Arun Soil Lab Pvt.Ltd.
Geotech and Material Consultants
Geotech and Material Consultants
Ensure and Assure safety of the structures
For a better and safe place to live and work with strong foundation
Quality Consiousness is Our Core Concept
For a better and safe place to live and work with strong foundation
Quality Consiousness is Our Core Concept
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We have completed 20 years of our existence.
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We are now having rock exploration facilities also.
Pavement Deflection Survey as per IRC: 81 - 1997
Basic Principles of Deflection Method, Pavement Condition Survey and its Measurements
Performance of flexible pavements is closely related to the elastic deflection of pavement under the wheel loads. The deformation or elastic deflection under a given load depends upon sub grade soil type, its moisture content and compaction, the thickness and quality of the pavement courses, drainage conditions, pavement surface temperature, etc.
In order to ascertain the sections where Benkelman Beam Test is to be done, one must first do the Deflection Survey which essentially consists of :-
(i) Condition Survey for collecting the basic information of the Road structure and based on this, the demarcation of the road into sections of more or less equal performance.
(ii) Actual Deflection Measurements as per criteria table given below.
In order to ascertain the sections where Benkelman Beam Test is to be done, one must first do the Deflection Survey which essentially consists of :-
(i) Condition Survey for collecting the basic information of the Road structure and based on this, the demarcation of the road into sections of more or less equal performance.
(ii) Actual Deflection Measurements as per criteria table given below.
Criteria for Classification of Pavement Sections
| Criteria | Pavement Condition |
| Good | No cracking, rutting less than 10mm |
| Fair | No cracking or cracking confined to single crack in the wheel Track with rutting between 10mm to 20mm |
| Poor | Extensive cracking and/or rutting greater than 20 mm; sections with cracking exceeding 20% shall be treated as failed |
In each road section of uniform performance as per para below minimum of ten (10) points should be marked at equal distance in each lane of traffic for making the deflection observations in the outer wheel path. The interval between the points should not be more than 50 m. On roads having more than one lane, the points marked on adjacent lanes should be staggered. In the transverse direction, the measurement points should be 60 cm from the pavement edge if the lane width is less than 3.5m and 90cm when the lane width is more 3.5m. For divided four lane highway, the measurement points should be 1.5m from the pavement edge.
Variability of deflections in a given section should be considered for detecting spots where extra deflection measurements have to be made. For this purpose, highest and lowest values in a group of ten should be compared with mean value. If highest or lowest values differ from the mean by more than one-third of mean, then extra deflection measurements should be made at 25m on either side of point where high or low values are observed. Pavement deflection is measured by the Benkelman Beam which consists of a slender beam3.66 metre long pivoted at a distance of 2.44 metre from the tip by suitably placing the probe between the dual wheels of a standard loaded Truck, having a rear axle weighing 8170 kg fitted with dual tyre inflated to a pressure of 5.60 kg/sqm. for loading the pavement. During actual tests, the total load and the tyre pressure are maintained within a tolerance of +/-1 percent and +/-5 percent respectively.
Variability of deflections in a given section should be considered for detecting spots where extra deflection measurements have to be made. For this purpose, highest and lowest values in a group of ten should be compared with mean value. If highest or lowest values differ from the mean by more than one-third of mean, then extra deflection measurements should be made at 25m on either side of point where high or low values are observed. Pavement deflection is measured by the Benkelman Beam which consists of a slender beam3.66 metre long pivoted at a distance of 2.44 metre from the tip by suitably placing the probe between the dual wheels of a standard loaded Truck, having a rear axle weighing 8170 kg fitted with dual tyre inflated to a pressure of 5.60 kg/sqm. for loading the pavement. During actual tests, the total load and the tyre pressure are maintained within a tolerance of +/-1 percent and +/-5 percent respectively.
