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Research and Development (R&D) Project Sites

Project Information
Project ID:   FHWA-PROJ-11-0041
Project Name:   Modified Flexural Strength Test
Project Status:   Active
Start Date:  May 15, 2011
End Date:  August 31, 2014
Contact Information
Last Name:  Ardani
First Name:  Ahmad
Telephone:  202-493-3422
E-mail:  ahmad.ardani@dot.gov
Office:   Office of Infrastructure Research and Development
Team:   Pavement Materials Team [HRDI-10]
Program:   Innovative Pavement Research and Deployment
Laboratory:   Concrete Laboratory
Project detail
Roadmap/Focus area(s):   Infrastructure Research and Technology Strategic Plan and Roadmap
Project Description:   The work for this study consisted of the following: (1) Six 4- by 4- by 14-inch beam molds will be fabricated at Turner-Fairbank Highway Research Center's (TFHRC's) machine shop.(2) Three different mixes with three different water-to-cement (W/C) ratios will be used. The aggregate includes gravel, limestone, and diabase. (3) Concrete mixes will be cast with two different beam sizes and tested at 28 days.(4) The results will be compared and a correlation will be established.(5) A report documenting the results will be published.
Goals:   The primary objective of this study is to examine the feasibility of using a smaller-size beam (4 by 4 by 14 inches) to conduct flexural strength testing (ASTM C-78) for concrete pavements in the field and in the laboratory. This objective will be achieved by comparing flexural strength test results obtained from the regular- and smaller-size beams. If good correlation is achieved, States may start using the smaller-size beams for quality assurance with more confidence.
Background Information:   A standard size beam (6 by 24 by 6 inches) without the molding frame weighs approximately 72 pounds (lb). Add the weight of the molding frame (51 lb) and the total weight becomes a backbreaking 122 lb. Conducting flexural strength testing with beams weighing in excess of 120 lb becomes a difficult and dangerous task that might injure testing personnel. Because of this, many States are using compressive strength even though the design of concrete pavements is based on flexural strength and normally there is not good correlation between the two tests.
Product Type:   Article
Draft standard, specifications, or guidelines
Research report
Technical report
Test Methodology:   Experimental
Expected Benefits:   The expected benefit is a safer and easier test.
Deliverables: Name: New American Association of State Highway and Transportation Officials specification for flexural strength testing.
Product Type(s): Research report, Article, Draft standard, specifications, or guidelines, Techbrief, Technical report
Description: The deliverable is a new modified American Association of State Highway and Transportation Officials (AASHTO) specification for flexural strength testing using a smaller-size beam.
Project Findings:   The results of the data analysis revealed a very good correlation between the flexural strength of smaller size beams and the traditional beam sizes.
FHWA Topics:   Research/Technologies--Turner-Fairbank Highway Research Center (TFHRC)
TRT Terms:   Flexural Strength
FHWA Disciplines:   Construction and Project Management
Pavement and Materials
Subject Areas:   Construction


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