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Minimum CBR value for road subgrade IRC

Sub-base materials comprise natural sand, gravel, laterite, brick metal, crushed stone or combinations thereof meeting the prescribed grading and physical requirements. The sub-base material should have a minimum CBR of 20 % and 30 % for traffic upto 2 msa and traffic exceeding 2 msa respectively CBR value of subgrade. 28.6 Design tra c The sub-base material should have a minimum CBR The design procedure given by IRC makes use of the CBR value, million standard axle concept, and vehicle damage factor. Tra c distribution along the lanes are taken into account. The design is meant for design tra The CBR (California bearing ratio) value is a penetration test that evaluates the mechanical strength of subgrades and basecourses that lay beneath new road constructions or pavements. Typical Values for subgrades are; Crushed stone CBR 20 to 100 Sandy Soils CBR 5 to 4

IRC method of design of flexible pavement

CBR method recommended by California state of highways: Data required for flexible pavement design: a. CBR value of soil subgrade b. CBR value of sub base course c. CBR value of base course d. Wheel load in KG or KN Wheel load is classified into three groups based on traffic conditions. Light traffic(3175 KG) Medium traffic(4082 KG) Heavy. Permissible variations in CBR values for 3 specimens as per IRC: 37-2001 CBR (per cent) Maximum variation in CBR value 5 ±1 5 -10 ±2 11 -30 ±3 31 and above ±5 Note: when variation is more than the above, the design CBR value should be the average of test results from at least six samples and not thre

compaction characteristics, CBR samples were prepared and soaked for 96 hours. After performing the three point CBR test, the CBR value for the natural soil was determined to be 4%. Looking back at the MoW manual [1],where improved subgrade requirements of minimum CBR 15% and maximum PI 25% are specified, you will notice that th Sub-base materials comprise natural sand, gravel, laterite, brick metal, crushed stone or combinations thereof meeting the prescribed grading and physical requirements. The sub-base material should have a minimum CBR of 20 % and 30 % for traffic upto 2 MSA and traffic exceeding 2 MSA respectively

A CBR value of 2% is usually found for clay, high-quality sub-base will have CBR values between 80% and 100%, and some sands may have values around 10%. The CBR testing can be applied to soils with a maximum particle size of 20 mm. For soils with bigger particles, other types of bearing capacity can be used like the Plate Bearing Test Fig. 6: Section of pavement as per IRC 37:2018 - 3% CBR 5.3 Problem Identification The proposed widening project alignment passes through stretches of soil having low soaked CBR value and the CBR of the borrow area material at the most location available is less than the minimum requirement defined by the IS code

California Bearing Ratio or CBR test is the ratio of the force per unit area required to penetrate a soil mass with a standard circular piston of 50 mm dia, at the rate of 1.25 mm/min to that of force required to penetrate sample of compacted stone having CBR of 100%.. CBR test Equipments; The standard load corresponding to 2.5 mm and 5 mm penetration of the plunger into the standard sample is. The resilient subgrade modulus value is estimated using CBR values in the absence of vigorous laboratory tests. For cohesive subgrades, a minimum of 95 % of AASHTO T 180, method D density (modified compaction) for the top 300mm and a minimum of 90 % for all fill areas below the top 300mm are recommended Granular Sub Base is a layer in road foundation just above the compacted sub-grade layer. GSB or granular sub-base prevents capillary water from rising; its particle size is so designed that the capillary action stops and cant go beyond GSB layer. Secondly, it works like a drainage layer where water can pass without damaging other road layers 8 T static / vibratory rollers as per guidelines of IRC: 37 - 2001. This stabilized subgrade has the minimum CBR value of 4 %. Hence the subgrade CBR = 4% is adopted for all categories road design. The width of stabilization has to be 1 m more than when the an be dropped, which would mostly found in SMC case. Also the drainage o The values of the MDD/OMC for the alignment / area of subgrade and minimum 10 in a section. Specified compaction for subgrade and shoulders - IRC - SP - 67 for sign board and IRC - SP - 35 for road marking. 21 What is minimum radius of design for National highway at a speed of 100 Km/ph? Minimum radius is 350 m in plain terrain

