Polishing Resistance Research Articles

Usefulness of porphyry and amphibolites as a component of concrete for airfield pavements

Coarse aggregate used as part of cement concrete is of primary significance for the obtained parameters of hardened concrete. In case of concretes intended for airfield pavements, the application of granite grit is recommended. Alternative to this type of aggregate in the form of porphyry and amphibolites aggregate was suggested. In order to assess the suitability of different aggregate types for concrete mixes, their bulk density, absorbability, polishing resistance, abrasion and crushing resistance were determined. Also, the internal structure of the suggested aggregates and its influence on changes of hardened concrete composite structure were subject to the assessment. The influence of aggregate type on the structure of cement matrix and contact areas between the matrix and aggregate grains were specified. The observed changes, in case of the internal structure of concretes based on porphyry and amphibolites aggregates, with reference to granite aggregate, resulted in changes of mechanical and physical parameters. Analyses included the determination of bulk density, absorbability, compression, bending and splitting resistance. According to the obtained laboratory test results, the significant influence of the aggregate type applied to the mix on parameters of hardened concrete, with regard to the application thereof to the airfield pavements was proved.

Study on micro-texture and skid resistance of aggregate during polishing

The skid resistance performance of pavement is closely related to the micro-texture of pavement aggregate, while there is very few research on the relationship between micro-texture and the skid resistance. In this paper, the optical microscope is used to acquire the surface morphology of three types of aggregates including basalt, limestone and red sandstone respectively, where a total of 12 indicators are developed based on the surface texture information. The polishing effect on aggregate is simulated by Wehner/Schulze (W/S) device, during the polishing procedure, the skid resistance are measured by British Pendulum Tester (BPT). Based on the results of independent T-test and the polishing resistance analysis, it shows that the surface texture of basalt is significantly different between limestone and red sandstone. Three indicators including the average roughness (Ra), the kurtosis of the surface (Sku) and the mean summit curvature (Ssc) are selected to describe the characteristics of aggregate micro-texture based on the correlation analysis. The contribution of micro-texture to the skid resistance can be described with the secondary polynomial regression model by these indicators.

A laboratory procedure for predicting skid and polishing resistance of road surfaces

Skid resistance of road surfaces is an important safety parameter. Decreasing skid resistance correlates with increasing number of accidents. The presented study aims for a correlation between lab-based polishing simulation and skid resistance measurement and evolution of the skid resistance under traffic in the field. A prediction model for skid and polishing resistance based on the Wehner/Schulze device was developed. The lab procedure as a basis for the model works on the hypothesis that a maximum level of skid resistance exists that can be regenerated even from a highly polished state by sandblasting of the surface. This hypothesis was verified for an asphalt and concrete surface material. The prediction model was set up by correlating field data on skid resistance and traffic volume from 14 test sections to cores taken from these test sections and tested in the lab. A linear regression links the cumulated traffic volume in the field with the number of polishing passes in the Wehner/Schulze device. Thus, it is possible to simulate millions of wheel passes within a couple of hours in the lab to generate equal skid resistance level and predict the skid resistance level of a road surface after years under traffic.

Evaluation of Skid Resistance Using CTM, DFT and SRT-3 Devices

Evaluation of skid resistance could be based on both microtexture and macrotexture. It is possible to measure this parameter using CTM (Circular Track Meter) and DFT (Dynamic Friction Tester) devices. Macrotexture is characterized by the MTD (Mean Texture Depth) parameter obtained by CTM measurements. Microtexture can be estimated by the coefficient of friction DFT20 at a slip speed 20 kph using low speed friction measurement devices such as DFT. In this paper the possibility of using CTM and DFT for assessment of wearing course made from SMA (Stone Mastic Asphalt), AC (Asphalt Concrete), Slurry Seal and exposed aggregate PCC (Pavement Cement Concrete) is presented. Eleven test sections were considered. In addition, coefficient of friction μ was measured by SRT-3 device with locked wheel at test speed 30, 60 and 90 kph. Good correlation between DFT20 and μ at tested speeds was observed. It found out that SRT-3 device is more sensitive to microtexture changes in the pavement but not to macrotexture. The influence of asphalt mixture composite, texturing method, polishing resistance of coarse aggregates on skid resistance were analyzed. The measured values of the DFT and CTM devices were used to calculate the IFI numbers for each test section according to the ASTM E1960-07(2011) standard. In addition based on IFI, the coefficient of friction F(S) was calculated at various slip speeds S. Consequently, different pavements surfaces were compared in regard to slip speed S. As the result of the analysis it was found that at low speed pavements made of AC had better skid resistance than SMA and exposed aggregate PCC, while at high speeds SMA and exposed aggregate PCC had better skid resistance than AC pavements. This information is valuable for proper maintenance of existing pavements and on the stage of designing.

