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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <title>Understanding Effects of Crushing Mechanism on Aggregate Morphology Using AIMS</title>
      <link>https://trid.trb.org/View/1974571</link>
      <description><![CDATA[The present study compared angularity, texture, sphericity and flat and elongation (F&E) ratio of three different sizes (P19-R12.5, P12.5-R9.5 and P9.5-R4.75) of coarse aggregate produced from two different types of crushing operations. The aggregates were collected from two different types of crushers: (i) the first crusher had jaw, cone and vertical shaft impactor (VSI) as primary, secondary and tertiary crushers, respectively; and (ii) the second crusher had jaw, horizontal shaft impactor (HSI) primary and secondary crushing unit, respectively. The angularity, texture, sphericity and flat and elongation (F&E) of aggregates were measured using aggregate image measurement system (AIMS) in accordance with the AASHTO TP81 method. Further, laboratory tests like angle of repose (AoR) and VCAdrc were conducted to identify the influence of aggregate morphology on the performance of aggregates. The results showed that aggregates produced from JH series of crusher had higher F&E ratio, higher texture and lower sphericity as compared to aggregates from JCV series of crusher. However, both the crushers JH and JCV produced aggregates with similar angularity. The aggregates produced from JH series of crusher show better performance over JCV produced aggregates.]]></description>
      <pubDate>Tue, 12 Dec 2023 09:02:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1974571</guid>
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      <title>Use of a Linear Crusher to Reduce Stoniness Fixed in Existing Gravel Wearing Course Layers</title>
      <link>https://trid.trb.org/View/2244350</link>
      <description><![CDATA[The most frequently occurring defect on the Western Cape Government’s Department of Transport and Public Works (the Department) proclaimed provincial gravel road network is stoniness fixed. Stoniness fixed consists of oversized aggregate (material retained on the 37.5-mm sieve) embedded in the existing wearing course layer, which reduces riding quality while also creating maintenance problems. The Department has traditionally utilized grid rollers as the method for breaking down in situ wearing course material, but it was found that harder materials (requiring more than eight grid roller passes) could be broken down more efficiently and effectively using a mobile crusher. The use of a linear crusher that would be able to break down hard wearing course material on the road was seen as a possible cost effective and efficient solution that would supplement current work methods. The Department investigated, selected, and acquired an FAE STC200 linear crusher and a John Deere 8245R tractor as shown in Figure 1 for further testing in the field. This study investigates the use of reworking existing gravel wearing course layers by way of a tractor-driven linear crusher to reduce the percentage of oversize material and consequently improve riding quality and maintainability. The testing of the selected tractor and crusher combination was done on three trial sections with stoniness fixed defects, and for which samples were taken and analyzed to determine the impact of the linear crusher on reducing stoniness fixed in existing gravel wearing course layers. The parameters analyzed focused on the percentage oversize index, shrinkage product, and grading coefficient before and after crushing.]]></description>
      <pubDate>Wed, 13 Sep 2023 13:43:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2244350</guid>
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    <item>
      <title>Investigation of the Effects of the Type of Crusher on Coarse Aggregate Shape Properties Using the Three-Dimensional Laser Scanning Technique</title>
      <link>https://trid.trb.org/View/1417365</link>
      <description><![CDATA[The fundamental shape/morphological properties of coarse aggregates including form, angularity, and surface texture are known to influence the performance of pavements. The coarse aggregate shape properties are affected by many factors, amongst others, the properties of the parent rock and the type of crusher or crushing operations. Therefore, quantification of the effects of the crusher type on the aggregate shape properties is important as it influences the bulk properties of pavement materials and therefore performance. Recent studies have demonstrated that laser scanning technique can be employed to better quantify the three-dimensional (3-D) shape properties of aggregate materials used in pavements. In this paper, the shape properties of quartzite aggregates crushed by using four different types of crushers were investigated. The results have demonstrated the extent to which the aggregate shape indices computed using laser scan results can be used to distinguish aggregate by-product from different crushers.]]></description>