  1. What is the optimum CBR value for a flexible pavement design? For a flexible pavement different layers are expected to have different CBR values..Embankment - greater than 8%..Sub grade - greater than 10%
  2. Then click on Load previous design to get the values of 90th percentile CBR and 80th Percentile CBR; As per IRC Code, 90th percentile subgrade CBR is to be used in the calculation for the design of flexible pavement such as Expressway, NH, SH, and Urban roads; And, 80th percentile subgrade CBR is to be used in the calculation for the design of.
  3. imum cbr values for a subbase layer of a, section 4 flexible pavement construction, specifications for road an
  4. ing Subgrade Strength For a new road project 1.2.1 Quick estimation of CBR 1.2.2 Typical presumptive design CBR values 1.3 Laboratory procedure for CBR test 1.3.1 General 1.3.2 Test procedure Chapter - 2 18 - 2
  5. Soaked CBR value in % 2 3 4 5 7 10 15 20 50 100 CHARACTERISTIC OF SUBGRADE APPROXIMATE K-VALUE CORRESPONDING TO CBR VALUES FOR HOMOGENOUS SOILS K- value (kg/sqcm/cm) 2.1 2.8 3.5 4.2 4.8 5.5 6.2 6.9 14 22.2 If k-value of subgrade is less than 6.0 kg/sqcm/cm, the Cement Concrete Pavement should not be laid directly over the subgrade
  6. The firstguidelines for the design of flexiblepavement, IRC:37-1970 was based on empirical approach using subgrade strength (CBR) and trafficin terms of number of commercial vehicles weighing 3t or more per day. In 1984, these guidelines were revised considering the design trafficin terms of cumulative number of standard axle load of 80 kN

ba se morth specifications for road and bridge works indian road congress 2013, what value of cbr is recommended for use of material as sub grade layer for laboratory and research purposes about specification of highway construction test or parameter which can be, chapter 3 construction and testing of subgrade what is subgrade subgrade embankmen Calculation of CBR- For 2.5mm, CBR = 9.4% For 5.0mm, CBR = 9.3 % CBR value of soil sample corresponding to 2.5 mm penetration is 9.4%. Since as per IRC 37 - 2012, sub-grade soil should have a minimum CBR of 8% for roads having traffic of 450 commercial vehicles per day or higher, hence selected soil sample meet the required specification

CBR value of subgrade. For these equivalency factors refer IRC:37 2001. The exact VDF values are arrived after extensive field surveys. The sub-base material should have a minimum CBR of 20 % and 30 % for traffic upto 2 msa and traffic exceeding 2 msa respectively. Sub-base usually consist of granular or WBM and the thickness should not. The study revealed that on the addition of the stabilizers with subgrade soil, the CBR value and MDD increased while OMC decreased. IRC: 37-2012, the standard for the thickness design of flexible pavements in India, specifies the use of select soil of minimum CBR 8.0% when traffic on the road is 450 commercial vehicles per day or higher IRC code strength criteria are verified against these minimum values. As per IRC: 51-1992 Guidelines for the use of Soil-Lime Mixes in Road Construction, Minimum CBR value for the lime stabilized sub base should be 15% for low trafficked rural roads, 20% for cumulative traffic up to 2 Msa and 30% for traffic exceeding 2 Msa California Bearing Ratio (CBR): Resistance Value (R-Value): The conversion from resilient modulus of the subgrade to k-value was updated in the fall of 2011 to better reflect published test results; the constant conversion factor of 19.4 as suggested in the AASHTO Guide for Design of Pavement Structures 1993 is no longer used Subgrade. The subgrade is the in situ material upon which the pavement structure is placed. Although there is a tendency to look at pavement performance in terms of pavement structure and mix design alone, the subgrade can often be the overriding factor in pavement performance. Figure 3. Subgrade work on SR 97 south of Bend, Oregon

