A decrease of the water requirement and content of cement and an increase of the density of concrete due to a decrease of the sand content and corresponding increase of the stony component are a positive aspect of increasing the size of the aggregate. In bituminous mixtures, flaky aggregates make for a harsh mix and may also crack and break up during compacting by rolling. Objective for determination of flakiness index of coarse aggregate, where the size of the coarse aggregate are larger than 6. The scope of this test is to provide test methods for determining the elongation index of coarse aggregate. If the amount of either the coarse or the fine aggregate thus obtained is substantially. Subsequently slump index and compressive strength of concrete were determined.
Flakiness and elongation flakiness index sieve set uta0410. Surface texture of coarse aggregates surface texture of the aggregates is the property of its surface that classifies it into polished or dull, smooth or rough. Dec 18, 2017 theory elongation index aggregate particles are classified as elongation when they have a length greatest dimension of more than 1. Flakiness index test is not applicable for aggregates sizes smaller than 6. Aggregate is separated into seven sieve fractions from 63. Flakey particles are those which are generally thin compared to their major dimensions. Finally, you can have numerical sum of flakiness index and elongation index to get combined f. The latter attained about 95% of its 28day value by 7 days and gained little at later ages. Particle is elongated when its length longest dimension is more than 1.
Elongation index is the percentage by weight of particles in it, whose largest dimension i. Such particles make poor concrete, since they are hard to compact, and e. Flakiness and elongation indices of coarse aggregate youtube. Aggregate angularity flakiness elongation index gilson co. Aggregate determination of the resistance to wear microdeval asdi. To evaluete the thickness and the elongation index of the aggregates particles, thickness gauge code 47d0540 and length gauge code 47d0541 can be used. Issuu is a digital publishing platform that makes it simple to publish magazines, catalogs, newspapers, books, and more online. Elongation index and flakiness index of coarse aggregate. Part 2flakiness index article pdf available in materials and structures 391. Elongation and flakiness test construction aggregate. Elongation and flakiness index of coarse aggregate with 0%, 5%, 10%, 15%, 20 % and 25% and impurity of fine aggregate with 0%, 2%, 4%, 6%, 8 % and 10% were adjusted while the amount of stone, sand, cement and water weer kept unchange.
Aggregate crushing value crushingtest of coarse aggregate duration. For measuring the coarse aggregate shape only, the multiple ratio shape analysis method mra is most desirable, and is much cheaper than all the other test methods. What is the significance of flakiness index and elongation index. Flakiness and elongation index, properties and testing of. Flakiness index and elongation index test on coarse aggregates. Lab equipments flakiness manufacturer from ahmedabad. Aggregate particles are classified as flaky when they have a thickness of less than 0. Is the combined flakiness and elongation index of aggregate is the. In the flakiness test, the flaky particles are separated from each size fraction by manual gauging and their quantities measured by weighing. Flakiness and elongation test free download as word doc.
Flakiness and elongation index of aggregate youtube. Definition of flakiness index and elongation index civil. The elongation and flakiness test involves sieving the aggregates through a sieve with long parallel openings as shown in the diagram below which measures the amount of aggregates which are elongated which determines the flakiness index. Similarly, the particle is considered as flaky if its thickness is less than 0. T 39 the above result of elongation index is less than 30%, hence satisfactory. This british standard, a section of the bs 812 series, describes methods for determining the flakiness index of coarse aggregate.
Elongation index and flakiness index of coarse aggregate bs 812. Determination of elongation index linkedin slideshare. Basic points, apparatus, procedure, results and inference are discussed in detail in the simplest form possible. This british standard, a part of the bs 812 series, describes the method for determining the elongation index of coarse aggregate. How to determine flakiness index and elongation index test. Bulk density and voias of coarse aggregate duration. Click here to go to elongation test flakiness index test is used to determine the particle shape of the aggregate and each particle shape being preferred under specific conditions. Coarse aggregates in high strength concrete given the critical role that the interfacial transition plays in highstrength concrete, the mechanical properties of coarse aggregate will have a more pronounced effect than they would in conventionalstrength concrete. Flakiness and elongation index of aggregate gilson co. Elongation index and flakiness index of coarse aggregate bs 812 part. Determination of the flakiness and the elongation index. Unfortunately, this book cant be printed from the openbook.
Determination of flakiness and elongation index of coarse aggregates posted on november 16, 2019 april 8, 2020 author admin comment0 575362 views hello friends, this is. Particle shape analysis of coarse aggregate using digital. Flakiness and elongation test construction aggregate. Dec 06, 2016 flakiness and elongation of aggregates and concrete properties published on december 6, 2016 december 6, 2016 27 likes 9 comments chemist mina ataalla follow. Coarse aggregate having flakier particles will adversely affect the strength of concrete. This method is based on the classification of aggregate particles as flaky when they have a thickness smallest dimension of less than 0.
