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Mechanical Properties Of Ultra High Strength Fiber Reinforced Concrete

Mohammed, Hafeez
http://rave.ohiolink.edu/etdc/view?acc_num=akron1431021338

Abstract Details

2015, Master of Science, University of Akron, Civil Engineering.
The usage of Ultra High Strength Fiber Reinforced Concrete (UHSFRC) with higher compressive strength (15,000-29,000 psi) in construction industry has been increasing worldwide. UHSFRC is also known as reactive powder concrete (RPC) which exhibits excellent durability and mechanical properties. This is one of the latest and emerging topics in the concrete technology. Structural elements cast with UHPC can carry larger loads and exhibit energy absorption capacity with smaller sections. The high compressive strength, higher tensile strength along with almost negligible water and chloride permeability therefore better durability of this new concrete material makes it UHSFRC. The basic principle in UHSFRC is to make the cement matrix as dense as possible, by reducing the micro cracks and capillary pores in the concrete and also to make a dense transition zone between cement matrix and aggregates. These special properties of concrete can be achieved by eliminating the coarse aggregates and replacing them with quartz sand of maximum size of 600 microns. The possibility of achieving high strength, durability, and ductility concrete encourages engineers to use this innovative material in many applications such as nuclear waste containment structures, high rise structures, long span bridges, walkways and in many more applications. iv Concrete (UHSFRC) using materials that are available locally are always economical since the patented products are very expensive and the materials such as silica sand and quartz powder are not readily available. The research also includes use of recognized mineral admixtures, natural river sand, steel fibers, and superplasticizers (Sika Viscocrete 2100 – 3% by weight of cement, Melflux 4930 – 1% by weight of cementitious material) without using any coarser aggregates, and an optimum dosage of silica fume was 15 % by weight of the cement. The structural integrity and durability of concrete used in shear keys is vital for the performance of bridges constructed using precast concrete components. The use of UHPC in the construction of shear keys can be a good solution for achieving long lasting bridge systems. The evaluation of UHPC shear key was conducted by connecting the precast concrete girders together via shear key. The test specimen was a simply supported beam with the shear key connection at mid span. The fresh and hardened mechanical properties of the UHSFRC were studied such as workability of the mix, compression test on cubes, split tensile test on cylinders, flexural tensile test for both reinforced and unreinforced concrete beams, rebar pull-out tests, impact test on panels and testing for shear keys. Two different curing practices were used in this work: Moist Curing (MC) and Heat Curing (HC). Two different types of cements used were ASTM Type I and Type III cements. Type I cement is commonly used in all the construction works whereas Type III cement is used in special applications where early high strengths are required. Both the cements are used for the comparative study, keeping all the proportions constant. v Compressive strength of 21,500 psi was achieved with concrete made of type III cement using moist curing practice. Split tensile strength of 2,300 psi and flexural strength of 3,300 psi were gained using Type III cement and moist curing practice. Highest compressive strength of 28,150 psi is achieved using heat curing practice. It was found that heat curing practice may be artificially inflating the compressive strength. The split tensile strength, and flexural strength results of heat-cured specimens have lower strength compared to moist cured specimens. The moment capacity of the fiber reinforced concrete is twice than the conventional concrete, due to the denser microstructure, absence of coarse aggregates, and cement silica reaction. Potential application of UHSFRC in shear keys of adjacent box beam girder bridges was demonstrated on small joint test specimens with sand blasted surface. It is concluded that the use of the mix design developed in this study for UHSFRC is feasible for such box beam bridges.
Anil Patnaik, Dr (Advisor)
Craig Menzemer, Dr (Committee Member)
Ping Yi, Dr (Committee Member)
196 p.
Civil Engineering
UHSFRC, High strength concrete, fiber reinofrced concrete, shear key

Recommended Citations

Citations

  • Mohammed, H. (2015). Mechanical Properties Of Ultra High Strength Fiber Reinforced Concrete [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1431021338

    APA Style (7th edition)

  • Mohammed, Hafeez. Mechanical Properties Of Ultra High Strength Fiber Reinforced Concrete. 2015. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1431021338.

    MLA Style (8th edition)

  • Mohammed, Hafeez. "Mechanical Properties Of Ultra High Strength Fiber Reinforced Concrete." Master's thesis, University of Akron, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1431021338

    Chicago Manual of Style (17th edition)

akron1431021338
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This open access ETD is published by University of Akron and OhioLINK.