CBR value for subgrade CBR Testing UK - Nationwide CBR

  1. 3.P K Jain PAVEMENT DESIGN AS PER IRC SP 72-2015 - View presentation slides online. .40 0.56 14.0 137.3 8.66 0.75 15.0 147.1 1l.42 0.98 New Road: Subgrade Strength It is necessary to scientifically carry out a soil survey and test the representative samples for standard IS classification tests, even when the CBR value of the subgrade.
  2. In case the road is expected to carry a large volume of very heavy trucks on a regular basis, spectrum of axle loads may have to be considered to avoid damage to pavements and design concept of IRC:58 may be used. 3.5 Characteristics of the Subgrade The strength of subgrade is expressed in terms of modulus of subgrade reaction, k, which is.
  3. imum of 100% of standard proctor compaction should be attain in subgrade. For clayey soil 95% and moisture content of 2% in excess of optimum value. Soil below subgrade should be compacted to 97% of standard proctor compaction. CBR

CBR value of subgrade soil as per IRC 37-2000 [8]. The design pavement thickness is determined as 760mm. The taken side by side with a minimum clearance of 0.2m. The width of each truck has been taken as 2.5m (Fig.2). designing and constructing road subgrades, Journal of Indian Roads Congress, 52(2), 263-317 evaluating the bearing capacity of subgrade soil for design, 5 4 1 california bearing ratio cbr the california density and molding, what is the minimum cbr values for a subbase layer of a road pavement cbr value of comparisons 21 further for prediction of soaked cbr by using nomograph as per irc sp 72 2007 as shown i road and bridge works indian road congress 2013, what is the minimum cbr values for a subbase layer of a road pavement cbr value of the subgrade sub base is also a data needed to finalise the thickness of the pavement see youre owner specification or contract to see if cbr is an appropriate measur

what is the minimum cbr values for a subbase layer of a, laboratory studies on strength and bearing capacity of gsb, cpwd specifications cpwd gov in, full text of irc 015 standard specifications and code of, see other formats internet archive, specifications for road and bridge works, 401 granular sub base 401 1 scope 401 2 (viii) Minimum subgrade CBR-value should be 2%; otherwise, the subgrade should be strengthened with a capping layer of at least 150 mm thickness having a CBR-value of 10%. (ix) The granular sub-base layer should have a minimum CBR-value of 20% for traffic up to 2 msa and 30% for traffic more than 2 msa 1. According to clause 4.2.1.5 of IRC:37-2001, where the CBR value of the subgrade is less than 2%, the pavement design should be based on the CBR value 2% of the subgrade besides a capping layer of 150 mm thick of material with a minimum CBR of 10% (normally sand) in addition to the sub base. But the following are frequently noticed Subgrade is the lower portion of the road which is basis of the CBR value of sub-grade CBR (IRC: 37 - 2001). California bearing ratio because this parameter increases with addition of coconut husk ash. Addition of coconut husk ash also increased the plastic limi

What is the minimum CBR values for a subbase layer of a

  1. The CBR test is one of the most commonly used methods to evaluate the strength of a sub grade soil, sub base, and base course material for design of thickness for highways and airfield pavement.. The California bearing ratio test is penetration test meant for the evaluation of subgrade strength of roads and pavements. The results obtained by these tests are used with the empirical curves to.
  2. Road Structure Cross Section is composed of the following components: Surface/Wearing Course. Base Course. Sub Base. Sub Grade. 1. Surface/Wearing Course in pavement cross section: The top layers of pavement which is in direct contact with the wheel of the vehicle. Usually constructed of material in which bitumen is used as binder materials
  3. Further, the subgrade strength class of IRC: 72 mentioned that quality of the subgrade is good, if the value of unsoaked CBR is in the range of 10% to 15%. Hence, the present study revealed that the CBR values of sand-25% MD and BCS-60% MD mixes meet the criteria of IRC [ 45 - 47 ] to select the subgrade material for the highway construction
  4. The thickness is satisfied with IRC: 37-2012, (CBR 5%). From solapur to sangareddy Pavement Details of GB & GSB with CBR 5% and traffic 106 MSA Type of pavement GB & GSB BC in mm 50 DBM in mm 135 GB in mm 250 GSB in mm 300 E (BC &DBM) in MPa 3000 E (Subgrade) in MPa 49.3 E (Base) in MPa 139.38 E (Sub-base) in MPa 102.0
  5. It has been recommended by Federal Ministry of Works and Housing [18] that the values of CBR for road base, subbase and subgrade should not be less than 80%, 30% and 10% respectively under soaked condition. It can be seen that samples T1 and T5 do not satisfy the condition for both road base and subbase