      <pubDate>Thu, 01 Sep 2016 09:07:21 GMT</pubDate>
      <guid>https://trid.trb.org/View/1417365</guid>
    </item>
    <item>
      <title>Recycling Pavements: Concrete Road Recycling is Now Commonplace, but How Did We Get Here?</title>
      <link>https://trid.trb.org/View/782556</link>
      <description><![CDATA[Concrete roads are now among the most recycled construction products in the world.  The old concrete is used in everything from new concrete pavements and bases to shoreline protection on coastal areas, lakes, and rivers.  This article offers an historical perspective on the discoveries and advancements in recycling, including early innovations and operational advancements through the years.  Recycled concrete aggregate (RCA) was developed in the 1970s and was primarily used in the road bases of new highway construction.  Flexural strength tests on concrete using RCA yielded excellent results, and freeze-thaw testing results were better for mixes using only crushed concrete than mixes using both crushed concrete and recycled asphalt pavement (RAP).  Other techniques developed include recycling the concrete onsite (as opposed to trucking it back to a plant for recycling), separating out embedded steel reinforcing from the broken concrete, quality control discoveries, and the use of RCA in airport runways.  The section on operational advancements describes the evolution of the breaking and crushing technologies, including the sophistication of new equipment.  The author describes dedicated equipment that provides more directed force than earlier equipment, including the drop-shoe stomper (a hammer attached to an excavator or backhoe that is raised by a cable and dropped), a mega-stomper (featuring a large plate operated by an auxiliary motor), a hydraulic hoe ram, guillotine breakers (which drop large plates onto pavement every few seconds), resonant breakers (which apply pressure to pavement using an offset cam motor with high frequency to apply breaking force), and roller breakers.  The author also describes changes in the ways that reinforcing steel is separated from the rubber, the operating principle of crushers, and the use of impactor and mobile crushers.  The author concludes that the greatest need to further use of RCA as aggregate in new concrete mixtures is for standard specifications.  The Federal Highway Administration (FHWA) has established guidelines for the use of RCA and recommends it for use in cement-treated or lean concrete bases, concrete aggregate, aggregate for flowable fill, and even asphalt.]]></description>
      <pubDate>Wed, 31 May 2006 09:30:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/782556</guid>
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    <item>
      <title>Shaping the Right Mix</title>
      <link>https://trid.trb.org/View/757601</link>
      <description><![CDATA[Many countries are introducing new specifications concerning the shape and surface texture of asphalt aggregates. Imposing tighter controls on aggregate shape should improve field performance and reduce maintenance costs.  This article describes how the aggregate industry is developing new crushing and screening practices to provide the required aggregates.  Cubical particles with sharply defined edges are said to perform best in asphalt.  For medium to heavy traffic applications, particles should be cubical, yet angular, to ensure good stability and rigidity.  Using cubical aggregate in asphalt also reduces the optimum bitumen content of the mixtures.  Aggregates with a rough surface texture provide high stability mixes for situations where rutting resistance is important.  A recent study on different types of crushing determined that rock-on-rock vertical shaft impactors produced the best aggregate for asphalt.]]></description>
      <pubDate>Thu, 14 Jul 2005 10:11:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/757601</guid>
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    <item>
      <title>PROCESSING AGGREGATES TO IMPROVE PARTICLE SHAPE</title>
      <link>https://trid.trb.org/View/744717</link>
