A quantity of aggregate shall be taken sufficient to provide the minimum number of 200 pieces of any fraction to be tested. Effects of aggregate size, shape, and surface texture on. The degree of packing of the particles of one size depends upon their shape. An increase in void content by these procedures indicates greater angularity, less sphericity, rougher surface texture, or combinations thereof. The shape of aggregate particles can significantly influence certain properties of concrete, both in its fresh and hardened states. Aggregate size d maximum mm test portion mass minimum kg 63 40 32 10 16 2,6 8 0,6. The sample shall be sieved with the sieves specified in table 1.
Pdf properties of concrete as influenced by shape and. Flaky or elongated materials, when used in the construction of a pavement, may cause the pavement to fail due to the preferred orientation that the. Exp 1 flakiness and elongation index civil engineers pk. In the master list of aggregate tests table, there are preparation activities for each test. Quantify shape, angularity and surface texture of aggregates using image analysis and study their effect on performance by dallas little senior research fellow. Effects of aggregate size, shape, and surface texture on the properties of bituminous mixturesa literature survey fred j. For example, rounded aggregates with small particle indexes will not retain the cone mold shape at any moisture content. Sieve the sample through the is sieves as specified in the table. You can use this list of tests to prepare for your visit to the lab.
Trbs national cooperative highway research program nchrp report 555. This edition completely replacesy 201the 9 labofebruarratory manual of test procedures. So, we should take care about the shape of aggregate. Due to high surface area to volume ratio, the flaky and elongated particles lower the. Aggregates are the principal material in pavement construction. Range of particle sizes found in aggregate for use in concrete. Determination of aggregate shape properties using xray. Flakiness and elongation index of aggregate youtube. The shape of aggregate particle has significant influence on performance of the bitumen pavement. Grading grading is the particlesize distribution of an aggregate as determined by a sieve analysis using wire mesh sieves with square openings. The strength of aggregate parent rock is determined by preparing a cylindrical shape specimens of size 25 mm diameter and 25 mm height.
In this experiment, flakiness index was used as independent variables and other properties such as gradation are kept constant as far as their properties met the specification required for the asphalt mixture. Shape and properties this chapter describes research on aggregate shape and properties, and on the shape and properties of general particles. This test is not applicable for sizes smaller than 6. Particle shape principally affects the wcm by its effect on water demand and amount of paste required for workability of a given mixture. Flakiness index and elongation index test on coarse aggregates. The two most common test methods to determine specific gravity are the astm c127 standard test method for relative density specific gravity and. Aggregate size is considered to include maximum size, size range, and gradation. The test results indicated that there is a good correlation between the some shape properties of aggregate and compressive strength keywords. Test methods for characterizing aggregate shape, texture. Therefore, there is a need to be able to completely characterize the shape of aggregate particles, in three dimensions, in order to develop computational models that. Aggregate crushing value test procedure and result.
While elongation index test is used to determine the quantity of aggregate particles that are elongated instead of cubicle in shape. In the smaller size ranges, microphotographs and special techniques were used to measure the aggregate shape. Trbs national cooperative highway research program nchrp webonly document 80, appendixes to nchrp report 555. Classification of aggregates based on size and shape. Standard test method for index of aggregate particle shape. A quantity of aggregate shall be taken sufficient to provide the minimum number of 200 pieces of. The earliest bituminous mixtures used the finer aggregate sizes and are generally referred to as sheet mixtures. Chapter 7 standard test procedures tests for aggregates and bricks may 2001 page 7. Flakiness index, elongation index and angularity number. The effect of the shape of inclusions on the properties of the composite material in which they are embedded depends on. The strength serviceability requirements of bitumen mixes such as stability, flow, voids.
The report also explores a test method that it is appropriate for use in central and field laboratories, which measures. Typical values substance specific gravity density lbft3 water 1. Alternate caa tests it is difficult to completely describe aggregate particle shape and its contribution to hma performance by looking just at the percentage of fractured faces. The effect of different percentages 0 to 50% of combined flaky and elongation aggregates cfea for pavement quality concrete pqc on the compressive and flexural strength of cement concrete and. This test is used to determine the particle shape of the aggregate and each particle shape being preferred under specific conditions. Standard test methods for uncompacted void content of fine. The test consists of subjecting the specimen of aggregate in standard mould to a compression test under standard load conditions see fig1. Test methods for characterizing aggregate shape, texture, and angularity contains appendixes b trough e of nchrp report 555. The test sample shall be subjected to a total 15 suchthe test sample shall be subjected to a total 15. These data sheets not only allow efficient data entry, but also put the information in the proper format for analysis. Making a sieve analysis test of coarse aggregate in a laboratory. Pavement interactive was developed by the pavement tools consortium, a partnership between several state dots, the fhwa, and the university of washington, as part of their effort to further develop and use computerbased pavement tools.
Coarse aggregate may be available in several different size groups, such as 19 to 4. When small amounts of coarser aggregates were added to the fine aggregate bitumen mixture, the mixtures were known as stonefilled sheet mixtures. This value is a quantitative measure of the aggregate shape and texture characteristics that may affect the performance of road and paving mixtures. The astm d 5821 method is based on the pennsylvania test method and was later adopted as the method for measuring coarse aggregate angularity within superpave mix design. This manual has the current versions of our laboratory test procedures. Recently, we have witnessed a number of advances in. For base course and construction of cement concrete types, the presence of flaky and elongated particles are considered undesirable. Aggregate shape, digital image processing, concrete, compressive strength 1 ataturk university, department of civil engineering, erzurum, turkey.
We know that aggregate is derived from naturally occurring rocks by blasting or crushing etc. Flakiness index test is used to determine the particle shape of the course aggregate. Maerz rock mechanics and explosives research center, university of missourirolla abstract aggregate size and shape measurements are increasingly becoming important issues in the mining, comminution, materials handling, and construction industries. Test methods for characterizing aggregate shape, texture, and angularity examines a methodology for classifying aggregates based on the distribution of shape, texture, and angularity characteristics. The particle shape of the aggregates is obtained by the percentages of flaky and elongated particles accommodate in it. However, if a test was identical to an aashto, ast, or mftp procedure it was not m duplicated in this manual. Note 2many aggregates, either from lithologic differences in the.
Also, the bond with the cement paste may be weakened due to the accumulation of bleed water under the relatively large surface areas of flat particles of aggregate. Read test methods for characterizing aggregate shape. But, the shape of aggregate will affect the workability of concrete. Properties of concrete as influenced by shape and t exture of fine a ggregate. Pdf determination of the flakiness and the elongation. Determination of the flakiness and the elongation index for the given aggregate sample. Pdf to determine impact of shape of course aggregate on. This paper brings together the findings and opinions found in the literature, published principally during the past 40 years, concerning the effects of aggregate size, shape, and surface texture on the properties of bituminous mixtures. Pdf effect of shape of aggregate on pavement quality. The elongation index of an aggregate is the percentage by weight of particles whose greatest dimension length is greater than ninefifths 1. Depending on the type of parent rock gives different compressive strength varying from a minimum of about 45 mpa to a maximum of 545 mpa. Fines generation during rock crushing, from each crusher type, chokefeeding the crushers.