IRC 37 states that in frost prone areas, minimum thickness should be 450 mm even when subgrade CBR warrants a lesser thickness. IRC SP:48, states that structurally strong layer like dense bituminous macadam (DBM) and bituminous concrete (BC) would be needed since heavy machinery for snow clearance operations are to be used If CBR corresponding to 2.5 mm penetration is greater it is considered as CBR value and if CBR corresponding to 5mm penetration is greater then the test is repeated and then again if this value comes to be greater, it is adopted as CBR value. As per IRC 37:2001, the thickness of different layers of pavements corresponding to the CBR value of. The pavement thickness design formula developed by the U.S corps of Engineers is given by. Where, t = pavement thickness in cm. P = Wheel load in Kg. CBR = California Bearing ratio in percent. = tyre pressure in Kg/cm 2. A = Area of contact in cm 2. Note: This formula is only applicable when the CBR value of sub grade soil is less than 12% • Aggregate impact value should less than 40% • Liquid limit should be less then 25% • Plasticity index should be less then 6%. • CBR value should be grater then 30%. a. For high volume roads CBR should be minimum 30% b. For low volume roads CBR should be less then 20%. • Gradation: (% passing by weight). Is sieves in m For the design of pavements to carry traffic in the range of 1 to 10 msa, use chart 1 and for traffic in the range 10 to 150 msa, use chart 2 of IRC:37 2001. The design curves relate pavement thickness to the cumulative number of standard axles to be carried over the design life for different sub-grade CBR values ranging from 2 % to 10 %

Flexible Pavement- Aspects of Basic Design as per IRC

Such a mix can be used as sub-base. The design, in this case, is based on CBR-value of the mix. A value of 20-30 in the field is considered adequate for use as a sub-base. The relevant IRC specification is IRC: 50-1973: Recommended design criteria for the use of cement-modified soil in road construction design of flexible pavement for low volume road and residential street A method is proposed to determine the total pavement thickness for IRC's flexible design curve based on analysis. It is assumed that total pavement thickness to equivalent single axle loads (ESAL) for a given subgrade California bearing ratio (CBR) value is T = K (ESAL. section 100 morth 4th revision these specifications shall apply to all such road and bridge works as are required to be executed under the contract or otherwise directed by the engineer in charge hereafter referred to as the engineer, subgrade strength evaluation the subgrade as per morth specifications for rural roads subgrade can be defined as The CBR values does not represent any of the basic strength properties of the soil. b] The punching sear under the CBR test condition does not in any way represent the stress on the subgrade through the flexible pavement layers due to traffic wheel loads. c] The specified four days soaking period may not be sufficient in some highly clayey.

A Study on Use of Red Mud as Sub-Grade in Road

period of four days and later tested. The following table gives the CBR value for different h/T ratios. Table 5 CBR Value for various h/T ratio h/T ratio 0 0.25 0.5 0.75 1.0 CBR % 2.5 18 32 44 55 4.2.DIRECT SHEAR TEST In this test a medium Direct Shear apparatus was used for testing samples of size 150mmX150mmX150mm. Th What is the CBR value for subgrade? A clayey soil generally has a low CBR value (less than 8). Sands are more granular and drain better and will generally have CBR values between 15 and 35. Gravel will have the best CBR values, generally 25 and up. That is why it is suggested to save the best material to cap the subgrade The main objective of this study is finding the correlation between the results of CBR laboratory test without soaked CBR Value and CBR soaked value. The correlation is based on the comparison CBR unsoaked test value and CBR soaked value of the soil. III. SCOPE Scope of work for this study is to observe the CBR value under different soaking. The C.B.R. values are usually calculated for penetration of 2.5 mm and 5 mm. Generally the C.B.R. value at 2.5 mm will be greater that at 5 mm and in such a case/the former shall be taken as C.B.R. for design purpose. If C.B.R. for 5 mm exceeds that for 2.5 mm, the test should be repeated Title: Improvement of local subgrade soil for road constuction by the use of coconut coir fiber, Author: IJRET Editor, Name: Improvement of local subgrade soil for road constuction by the use of.

