Investigation of the Effects of the Type of Crusher on Coarse Aggregate Shape Properties Using the Three-Dimensional Laser Scanning Technique (original) (raw)
Related papers
The influence of stone crushing processes on aggregate shape properties
Road Materials and Pavement Design, 2018
Aggregate shape properties have a direct influence on the behaviour of pavement materials. The crushing process is the main factor responsible for generating these shape properties; however, there has hardly been any effort directed toward optimising the performance of pavement materials by altering the crushing techniques to produce aggregate particles with desired shape properties. The aim of this research is to analyse how the crushing process influences aggregate shape properties. Form, angularity and surface texture of five coarse and five fine aggregates, from three different quarries, were evaluated by means of digital image processing and were categorised by two different classification systems. The jaw crusher produced coarse aggregates with a better combination of sphericity and angularity during the first crushing stage. Fine aggregates produced by cone crushers in the final crushing stages were more elongated, but had a greater angularity than fine aggregates produced by the primary jaw crusher.
A new three-dimensional (3D) laser scanning device has been acquired by CSIR Built Environment to determine rock aggregates shape and surface properties. The overall objective is to employ laser-based techniques to accurately determine characteristics of shape, volume, angularity, surface texture, surface area, and grading of rock aggregates that influence performance of road and airfield pavements in South Africa. This paper presents results obtained from a comprehensive scanning evaluation program for the 3D laser device using fifteen different spherical and twelve cubic shaped objects. The laser device was evaluated for accuracy and repeatability to compute aggregate surface area and volume properties. The results showed that the laser device measurements were in very good agreement with the computed theoretical values of the spherical and cubical objects. Thus, there is potential that the laser device will provide accurate and reliable shape and surface properties of rock aggregates to efficiently rank and utilize the sources of aggregate stockpiles used for pavement construction.
Quantification of aggregate grain shape characteristics using 3-D laser scanning technology
Aggregate shape and surface characteristics influence the performance of both bound and unbound pavement materials. This paper presents some results of an ongoing study on the characterization of aggregates using a threedimensional (3-D) laser scanner technology. A sample of coarse aggregate andesite particles passing 19.0 mm and retained on 13.2 mm sieve was used for the study. The 3-D images from the laser scanning device were fully utilized in quantifying the shape descriptors in order to identify the differences between individual aggregates. It was possible to quantify differences in particle shape characteristics at the small particle scale. The study has demonstrated the advantages of the innovative 3-D laser scanning technology to quantify the shape characteristics of aggregate particles.
Shape Characterizing of Aggregates Produced through Different Crushing Techniques
Coatings
The aggregate shape properties produced from the different crushing techniques influence the performance properties of the asphalt mixtures. The objective of this study was to classify the aggregates into spherical, flat, elongated and flat, and elongated shapes, collected from impact crusher and jaw crusher of two sources, and to calculate the shape parameters, such as aspect ratio, shape factor, form factor, sphericity, roundness, and angularity index. In addition, this study also investigated the effects of this classification on the Marshall stability and volumetric properties of asphalt mixtures prepared from the respective shape of aggregates. The results showed that the aggregate of different fractions (passing 37.5 mm and retained on 4.75 mm) produced from the jaw crusher of Margalla quarry showed better shape parameters. The spherical aggregates collected from all crushers showed 20–30% higher Marshall stability of the blends by improving the mechanical and volumetric prope...
Advanced and automated laser-based technique to evaluate aggregates
The Council for Scientific and Industrial Research (CSIR) is undertaking a research project to investigate the use of laser-based scanning technology to quantify the morphological/shape properties (i.e., form-flatness, elongation and sphericity; angularity; surface texture) of aggregates used in pavements and railway ballast. To date, no automated method is available for direct measurements of shape properties of these materials in Africa. The objective of this paper is to present a three-dimensional laser scanning technique to determine flatness, elongation and sphericity of aggregates used in South African roads. A three-dimensional (3-D) laser scanning device was used to obtain the dimensions, surface area, volume, and subsequently, compute flat and elongated ratio of six different aggregate samples. The results were compared with the standard manual method that is currently used by the road industry to quantify aggregate shape properties. It is expected that, this study would influence decisions to improve aggregate material characterization and pavement design.
