It is widely used all over the world evaluation of the requirements of strengthening of flexible pavements. The following accessories are added to the usual benkelman beam. Applications the road surface texture can be measured by sand patch method. Results of deflection measurement by benkelman beam method and determination of the characteristic deflection. The benkelman beam is used with a loaded truck typically 80 kn 18,000 lb on a single axle with dual tires inflated to 480 to 550 kpa 70 to 80 psi. Deflection beam has been in use in india for more than two decades by different organizations. Benkelman beam deflection bbd test benkelman beam is less expansive deflection measuring equipment and method of study is simple and easy to carry out. With the benkelman beam measurement method, the vertical deflection of the road surface is measured after a defined load of 5 tons has rolled away. Design of overlay for flexible pavement civil iitb. Benkelman beams shall be calibrated in accordance with appendix a of this method. Pdf conventionally in india overlay of flexible pavement design is carried. Aashto t 25601, standard method of test for pavement deflection measurement 3 istilah dan definisi istilah dan definisi yang digunakan dalam standar ini sebagai berikut. Possible method of determining structural number for.
Adjustable feet for benkelman beam, complete with two spirit level calibration device 80b01803 calibration device for 80b0180 benkelman beam apparatus. The vertical deflection is recorded by a special measuring beam, which is mounted on a. Pdf evolution of the deflection according to truck. Benkelman devised the simple deflection beam in 1953 for measurement of pavement surface deflection. Referenced documents purchase separately the documents listed below are referenced within the subject standard but are not provided as part of the standard aashto standard. Part ii of this report presents the recommended testing procedures, equipment, and personnel requirements for conducting the benkelman beam test. Overlay design by benkelman beam road surface standard. Pdf mechanistic design of overlay based on benkelman beam.
Deflections by fwd with guidelines of irc115 and by benkelman beam with guidelines of irc81 were measured on selected sections. Pavement evaluation by benkelman beam of state highway. Related items highlow detector rolling straight edge measures planeness of pavement surfaces, such as highways, airport runways, bridge decks. Accurate sand patch testing cannot be carried out when road. Beams that do not conform must not be used on roads and maritime services projects. Data acquisition system qtdas capable of logging test data at every 50mm travel of the test. Pavement composition from trial pits and core cutter method. Ai deflection method the overlaid pavement is considered as a two layer system with ac overlay as layer 1 and the existing pavement as layer 2. It was decided that 8 sets of observations of the benkelman beam.
It should be used to find out the overlay thickness of the. Experimental setup of benkelman beam deflection equipment the arrangement was made for benkelman beam deflection test on runway for evaluation of structural capacity of existing flexible pavement. Pddx pavement deflection data exchangetechnical data guide, version 1. Cara uji lendutan perkerasan lentur dengan alat benkelman. Measures the deflection of a flexible pavement under moving wheel loads. The beam pivot bearing and the dial gauge must move freely without friction or slop. The method is suitable for bituminous surface course and concrete pavement surface with texture depth greater than 0. Pavement deflection is measured by the benkelman beam which consists of a slender beam 3.
Comparison of falling weight deflectometer with other. The h3220a benkelman beam apparatus is a convenient and accurate device. The requirements of a typical benkelman beam as shown in figure 4 are listed in test methods t160 and t199. Lwd deflectometer devices are dynamic nondestructive testing tools commonly used in the field of pavement systems to meas. General a the surface under the beam shall be sound and. To lay down a uniform procedure for the design of flexible overlays using the benkelman beam deflection technique tentative guidelines of flexible road pavements using benkelman beam deflection technique irc.
Benkelman beam test has also been conducted following irc 81 1997on the entire road network to design the overlay. Deflection should be find out by benkelman beam deflection test. The h3220a benkelman beam apparatus is a convenient and accurate device used for measuring the deflection of flexible pavements under moving wheel loads. History of benkelman beam deflection technique2 development of methods such as benkelman beam deflection method for evaluation of structural capacity of existing flexible pavements and also for estimation and design of overlays for strengthening of any. T256standard method of test for pavement deflection measurements. Lecture series on introduction to transportation engineering by prof. By considering the existing pavement as a homogeneous half space, and using the characteristic deflection the modulus value of layer 2 is found out from e2 1. The method also describes the procedure for the calibration of the deflection data acquisition system ddas and bwl4 manual, queensland. Test method tnz t1 1977 benkelman beam test dear cetanz member, please find attached the results from the benkelman proficiency testing organised by cetanz in may 2008. The entire apparatus, must be sturdy, rigid and without slop. By suitably placing the probe between the dual wheels of a loaded truck, it is possible to measure the rebound and residual deflections of the pavement structure.