Investigation of synthetic, self-sharpening aggregates to develop skid-resistant asphalt road surfaces

The primary objective of this research was to investigate and develop a “self-sharpening road surface” that exhibits a consistently high skid resistance throughout the polishing process which occurs in the course of normal pavement use. High-strength shale ceramsite (HSSC) is made by heating high-strength shale to about 1200°C in a rotary kiln. It was laboratory-tested to measure its wear and polishing behavior. Subsequently, asphalt specimens were prepared using coarse HSSC aggregates and tested for their polishing resistance, high temperature rutting, low temperature cracking and water stability. The results of tests on the HSSC aggregates showed that their honeycomb-like structure can lead to the continuous regeneration of the texture in the course of polishing, and thus a positive effect on the skid resistance. Data from tests of the HSSC asphalt mixture led to a recommendation that 60% HSSC was the best composition for manufacturing roads that exhibit long-term skid resistance whilst still satisfying other pavement performance requirements.

Experimental procedure for evaluation of coarse aggregate polishing resistance

This paper presents the development of experimental methods for measuring aggregate textural retention, which is a very important property that influences pavement skid resistance. The 2nd version Aggregate Image Measurement System (AIMS-II) is used to measure coarse aggregate surface texture before and after different polishing time intervals in a modified Micro-Deval (MD) test procedure. The use of AIMS-II to compare aggregate surface texture and the evolution of aggregate polishing curves was verified and determined to be successful because AIMS-II texture measurement closely reflected historical data on aggregate frictional properties obtained by Illinois Department of Transportation (IDOT). Analytical functions, considering aggregate surface texture at different polishing times, were then used to describe the initial texture, rate of polishing, and terminal texture. Statistical analysis was used to determine that the required polishing time to achieve terminal texture in the modified MD is 210min.

Influence of freeze–thaw on the polishing resistance of coarse aggregates on road surface

The aggregates used for surface layers are of central importance for the skid resistance of a road as they are subjected to a combined load due to traffic and weather conditions. In this paper, different aggregates are selected and two plate specimens are produced using each aggregate. One of the test plates is subjected to solely polishing load and the other one was treated with a combined load of polishing and freeze–thaw cycles. By comparing the texture changes and the skid resistance development, a statement is derived on the impact of a freeze–thaw effect for the short-term and long-term development of skid resistance.

Evaluation of polishing and degradation resistance of natural aggregates and steel slag using the aggregate image measurement system

Aggregate resistance to polishing and degradation can be related to the change in some of those aggregates particles’ characteristics. Polishing resistance can be related to the loss of surface texture, and it can affect asphalt pavements’ microtexture, influencing its skid resistance. Degradation resistance is related to the loss of angularity and to the aggregates’ breakage. It affects pavement distresses’ resistance and aggregate gradation. The methodologies used to evaluate these characteristics produce results that are mostly not representative. This paper aims to present a digital image processing (DIP) technique to evaluate aggregates’ resistance to polishing and degradation, along with the use of the Los Angeles abrasion equipment. The aggregate image measurement system was used to analyse the aggregates mainly not only with respect to angularity and surface texture, but also with respect to sphericity and flatness/elongation particle percentage, before and after the polishing and the degradation processes. Three natural aggregates (granite, gneiss and phonolite) collected from Brazilian quarries, and one by-product (steel slag) were evaluated. The findings from this study can be used to rank aggregates with respect to their shape properties. With the results obtained for the steel slag, it can be concluded that this material was the most resistant to polishing when compared with the natural aggregates.

