GAP-GRADED CONCRETE RESEARCH

In many parts of Louisiana the sources of naturally occurring continuously-graded aggregates are being depleted without any expectation of replacement. Many of the available marginal aggregate sources are rejected because of gap-grading, i.e., certain particle sizes are lacking, or the sizes and quantities of the coarse aggregate do not meet the existing specification requirements. This report describes a study which was undertaken to compare the behavior of gap-graded concretes with the behavior of continuously-graded concretes to determine whether or not the gap-graded concrete mixtures were comparable to the continuously-graded concrete mixtures. The five factors investigated in this study were coarse aggregate gradation, water-cement ratio, cement content, fine aggregate content, and length of curing. The fundamental material properties evaluated were compressive strength, modulus of elasticity, tensile strength, Poisson's ratio, and tensile strain, while the properties of the plastic concrete mix which were investigated included slump, density, air content, and workability. The results of an evaluation of the homogeneity of the variances among and within the concretes indicate that, for most fundamental engineering properties, the variances were essentially the same for all gap-graded concretes and the continuously-graded concrete. And in addition, direct comparisons of mean property values indicated that the gap-graded concretes, in general, equalled or exceeded those of the continuously-graded concretes. This conclusion is general in scope since it is based upon a wide variety of workable and nonworkable concrete mixes. /FHWA/

• Supplemental Notes:
  • Sponsored by and conducted in cooperation with Louisiana Department of Transportation and Development; and DOT, Federal Highway Administration.
• Corporate Authors:

  Louisiana Tech University, Ruston

  Department of Civil Engineering, 600 W Arizona Avenue
  Ruston, LA  United States  71272
• Authors:
  • Hadley, W O
• Publication Date: 1977-2

Media Info

• Pagination: 120 p.

Subject/Index Terms

• TRT Terms: Alternatives analysis; Compressive strength; Concrete; Fine aggregates; Modulus of elasticity; Plasticity; Poisson ratio; Tensile strength; Testing; Water cement ratio
• Uncontrolled Terms: Comparative analysis
• Old TRIS Terms: Continuous grading; Graded fine aggregate; Poissons ratio
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00165753
• Record Type: Publication
• Source Agency: Federal Highway Administration
• Report/Paper Numbers: FHWA-LA-77-73-1 Final Rpt.
• Contract Numbers: La HPR Stdy-73-1C(A)
• Files: TRIS, USDOT
• Created Date: Mar 7 1978 12:00AM