Differential Thermal Analysis of the Freeze-Thaw Mechanisms in Concrete

The freezing of water in concrete may create highly disruptive internal forces, depending upon the degree of saturation of the voids and the extent of the resulting dilations. Heretofore, it has not been possible to measure the internal pressures accompanying freezing; and it is this aspect of the automatic freeze-thaw testing of concrete with which the present study was concerned. By the use of thermocouples, imbedded in concrete and referenced to an ice-water bath, it was possible to plot, on an automatic multivolt potentiometer recorder, an isothermal phase change for the absorbed water, and to demonstrate a depression of the freezing point of the water with increasing confining pressures. It was also possible, at least in a general way, to relate the progress of damage in the concrete to increased absorption and freezing point depression

Synthesis of Procedures to Forecast and Monitor Work Zone Safety and Mobility Impacts

Administrative Final Rule CFR Part 630 Subpart J Work Zone Safety and Mobility requires that state transportation agencies (STAs) develop policies to investigate the safety and mobility impacts as early as possible in the project development process. The rule provides some flexibility by allowing each state to set its own procedures and policies to comply with the rule and by allowing states to seek solutions which are commensurate with the severity of the potential impacts and require the most aggressive planning for Significant Projects. This report provides a synthesis of what is currently being done by STAs across the country to plan, manage, operate, and evaluate work zone safety and mobility. The research to develop this synthesis was broken into three distinct steps. The first step was to review the literature regarding work zone safety and mobility strategies. The second was to conduct interviews with staff members at 30 STAs. The last step was to conduct more detailed case studies of three STAs. The authors found that only California and Ohio (there may be more states than this, but these were the two discovered) had really thought about work zone impacts throughout the life-cycle of project development and project delivery and had documented the roles and interactions between different offices. Most agencies interviewed lacked objective performance data, although many described processes where they have experts review and evaluate work zones on a periodic or continuous basis

An analysis of high power stripline structures

SIGLEAvailable from British Library Document Supply Centre- DSC:DX182112 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Skid Resistance Studies in Kentucky (An Overview – 1974)

To free Kentucky of slick roads is the high goal toward which Kentucky has been striving since 1950\u27s. A very capable fellow engineer used to say that there was more satisfaction in being able to take down a Slippery When Wet sign than in erecting one. Considerable effort has been devoted to the development and adaptation of improved methods of skid resistance testing and to the standardization of testing devices (1, 2, 3, 4). Methods of tests have included the NCSA friction wheel (bicycle wheel), automobile deceleration, skewed-wheel (skewed front-wheels of an automobile), skidding automobile, and the skid-test trailer. The development and standardization of a trailer method of test in recent years represents significant progress in the measurement area. From the outset of our skid resistance measurement program, evaluations of pavement design, construction and maintenance practices were of utmost concern. In fact, the first field tests -- made in 1953 -- resulted in changes of the design mix in the use at that time (5). Every type of pavement and sealing and deslicking treatment used in the state have been monitored and assessed as to their friction properties (1, 6, 7). Insights gained have been applied towards the development and refinements of wearing surfaces. Skid resistance standards for maintenance and mix design purposes must be established if meaningful improvements in highway safety are to be realized. Arbitrary judgements as to minimum requirements will not suffice because the safety and economics involved are much to important to every highway user. Efforts to derive minimum skid resistance requirements in Kentucky were based on accident statistics. Critical values have been determined for rural, four-lane, controlled access roads (interstates and parkways) (8). Critical values for rural, two-lane roads (U.S. routes) are forthcoming. Studies of pavement slipperiness have received renewed emphasis as a result of attention directed towards highway safety. Congress recognized the element of pavement skid resistance in the Highway Safety Act of 1966 and the resulting Highway Safety Program Standard !2, dated June 27, 1967. Most recently, Instructional Memorandum 21-2-73, dated July 19, 1973, stressed the importance of pavement skid resistance in providing safe highways. Kentucky has continued to progress in this vital area