Calculate the total flakiness index in percent as follows. Flakiness and elongation index of aggregate youtube. The particle is considered as elongated if its length is more than 1. Pdf determination of the flakiness and the elongation index for. Elongation index is the percentage by weight of particles in it, whose largest dimension i. Interlocking of the aggregate is inversely proportional to the flakiness index or the elongation index. Objective particle shape and surface texture influence the properties of freshly mixed concrete more than the properties of hardened concrete. Aggregates which are flaky and elongated are detrimental to the higher. Flaky and elongated particles are considered undesirable for base coarse.
Flakiness index test is used to determine the particle shape of the aggregate and each particle shape being preferred under specific conditions. The 3d laser scanning device was used to scan the coarse aggregate particles i. Apr 07, 20 flakiness and elongation index of aggregate. Aggregate are granular material, derived from the most part from the natural rocks, crushed stones, or natural gravels and sands.
Therefore, aggregate properties are very important. Quarter the aggregate sample to obtain a minimum of 200 particles passing the 78in. Laserbased approach for determining flakiness index of aggregates used in pavements j anochieboateng, j komba and j oconnell. For pavements either bituminous or nonbituminous, elongation index of coarse aggregate should not be more than 15%. Detailed video on laboratory experiments with subtitles. Aggregate retained on the 75 mm and passing the 4,75 mm sieve is not included in the test. Aggregate are the important constituent in concrete. Elongation index and flakiness index of coarse aggregate bs 812. Laserbased approach for determining flakiness index of aggregates used in pavements j anochieboateng, j komba and j oconnell csir built environment, bldg 2c, p o box 395, pretoria, 0001, south africa. May 08, 20 objective for determination of flakiness index of coarse aggregate, where the size of the coarse aggregate are larger than 6. The flakiness index of an aggregate is the mass of particles in that aggregate which will pass the appropriate slot or slots for the individual size fraction expressed as a percentage of the total mass of that aggregate. The computed flakiness indices were in good agreement with the measurements from the standard methods, thus. Retained on flakiness percentage of bakiness index.
Flakiness and elongation indices aggregate particle shape characteristics and variations can affect the workability and strength of concrete. What is the significance of flakiness index and elongation index. What is the significance of flakiness index and elongation. Flakiness and elongation of aggregates and concrete properties published on december 6, 2016 december 6, 2016 27 likes 9 comments. A study on influence of shape of aggregate on strength and. The procedures for their measurement are specified in bs812, section 105.
Aggregate is separated into seven sieve fractions from 636. Is the combined flakiness and elongation index of aggregate. Subsequently slump index and compressive strength of concrete were determined. Effect of aggregate flakiness on the compressive strength of. The elongation index is found by separating the elongation particles and expressing their mess as a percentage of the mass of sample tested.
Elongation index is the % by weight of particles whose greater dimension is greater than 45 of the mean dimension. The influence of the shape of the coarse aggregate on some. Influence of combined flakiness and elongation indices of. Particle shape analysis of coarse aggregate using digital. Generally, this parameter is determined by calculating a ratio between the different dimensions of the particles and by comparing this ratio to a flatness or elongation limit. This british standard, a section of the bs 812 series, describes methods for determining the flakiness index of coarse aggregate. Definition of flakiness index and elongation index. Flakiness index and elongation index test on coarse aggregates. Report the elongation index in percentage rounded off to the nearest whole number. 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 particles are classified as flaky when they have a thickness of less than 0. 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. Similarly, the particle is considered as flaky if its thickness is less than 0. The standardized methods used for this purpose vary among countries, but all of them are.
Draw a horizontal line at 50% passing from the vertical scale to intersect with the grading curve. 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. Elongated and flaky stones are normally not very suitable for road works since the shape and the size make them difficult to compact. Exp 1 flakiness and elongation index civil engineers pk. Theory elongation index aggregate particles are classified as elongation when they have a length greatest dimension of more than 1. Initially an aggregate samples were collected from the stone crusher two types and prepared with different proportions of flakiness and elongation indices to conduct tests on properties of aggregates and compressive strength and flexural strength tests on concrete. Roughtextured, angular, and elongated particles require more water to produce workable concrete than smooth, rounded compact aggregate. Both flakiness and elongation tests are not applicable to sizes smaller then 6. Methods of test for aggregates for concrete, part i. Maximum permitted elongated index is 35, 40 or 45% for aggregate sizes 2. Particle shape and surface texture influence the properties of freshly mixed concrete. Effect of aggregate flakiness on the compressive strength.
