Effects and observations of surcharge load on the laboratory CBR and resilient modulus values of roadbed soil

A silty sand subgrade soil was tested for soaked CBR in the laboratory under different surcharge loads of 44.5, 89, 178 and 267 N. Four sets of samples (two samples per set) were compacted at 95% of modified AASHTO compaction and tested according to ASTM (D1883–87). A strong correlation between the strength ratio CBRL/CBR45 (where CBRL refers to the soaked CBR for any surcharge load L, while CBR45 corresponds to 44.5N surcharge load) for different levels of surcharge load, was found. Using other data for clayey soils, suggests that the correlation between the strength ratio CBRL/CBR45 and surcharge load is insensitive to soil type. The resilient modulus MR of soil tested was investigated using the ultrasonic wave propagation technique. The four CBR sets were tested for MR before and after soaking. The study revealed that the resilient modulus, similar to CBR, increased with surcharge load and a correlation between MR and corresponding soaked CBR was developed.

[1]  W Heukelom,et al.  DYNAMIC TESTING AS A MEANS OF CONTROLLING PAVEMENTS DURING AND AFTER CONSTRUCTION , 1962 .

[2]  Á. Kézdi,et al.  Handbook of soil mechanics , 1982 .

[3]  K. Terzaghi.  Theoretical Soil Mechanics , 1943 .

[4]  S F Brown,et al.  COMPUTER PROGRAMS FOR ANALYTICAL DESIGN OF ASPHALT PAVEMENTS , 1984 .

[5]  W D Powell,et al.  THE STRUCTURAL DESIGN OF BITUMINOUS ROADS , 1984 .

[6]  Kenneth H. Stokoe,et al.  MODULI OF PAVEMENT SYSTEMS FROM SPECTRAL ANALYSIS OF SURFACE WAVES , 1982 .

[7]  M L Bobrow,et al.  On planning and design. , 1976, Hospital forum.

[8]  Braja M. Das.  Fundamentals of Soil Dynamics , 1983 .

[9]  S F Brown,et al.  THE STRUCTURAL DESIGN OF ASPHALT PAVEMENTS BY COMPUTER , 1980 .

[10]  Robert Horonjeff,et al.  Planning and design of airports , 1950 .

[11]  D. A. Preece,et al.  An introduction to the statistical analysis of data , 1979 .

[12]  E. J. Yoder.  Principles of Pavement Design , 1959 .

[13]  D. W. Hight,et al.  AN ANALYSIS OF THE CALIFORNIA BEARING RATIO TEST IN SATURATED CLAYS , 1982 .

[14]  Tll Orr,et al.  THE INTERPRETATION OF REPEATED LOAD PARAMETERS FOR A GLACIAL SUBGRADE FROM SOIL PROPERTIES --PROCEEDINGS OF THE FIFTH INTERNATIONAL CONFERENCE ON THE STRUCTURAL DESIGN OF ASPHALT PAVEMENTS HELD DEFLT UNIVERSITY OF TECHNOLOGY, AUGUST 23-26 1982. VOL 1 AND 2. -- NETHERLANDS , 1982 .

[15]  C A O'flaherty.  HIGHWAYS. VOLUME 2. HIGHWAY ENGINEERING. 3RD EDITION , 1988 .

[16]  R. J. Salter,et al.  Highway design and construction , 1979 .

[17]  S F Brown,et al.  PAVEMENT FOUNDATION DEVELOPMENTS , 1989 .

[18]  J. Mc Cluskey.  Road design and the landscape architect , 1989 .