Some natural aggregate deposits, called pitrun gravel, consist of gravel and sand that can be readily used in concrete after minimal processing. Unbound aggregate base layers support traffic loads from the asphalt concrete surface. The technique of sieve analysis is used for gradation of aggregate for use in concrete and for other applications. Chapter four unbound aggregate base characterization for design. It is located under the surface layer consisting of the wearing course and sometimes an extra binder course if there is a subbase course, the base course is. Aggregate base course shall have minimum uniform thickness after compaction of dimensions indicated. Aggregates types of aggregates coarse aggregate, fine. The thicknesses and ages of the pavement and base course aggregate layers are shown in table 1. Generally account for 30 percent of the cost of a pavement structure 2.
Wbdg is a gateway to uptodate information on integrated whole building design techniques and technologies. Our crushed stone base course material in laos and in india all measured at more than 100. Stabilized using cementitious materials blends of cement, fly ash, slag, lime. Manual mixing is permitted where the width of laying is small for mechanical operations.
Do not place aggregate on unstable base, as determined by the engineer. T 85 specific gravity and absorption of coarse aggregate t 112 clay lumps and friable particles in aggregate t 248 reducing field samples of aggregate to testing size t 304 uncompacted void content of fine aggregate astm test methods d 4791 flat particles, elongated particles, or flat and elongated particles in coarse aggregate. Base course material shall conform to one of the following gradations as specified. Construction rock class 6 aggregate base course 34 roadbase class 6 aggregate base course is 100% post consumer concrete and meets or exceeds the colorado department of transportation cdot specifications. Class 6 aggregate base course 34 roadbase class 6 aggregate base course is 100% post consumer concrete and meets or exceeds the colorado department of transportation cdot specifications. Road milling materials, including the reclaimed asphalt pavement rap and the reclaimed cement stabilized basecourse rai, have been widely used as the recycled aggregates ra to prepare cement stabilized cold recycling mixtures cscrm used in highway rehabilitation. Where not indicated, compacted thickness shall be 6 inches. Department of transportation federal highway administration. Cement and concrete technology eciv 3341 second semester 20092010 course outline. Natural aggregates are generally extracted from larger rock formations through an open excavation quarry. Aggregate base course section 303 concrete surface course class d8 subsection 403. It is located under the surface layer consisting of the wearing course and sometimes an extra binder course.
The aggregate shall be select granular materials, comprised of crushed or uncrushed. This scarifying shall be considered incidental to placing the course, and no separate payment will be made. Pdf on jan 1, 2007, greg arnold and others published the effect of grading on the. A weight of empty basket in water a weight of aggregate and basket in water c. Standard specifications for construction and materials. Aggregate base course article about aggregate base. Long term performance of gravel base course layers in asphalt. The original gravel roads maintenance and design manual was published in 2000.
The concrete mixtures incorporate either basalt or crushed limestone, aggregate sizes of 12 mm h in. The component particles will vary in size from 20 mm down to dust. The september 2017 revisions to the standard specifications are now available for download. Knowledge of cement origin, properties and types knowledge of aggregate properties and classification knowledge fresh and harden concrete properties using concrete laboratory to find concrete properties course conduct. Below is an index of all the specifications that can be viewed andor downloaded individually.
The function of the coarse aggregate is to act as the main loadbearing component of the concrete. Charactereistics, specifications, environmental considerations, availability tuncer b. This product has reinforcing steel removed and pieces no larger than. The aggregate of each type is further subdivided into many types and classification based on its size. Using electrical properties to classify the strength. The goal of whole building design is to create a successful highperformance building by applying an integrated design and team approach to the project during the. Aggregates are used as the base, subbase, andor surface of roads in several forms. High strength and elasticity are desirable in aggregate base and surface courses. Aggregate base ab is typically made of a recipe of mixing different sizes of crushed. The work to be performed includes the preparation of the aggregate base course foundation. Pdf the effect of grading on the performance of basecourse. Definition aggregate is the term used to describe rock used for road making and refers to an assembly of discrete particles i. Standard engineering design specifications effective 912017 the september 2017 revisions to the standard specifications are now available for download. Pdf properties and composition of recycled aggregates from.
Ensure the exposed aggregate base course layer remains smooth, compacted, and uncontaminated. Maintain the aggregate in a smooth, stable condition and provide dust control until removed or surfaced. Aggregate for class 1, class 2, and class 3 aggregate subbases shall be clean and free from vegetable matter and other deleterious substances, and shall be of such composition that it can be compacted readily under watering and rolling to form a firm, stable base. Recycled aggregate an overview sciencedirect topics. Practices for unbound aggregate pavement layers 20. The goal of whole building design is to create a successful highperformance building by applying an integrated design and team approach to the project during the planning and programming phases.
Physical properties of aggregates 54 aggregate tests consensus properties required source properties optional aggregate criteria based on aggregate blend based on traffic and depth into pavement design aggregate structure 0. Ufgs 32 11 23 aggregate base course wbdg whole building. This design feature is the primary difference between class i and class ii base courses. Class i base courses that are stabilized with cement must always be produced in a central mix plant. Aggregate base course shall consist of crushed gravel or crushed stone, conforming to the quality requirements of aashto m 147. Base aashto design guide bender36 structural op 16 jun 10 08. Aggregate base course article about aggregate base course. The percentage composition by weight of class 1, class 2, and class 3 aggregate. Stabilized with other materials resins, fibers, geosynthetics, etc. The aggregate base course shall be constructed to the width and section sho wn in the drawings. Materials specified for use in the construction of subbase and base courses for flexible and rigid pavements include the following. Recycled concrete and masonry rcm which is graded aggregate produced from sorted and clean waste concrete and masonry typically for road sub base applications.