      <description><![CDATA[Particle shape has an influence on the performance of aggregates in most applications. For uses such as hot mix asphalt, crushed aggregate base and Portland cement concrete, shape plays a major role either in the preparation and placement or in the performance of the product, or both. For other applications such as drainage layers, drainfields, erosion control, etc., shape plays a minor role. Properties such as shear strength, stability, voids and density, as well as workability and finishability are all influenced by particle shape. Processing of aggregates is the single most important factor in determining particle shape. During the production of crushed aggregates, particle shape can either be improved or diminished, depending on the selection and operation of crushing equipment. A preliminary task of research study ICAR 102 - Increased Use of Fines in Portland Cement concrete, was the processing of over 40 aggregate sources through a vertical shaft impact crusher. The goal was to produce multiple fine aggregate products for each source having a wide range of particle shape and gradings having high fines contents. These products would be evaluated for use as fine aggregate for concrete. The equipment proved to be beneficial in producing fine aggregates from coarse aggregates and in reshaping fine aggregates. In both cases, fine aggregates having good particle shape were produced.]]></description>
      <pubDate>Sun, 21 Nov 2004 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/744717</guid>
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      <title>EXPERIENCE IN CEMENT GRINDING BY TUBE MILLS USING SMALL GRINDING MEDIA</title>
      <link>https://trid.trb.org/View/269837</link>
      <description><![CDATA[Aalborg Portland Cement has brought into service a Combidan mill which differs from conventional tube mills by using small grinding media in the fine grinding compartment.  The mill has been found to produce a power saving of between 10 and 18%, while the finished product exhibits a steeper particle size distribution curve - and thus also higher early strength for the same specific surface - than cement produced in conventional tube mills.]]></description>
      <pubDate>Fri, 27 Aug 2004 21:56:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/269837</guid>
    </item>
    <item>
      <title>PRIMARY COMMINUTION IN CLINKER GRINDING PLANTS</title>
      <link>https://trid.trb.org/View/269835</link>
      <description><![CDATA[The results of the investigations and experience described in this article show that the roller mill and the impact mill appear suitable for primary comminution in cement grinding plants.  Because of the risk of scoring of the roller surfaces and the narrow feed particle size range associated with the roller mill, the impact mill is to be preferred.  Because its wearing parts are made of abrasion-resistant cast iron the impact mill is suitable also for the comminution of abrasive material.  As a result of installing such a mill the throughput of an existing plant can be increased, and the capital cost of a new plant to be designed can thereby be reduced.]]></description>
      <pubDate>Fri, 27 Aug 2004 21:56:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/269835</guid>
    </item>
    <item>
      <title>CEMENT GRINDING IN THE TWIN-ROLL MILL</title>
      <link>https://trid.trb.org/View/269834</link>
      <description><![CDATA[Savings in electrical energy in cement manufacture are possible in the process stage constituted by cement grinding.  Because of the determinate conditions of loading to which the feed material is subjected, compressive comminution in the highly-loaded material bed is especially advantageous.  The twin-roll mill can alternatively be used as a primary mill for an existing ball mill operating in closed circuit with air separator equipment.  In such cases it is possible to obtain increases of up to 25 per cent in capacity and, in addition, energy savings of between 10 and 20 per cent.]]></description>
      <pubDate>Fri, 27 Aug 2004 21:56:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/269834</guid>
    </item>
    <item>
      <title>INFLUENCE OF MILL VENTILATION ON GRINDING EFFICIENCY</title>
      <link>https://trid.trb.org/View/269830</link>
      <description><![CDATA[The reason why closed-circuit grinding is far more economical than open-circuit grinding is the coarser material in the closed-circuit grinding mill.  By ventilation of mills, ground material is drawn out from the mill with the ventilation air, the material remaining in the mill thus becoming coarser, which improves grinding economy. In fully air-swept mills, the strong ventilation may cause internal separation, which is of great importance to the grinding.  This is probably the reason why fully air-swept mills often operate as economically as semi air-swept mills.]]></description>
      <pubDate>Fri, 27 Aug 2004 21:56:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/269830</guid>
    </item>
    <item>
      <title>A LOVE FOR THE CRUSH : CLEVELAND-BASED RECYCLE CONTRACTOR RUNS EASTERN U.S. TO CUSTOM-CRUSH FOR CUSTOMERS</title>