Evolution of the deflection according to truck overloading. The results of the deflection measurements from the fatickkaolack road with modulation of the axle load of 10, and 16 tons are given in table 1 the results showed that the values read on the beam in the case of the load of 10 tons to the axle vary. Flexible road pavement using benkelman beam deflection bbd technique. It should be used to find out the overlay thickness of the flexible over flexible pavement as per irc81 1997. Nine laboratories took part in the benkelman beam proficiency test. E benkelman beam a benkelman beam is shown in figure 2. Even though there are many methods for designing of overlays such as, lacroix deflectgraph, dynaflect, falling weight deflectometre fwd and benkelman beam deflection technique among all these bbd technique is the easy and convenient method as mentioned earlier as well.
The design results obtained from both the methods are compared. The magnitude of rebound deflection of a flexible pavements when a standard wheel load of truck is moved forward is measured. Deflection testing of earthwork and pavement layers roads and. The original deflection measuring method, using the benkelman beam adopted on washo road test fig. Benkelman beam bb devices should be corrected by a factor of ground water table seasonal factors and temperature correction and a correction factor of the load test if not exact test load of 8. Deflectometer rdd, benkelman beam deflectometer bbd. Operating on a simple lever arm principal, the device consists of a reference beam body, twopart probe beam, and rear zero adjustment assembly.
Using fwd data with me design and analysis, volume iii. Sample is brought to lab and plasticity index, liquid limit, specific gravity etc. Development correlation between benkelman beam deflection and falling. Measuring the bearing capacity of forest roads with an. Benkelman beam evaluation of structural capacity of existing pavement estimation and design of over lay for strengthening of weak pavement 5. The correlation between the heavy vibrator and members of the benkelman beam family is poor.
Comparative studies between benkelman beam deflections. Remaining fatigue and rutting life after and before overlay were. Rebound deflection using benkelman beam irc 81, 1997. It was decided that 8 sets of observations of the benkelman beam deflection test may be taken. The deflection of the pavement surface produced by the test load is transmitted to the other end of the beam where it is measured by means of a dial gauge or a recorder. Both the fwd and instrumented benkelman beam are used in new zealand to measure the deflection bowl. Pdf on jan 1, 2018, fatou samb and others published evolution of the deflection according to truck overloadingcomparison between benkelman beam method and fem of lateritic pavements find. Portable deflection beams come in a variety of designs and styles, some of which do not conform to roads and maritime services requirements. Comparison study of overlay design for engineering. Standard test procedure for benkelman beam deflection.
Benkelman beam adalah revisi dari sni 0324161991,metode pengujian lendutan perkerasan lentur alat benkelman beam. The a e dimension can be determined from the following a e 4 recommends that the deflection. Standard guide for general pavement deflection measurements. Two calibrated modified benkelman beams figure 1 with a data acquisition system and accessories. Benkelman beam apparatus, asphaltbituminous mixture. A method for determining allowable spring deflection with the benkelman beam was developed from a literature survey and from a closely related field study. The beam test shall be as per nzta specification t1 except that the recordings for bowl deflection shall not be recorded or used in. Dimensions a and b must be recorded on form bb1 for each beam together with the benkelman beam no. Collection and interpretation of pavement structural.
Sudhakar reddy, department of civil engineering, iit kharagpur. The amount of rebound deflection can be determined by the formula 3 below. Results of deflection measurement by benkelman beam method and determination of the characteristic deflection the results of the deflection measurements from the fatickkaolack road with modulation of the axle load of 10, and 16 tons are given in table 1. Strength evaluation of flexible pavement of runway using. This test method sets out the procedure for measuring the rebound deflection of a flexible pavement or road formation using a portable deflection beam under both a standard wheel load and tyre pressure. For the love of physics walter lewin may 16, 2011 duration. Methodology and working of the benkelman beam is as follows. Texture depth using sand patch method bs 598 part 105, 1990. Tests pits are dug at approximately to m intervals depending on benkelman beam deflection method uniformly in performance of pavement structure in order to determine the pavement details such as, thickness and composition of the pavement layers and the type of sub grade below. Benkelman beam evaluation of structural capacity of existing pavement estimation and design of over lay for strengthening of weak. Traffic studies including axle load surveys using portable weigh bridge trl.
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