Use of Advanced Aggregate Imaging Systems to Evaluate Aggregate Resistance to Breakage, Abrasion, and Polishing

Aggregate gradation and shape properties are known to affect pavement mechanistic response and performance significantly. Under repeated traffic loading, aggregate particles in pavement courses are routinely subjected to degradation through attrition, impact, grinding, and polishing mechanisms, which alter their shape and size properties. Machine vision provides an objective and quantitative measurement of aggregate particle shape or morphological properties, including flatness and elongation, angularity, and surface texture. This paper focuses on the effectiveness of two advanced and validated aggregate imaging systems: an enhanced University of Illinois aggregate image analyzer (E-UIAIA) and a second-generation aggregate imaging system (AIMS-II)—for capturing changes in shape and size properties of aggregate particles caused by breakage, abrasion, and polishing actions. The micro-Deval apparatus was used in the laboratory to evaluate field degradation and polishing resistance of 11 aggregate materials with different mineralogical properties, collected from throughout Illinois and neighboring states. More than 26,000 particles were scanned with both imaging systems at various time intervals, and changes in aggregate morphological indexes were recorded. Despite differences in image acquisition and processing capabilities, both E-UIAIA and AIMS-II successfully quantified changes in morphological properties of particles from the micro-Deval tests. However, AIMS-II more closely reflected historical data on aggregate frictional properties obtained by the Illinois Department of Transportation. The imaging results were used to develop regression-based statistical models for determining aggregate polishing and degradation trends by considering both rate and magnitude of changes in shape properties.

Correlations between mechanical and geometrical parameters in aggregates: a tool for quality assessment and control

Correlations between mechanical and geometrical parameters in aggregates can be used as quality and performance prediction tools. I evaluated the following parameter pairs: dry and wet resistance to wear (MDE & MDS), and resistance to fragmentation (LA); polishing resistance and abrasion (PSV–AAV); and flakiness and shape index (FI–SI). The data set comprises slags, sedimentary, igneous, and metamorphic rocks tested according to EN standard test methods. FI and SI are positively correlated (r = 0.83) and can be well described by the 1:1 line. Wet and dry resistance to wear are strongly correlated (r = 0.98) with MDE ≈ 2·MDS. Dry resistance to fragmentation (LA) and wet resistance to wear (MDE) are well correlated (r = 0.81), and can be described with the equation LA = 4.95×MDE 0,61 (R2 = 0.69). According to the PSV–AAV correlation, aggregates are divided into two groups with contrasting behavior. Limestones and slags (r = −0.49 to −0.69) exhibit high polishing for high abrasion resistance (high PSV–low AAV), whereas sandstones and mafic to intermediate volcanics (r = 0.44 to 0.39) exhibit high polishing for low abrasion resistance (high PSV–high AAV). Peridotites belong to either PSV–AAV group depending on the soft minerals.

Development of Polishing Fluids for Titanium Alloy Using Lapping Tape – Effects of Components in the Polishing Fluids on Polishing Characteristics –

To polish to hard-to-cut titanium alloy (Ti-6Al-4V), a method employing a lapping tape is proposed and titanium alloy polishing fluids are developed. The effects of each of the components of a soluble polishing fluid on the polishing characteristics, such as surface roughness, tangential polishing resistance, and stock removal, are investigated through experiments. The results indicate that polishing only with a potassium oleate solution, which is a long-chain fatty acid solution, creates the best surface. A fatty acid is focused on, and the effects on the polishing characteristics of changing the carbon number are studied. As a result, it is found that surface roughness can be suppressed when titanium alloy is polished with only a fatty acid surfactant solution of carbon number 12 or higher.

Evaluating on the Skid Resistance of the Aggregates Based on Mineralogy

Four groups of granite aggregates with different mineral structures were investigated. They were formed into test plates with a flat surface and polished with the Aachen Rafeling Tester using quartz powder and quartz sand as the polishing agent respectively. At the end of each polishing stage, the friction coefficient of these plates was measured with the skid resistance tester (SRT) and the Wehner/Schulze test apparatus (PWS), which represent different contact conditions. By comparison of the different friction development in the course of polishing, the influence of mineral composition and crystal size on the polishing resistance and friction coefficient of the aggregates is determined. This new methodology can be applied to evaluate the long-term skid resistance of the aggregates for road engineering.

