Transportation Engineering Commons^™

Relationship Between Kentucky Cbr And Slake Durability, Tommy C. Hopkins

Kentucky Transportation Center Research Report

The design of pavements requires a knowledge of the relative strength and durability of subgrade materials. In Kentucky, the CBR (California Bearing Ratio) test is used to define the relative bearing strength of subgrade materials. Pavement thickness can be obtained if traffic loadings and CBR values are known. Durability of subgrade materials can be characterized using the slake-durability test. The purposes of this study were to correlate values of (soaked) KYCBR and slake-durability indices and examine the swell potential of compacted shales. Correlations were developed between soaked KYCBRs and slake-durability indices obtained from three different slake-durability I testing procedures. The …

Thickness Design Curves For Portland Cement Concrete Pavements, Herbert F. Southgate, Robert C. Deen

Kentucky Transportation Center Research Report

Past experience indicates that thickness designs using portland cement concrete best agree with criterion used in the Portland Cement Association's design method for 18-kip EAL of 2 to 3 million or less. For EALs greater than 2 to 3 million, past experience best agrees with criterion developed from the AASHO Road Test. Research herein indicates the two criterion become asymptotic to each other at approximately 2.5 million EAL. For a variation in thickness and elastic moduli in portland cement concrete, dense-graded aggregate, and sub grade elastic modulus, research indicates that a general conic equation (included herein) very closely duplicates the …

Frictional Performance Of Pavements And Estimates Of Accident Probability [Dec. 1980], James L. Burchett, Rolands L. Rizenbergs

Kentucky Transportation Center Research Report

Objectives of this study were to evaluate standard and experimental surfaces throughout Kentucky in terms of skid resistance and effects of traffic, and to provide criteria for judging suitability of these surfaces to satisfy requirements for skid resistance and economics. The effects of traffic were quantified by regression analysis and scatter of data. Criteria included an estimate of accident risks, effects of speed on skid resistance, and seasonal variations in skid resistance.

Pavements on low volume roads (less than 1,000 vehicles per day) maintained adequate skid resistances. Open-graded friction courses, with the possible exception of sections using phosphate slag aggregate, …

Skid Resistance Of Pavements [Sept. 1972], Rolands L. Rizenbergs, James L. Burchett, Cass T. Napier

Kentucky Transportation Center Research Report

Standard pavement types and experimental surfaces on roads throughout Kentucky were evaluated in terms of skid resistance and effects of traffic, wear, and polishing. Friction-vs-speed gradients and the relationships between locked-wheel and incipient friction were determined. Asphaltic concrete pavements on high-speed, four-lane roads were found to be significantly more skid resistant than on two-lane highways and somewhat more skid resistant than concrete surfaces (especially those containing calcareous gravel aggregates). Sand-asphalt surfaces containing significant proportions of limestone sands showed inadequate level of friction for the traffic sustained. Several experimental sand asphalts without limestone sands exhibited greater skid resistance; Kentucky rock asphalt …

Florida Skid Correlation Study Of 1967 – Skid Testing With Automobiles, Rolands L. Rizenbergs

Kentucky Transportation Center Research Report

The inclusion of automobiles in the Florida skid correlation study was promoted by the recognition of the following needs: 1) to compare stopping-distance measurements obtained with different instrumentation, 2) to suggest a standard method of stopping-distance testing, 3) to relate skid-resistance measurements of trailer-type testers with stopping distances of automobiles, and 4) to explore other skid-resistance measurements techniques using an automobile.

The vehicles were all full-size automobiles. Each vehicle was instrumented to measure a distance from a predetermined pressure in the brake hydraulic system to where the vehicle came to rest. Stopping distance in most of the automobiles was read …

Proposed Working Plan For A Study Of The Properties Of Coarse Aggregates, Kentucky Highway Materials Research Laboratory

Kentucky Transportation Center Research Report

Among the numerous materials used in the construction of highways probably none is more important or perplexing than coarse aggregate. Through past research and experience a group of procedures and specifications for selecting aggregates suitable for pavements has been developed. These acceptance tests deal almost entirely with physical properties such as gradation, soundness, absorption, abrasion, etc. However, recent data accumulated by field observations and surveys (1), (7), (8)* have indicated that some materials passing the specifications have undesirable properties which cause difficulties over a long period of time. Consequently, research directed toward a more thorough investigation of aggregates has become …