A study on influence of shape of aggregate on strength and. Dec 12, 2017 flakiness and elongation index of coarse aggregate particle shape and surface texture influence the properties of freshly mixed concrete more than the properties of hardened concrete. Qualitative and quantitative assessment of gravel deposits between. Is the combined flakiness and elongation index of aggregate.
The elongation index is found by separating the elongation particles and expressing their mess as a percentage of the mass of sample tested. For base course and construction of bituminous and cement concrete types, the presence of flaky and elongated particles are considered undesirable as these cause inherent. The particle shape of aggregate is determined by the percentages of flaky and elongated particles contained in it. Elongation index and flakiness index of coarse aggregate bs. The length gauge elongation index bs, is used to measure the elongation index of aggregates. Shape tests on coarse aggregates such as flakiness index and elongation index, its importance in concrete.
Effect of the maximum size of coarse aggregate on the main. Calculate the total flakiness index in percent as follows. Exp 1 flakiness and elongation index civil engineers pk. Aggregate is termed as flaky when its least dimension i. The elongation index of an aggregate is the percentage by weight of particles whose greatest dimension. The flakiness index of the aggregate is the percentage by weight of particles in it, whose least dimension thickness is less than three fifth of their mean dimension. The percentage by weight of flaky particles present in a given test sample. Plot the grading of the aggregate on a aggregate gradation chart, mat 67. It is measured on particles passing through mesh size of 63mm and retained on mesh size of 6. The mra provides the distribution of shape in an c h a p t e r 4 conclusions and suggested research aggregate sample, but it cannot be used for measuring angu larity or texture. Theory of flakiness index and elongation index tests the particle shape of aggregates is determined by the percentages of flaky and elongated particles contained in it. In order to determine the effect of flakiness index on the bituminous mix, a number of aggregate.
Mean size of aggregates is defined as the mean of two seive sizes, between which the particle is retained. Elongation test and flakiness tests are known as shape tests and are performed on aggregate. Flat and elongated particles of coarse aggregates have a tendency to fracture more easily than other aggregate particles. Flakiness and elongation of aggregates and concrete properties published on december 6, 2016 december 6, 2016 27 likes 9 comments. The use of coal mill reject in the concrete industry may be a replacement of stone aggregate with advantages like. Objective particle shape and surface texture influence the properties of freshly mixed concrete more than the properties of hardened concrete. The aggregate to be classified is separated into six sieve fractions from 6. Elongation index test on coarse aggreagtes the constructor. Oct 09, 2015 detailed video on laboratory experiments with subtitles. When an aggregate particle has a thickness less than 0. Aggregate elongation index tests open geotechnical.
Flakiness and elongation index of coarse aggregate particle shape and surface texture influence the properties of freshly mixed concrete more than the properties of hardened concrete. Flakiness sieves, aggregates testing equipment, controls. Flakiness and elongation of aggregates and concrete properties. Pdf aggregate shape is considered to be a key parameter for concrete and bituminous mixtures design. As expected, coarse aggregate modulus was reflected in concrete modulus. In case of gravel it is determined by its angularity number. Roughtextured, angular, and elongated particles require more water to produce workable concrete than smooth, rounded compact aggregate. This standard specifies a method for determining the flakiness index of coarse aggregate that passes a sieve of aperture size 75 mm and that is retained on a sieve of aperture size 4 750 om. The other properties of aggregate such as bulk density, impact value, water absorption have been studied for different shapes of aggregates. Conclusions and recommendations the national academies press. Additionally, flat and elongated particles of aggregate, for some construction uses, may interfere with. What is the use of flakiness index in concrete road work.
Hence we offer thickness gauge and length gauge to check flakiness and elongation index of the aggregate respectively. Paper open access related content effect of different coarse. Each lightweight aggregate lwa used in this study had. The flakiness index of an aggregate sample is found. The consumption of cement with an increase of the size of the aggregate from 40 to 80 mm, other conditions being equal, decreases by 20. The dried aggregates sample is allowed to passing and retained on a set of sieve. What is the use of the elongation and flakiness index. While tested for gradation, the coarse aggregates ranged from uniform to gap graded. The amount of flakiness is denoted by flakiness index. Jul 31, 2015 flakiness and elongation index of aggregate bput digital learning resources. Determination of flakiness and elongation index of coarse. Flakiness index and elongation index of coarse aggregates free download as word doc.
Standard test method for index of aggregate particle shape. Adjustment of flaky aggregates flakiness index test is applicable on those aggregate sizes bigger than 6. The figure 1 depicts slum value of a1 coarse aggregates for all five groups. However, aggregate characteristics other than strength, such as the size, shape, surface texture, grading and mineralogy are known to affect concrete strength in varying degrees. Aggregate to be classified is separated into seven sieve fractions from 63 to 6.
