tongji University),Ministry of Educationthe Fundamental Research Funds for the Central Universities(No.2013B03514)
文摘The tensile strength of a corroded rebar in a 53-year-old concrete structure was studied. The microstructure of the metallic substrate, the fracture surface, and the corrosion product layers were investigated. Metallographic observation results showed that the carbon steel was constituted of ferrite and some pearlite. The tensile test results indicated that the corroded rebar presented low strength and elongation. In addition, the fracture surface of the rebar in the tensile test displayed dimple fracture behavior. The Raman spectroscopy results indicated that corrosion products at the general corrosion zone were obviously different from those at the localized corrosion zone. The rust layer at the general corrosion zone was composed of goethite （α-FeOOH）, magnetite （Fe304）, and hematite （α-Fe203）, while that of the pitting zone was made of feroxyhyte （δ-FeOOH）, goethite （α-FeOOH）, and hematite （α-Fe203）. However, the general tendencies that the corrosion products were constituted of a mix of oxides and hydroxides, the oxides mainly existed in the internal part and the hydroxides more presented in the external layer were observed.
