Properties and Behavior of Engineering Materials
Laboratory 4:
Compressive, Flexural, and Tensile Strength of Concrete
Lab Section: TH 2–5 PM Unique #: 15785
Lab TA: Janaki Vamaraju
Solutions:
1.) In this lab, concrete cylinders and beams created from Lab 3 were tested for compressive, flexural, and tensile strength. The compressive strength of the concrete was found by applying an axial load on the cylinder until the cylinder failed. The flexural strength was calculated by subjecting transverse loads at the third points of the beam until failure. The tensile strength of concrete was found from applying a uniform line load along the length of the cylinder until failure. The failure loads of the concrete samples and other raw data from testing was collected onto tables and placed in Appendix A. The notation used throughout the report is shown in Appendix B. Engineering equations used to analyze the data are shown in Appendix C.
The compressive, flexural, and tensile tests were performed several times with the concrete samples at an age of 7 days old and 28 days old to improve the accuracy of the results. The compressive, flexural, and tensile strength values were calculated and then averaged. The average compressive, flexural and tensile strength of the different concrete mixtures are shown in Table 1.
Table 1: Average Strengths of Concrete Samples
Age (days)
Average Concrete Strengths (psi)
Designed
3000 psi
4500 psi
6000 psi
7
Compressive
2504.3
3030.3
4855.3
Tensile
293.4
335.1
466.9
Flexural
595.2
568.0
799.2
28
Compressive
3443.8
4020.5
5412.9
Tensile
276.0
270.3
334.6
2.) The flexural strength is related to the specified design compressive strength by the equation below. (Ferron, 2014)
This equation can be altered to determine if the measured flexural strength is within an acceptable range when compared to the designed compressive strength. By
References: Ferron, R., & Foillard, K. (2014). “Laboratory 4, Compressive, Flexural, and Tensile Strength of Concrete,” CE 314K Laboratory Manual, Austin, TX: Department of Civil, Architectural, and