The standard testing procedure for this is the american society of testing. Those particles that are predominantly retained on the 4. Aggregate base course shall be applied over the prepared sub grade or sub base and compacted in accordance with section 26 of the caltrans standard specifications. The finish of finished aggregate base course at any point shall not vary more than 12 inch above or below the indicated grade. February 2, 2016 maintenance aggregate supply contract no. Aggregate definition, formed by the conjunction or collection of particulars into a whole mass or sum. The base course or basecourse in pavements is a layer of material in an asphalt roadway, race track, riding arena, or sporting field. Recycling concrete and asphalt has been taking place in the usa since at least the early 1970s nanasy 1972, and by the 1990s was a wellestablished activity. Development of a catalog of resilient modulus values for. Gravel roads construction and maintenance guide lara.
Recycled aggregate occurs as either recycled concrete aggregate rca or recycled asphalt pavement rap. Properly compacted material will be considered as part of the underlying course and shall meet all. The base course or basecourse in pavements is a layer of material in an asphalt roadway, race. This 2010 edition of the west virginia division of highways standard specifications, roads and bridges, has been issued with the intent for use on all projects in which bids are received after november 1, 2010. Stabilization may be accomplished by mixing base course material into the underlying course and compacting by approved methods. Currently, only the use of coarse aggregate derived from construction or demolition waste is recommended for use in new concrete construction.
The mixture shall contain not more than 8% by weight of lime. Sponsoring agency name and address texas department of transportation. Sample size 2 kg or less, readability and sensitivity to 0. This method of test is used to determine the particle size distribution of aggregates by dry sieving only. If there is a subbase course, the base course is constructed directly above this layer.
A foundation or footing course, as the lowest course in a. Composition of the aggregate, in percentages by weight, shall conform. If placing hma surface over the aggregate surface course. Standard specifications section 800coarse aggregate. Uses of aggregates in construction, roads, railway and other. Reviewed are books on shakespeare by josephine waters bennett. These qualities minimize the rate of disi ntegration and maximize the stability of the compacted material. This material is a blend of crushed and natural materials processed to provide a dense graded mix often referred to as mechanically stabilized base course. Types of aggregates include coarse aggregate and fine aggregate. Aggregates for concrete bination of gravels or crushed stone with particles predominantly larger than 5 mm 0. The base course shall be built in a series of parallel lanes using a plan of processing that reduces longitudinal and transverse joints to a minimum. Standard engineering design specifications effective 91. Aggregates are the most mined materials in the world. The aggregate shall be free from lumps, balls of clay, or other objectionable matter, and shall be durable and sound.
Standard engineering design specifications harris county, texas. This section covers the requirements for the characteristics, source, supply and storage of sub base and base course pavement materials b. Class i base course section 301 class i base courses will be placed on a subgrade layer built in accordance with specification section 305. Aggregate shall not be placed when the air temperature is less than 35f.
Aggregate base is a construction aggregate typically composed of crushed rock capable of passing through a 20 millimetres 3. Effects of recycled aggregate composition on the mechanical. Stabilized with bituminous materials bitumen or tar. This procedure manual provides a guide to the correct construction practices and. Base course the lowest course on a masonry wall or pier, may also be part of the footing. Aggregate base subbase aggregate pavements or shoulders summary of gradation requirements. The first layer of material laid down in construction of a pavement. The various layers composing a flexible pavement and the functions they perform are. Aggregate is also used for base and subbase courses for both flexible and rigid pavements. Strength is a measure of the ability of an aggregate particle to stand up to pulling or crushing forces. This item shall consist of treating the existing subgrade with water and lime according to these specifications and in substantial conformity with the lines, grades, compacted thickness, and cross section shown on the plans. The coarse aggregates should not appear particularly flaky or. Compact the aggregate base as specified in subsection 302.
The material can be made of virgin newly mined rock, or of recycled asphalt and concrete. The mixture shall be composed of the soil in the existing subgrade, lime, and water. Compact the aggregate layers to a uniform thickness, no greater than 6 inches. Materials specified for use in the construction of sub base and base courses for flexible and rigid pavements include the following. Knowledge of aggregate properties and classification. Tr 115 introduction these methods of test are designed to determine the particle size distribution of fine and coarse. The effects of aggregate type, size, and content on the behavior of normal and highstrength concrete, and the relationships between compressive strength, flexural strength, and fracture energy are discussed. The fine aggregate serve the purpose of filling all the open space in between the coarse particles. Sieve analysis of fine and coarse aggregate dotd designation. Construction aggregate, or simply aggregate, is a broad category of coarse to medium grained particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Road milling materials, including the reclaimed asphalt pavement rap and the reclaimed cement stabilized base course rai, have been widely used as the recycled aggregates ra to prepare cement stabilized cold recycling mixtures cscrm used in highway rehabilitation.
Chapter three granular base and subbase construction practices. If the required compacted depth of base course exceeds six 6 inches, the base shall be constructed in two 2 or more layers of approximate equal. Maintain the aggregate base course layer at the required line, grade, and cross section until placement of the next layer. Coarse aggregate is also described by its bulk density, which is a property that can easily be tested in the laboratory. Sampling equipment required for aashto t 2 or itm 207.
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