Flexible Pavement Design by California Bearing Ratio Metho

Concept: As per IRC: 37-1970 . The laboratory test conditions should represent the field conditions as closely as possible. Compaction in the field is done at a minimum of 97 per cent of laboratory density at moisture content corresponding to the optimum moisture content.. For the different types of soils used in subgrade, a minimum of six to eight average CBR values (average of three tests. The minimum curve radius is governed by two factors: 1) the design speed and allowable super elevation and friction, 2) the minimum turning radius of design vehicle. The maximum allowable values of super elevation and friction, i.e. e=0.07 to 0.1, and f=0.15, limit the centrifugal ratio to 0.22 to 0.25 For 20% addition of flyash CBR value of the soil increases from 3% to 21%. Soaked CBR value is considered for design of pavement as per IRC: 37 (2001) guidelines. Flyash shows good improvement in soaked condition which indicates a favorable change that flyash have good drainage property and can be used effectively in pavement subgrade Recommended Minimum and Maximum Limits 12 General Notes and Specifications 13 Subgrade, subgrade treatment or subbase 13 Aggregate Courses 13 Surface Course 14 Minimum Designs (Limited to Secondary Road Improvement Projects with ADT ≤ 50) 14 Design Methods for Rigid Pavement 14 Drainage Considerations for Flexible and Rigid Pavements 1 TBR value for geogrid is range from 1.5 to 70 and for geotextiles is range from 1.5 to 10 depending on the type of geogrid, its location on the road, and the testing scenario [4]. TBR can also find from Fig. 2. Fig-2: Typical TBR value of reinforced and unreinforced pavement [4] BCR= Tr/T

Hossain believed that the CBR test is still one of the most widely used tests for evaluating the competency of pavement subgrade; however, there are variations in the procedure followed by different agencies (e.g., in terms of size of mould, compaction techniques, and efforts), and it was found that correlations between resilient modulus values. Annex XI The material properties should be tested in laboratory as per test from EGR 5031 at University of Engineering & Technolog The Minnesota Department of Transportation provides its home page with links to its regional offices, bid letting, construction, future highway plans, hot topics, jobs, library, licensing information, map sales, news, public meetings, research, road & travel information, and related links

• The CBR of the subgrade can be estimated by conducting actual CBR tests in the laboratory, as per the standard test procedure laid down in IS 2720 (Part 16). • Minimum 3 tests per km are required to reach the design CBR. • 4-day soaked CBR tests are required to be conducted in areas having rainfall intensity greater than 1000 mm per year The normal road land width for a major district road in open area, is. A. 45 m. B. 25 m. C. 15 m. D. 12 m. Answer: Option B. 2. When an up gradient of a highway meets a downgrade, the vertical curve provided, is known as The minimum design speed of various types of highways in plain terrain is the same as the ruling design speed of. A. IRC:SP-72-2015 GUIDELINES FOR THE DESIGN OF . FLEXIBLE PAVEMENTS FOR LOW VOLUME RURAL ROADS 1.3.2 The subgrade strength parameter is evaluated in terms of 4-day soaked CBR values except in areas with annual rainfall less than 500 mm and where the water table i STEP 2. Subgrade CBR Enter the subgrade CBR value as defined in paragraph 315 of AC 150/5320-6D. High values of CBR (i.e. >20) may not be appropriate for this design method. Thickness results from high CBR subgrade layers may appear incorrect as the program will default to minimum thickness requirements as identified in 150/5320-6D

