Very very thank you sir I can't find the how to run kgp back software after watching your video I am able to use kgp back software thankyou sir god bless you and keep uploaded this wonderful knowledgeable vidios. Thank you sir
Nice video Sir. Our company has an almost identical KUAB in Bolivia, so it's good to see a similar FWD in other countries. I just want to know why you have two rows of buffers below the weights. Is it something related to the pulse duration? Thank you
Thank you sir, very useful video. Can you do another presentation showing how to distinguish between different layers of flexible pavement in a test pit and how to evaluate strength of each layer.
Sir i would request you please kindly provide a lecture on FWD data collection for Airfield Pavements and Back calculation of material properties and over lay design If possible please
Sir, Can milling is permitted for overlay of bituminous surface after FWD test.Miling out existing bituminous surface may reduce the strength of pavement.sir,pl clarify this
Design Life in IRC 37: 2019 is 20 years for flexible pavement and in IRC 115 : 2014 it is suggested for 10 to 15 years for design of overlay, basically my question is if we are going to widen existing two lane carriageway to2 Lane + PS, which traffic calculation will govern design either IRC 37 or IRC 115. Other query is if in widening for 30 MSA traffic and 8% Subgrade CBR crust thickness is 200 mm GSB + 250 mm WMM+ 95 MM DBM + 40 MM BC and overlay thickness by FWD test we are getting 90 mm BC over 120 mm existing Bituminous part, how layers will match in this case? Kindly explain my query
IRC 115 is for the purpose of overlay design only, not for the design of pavements. Layers must be matched from subgrade level. You need to dig the side so that base course layers in two pavements is at the same level.
Sir I would request you to please provide videos on various pavement compositions. Like CTB, CTSB, RAP. Also sir please cover how we can convert different layer thickness into equivalent bituminous layer thickness.
Sir In IRC 2015 given example so many problems... so i confused. Because 1st problem is poisonous ratio new payment of BT layer we take as par new pavement design is 0.35 as per IRC 37 andIRC 115 given 0.5. 2) 2nd problem is Va-Vb we can change va-vb in different different project y we take Va 3.5 and Vb 11.5 as per IRC 115 example. 3) in IIT PAVE how many analysis point use and how much radius use in road project? . Because in IRC 37-2018 IIT PAVE USE DIFFERENCE PARAMETERS AND IRC 115 USE DIFFERENCE PARAMETERS SO CAN U suggest me which can we used .
Yes, there is a confusion in Poisson ratio as suggested in IRC 115 and IRC 37. You can take any. There is very little effect of Poisson ratio on results. Generally we take 4 points for analysis. one at the depth of bituminous layer and radial distance zero, Two at same depth but radial distance 155 mm. three at the top of subgrade layer and radial distance zero, fourth, at top of subgrade layer and radial distance 155 mm. I have explained in my video on Design of Flexible pavement aslo. It is available in Hindi and English both. Watch it once.
There is no other procedure for Rigid Pavements. An FWD is used on rigid pavement to evaluate the load transfer across slabs and can be used to detect large voids when significant erosion of the base material has occurred under the slab joints. An FWD is commonly used to determine the variability of overall deflection along the roadway alignment. The test pocedure is same.
Sir, if the existing Pavement has stabilized layers like BSM, or CTB/CTSB then during the use of KGPBACK software in which layer type should these layers be considered? Either Bituminous layer or Granular layer.. Especially incase of BSM with foamed bitumen?
Dear Sir, I would like to get clarity on the Remaining fatigue life, in your video it comes out as 11.07 msa which is less than 100 msa (design life). So if I have similar case where my remaining fatigue life is 17.1 MSA and 19 MSA (design) then, whether this will also require the overlay to match the design MSA 19 requirement?
Thank you so much sir Sir, if i have deflection data at 200 m interval for a 4 km stretch , then should I input the deflection data at each interval one by one in KGPBACK or is there any other way to get the output from KGPBACK by giving deflections along the chainage at a time?
Please note that IRC 115(2014) states that the subgrade modulus is 59.6 and the corresponding ranges selected for subgrade modulus are 57.2 to 83.4. But upon calculation the lower bound value comes out to be 1.2*59.6*0.8= 57.2 and the upper bound value comes out to be 1.2*59.6*1.2= 85.82 instead of 83.4 as mentioned in IRC 115(2014) pg 32. Please clarify
It does not matter whether it is 85 or 83. This range is given to the software to start the iteration and the final value will depend on the deflection values and layer thicknesses. The software has some weakness and I am sure these will be removed in the next revision.
Sir, 1. Can we put 40mm BC and 55 mm DBM over existing BC. 2. Can we lay DBM over existing BC being inferior grade. 3. Or we have to mill the existing BC before laying 55m DBM and 40 mm BC.
Arun Ji, It is always good to mill the existing BC if you can. It will save both natural resources and environment. If not possible, you can certainly put DBM layer over existing BC. Remember, you need overlay on a road because the existing structure has become weak. So BC is now a weak layer.
15th percentile value of any data set is the value above which 85 percent data would lie. So if you a series of data (for example Mr values estimated at different locations of a highway) then arrange them in decreasing order and locate the value below which only 15 % values lie. This can also be done by making a frequency table and plotting cumulative frequency curve in excel sheet.
The second deformation modulus EV2 is a very popular index of compaction standard of soil foundation in Germany, France and other European countries, but not in India. I will certainly make a video on Effective Modulus of Subgrade Reaction (K).
Sir F.W.D. The value of deflection is obtained from the test. Then how is the modulus value of each layer obtained? Sir please explain. It will be so kind of you. Thank you
Modulus of eavh layer is obtained using KGPBACK software. It is a program based on Genetic Algorithm and comes with the IRC code. I have explained this method in the video also.
You wrote same in both cases. The Poisson ratio of bitumnous layer will increase with temperature. Test temp in FWD is higher than what we take in pavement design.
Unfortunately, I also do not have it. I made this video when I was in CRRI and took the help of one scientist there. Will try to get it for you, if possible.
There are no Excel sheets for this analysis. It is done through a software, which is provided by the IRC alongwith the code. You can download it www.geotran.in/back-calculation-software
please explin the normaliseation of fwd ಡಾಟಾ for standard load on rigid pavement with a set of data ! I it's only the you for correct person to solve my problem so I am requesting you sir please explin me !
m 0.4 P 40000 r 1500 (1200+1500+1800)/3 w 0.107 (0.134+0.107+0.08)/3 E 66.67 53.34 66.67*0.8 80.00 66.67*1.2 Im getting E value as 66.67 by using above parameters. Can you please tell me what I did wrong
@@SatishIITR As per code r is average of radial distances and w is average of surface deflections measured at 1200 mm, 1500 mm and 1800 mm. My question is by using parameters for calculating subgrade modulus range Im getting the answer as 66.67 MPa
