Using Geogrids for Base Reinforcement as Measured by Falling Weight Deflectometer in Full-Scale Laboratory Study

Author(s):  
Thomas C. Kinney ◽  
Danielle Stone ◽  
John Schuler

A model road was constructed in a laboratory. The road consisted of asphalt over a crushed rock base and a silty sand and gravel subbase. The silty sand and gravel were placed in a very loose state to simulate a thaw-weakened, poor-quality subbase. The water table was kept at 152 mm (6 in.) below the bottom of the asphalt. The model road was divided into three sections. A geogrid was installed at the bottom of the base course material in two of the test sections, and the third was left as a control section. A falling weight deflectometer was used to measure the dynamic response of the pavement structure. The traffic benefit ratio is defined as the expected life (equivalent single-axle loads) of one section divided by the expected life of another section. The Alaska Department of Transportation and Public Facilities asphalt pavement design procedure and the NCHRP pavement design procedure were used to compare the test sections. The results from the two procedures were very similar. By using either procedure, the life of the pavement with respect to reinforcement was on the order of 2 to 4, depending on the type of grid and the depth of base course material.

2019 ◽  
Vol 10 (2) ◽  
pp. 101-112
Author(s):  
M. Seyfe ◽  
A. Geremew

Cinder gravels are pyroclastic materials associated with recent volcanic activity which occur in characteristically straight sided cone shaped hills. The aim of this study was to use this marginal material which is abundantly available in many parts of Ethiopia by modifying their properties through mechanical blending and chemical stabilization. Results of physical and mechanical test conducted on cinder gravel samples prove their marginality to be used as base course materials especially for highly trafficked roads. An experimental investigation were carried by blending cinder gravels with conventional crushed stone bases course material, Crushed Stone Aggregate (CSA), in proportions of cinder/ Crushed Stone Aggregate (CSA) (10/90, 20/80, 30/70, 40/60 and 50/50) and treating with 6. 8 and 10% of cement. According to results of sieve analysis, Aggregate crushing value (ACV), flakiness index and California Bearing Ratio (CBR), 30% of Crushed Stone Aggregate (CSA) can be replaced by cinder gravels for use as Fresh, crushed rock (GB1) material and for cement treated cinder gravels adding 6% and 8% cement make them suitable for use as Stabilized base course (CB2) and (CB1) base course materials respectively, referring to their 14 day compressive strength as determined by Unified compressive strength test(UCS) test.


Author(s):  
Judith B. Corley-Lay

A first generation mechanistic empirical pavement design procedure was developed using falling weight deflectometer deflections taken over a 3-year period at 16 test sections in Siler City, North Carolina. Information available for use in developing the procedure included deflection data, surface and air temperature, coring thicknesses at each test location, pavement performance records regarding rate of cracking, and traffic records. Jung's method, based on the curvature of the deflection bowl, was used to calculate strain at the bottom of the asphalt layer as a measure of fatigue. This calculated strain was used to obtain a calculated number of load repetitions to failure. Comparision of actual loads to failure with calculated loads to failure resulted in a table of shift factors by pavement type.


Author(s):  
Shinichiro KAWABATA ◽  
Tatsuya ISHIKAWA ◽  
Takumi MURAYAMA ◽  
Shuichi KAMEYAMA

2012 ◽  
Vol 178-181 ◽  
pp. 1699-1705
Author(s):  
Fa Liang Lu ◽  
Jin Li

To test and inspect the chemical compositions and mechanical properties of the steel slag produced by the converters of Jigang Group co. ltd, and study the feasibility of using the steel slag as base course material. Prepare cement stabilized steel slag specimens with different contents of cement mixed for the unconfined compressive strength test. Determine through test its strength after 7 days and 28 days and its water stability after 7 days’ soaking. Prepare in the same method of two different kinds of cement and coal ash stabilized specimens with different contents of coal ash mixed for the unconfined compressive strength test, to test its strength and water stability. The comparison on mechanical property with cement stabilized macadam indicates that the cement stabilized steel slag and cement with coal ash stabilized steel slag both have favorable mechanical property and water stability and the steel slag produced by the converters of Jigang Group co. ltd can be popularized for use as base course material.


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