Flexible Pavement Design with BBD, VDF, MSA analysi

Alternatively, CBR values can be estimated from observations a nd emp irc lostg, buh y undertaken by experienced designers or geotechnical engineers. Both BS 7533 - 1 & 2 gives advice on determining CBR values which is summarised as follows:- The degree of subgrade drainage must also be considered when deciding the appropriate CBR value to be. A useful parameter for determining the strength of subgrade material is the California Bearing Ratio (CBR). CBR values are indices of soil strength and swelling potential. They represent the ratio of the resistance of a compacted soil to penetration by a test piston to penetration resistance of a standard material, usually compacted, crushed. Calculate the CBR values for penetration of 2.50mm and 5.00mm. Corresponding to the penetration value at which CBR is to be desired, take the corrected load values from the load penetration curve and calculate the CBR from the equation PT x Cf California Bearing Ratio = ----- x 100. PS Penetration in mm 80 70 60 50 40 30 20 10 NO CORRECTION. Road congress(IRC) has provided guide lines for minimum thickness of each course which is based on million standard axles(msa), CBR value of GSB and of subgrade. IRC has suggested material to be as filler being soil comprising definite plasticity properties. In view bulk requirements of GSB, to reduce cost and preserve natura Part-8), OMC, Soaked CBR at max dry density and OMC, free Swell Index along with Wet sieve analysis results shall be conducted and form part of the DPR. Where ever required, effective CBR should be determined as per IRC:37-2012 Clause 5.2. 5.ROAD INVENTORY Road inventory is conducted for collecting data by directly measuring the conditions of road

the California bearing ratio (CBR) test, unconfined compressive strength (UCS) test The corresponding CBR values were more than four times higher than the minimum required for designing road pavement. The resilient modulus of the soil stabilised with Relative CBR values for subbase and subgrade soils..23 Table 2.11: Subgrade. The values of stabilization should be a minimum of 15cm, 20-23cmand 25-30cm deep for marginal soil, poor soil and worst soil respectively. [7] CONCLUSIONS Subgrade is the lower most layer of road structure. Subgrade should be stabilized to bear the load of other road layers and also to take loads of repeated traffic load Lean Concrete Subbase Depth vs kc, pci, (LS=1) 4 in 6 in: 8 in. 10 in 50 104 156. 205: 262 100 192 271: 354. 443 150 274 37 3.1. Calculation of pavement thickness as per IRC-372012 From the CBR values obtained for different dosage of stabilizers its corresponding pavement thickness are calculated using IRC-37-2001 are mentioned as Follows; For all above pavement thickness a subgrade layer of 600mm was assumed as per the journal and literature study survey PLACED ON THE SUBGRADE OF A GRAVEL ROAD TRAFFIC ADT (in both directions) Subgrade Soil Recommended Total Minimum Thickness of Gravel+ A1, A2, A3 soils or if CBR > 7 150mm < 200 A4, A5, A6, A7 soils or if CBR is between 3 and 7 200mm A1, A2, A3 soils or if CBR > 7 200mm > 200 A4, A5, A6, A7 soils or i

two layer system comprising of blanket and prepared subgrade layer over the normal fill layers. Both the two alternate systems have been specified for 25T, 30T & 32.5T axle loads cases. Concept of CBR based value for subgrade soil selection has been incorporated on the pattern of Highways design, as given in Code IRC:37 Design of Flexibl requirements for cement modification or stabilization of subgrade soil are summarised in Table 3. Table 3: Soil Characteristics for Cement Modified Soil/Improved Subgrade/Capping Layer Properties Specified Value Liquid Limit (%) <45 Plasticity Index <20 Organic Content (%) <2 Total SO4 content 0.2 % Max Minimum Laboratory CBR at specified. Subgrade is taken into account per layer in the individual pavement designs and a general design subgrade CBR is not used. **Forclimatic area according to Weinert N > 4 (and N < 4). value directly, many of the in consistences caused by converting to CBR would be eliminated. 4.6

