A New Image Analysis Technique to Quantify Particle Angularity

Angularity is a fundamental morphological descriptor of a particle; it determines the aggregate performance in asphalt and concrete works. This paper introduces an innovative matlab based image analysis technique to quantify the angularity of an aggregate. The algorithm is based on application of two successive b-spline smoothing techniques around the aggregate profile. The first b-spline smoothing curve is generated by joining the mid-points of the adjacent segments; and the second smoothing curve is generated by a smoothing function upon the first b-spline. Then the distribution of the perpendicular distance between these two-b-splines is evaluated, which provides an excellent estimate to the aggregate angularity. In this paper the angularity index of six aggregate samples is determined using our new technique. Then we compared the index obtained with an existing Aggregate Imaging Measurement System (AIMS) and the measurement from the two methods revealed good similarity. Therefore our new method can be considered as a useful alternative in the aggregate industry for distinguishing the angularity of the samples obtained from different sources.QS201

A New Image Analysis Technique to Quantify Particle Angularity

Angularity is a fundamental morphological descriptor of a particle; it determines the aggregate performance in asphalt and concrete works. This paper introduces an innovative matlab based image analysis technique to quantify the angularity of an aggregate. The algorithm is based on application of two successive b-spline smoothing techniques around the aggregate profile. The first b-spline smoothing curve is generated by joining the mid-points of the adjacent segments; and the second smoothing curve is generated by a smoothing function upon the first b-spline. Then the distribution of the perpendicular distance between these two-b-splines is evaluated, which provides an excellent estimate to the aggregate angularity. In this paper the angularity index of six aggregate samples is determined using our new technique. Then we compared the index obtained with an existing Aggregate Imaging Measurement System (AIMS) and the measurement from the two methods revealed good similarity. Therefore our new method can be considered as a useful alternative in the aggregate industry for distinguishing the angularity of the samples obtained from different sources.QS201

A New Image Analysis Technique to Quantify Particle Angularity

Angularity is a fundamental morphological descriptor of a particle; it determines the aggregate performance in asphalt and concrete works. This paper introduces an innovative matlab based image analysis technique to quantify the angularity of an aggregate. The algorithm is based on application of two successive b-spline smoothing techniques around the aggregate profile. The first b-spline smoothing curve is generated by joining the mid-points of the adjacent segments; and the second smoothing curve is generated by a smoothing function upon the first b-spline. Then the distribution of the perpendicular distance between these two-b-splines is evaluated, which provides an excellent estimate to the aggregate angularity. In this paper the angularity index of six aggregate samples is determined using our new technique. Then we compared the index obtained with an existing Aggregate Imaging Measurement System (AIMS) and the measurement from the two methods revealed good similarity. Therefore our new method can be considered as a useful alternative in the aggregate industry for distinguishing the angularity of the samples obtained from different sources.QS201

Elimination of n phase in WC-Co cemented carbides during laser powder bed fusion by powder coating compensation strategy

The formation of n phase induced by the C-loss for the laser powder bed fusion (LPBF) of WC-Co cemented carbides largely deteriorates the fracture toughness. The current approach of mixing C additive into powder cannot mitigate the n phase formation. This study proposed a new carbon compensation strategy of coating carbon resource on powder surface by fluidized bed chemical vapor deposition to address this issue. C nanoparticles and carbon nanotubes (CNTs) were selectively deposited on WC-Co powder to make uniform C- and CNTs-coated powders by tuning the deposition temperature. Compared with CNTs-coated powder and C-WC-Co powder mixtures, the C-coated powder was more effective in impeding the n phase formation because it had higher reactivity and stronger dissolution ability to compensate the C-loss in the Co-W-C liquid. However, the single-carbon compensation was not enough to eliminate the n phase due to the extreme nonequilibrium characteristics of LPBF, which required secondary heat treatment. The conventional heat treatment procedure of 1000 degrees C for 3 h eliminated the n phase for the C-coated powder but failed for the C-WC-12Co powder mixtures. Because of the absence of n phase, the heat-treated sample made from C-coated powder exhibited the highest transverse rupture strength