The flakiness index of course aggregate is defined in percentage by weight of aggregate particles and least dimension thickness of those particles should not be less than 0. Effect of coarse aggregate on elastic modulus and compressive. While elongation index test is used to determine the quantity of aggregate particles that are elongated instead of cubicle in shape. Draw a horizontal line at 50% passing from the vertical scale to intersect with the grading curve. An aggregate is classified as being elongated if it has a.
Elongation index is the % by weight of particles whose greater dimension is greater than 45 of the mean dimension elongation index wt of aggregate retained on specified gauge total wt of aggregate taken. Quarter the aggregate sample to obtain a minimum of 200 particles passing the 78in. Flakiness index and elongation index of coarse aggregates. Elongation index of an aggregate is the percentage by weight of particles whose greatest dimension length is greater than one and fourfifth times 1. To determine the flakiness index of the coarse aggregate. The particle is considered as elongated if its length is more than 1. Determinations for the flakiness index and flakiness and elongation of aggregate use a british standard classification system consisting of a thickness gauge for determining flakiness index and a metal length gauge for determining elongation index. Aggregate is separated into seven sieve fractions from 636. Particle shape and surface texture influence the properties of freshly mixed concrete. Conclusions for the wide range of coarse aggregate stiffness used, combined with a single, high strength, low watercement ratio mortar, the following conclusions may be drawn.
Shape indices such as an elongation index and a flakiness index were. Now, you need to find the amount of elongated particles to the aggregates which passed flakiness test. Proportional calipers are efficient devices that quickly determine percentages of elongated and flat particles in coarse aggregate fractions. The flakiness of aggregate is determined by measuring the thickness of individual particles. Roughtextured, angular, and elongated particles require more water.
The maximum size of a wellgraded coarse aggregate of a given. If elongated particles are used for pavement base course construction, they may break down easily under. Retained on flakiness percentage of bakiness index. Easily share your publications and get them in front of issuus. The aggregate to be classified is separated into seven sieve fractions from 6. Determination of the flakiness and the elongation index for the given aggregate. 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.
The flakiness and elongation rocks are not suitable for road construction because this type of rocks will make the road surface not balance and easy to damage. Not so much different between both of the two values. Special specifictions part i recommended limits for aggregates used for all concrete worksaggregates used in all concrete worksshall comply with the requirements ofthe following reccomended limits. Cement concrete produced with natural and coarse aggregates.
The aggregate strength is usually not a factor except in lightweight and high strength concrete. The test is carried on aggregate sizes between 63 mm and 6. Flakiness index is the percentage by weight of particles in it, whose least dimension i. Interlocking of the aggregate is inversely proportional to the flakiness index or the elongation index. Elongation index of an aggregate is the percentage by weight of particles whose greatest dimension length is. What is the significance of flakiness index and elongation.
To study the strength characteristics of concrete by. The elongation index of an aggregate is the percentage by weight of particles whose greatest dimension length is greater than ninefifths 1. When the coarse aggregate does fracture, the gradation will likely change which may be detrimental to the mix. Aggregates which are flaky and elongated are detrimental to the higher. Is the combined flakiness and elongation index of aggregate is the numerical sum of separate elongation index and flakiness index.
Elongation value is 0% because the aggregate is rounded so no any retain value. Aggregate retained on the 75 mm and passing the 4,75 mm sieve is not included in the test. Aggregate particles are classified as elongated when they have a length greatest dimension of more than 1. Definition the flakiness index of a coarse aggregate is the mass of particles in that aggregate, expressed as a percentage of the total mass of that aggregate, which will pass the slot.
As the percentage of laterite increases, there was a reduction in all these characteristics even with the particle size of coarse aggregate reduction due to loss from the aggregate paste interface zone. Elongation index for classification of aggregate particles. Aggregates that flaky could always lower the workability of concrete and also affects its longterm durability. Conclusion based on the objective for this experiment is to identify the flakiness and elongation index of the given aggregrate samples, we indentified the flakiness and elongation is not influenced each other. Objective for determination of elongation index of coarse aggregate, where the size of the coarse aggregate are larger than 6. Dry density of soil compaction test by core cutter method and calculations road construction civil. In this video, i had given full detail practical procedure of determining flakiness and elongation index of coarse aggregate. Aggregate quality for road construction will also influence the road performance.
Methods of test for aggregates for concrete, part i. Flakiness and elongation tests are not applicable to sizes smaller than 6. For impact crushed a1 coarse aggregates slump values were evaluated for all five groups and it was evident from experiment that, there was a steady decrease in slump value with the decrease of wc ratio. B elongation index test 1 sample of aggregates were prepared. It is mentioned in the test procedure bismorth that while doing combined flakiness and elongation test, the flaky aggregates should be separated initially. Determination of the flakiness and the elongation index for the given aggregate sample. If you need to print pages from this book, we recommend downloading it as a pdf. Determination of flakiness index of the coarse aggregate. After weighing, the flakiness index is calculated as the ratio of the mass of flaky particles to the total mass of the aggregate sample expressed as a percentage.