The flakiness index of an aggregate sample is found. The percentage of flaky and elongated particles that it contains. Aggregate is termed as flaky when its least dimension i. Aggregate angularity flakiness elongation index gilson co.
The percentage by weight of flaky particles present in a given test sample. The flakiness index of aggregates is the percentage by weight of particles whose least dimension thickness is less than three fifths 0. Doc flakiness index and elongation index of coarse. 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. Oct 09, 2015 detailed video on laboratory experiments with subtitles. Therefore, aggregate properties are very important in hma because it will affect the performances of the hma. The influence of combined flakiness and elongation indices on marshall properties of coarse aggregate with nmas 12.
Bulk density and voias of coarse aggregate duration. Is the combined flakiness and elongation index of aggregate is the numerical sum of separate elongation index and flakiness index. The test is not applicable to materials passing the 6. The test is carried on aggregate sizes between 63 mm and 6. Elongation index and flakiness index of coarse aggregate bs 812 part. Flakiness and elongation of aggregates and concrete properties. May 08, 20 objective for determination of elongation index of coarse aggregate, where the size of the coarse aggregate are larger than 6. Aggregates make up between 80% to 90% of total volume or 94% to 95% of the mass of hot mix asphalt hma. Determination of the flakiness and elongation index for the given aggregate. Fundamental aggregate shape properties anochieboateng et al. Apr 19, 2006 aggregate shape is considered to be a key parameter for concrete and bituminous mixtures design.
According to bs specifications flakiness index of the aggregate used for the road construction should not be greater than 35 % and elongation index should not be greater than 45 %. 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. Aggregate shape is considered to be a key parameter for concrete and bituminous mixtures design. Definition of flakiness index and elongation index civil. Elongation index and flakiness index of coarse aggregate bs. What is the use of the elongation and flakiness index. Part 8 materials manual april section 933 method for. For determination of flakiness index of coarse aggregate, where the size of the coarse aggregate are larger than 6. A flaky particle is the one whose least dimension thickness is less than 0. Flakiness and elongation index of aggregate gilson co. This method is based on the classification of aggregate particles as flaky when they have a thickness smallest dimension of less than 0. Flakiness and elongation index, properties and testing of. Proportional calipers are efficient devices that quickly determine percentages of elongated and flat particles in coarse aggregate fractions. The particle shape of the aggregate is determined by.
Flat particles, elongated particles, or flat and elongated particles in coarse aggregate astm d 4791 glossary flat and elongated particles of aggregate those particles having a ratio of length to thickness greater than a specified value. This test is not applicable to sizes smaller than 6. Determination of the flakiness and the elongation index for the given aggregate. Dec 18, 2017 theory elongation index aggregate particles are classified as elongation when they have a length greatest dimension of more than 1. Roughtextured, angular, and elongated particles require more water. Flakiness index is the percentage by weight of particles in it, whose least dimension i. Thickness the maximum dimension perpendicular to the length and width. The standardized methods used for this purpose vary among countries, but all of them are slow and lack precision. Flakiness and elongation indices of coarse aggregate youtube.
Determination of elongation index linkedin slideshare. Dec 06, 2016 flakiness and elongation of aggregates and concrete properties published on december 6, 2016 december 6, 2016 27 likes 9 comments. Aggregate is separated into seven sieve fractions from 63. Nearly all the samples were found within the specified limits of astm specifications and are appropriate material for concrete, asphalt and suitable as dimension stone. Objective for determination of elongation index of coarse aggregate, where the size of the coarse aggregate are larger than 6. Flakiness index and elongation index of coarse aggregates. Bs1241 specifies a flakiness index not exceeding 30% irrespective of the aggregate size. Regarding shape analysis of the coarse aggregate, only the flakiness and elongation are measured. 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.
Shape tests on coarse aggregates such as flakiness index and elongation index, its importance in concrete construction, methods of. The flakiness index of an aggregate sample is found by separating the flaky particles and expressing their mass as a percentage of the mass of the sample tested. The percentage by weight of the elongated particles present in a given test sample. The amount of flakiness is denoted by flakiness index. Elongation index and flakiness index of coarse aggregate. Flakiness and elongation test construction aggregate road.