Modern Civil and Structural Engineering

Download PDF (654.5 KB) PP. 39 - 52 Pub. Date: July 1, 2018

DOI: 10.22606/mcse.2018.23001

• Farhad Reza^*
  Department of Mechanical & Civil Engineering, Minnesota State University, Mankato, Minnesota, United States

High-strength concrete is useful for a number of applications in construction. One drawback of the material is its relatively high brittleness which can lead to sudden and catastrophic failure. A potential improvement in ductility could be achieved by incorporating fiber reinforcement. In this paper, results from an experimental program to characterize flexural strength and flexural toughness for high strength concrete with compressive strength of 103 MPa (15,000 psi) reinforced with steel fibers are presented. Three different techniques for measuring deflection and controlling the experiments were utilized including crack mouth opening displacement control, ram control, and load-point control. Toughness indexes were evaluated according to ASTM C1018, and Japan Society of Civil Engineers (JSCE) standard test methods for measuring flexural toughness of fiber-reinforced concrete. Two types of fibers, namely hooked-end and crimped fibers were investigated. Three different fiber volume percentages were utilized, namely 0.5%, 1.0% and 1.5%. The JSCE toughness index was highly sensitive to fiber volume, while the I5 toughness index and flexural strength were also sensitive but to a lesser extent. Notch sensitivity or size effect appeared to exist for flexural strength, and hooked-end fibers provided higher flexural strength than crimped fibers.

Fracture toughness, fiber-reinforcement, bending strength, mechanical properties, high-strength concrete.

[1] ACI Committee 544, State of the Art Report on Fiber-Reinforced Concrete, American Concrete Institute, Farmington Hills, Mich., 1989.

[2] V. S. Gopalaratnam, and R. Gettu, “On the characterization of flexural toughness in fiber-reinforced concretes,” Cement & Concrete Composites, vol. 17, pp. 239-254, 1995.

[3] American Society for Testing and Materials (ASTM), Standard Test Method for Flexural Toughness and First Crack Strength of Fiber-Reinforced Concrete (Using Beam with Third-Point Loading), American Society for Testing and Materials, ASTM C1018-97, Philadelphia, Pa., 2001.

[4] American Society for Testing and Materials (ASTM), Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading), American Society for Testing and Materials, ASTM C78-00, Philadelphia, Pa., 2001.

[5] American Society for Testing and Materials (ASTM), Standard Test Method for Flexural Performance of Fiber-Reinforced Concrete (Using Beam with Third-Point Loading), American Society for Testing and Materials, ASTM C1609-12, Philadelphia, Pa., 2017.

[6] Japan Society of Civil Engineers (JSCE), Method of Test for Flexural Strength and Flexural Toughness of Fiber-Reinforced Concrete, Standard SF-4, Japan Society of Civil Engineers, Tokyo, 1984.

[7] ACI Committee 544, Measurement of Properties of Fiber-Reinforced Concrete, American Concrete Institute, Farmington Hills, Mich., 1989.

[8] P. N. Balaguru, and S. P. Shah, Fiber-Reinforced Cement Composites, McGraw-Hill, New York, New York, 1992.

[9] N. Banthia, and J. F. Trottier, “Test methods for flexural toughness characterization of fiber reinforced concrete: some concerns and a proposition,” ACI Materials Journal, vol. 92, no. 1, pp. 1-10, 1995.

[10] S.T. Islam, Study of Some Parameters Affecting the Measured Flexural Toughness of Fiber Reinforced Concrete, Master’s Thesis, University of British Columbia, Vancouver, 2012.

[11] V. Gopalaratnam, S.P. Shah, G. B. Batson, M. Criswell, V. Ramakrishnan, and M. Wecharatana, “Fracture toughness of fiber reinforced concrete,” ACI Materials Journal, vol. 88, no. 4, pp. 339-353, 1991.

[12] N. Banthia, and A. Dubey, “Measurement of flexural toughness of fiber-reinforced concrete using a novel technique – part 1: assessment and calibration,” ACI Materials Journal, vol. 96, no. 6, pp. 651-657, 1999.

[13] P. Soroushian, and Z. Bayasi, “Fiber-type effects on the performance of steel fiber reinforced concrete,” ACI Materials Journal, vol. 88, no. 2, pp. 129-134, 1991.

[14] P. Balaguru, R. Narahari, and M. Patel, “Flexural toughness of steel fiber reinforced concrete,” ACI Materials Journal, vol. 89, no. 6, pp. 541-546, 1992.

[15] Q. Chunxiang, and I. Patnaikuni, “Properties of high-strength steel fiber-reinforced concrete beams in bending,” Cement and Concrete Composites, vol. 21, pp. 73-81, 1999.