An Improved Asphalt Penetration Test Method

A traditional penetration test only measures the total penetration within 5 s. The penetration process is not monitored, and therefore, a large amount of information on the deformation properties of asphalt is not used. This paper documents a study to use a high-speed camera to quantify the entire penetration process and use the Finite Element Method (FEM) to interpret the penetration process using a viscoelastic model. The penetration–time relationships of several asphalt binders (70#, 90#, a rubber modified binder, and a styrene-butadiene-styrene (SBS) modified binder) have been acquired using the new method, and the FEM modeling of the penetration processes is performed. The results show that both stress relaxation and creep appear during the penetration process. The results indicate that the improved test method and its data interpretation procedure may better characterize the properties of asphalt binder, which may extend the applications of the traditional penetration test

Elimination of n phase in WC-Co cemented carbides during laser powder bed fusion by powder coating compensation strategy

The formation of n phase induced by the C-loss for the laser powder bed fusion (LPBF) of WC-Co cemented carbides largely deteriorates the fracture toughness. The current approach of mixing C additive into powder cannot mitigate the n phase formation. This study proposed a new carbon compensation strategy of coating carbon resource on powder surface by fluidized bed chemical vapor deposition to address this issue. C nanoparticles and carbon nanotubes (CNTs) were selectively deposited on WC-Co powder to make uniform C- and CNTs-coated powders by tuning the deposition temperature. Compared with CNTs-coated powder and C-WC-Co powder mixtures, the C-coated powder was more effective in impeding the n phase formation because it had higher reactivity and stronger dissolution ability to compensate the C-loss in the Co-W-C liquid. However, the single-carbon compensation was not enough to eliminate the n phase due to the extreme nonequilibrium characteristics of LPBF, which required secondary heat treatment. The conventional heat treatment procedure of 1000 degrees C for 3 h eliminated the n phase for the C-coated powder but failed for the C-WC-12Co powder mixtures. Because of the absence of n phase, the heat-treated sample made from C-coated powder exhibited the highest transverse rupture strength

The Effect of Molecular Isomerism on the Barrier Properties of Polyimides: Perspectives from Experiments and Simulations

A novel carbazole-containing diamine (M-2,7-CPDA) isomer of our previously reported diamine 2,7-CPDA, has been synthesized using a two-step synthesis. Compared with 2,7-CPDA, the substituted position of amino is changed from para to meta for M-2,7-CPDA. The two diamines were polymerized with pyromellitic dianhydride (PMDA) to prepare two isomeric polyimides (M-2,7-CPPI and 2,7-CPPI), respectively. The effects of para/meta isomerism on microstructures and gas barrier performances of the two isomeric polyimides were studied by positron annihilation test, X-ray diffraction and molecular simulation. The results display that meta-connected M-2,7-CPPI has less ordered chain structure and weaker hydrogen bonding than para-connected 2,7-CPPI, which leads to loose chain stacking and thereby increased free volumes of M-2,7-CPPI. The higher free volumes promote the solubility and diffusivity of gas in M-2,7-CPPI. As a result, the meta-linked M-2,7-CPPI shows a lower gas barrier than its para-linked analog. The work provides guidance for the design and synthesis of high-performance barrier polymers

The State of the Art: Application of Green Technology in Sustainable Pavement

A wide range of literature on predominant green technologies for sustainable pavements is summarized in this paper. It covers two major aspects: energy harvesting technologies and permeable pavement systems. Fundamental mechanics of energy harvesting techniques and possible designs of energy harvesters are described, with the evaluation of energy conversion efficiency, and advantages and disadvantages. In addition, the designs of permeable pavement systems are discussed, along with their advantages and disadvantages. The latest technical innovations are highlighted. It is found that green technologies are promising for developing more sustainable pavements. Application issues are also pointed out, including construction challenges, durability, and life-cycle cost-benefit assessment. Future research directions are suggested to address practical challenges, such as efficient design, construction challenge, timely maintenance, and life-cycle performance assessment