Costs associated with the intermediate aggregate may be offset by reducing cement content and increasing the concrete quality. The combined gradation will include the hydrated lime. A mathematical method for blending aggregates for a. Optimized aggregates gradations for portland cement concrete. A standard mix and three variable mixes using a uniform gradation, increased aggregate amount, and increased aggregate size were used. October 2012 sieve analysis of fine and coarse aggregates fop for aashto t 27. Mike day everything about concrete recommended for you. Originally developed for efficient design of asphalt mixes, the bailey method represents a systematic approach to blending aggregates to ensure adequate aggregate interlock as the backbone of an. Aggregate voids content 5 figure 4 shows the cf chart and 818 chart results of blending different proportions of the no.
Sep 05, 2017 astm classification blending of aggregates. Included is the production of three optimization charts that may be required to be included in the concrete mix. Blends that plot far below the power chart line are too coarse and tend to segregate. Aggregate blending the bailey method originally developed by robert d.
Often, aggregates from more than one source or stockpile are used to obtain the final aggregate gradation. Specifying concrete mixtures with wellgraded wg combined aggregates can be controversial. Characteristics of fine and coarse aggregate ce 3243, prop. Optimized aggregates gradations for portland cement. Aggregate gradation asphalt content degree of compaction hard soft dense open high low high. Concrete aggregate combined gradation example page 5 of 6 combined aggregates that tend to plot above the power chart line will tend to be stiff and may require high doses of high range water reducer. Effect of continuous wellgraded combined aggregate grading. The gradation data may be used to calculate relationships between various aggregate or aggregate blends, to check compliance with such blends, and to predict trends during production by plotting gradation curves graphically, to name just a few uses. Pdf selecting the optimum graphical method to find aggregate. Blending material is selected natural or crushed mineral aggregate combined with the produced aggregate to meet specifications.
A mathematical method for blending aggregates for a desired. Chapter 2 design and control of bituminous mixtures using. To ensure workability and constructability so that. Lec highway engineering aggregate tests gradation and. Those responsible for selecting the proportions for the concrete mixture shall have the responsibility of determining the proportions of. Aggregate blending optimization optimize aggregate blending using the automated tools like blend to minimum price, blend to target, or blend to midspec. Pdf gradation, design, and cost consideration in blending. Physical properties of aggregates rowan university. Effect of continuous wellgraded combined aggregate grading on concrete performance phase a. The term generally applies to dense graded aggregate.
The solution aggregateblending problem is formulated as a multiob was. Effect of continuous wellgraded combined aggregate. This example presents some basic computations for optimizing a blend of multiple aggregates. As well as, and not short of improving future gradation from a gapgraded to a more dense gradation.
Combined blend gradation 50 20 80 sieve % passing a 100 b 97 c 76 d 63 e 39. Sample reduction equipment required for aashto t 248. The outcome of these evaluations resulted in the introduction of a new blend aggregate grading band for the. The particle size distribution, or gradation, of an aggregate is one of the most influential aggregate characteristics in determining how it will perform as a pavement material. Concrete aggregate combined gradation example general mdt is moving toward optimized gradations for concrete aggregate. Scope sieve analysis determines the gradation or distribution of aggregate particle sizes within a given sample. Used in conjunction with other tests, the sieve analysis is a. Improving concrete through optimizing aggregate gradation. The gradations should be current and are typically the average of more than one individual test for each aggregate. Extract these samples to determine if the average extracted gradation conforms reasonably with the starting formula gradation.
Fine gradation, f sshaped gradation, s coarse gradation, c 2 aggregate sizes 9. The standard sieves for coarse aggregate have openings ranging from 1. Aggregate blending the bailey method originally developed by robert. Advocates14 argue that such mixtures have optimized packing and minimal voids and therefore minimize the cementitious paste required for a given workability. Note 1consider material availability, mixture strength, handling, compaction. Grading is the particlesize distribution of an aggregate as determined by a sieve analysis. In hma, gradation helps determine almost every important property including stiffness, stability, durability, permeability, workability, fatigue resistance, frictional resistance and moisture susceptibility roberts et. Strengththe influence of aggregate gradation on the compressive strength of finished concrete block will determine the necessary cement content to. Binder material, for binding and gradation requirements, is fine, natural soil particles or crusher dust, free from grass, roots, weeds, humus, or other deleterious matter. For certain mixtures, it is beneficial to include an intermediate aggregate, in addition to the traditional rock and sand, to improve aggregate packing. Material blending is a critical need for the aggregate, asphalt, and concrete material industries.
