Sir, You have same energy in teaching. I still remember your classes in IIT Roorkee. I have never been a meritorious civil engineering student but all your lesson are very useful in my Job today. Thanks alot sir. Edison Singh PWD, UP
Thank you for the videos, sir. I have a query regarding the selection and casting of beams for determining flexural strength. Should the beam size be based on the Nominal Maximum Aggregate Size (NMAS) or any other criteria? For example, if the NMAS is 37.5 mm, which beam size would be appropriate for casting-500x100x100 mm or 700x150x150 mm? Additionally, if I use a 4.89 kg rammer for compaction, how many layers and blows should be applied for each of these beam sizes? Is there any code to follow?
This size of 100x100x500 is taken as the stadard beam size for cement - aggregate mix. For soil-cement mix, a smaller size can be adopted. Better not to compact with hammer, do it through vibratory plate.
Sir for CTSB mix design the gradation of mix design as IRC 37-2018 clause no 7.3.1 recommended gradation as per Grading IV of Table 400-1 of MORTH Specification. In MORTH for CTSB layer the Gradation as per Table 400-4 recommended for Sub base/ Base. for this which gradation we take in field for Cement Treated Sub Base Layer gradation Table 400-1 or Table 400-4
Thank you sir 🙏. Sir please make a video related to traffic signal design. In that video solve 2 to 3 problems, then it is better understanding for everyone sir
There is no method as such to correct the field dry density, once the layer has been compacted and cured. Low density might be due to delayed compaction (generally compaction of a CTB layer must be completed within 2 hours of its mixing). Now you can check in-situ UCS of the layer and see if it is within the limits. If the core taken from the site does not have 7 days UCS also within permissible limits then you should reject the layer.
Thank you very much Sir for your valuable information. Actually I am working at NHAI projects and I have faced this problem some times and I also want to know how to calculate cement content in CTB, if the sample has been taken from site as no procedure or methodology has been given in IRC 37 and IRC:SP: 89@@SatishIITR
ASTM C 85 gives a method to get the cement content in Hardened concrete. The method is quite tedius, but gives accurate result. @@dr.p.ganapatinaidu8698
@@SatishIITR 404.5 Strength Cement treated soil sub-base/base shall be tested for the unconfined compressive strength value at 7 days, actually obtained in situ. In case of variation from the design UCS, in-situ value being on lower side, prior to proceeding with laying of base/surface course on it, the pavement design shall be reviewed for the actual UCS value. The extra pavement thickness needed on account of lower UCS shall be constructed by the Contractor at his own cost. (MORD extract)
Thanks for the explanation, my question is: how to calculate the resilient modulus (Eb) for a cement-treated base layer with an unconfined compressive strength of 450 psi at 7 days. I have an exam next week and I am stuck. Kindly help.
E = 1000 times 28 days UCS OR Maximulm Flexural strength is taken 20% of UCS Watch my video on Design of Flexible Pavement, it will be clear. It is available in both Hindi and English.
@@SatishIITR Appreciate your reply. the only info I have is UCS 450 psi at 7 days. I am still confused about calculating E so I can calculate SN to determine the base layer thickness. any advice? Thanks in advance.
There is no such single relaton as it depends on strength (grade) of the concrete. As stated in BS 1881, the compressive strength of concrete gained by cylinder specimens is equal to 0.8 times of the compressive strength gained by cube specimens. However, in fact, this ratio is not always precise in the applications.
CBGM is popular in UK and is extensively used for foundation as well as base of a pavement. CBGM allows use of RAP and other local materials also and it is designed as we design Dry Lean Concrete for base in a rigid pavement (aggregate - Cement Ratio).
Yes sir, I am sharing your every concept with my friends and colleagues. Looking forward for more brilliant concepts in Pavement Engineering, Traffic and Highway Engineering.
Another great video Sir! Will be sharing with the wider audience.
Much appreciated! Thanks.
Sir,
You have same energy in teaching. I still remember your classes in IIT Roorkee. I have never been a meritorious civil engineering student but all your lesson are very useful in my Job today. Thanks alot sir.
Edison Singh
PWD, UP
Thanks Edison, for your remembrance. Keep watching and share the link in your groups also
Explained Superb sir
Glad to know that you liked it. Please share the link with your friends also.
Thank you for the videos, sir. I have a query regarding the selection and casting of beams for determining flexural strength. Should the beam size be based on the Nominal Maximum Aggregate Size (NMAS) or any other criteria?
For example, if the NMAS is 37.5 mm, which beam size would be appropriate for casting-500x100x100 mm or 700x150x150 mm? Additionally, if I use a 4.89 kg rammer for compaction, how many layers and blows should be applied for each of these beam sizes? Is there any code to follow?
This size of 100x100x500 is taken as the stadard beam size for cement - aggregate mix. For soil-cement mix, a smaller size can be adopted.
Better not to compact with hammer, do it through vibratory plate.