Modified Micro-Deval Procedure for Evaluating the Polishing Tendency of Coarse Aggregates

Coarse aggregates in asphalt concrete should be tough and durable to withstand hot-mix asphalt production, transportation, construction, traffic loads, and environmental effects. The morphology of such aggregates plays an important role in aggregates' mechanical properties and influences asphalt pavement skid resistance, an essential characteristic of pavement performance. The predominant aggregate resources in western Virginia are carbonate rocks. The mineral components tend to be relatively soft, and when subjected to abrasive wear under traffic, the aggregate surface polishes fairly rapidly. This situation leads to smoothing of the surface and creates potential safety issues due to loss of surface friction. Considering all aspects, the increasingly popular Micro-Deval (MD) apparatus was used to assess the abrasion–polishing (A-P) resistance of coarse aggregates suspected to show a range of polishing characteristics. Although the conventional focus of the MD test is on attrition or degradation (mass loss) reflecting particles' durability, such attrition or degradation also induces a polishing effect on susceptible particles and consequently was selected for this study. Hence, a suite of carbonate and noncarbonate coarse aggregates from 10 Virginia sources was tested in the MD with the standard procedure and a cyclical A-P procedure. Also, two-dimensional digital aggregate images, before and after abrasion, were obtained and analyzed with the use of specialized software to characterize morphological parameters (shape, angularity, texture). Testing results showed that wear-resistance aggregate groupings based on the A-P procedures were consistent with the polishing tendency based on lithologic characteristics. Abrasion effects induced by both MD procedures were subjectively discernable. Trends could be perceived in the image analysis data, but the differences were not statistically verified.

The influence of alteration on the engineering properties of dolerites: The examples from the Pindos and Vourinos ophiolites (northern Greece)

The influence of alteration on the physico-mechanical properties of dolerites from the Pindos and Vourinos ophiolites, northern Greece, is investigated. Quantitative petrographic analysis shows that the samples display various percentages of secondary minerals. Two new micropetrographic indices are calculated from the results of petrographic modal analysis for the engineering assessment of dolerites: the micropetrographic strength index I ps and the replacement index I rep . The samples are also tested to determine water absorption, apparent density, total porosity, sand equivalent, uniaxial compressive strength, Los Angeles abrasion value, aggregate impact value, aggregate abrasion value and polished stone value. The influence of alteration on the rock quality and especially the relationships between the proposed micropetrographic indices and the engineering parameters are determined using regression analysis and the derived equations were verified by the t-test and the F-test. The relationships between the I ps and I rep indices and the engineering properties show that alteration products generally result in mechanically weaker rocks. However, the results of the physico-mechanical tests indicate that dolerites retain their strength and durability due to the low proportions of soft minerals and microcracks, along with the preservation of their igneous textures. The polishing resistance is the only engineering parameter that is positively affected by alteration processes, as expressed by the I ps index. Particularly, the replacement of the primary mafic minerals by secondary minerals, expressed by the I rep index, can enhance the polishing resistance of dolerites when used in the wearing surface of a road. The results also indicate strong positive correlations between the chlorite content and the water absorption and total porosity values.

Improvement of Pad Life in Mirror Polishing for GaAs Wafers

GaAs wafers have contributed greatly to improve the performance of light-receiving and light-emitting devices. For such applications, a very low level of roughness, of the order of 0.1nmRa, is required on GaAs wafers. If a polishing pad is used for a long time, the polishing rate decreases and the roughness on the wafer increases with increase of polishing time. In this study, the surface morphology of the polishing pad was focused as a dominant factor affecting the polishing rate, and, using an image processing technique, a quantitative approach was tried based on an optical microscope image. For the purpose of increasing the lifetime of polishing pads, a further study was made in which the polishing resistance, which correlates strongly with the polishing rate, was monitored.

Proposal of Mirror Finishing Technology without Using a Polishing Pad. Development of 4-Body Finishing Technology Using Polymer Particles.

A polishing pad has so far been indispensable in conventional polishing method for most industrial materials. However, many problems, such as wear and glazing of pad surface, variation in removal rate over time, poor repeatability and difficulty in process control, and necessity of in-situ conditioning of pad surface, remain to be solved. A mirror polishing method using no polishing pad is therefore proposed, in which polymer particles are supplied together with abrasive grains on to a tool plate that could be made of hard materials. The polymer particles serve as countless micropads in the work-to-plate gap for polishing action, as well as spacers preventing contact between the tool plate and the workpiece. The feasibility of this method has been verified through polishing experiment of silicon wafers. Higher removal rate of material and higher form accuracy, easier process control and higher stability at less polishing resistance, and hence lower power consumption have been obtained than using a polishing pad. Also it is found that the properties of polymer particles and the surface roughness of tool plate have very important effects on polishing characteristics.

