Soil Support Value Research Articles

A Methodology for Determination of Resilient Modulus of Asphaltic Concrete

Resilient modulus, , is an important parameter for designing pavements. However, its determination by resorting to cyclic triaxial tests is tedious and time consuming. Moreover, empirical relationships, correlating to various other material properties (namely, California Bearing Ratio, CBR; Limerock Bearing Ratio, LBR; R-value and the Soil Support Value, SSV), give vast variation in the estimated results. With this in view, an electronic circuitry, which employs bender and extender elements (i.e., piezo-ceramic elements), was developed. Details of the circuitry and the testing methodology adopted for this purpose are presented in this paper. This methodology helps in determining the resilient modulus of the material quite precisely. Further, it is believed that this methodology would be quite useful to engineers and technologists for conducting quality check of the pavements, quite rapidly and easily.

Energy consumption comparison for different asphalt pavements rehabilitation techniques used in Chile

In developing countries without the availability of reliable pavement management systems, recycling techniques may offer the best alternative for pavement structural rehabilitation. However, for many government officials and contractors there is a clear understanding of the technical advantages of recycling but not a clear perspective of cost saving. Since cost is a relative value among different regions of any country the following work makes an energy analysis of the construction process of the three different rehabilitation techniques available in Chile. Three different structural pavement rehabilitation alternatives were studied and compared using an energy consumption methodology: • Asphalt overlay; • Reconstruction; • Cold in place recycling with foamed asphalt. The methodology considers different project scenarios by combining expected traffic and soil support values. For each rehabilitation technique and scenario, the construction processes were analyzed and the design layers were transformed to equivalent energy units (MJ/m 2). Results show that cold in place recycling utilizes the lowest amount of energy compared with reconstruction or an asphalt overlay in all the scenarios studied, producing more differences when rehabilitating roads for less trafficked roads. The study also concludes that aggregate haulage distance is the most sensitive factor on total energy consumption when comparing the three alternatives.

Prediction of CBR Using Dynamic Cone Penetrometer

California Bearing Ratio (CBR) value is very popular among highway engineers as a soil support value for pavement design. However, since CBR cannot be easily determined in the field, prediction of CBR values from other soil support tests such as Dynamic Cone Penetrometer (DCP) is a valuable alternative. In this study penetration depth (D) of the dynamic cone penetrometer from the laboratory prepared samples were correlated with laboratory CBR's for a number of different soil types ranging from clay to gravely sand. Unique models were found for each type of soil with good coefficient of determination (R2) and low standard error of estimate. The combined data gave also a correlation between CBR and D which compare very well with those obtained from other studies.

Evaluation of Pavement Bearing Characteristics Using Florida Limerock Bearing Ratio Test

A laboratory study performed to evaluate pavement bearing characteristics by the Florida limerock bearing ratio (LBR) test is presented. The LBR is a modification of the California bearing ratio test and has been widely used in Florida for the design of pavement structures. The LBR evaluation is part of a larger research project studying existing pavement conditions in Florida. A field experimental program was recently conducted on 20 selected pavement sites across the state of Florida. The LBR test was performed on pavement soils obtained from the field test sites. The LBR test results were analyzed and compared with the field test results. The AASHO Road Test layer coefficient values (a2) and soil support values (SSVs), which have become classic reference values over more than two decades, were evaluated by using the LBR and field test results. It was concluded that the LBR values could be used to estimate the SSVs for the design of flexible pavements in Florida. The correlation relationships between the LBR values and SSVs were evaluated to better characterize the pavement structures in Florida.

Evaluation of Pavement Bearing Characteristics Using Florida Limerock Bearing Ratio Test

A laboratory study performed to evaluate pavement bearing characteristics by the Florida limerock bearing ratio (LBR) test is presented. The LBR is a modification of the California bearing ratio test and has been widely used in Florida for the design of pavement structures. The LBR evaluation is part of a larger research project studying existing pavement conditions in Florida. A field experimental program was recently conducted on 20 selected pavement sites across the state of Florida. The LBR test was performed on pavement soils obtained from the field test sites. The LBR test results were analyzed and compared with the field test results. The AASHO Road Test layer coefficient values (a2) and soil support values (SSVs), which have become classic reference values over more than two decades, were evaluated by using the LBR and field test results. It was concluded that the LBR values could be used to estimate the SSVs for the design of flexible pavements in Florida. The correlation relationships between the LBR values and SSVs were evaluated to better characterize the pavement structures in Florida.