Influence of crusher type in the shape of fine crushed aggregate grains
Revista IBRACON de Estruturas e Materiais
Quarries have invested in equipment to increase production and improve the quality of their products, such as vertical shaft impact crushers (VSI). This type of crusher works with autogenous comminution of the material to improve the shape of the coarse aggregates. However, there are few studies about the influence of crushers in the shape of fine aggregate grains. In this context, gneiss and granite fine crushed aggregates, produced in cone crushers and VSI were studied. Parameters such as coefficient of volumetric shape, aspect ratio, and circularity were used to compare these aggregates with the river sand. The results showed that there is a difference between the shape of the sand river and the fine crushed aggregates. Among the crushed aggregates, those from the VSI showed improvements in grain shape, compared to aggregates from cone crushers. However, this improvement decreases with the reduction of grain size. Mortars produced with the studied aggregates were also evaluated. ...
Shape Analysis of Fine Aggregates Used for Concrete
Image Analysis & Stereology, 2016
Fine aggregate is one of the essential components in concrete and significantly influences the material properties. As parts of natures, physical characteristics of fine aggregate are highly relevant to its behaviors in concrete. The most of previous studies are mainly focused on the physical properties of coarse aggregate due to the equipment limitations. In this paper, two typical fine aggregates, i.e. river sand and crushed rock, are selected for shape characterization. The new developed digital image analysis systems are employed as the main approaches for the purpose. Some other technical methods, e.g. sieve test, laser diffraction method are also used for the comparable references. Shape characteristics of fine aggregates with different origins but in similar size ranges are revealed by this study. Compared with coarse aggregate, fine grains of different origins generally have similar shape differences. These differences are more significant in surface texture properties, whic...
Laser-based approach for determining flakiness index of aggregates used in pavements
There are concerns about the standard methods/procedures for quantifying shape properties of rock aggregates used in road and airfield pavements. The CSIR has recently acquired a portable three-dimensional (3D) laser scanning device to address some of these concerns, i.e., to automate the determination of aggregate shape properties including form, angularity, texture, and flatness/flakiness. This paper presents a new approach to determine the flakiness index of rock aggregates used in pavements. The 3D laser device was used to directly measure the volume of aggregate samples used in five typical South African asphalt mixes. The results obtained from the laser device were used to compute flakiness index of the aggregate samples. The computed flakiness indices were in good agreement with the measurements from the standard methods, thus validating the correctness of the laser approach and the effectiveness of the volume method to compute flakiness index.
A new and innovative three-dimensional (3-D) laser based technique was employed to accurately determine the morphological (shape) properties of aggregates used in asphalt mixes. The objective of this paper is to investigate the influence of shape properties (i.e., form, angularity and surface texture) of coarse size fractions of three aggregates on rutting performance of asphalt mixes. The asphalt mixes were manufactured using designed (blended) aggregates, and tested with the Hamburg wheel tracking test. It was established that the 3-D laser scanning technique could clearly differentiate between the form, angularity and surface texture characteristics of the three aggregates studied. The results obtained from the study indicate that a more angular and textured aggregates provide better resistance to rutting, thereby improving the performance of asphalt mixes.
Real Time Laser Scanning of Aggregate Materials in Highway Construction
2016
The quality and service life of the roadways that make up the highway transportation infrastructure are dependent upon the selection and use of high quality aggregate materials. Five state transportation agencies participated in this Transportation Pooled Fund (TPF) study, which was designed to demonstrate the use of laser scanning as a means to assess, in real-time, the quality of aggregate used in highway construction. Participating states included Kansas, New York, Ohio, Oklahoma, and Pennsylvania. The referenced technology is based on a process referred to as Laser Induced Breakdown Spectroscopy (LIBS). In this process, a high-powered laser pulse is used to excite atoms that make up the aggregate. This excitation results in the emission of light from a range of unique wavelengths (spectrum) that can be thought of as a "fingerprint" of the material. The development of a database of spectra or fingerprints of many aggregate materials with known engineering properties provides the basis for employing numerical techniques (models), similar to "fingerprint matching," to identify the properties of unknown aggregate material. Scanning data generated in this demonstration show that the technology can differentiate between approved and unapproved aggregate sources. It has the potential to quantify specific test parameters such as acid insoluble residue (AIR), Micro-Deval loss, and specific gravity, as well as to identify the presence of deleterious materials, such as reactive chert, ASR and ACR, and D-cracking susceptible aggregate. It can be used to identify the aggregate source or sources of a stockpile of unknown material(s). A total of 113 aggregates supplied by the participating states were laser-scanned using a field prototype system located in a field materials testing laboratory in South Bethlehem, New York. The analyses in this demonstration focused on specific gravity (bulk and SSD) and absorption, D-cracking, acid insoluble residue, Micro-Deval, and Los Angeles (LA) Abrasion Loss. The results show that laser scanning can successfully predict the properties of aggregate, opening up a whole new way of analyzing aggregate materials. Based on the results presented, recommended future work is outlined, some of which has been initiated and presented herein to refine the scanning and modeling process to enhance data quality.