      <link>https://trid.trb.org/View/728528</link>
      <description><![CDATA[Independence Recycling provides crushing services to a large group of customers east of the Mississippi with nine portable horizontal shaft impact crushing plants that produce more than 3 million tons of materials to customers' specifications each year. At a typical job, it supplies a two-person team that works with a crushing plant, loader and command trailer.  Most plants move at least seven to 10 times a year and are scheduled to visit sites year-round and are matched to the needs of each job. Plants vary in size and capabilities, with the largest being the IROCK RDS-25 that uses two trailers to travel but can be erected without a crane or other lift. It can process concrete in chunks as large as three feet across, though 24 inches is the preferred operating size.]]></description>
      <pubDate>Tue, 03 Dec 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/728528</guid>
    </item>
    <item>
      <title>HAMMERS HELP STOP T-REX ROAR!</title>
      <link>https://trid.trb.org/View/721478</link>
      <description><![CDATA[A five-year project to add lanes and light rail lines to Interstates 25 and 225 in Denver, Colorado, also is requiring the removal and replacement of many bridges and structures. The concrete has to be sized and all the rebar has to be removed from the concrete.  This article describes the demolition work and the machinery that will be used to complete the project.   A large cutter crusher with a maximum jaw opening of 900 mm coupled with a maximum cutting force of 28,758 kg and a maximum crushing force of 152,409 kg will be used for much of the demolition.]]></description>
      <pubDate>Mon, 08 Jul 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/721478</guid>
    </item>
    <item>
      <title>FEEDING AN INSATIABLE NEED</title>
      <link>https://trid.trb.org/View/710652</link>
      <description><![CDATA[The construction industry's demand for aggregate is immense. New crushing and sorting machinery is being produced in order to meet this demand with cleaner aggregate and increased production. This article describes several available crushing and screening machines.  These units produce aggregates from rock using a series of processes.  Large pieces of rock are crushed into different sizes using a jaw crusher, then the crushed stone passes through vibrating screens where it is separated into the various sizes required for a specific job. New mobile and semi-mobile crushing units can be transported by road and operated in smaller yards.  Some crushing and screening units can be combined to produce an advanced system capable of processing a large variety of aggregate products.]]></description>
      <pubDate>Mon, 22 Apr 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/710652</guid>
    </item>
    <item>
      <title>WAR ON HIGHWAY WASTE</title>
      <link>https://trid.trb.org/View/710646</link>
      <description><![CDATA[Recycling of highway products is becoming increasingly common. Some countries have passed legislation requiring recycling, but even without legislation, contractors are realizing that recycling is cost-effective.  A road-widening project between Seoul and Daejon in Korea is one example of successful recycling. South Korean law requires that all asphalt from old highways be recycled.  To ease asphalt recycling for the project, a crusher was rented that could travel to the stockpiles of asphalt. Asphalt is loaded into the unit in 400mm radius blocks, and the machine has processed about 17,000 cubic meters thus far.  The recycled asphalt is being re-used as sub-base and as material in embankments.]]></description>
      <pubDate>Sat, 20 Apr 2002 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/710646</guid>
    </item>
    <item>
      <title>ROADTRAIN CUTS COSTS ON IOWA ROADS</title>
      <link>https://trid.trb.org/View/668883</link>
      <description><![CDATA[A road-recycling train solves many problems by performing the entire job of crushing and recovering road materials on-site in an efficient, cost-effective, and safe manner. This eliminates the need for approximately 20 trucks and drivers and 2 loaders at the site of a road surface recovery/recycling project. The specifications of a 200-foot-long, multi-wheeled roadtrain designed and built for a project in Iowa are described. The roadtrain crushes the lifted road surface on the move, and creates enough aggregate product to load a truck in 1.5 minutes. Other features of this type of heavy machinery are also provided.]]></description>
      <pubDate>Wed, 11 Oct 2000 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/668883</guid>
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