Proposal of New Polishing Technology without Using a Polishing Pad

A polishing method that uses no polishing pad is proposed, in which fine polymer particles are supplied together with abrasives onto a hard tool plate. The polymer particles prevent direct contact between workpiece and tool plate and serve as countless micro pads rubbing the abrasives against the workpiece for polishing action, so that not only slurry supply to and removal of polishing by-products from the work-plate gap are kept good and constant, but also excessive frictional resistance may be suppressed. Polishing experiments with silicon wafers have shown that the method is feasible and characterized with higher material removal rates and less polishing resistance than conventional polishing.

Aggregate Polishing Resistance Pre-Evaluation

Current methods of pre-evaluation of aggregates for bituminous surface courses such as the British Pendulum and British Polishing Wheel and chemical or mineralogical methods are only able to identify clearly aggregates with a high probability of performing well. There is little agreement among researchers as to what engineering properties will provide adequate frictional resistance at various average daily traffic (ADT) levels. The lack of agreement has led to conservative polish-resistance specifications and subsequently higher pavement costs. The Tennessee Textural Retention Method (TTRM) uses single size aggregate (6.35 to 9.52 mm), the Los Angeles Abrasion device, and a modified version of the AASHTO TP 33 device to evaluate particle shape and texture throughout simulated aging. In this evaluation, using 25 Tennessee aggregates, the TTRM was used to characterize aggregate polish-resistance performance at various ADT levels by comparing the results obtained on other aggregates with the results from fie...

Aggregate Polishing Resistance Pre-Evaluation

Current methods of pre-evaluation of aggregates for bituminous surface courses such as the British Pendulum and British Polishing Wheel and chemical or mineralogical methods are only able to identify clearly aggregates with a high probability of performing well. There is little agreement among researchers as to what engineering properties will provide adequate frictional resistance at various average daily traffic (ADT) levels. The lack of agreement has led to conservative polish-resistance specifications and subsequently higher pavement costs. The Tennessee Textural Retention Method (TTRM) uses single size aggregate (6.35 to 9.52 mm), the Los Angeles Abrasion device, and a modified version of the AASHTO TP 33 device to evaluate particle shape and texture throughout simulated aging. In this evaluation, using 25 Tennessee aggregates, the TTRM was used to characterize aggregate polish-resistance performance at various ADT levels by comparing the results obtained on other aggregates with the results from field proven performers. The TTRM ranked all Tennessee proven performing siliceous limestones and gravels in the appropriate ADT category for which they are currently approved. In addition, new promising aggregate sources were revealed. The test method had a coefficient of variation for aggregate ratings of less than 3 percent for a nine-sample repeatability test. In addition, the maximum coefficient of variation of voids tests at any given aging revolution for an individual aggregate never exceeded 2 percent. The method may be helpful in pairing aggregate polish-resistance performance with pavement need based on ADT.

Laser Induced Damage in Optical Materials: 6th ASTM Symposium

The Sixth ASTM-ONR-NBS Symposium on Laser Induced Damage in Optical Materials was held at the National Bureau of Standards in Boulder, Colorado on 22-23 May 1974. Over 150 attendees at the Symposium heard thirty-one papers on topics relating to laser induced damage in crystalline and nonlinear optical materials, at dielectric surfaces, and in thin film coatings as well as discussions of damage problems in the ir region due both to cw and pulsed irradiation. In addition, several reports on the theoretical analysis of laser-materials interaction relative to the damage progress were given, along with tabulations of fundamental materials properties of importance in evaluation of optical material response to high-power laser radiation. Attention was given to high-power laser system design considerations that relate to improved system performance and reliability when various damage mechanisms are operable in such systems. A workshop on the machining of optics was held, and nine papers on various facets of the topic were presented dealing with machining procedures, surface characterization of machined elements, coating of machined components, and the polishing and damage resistance of polished, coated, and bare metal reflectors.