2-5. Selection of design CBR for select materials, subgrade, and subbases. Design CBR values for select materials, subgrade, and subbases are to be selected in accordance with EM 1110-3-141, except as modified in table 2-1. Where freezing temperatures will penetrate int Pavement Design Manual September 29, 2017 Page 1 1.0 INTRODUCTION This manual provides the procedures used by the Arizona Department of Transportation for the desig As per IRC: 37- 2001 (1) the subgrade must have a minimum CBR value of 2%. When any material present as a subgrade material does not conform to this specification, capping layer of any suitable material whose California Bearing Ratio (CBR) value not less than 10% must be provided between the subgrade and the sub base estimated from its respective CBR-value which is based on the following empirical relationship: The relation between resilient modulus and CBR is given as: E (MPa) = 10*CBR for CBR < 5 and = 176*(CBR) 0.64 for CBR > 5 (1) E = Resilient modulus of subgrade soil. For each CBR of subgrade and modulus of soil

California bearing ratio typical values CBR Testing UK

subgrade can influence the thickness of road structure, strength and the cost in construction stage. California Bearing Ratio (CBR) is a commonly used indirect method to assess the stiffness modulus and shear strength of subgrade in pavement design work. Basically, subgrade must be stable in performance to carried load in any weather subgrade soil gets saturated and leads to a gradual loss in its bearing capacity and CBR value. With low CBR values and loss in bearing capacity of soil, axle load remaining the same, deterioration of pavement gets accelerated. It is important to ensure the drainage of storm wate and lowering of subsoil water so that subgrade remains dry

Cbr Test of Soil-10+ Most Important Notes to Remember

Subgrade and Subbases Design • Subgrade strength is not a critical element in the thickness design. • Has little impact on thickness. • Need to know if pavement is on: • Subgrade (k ≈ 100 psi/in.), • Granular subbase (k ≈ 150 psi/in.), • Asphalt treated subbase (k ≈ 300 psi/in. 4.2 In-situ Subgrade Properties 8 4.3 Subgrade Treatments 9 4.4 Sub-base 10 5. DESIGN OF FLEXIBLE PAVEMENT 11 For granular soils, California Bearing Ratio (CBR) test is the most common way for determining the elastic modulus of subgrade. Reference can be There is no precise direct relationship between CBR values and the elasti 3.1 TYPICAL PRESUMTIVE DESIGN CBR VALUES(table 3.1) Description of Subgrade soil IS Soil Classification Typical Soaked CBR value(%) Highly plastic clays CH, MH 2-3 Silty clays and sandy clays ML, MI CL, CI 4-5 Clayey sands and Silty sands SC, SM 6-1

Road Standards and Paving Standards. ASTM's road and paving standards provide the specifications and test methods pertinent to the material, physical, mechanical, performance, and application requirements of road surfaces and pavements. These geotechnical surfaces are laid down on specified areas intended to sustain either or both foot and. The minimum CBR value of subgrade filler is required according to JTG F10-2006 , as shown in Table 5, and results of the CBR tests are shown in Table 6. It can be seen that the CBR value of the recycled construction waste mixture is 97.66%, which meets the requirements of subgrade, and the amount of swelling can be ignored accordance with IRC:37-2001 for a design period of 15 years. Traffic assumed for the same is 10% of the design traffic for main carriageway. Therefore, 10% of 58 million ESAL, i.e. 6 million ESAL is considered asdesign traffic for service road. Based on IRC: 37-2001, for subgrade CBR of 8% (as subgrade Here roads are designed as per existing provisions of IRC-SP-62 2014 Name of Work- Laxmi Bai Park to Rameri Marg of Distt. Hamirpur (A)Design of Cement concrete pavement (3.0 m wide) as per IRC SP: 62-2014 Design Data Initial CVPD=A A≔ 34 Soaked Subgrade CBR of Subgrade CBR=2.9 Design CBR is defined as 2/3 of the soaked CBR value. VDOT Specifications for SM-4.75, SM-9.0, SM-9.5, SM-12.5, and IM-19. can be found in Section 211 of the 2016 VDOT Road and Bridges Specification Book the subgrade from shearing when subjected to aircraft loads. The procedure developed for aggregate-surfaced pavements is based on the same principle of protecting the subgrade from shearing by providing sufficient cover of aggregate material with a minimum CBR value