Research on Chloride Penetration Resistance of Hybrid Fiber Reinforced Self-Compacting Concrete
The properties of chloride penetration of hybrid fiber reinforced self-compacting concrete (SCC) were investigated in this study. The results show that the chloride penetration resistance of concrete can be improved by single incorporation either carbon or cellulose fibers. The concrete chloride diffusion coefficient DRCM of 12-cm length carbon SCC with fiber content of 1.7, 2.72, and 3.4 kg/m3 decreases by 10.3, 25.5, and 18.2% compared to reference concrete without any fibers, respectively. Moreover, the concrete chloride diffusion coefficient DRCM of cellulose SCC with fiber content of 1.2, 1.6, and 2.0 kg/m3 decreases by 18.8, 22.4, and 26.7% compared to reference concrete, respectively. Based on the results of orthogonal experimental design, the chloride diffusion coefficients DRCM of hybrid fiber reinforced SCC are listed in order of importance, as follows: length of carbon fiber > content of carbon fiber > content of cellulose fiber; furthermore, the hybrid of 2.72-kg/m3 carbon fiber with length of 12 mm and 2.0-kg/m3 cellulose fiber exhibits the most significant effect on chloride diffusion coefficients DRCM of SCC.
The properties of chopped basalt fibre reinforced self-compacting concrete
Abstract The use of basalt fibre in the production of self-compacting concrete (SCC) has been studied to identify how the fresh and hardened properties of SCC are affected by the addition of fibre. The basalt fibres of 3, 6, 12 and 24 mm in length are incorporated into the SCC mixtures as 0%, 0.1%, 0.3% and 0.5% of concrete volume. After the progression of flow diameter, T500 flow time and V-funnel time tests on the fresh SCC, the tests of compressive strength, flexural strength, splitting tensile strength, rapid chloride permeability and water penetration have been conducted to identify the hardened properties of SCC produced with basalt fibre. The response surface method is employed in the conducted multi objective optimization analysis considering the maximisation of the compressive, flexural and splitting tensile strength parameters while minimising the response criterion of rapid chloride permeability and water penetration depth. The results reveal that the use of basalt fibre decreases the workability but improves the mechanical properties of SCC. The highest flexural and splitting tensile strength results are obtained from the concrete mixtures incorporated with the content of 0.5% fibre having the length of 24 mm. Whereas, the highest compressive strength result is obtained from the mixtures containing the fibre content of 0.1% for the utilised fibre lengths of 12 mm and 24 mm. The optimum volume fraction and length of basalt fibre are determined as 0.49% and 21.12 mm considering the optimized strength and permeability based durability properties of SCC.
Self-Consolidating Concrete for Precast, Prestressed Concrete Bridge Elements
This report presents recommended guidelines for the use of self-consolidating concrete (SCC) in precast, prestressed concrete bridge elements. These guidelines address the selection of constituent materials, proportioning of concrete mixtures, testing methods, fresh and hardened concrete properties, production and quality control issues, and other aspects of SCC. The report also presents recommended changes to the AASHTO Load and Resistance Factor Design (LRFD) Bridge Design and Construction Specifications, and test protocols for evaluating some of the properties of SCC. The information contained in the report will guide materials and bridge engineers in evaluating, selecting, and specifying SCC mixtures for use in precast, prestressed concrete bridge elements, thereby facilitating fabrication, improving working environment and safety, and reducing cost. The information contained in the report will be of immediate interest to state materials and bridge engineers and others involved in specifying and evaluating concrete mixtures for use in highway bridges.