Pdf gradation of aggregates and its effects on properties. Follow the steps shown below to blend aggregate using fineness modulus value. Three blends of fine, medium and coarse gradations in order to compare each of variations, the medium gradation of each variation were chosen from sieve diagram. All aggregate blends contain an amount and size of voids, which are a function of the packing characteristics of the blend. Aggregate packing gradation continuouslygraded, gapgraded, etc. Standard practice for determination of optimum emulsified asphalt content of cold inplace recycled mixtures acrobat, 52 kb wflhd sampling and testing methods acrobat, 3. Determination of the rap or ras aggregate bulk specific gravity a. Aggregate stockpiling and handling iaap 2019 convention.
Superpave design guidelines for using hotmix recycled. To determine the effect of blending locally available materials and determine the potential benefits resulting from using optimized gradation in concrete mixes. Aggregate blending using genetic algorithms article pdf available in computeraided civil and infrastructure engineering 206. Selection of the design aggregate structure design blend consists of determining the aggregate stockpile proportions and corresponding combined gradations of the mix design. A method is developed and documented in this paper for use in aggregate mix design of stabilized base or asphalt concrete design where it is necessary to blend several available aggregate materials to obtain the desired optimum gradation. On aggregate grading is good concrete performance dependent on meeting grading limits. Calculate the cumulative percentage of retained aggregate on each sieve. Combined aggregate gradations were evaluated for mechanical and durability characteristics for paving mix designs. Specification bands coarse medium fine which blend is best. Determine aggregate gradations for individual aggregate fractions and.
The aggregate particle size is determined by using wiremesh sieves with square openings. If the aggregate particles are significantly coated with fines, the extracted gradation is usually finer on the smaller sieves because the fines are picked up. There is not necessary to make sieve analysis of the mixture to obtain desirable gradation. Step by step guide for blending aggregates using fineness modulus value step1 calculate fineness modulus of fine aggregate sieve the fine aggregate using sieves ranging from 80 mm to 150 micron.
Fineness modulus is calculated by dividing by 100 the sum of the cumulative percents retained on specified sieves. Pdf selecting the optimum graphical method to find. Aggregate blending is the process of intermixing two or more fine or coarse aggregates to produce a combination with improved grading or other properties. Aggregate blending bulk density and void content introduction to flexible and rigid. How to form, pour, and stamp a concrete patio slab duration. Combined blend gradation 50 20 80 sieve % passing a 100 b 97 c 76 d 63 e 39 f 25 g 17 h 11 i 7 j 5 k 4. Lec highway engineering aggregate tests gradation and blending free download as pdf file. Characteristics of aggregates gradation specific gravity moisture content strength freezethaw resistance cost. Better utilization of the aggregates decreased production of co emissions illustration of minimizing paste content by blending aggregates to fill void space with smaller aggregates in lieu of paste. Aggregate selection is based upon layer location, traffic level, and traffic speed.
For fine aggregates, the fineness modulus ranges from 2. Blending material is selected natural or crushed mineral aggregate. To ensure workability and constructability so that the mixes can be easily used in engineering applications. Aggregate blending the ability to blend aggregates to meet a specified target is a must. The determination of aggregate proportions depends strongly on the number of aggregate types to be blended, and the.
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. For each aggregate used in the mix design, include a gradation analysis that is representative of the aggregate. Factors which enter into a discussion of aggregate gradation are. The seven standard astm c 33 aashto m 6m 80 sieves for fine aggregate have openings ranging from 150 m to 9.
The proportions of aggregate directly affect the performance of hma depending on their shape, texture, and strongly on the gradation. Graphical methods, aggregate, blending, gradation, proportions, hma. Note 1 consider material availability, mixture strength, handling, compaction. If you are wasting time exporting material gradations to a spreadsheet to perform material blending or your mix design software does not provide adequate blending tools then it is time to step up to the powerful blending tools that are an integral. Average the test results n5 to 10 for asphalt content and gradation. Highway engineering aggregate tests gradation and blending. Bailey method for gradation selection in hotmix asphalt mixture.
1155 1369 1531 1569 1280 242 179 112 238 1100 141 885 1346 1280 732 874 1078 970 1378 449 1179 261 158 1292 874 735 223 668 762 383 651 1439 138 831 1299 905 64 596 951 874 1169 851 1033 34 31