Very clearly explained sir 🙏
Thanks for liking. Keep watching
Sir for CTSB mix design the gradation of mix design as IRC 37-2018 clause no 7.3.1 recommended gradation as per Grading IV of Table 400-1 of MORTH Specification. In MORTH for CTSB layer the Gradation as per Table 400-4 recommended for Sub base/ Base. for this which gradation we take in field for Cement Treated Sub Base Layer gradation Table 400-1 or Table 400-4
Your point is valid, but in my opinion you should go by IRC 37
@@SatishIITR Thank you sir for your guidance
Thank you sir 🙏. Sir please make a video related to traffic signal design. In that video solve 2 to 3 problems, then it is better understanding for everyone sir
OK, noted. It will then be a long lecture
@@SatishIITR Thank you Very much sir
Thank you sir, my some query is: field dry density Cement treated Base (CTB) fails, how to recheck, and what is the next procedure for F.D.D checking.
There is no method as such to correct the field dry density, once the layer has been compacted and cured. Low density might be due to delayed compaction (generally compaction of a CTB layer must be completed within 2 hours of its mixing).
Now you can check in-situ UCS of the layer and see if it is within the limits. If the core taken from the site does not have 7 days UCS also within permissible limits then you should reject the layer.
Thank you very much Sir for your valuable information. Actually I am working at NHAI projects and I have faced this problem some times and I also want to know how to calculate cement content in CTB, if the sample has been taken from site as no procedure or methodology has been given in IRC 37 and IRC:SP: 89@@SatishIITR
ASTM C 85 gives a method to get the cement content in Hardened concrete. The method is quite tedius, but gives accurate result. @@dr.p.ganapatinaidu8698
@@SatishIITR 404.5 Strength
Cement treated soil sub-base/base shall be tested for the unconfined compressive strength value at 7 days, actually obtained in situ. In case of variation from the design UCS, in-situ value being on lower side, prior to proceeding with laying of base/surface course on it, the pavement design shall be reviewed for the actual UCS value. The extra pavement thickness needed on account of lower UCS shall be constructed by the Contractor at his own cost. (MORD extract)
Sir, whether we used iron slag as coarse aggregate in CTSB Design
You mean steel slag? Yes, you can use
@@SatishIITR yes sir steel slag
Sir can you please let me know the compaction method for ucs in cube
Can be vibratory or hammer.
Thanks for the explanation, my question is: how to calculate the resilient modulus (Eb) for a cement-treated base layer with an unconfined compressive strength of 450 psi at 7 days. I have an exam next week and I am stuck. Kindly help.
E = 1000 times 28 days UCS
OR Maximulm Flexural strength is taken 20% of UCS
Watch my video on Design of Flexible Pavement, it will be clear. It is available in both Hindi and English.
@@SatishIITR Appreciate your reply. the only info I have is UCS 450 psi at 7 days. I am still confused about calculating E so I can calculate SN to determine the base layer thickness. any advice? Thanks in advance.
@@nawarmofti288 In my opinion, you should convert this UCS in MPa and then find Mr. as 20 % of this UCS.
@@SatishIITR Thanks.
sir are ctsb cubes are immersed in water for curing?
No, here cement quantity is very low and hence these are cured under moist conditions
@@SatishIITR thank you Sir
Sir What is the relation between UCS value and Compressive Strength of Cube in CTB Mix design if any?
There is no such single relaton as it depends on strength (grade) of the concrete. As stated in BS 1881, the compressive strength of concrete gained by cylinder specimens is equal to 0.8 times of the compressive strength gained by cube specimens. However, in fact, this ratio is not always precise in the applications.
Sir How and when we should check the field dry density of CTSB and CTB layer after laying and what will be it's value ?
Density should be around 97 percent of lab value.
@@SatishIITR sir when FDD is done after laying
sir the above design procedure of CTSB is used for natural aggregates. Does the same procedure is used for designing of CTSB for recycled aggregates?
yes, procedure is same.
@@SatishIITR thank you sir ji
Sir, what is the basic difference between CTB and CTSB ? same design mix and procedure for both is given in MORTH specification?
Difference is only of the stregth requirement. Rest is same
Sir please post ctsb cube casting manually with irc specifications
Do you mean design of CTSB as per IRC?
@@SatishIITR sir, i too have the same doubt.., how to compact the sample in cube.., statically or dynamically?
@@sandeepreddy2235 can use any method, important is to achieve the density.
Sir, How is this Cement treated Base (CTB) different from Cement Bound Granular Mixture (CBGM). Can you please guide me
CBGM is popular in UK and is extensively used for foundation as well as base of a pavement. CBGM allows use of RAP and other local materials also and it is designed as we design Dry Lean Concrete for base in a rigid pavement (aggregate - Cement Ratio).
Sir can you share a link for the Stabilized Subbase design process ..
and I think CTSB and CTGSB are the same am I right ??
CTSB and CTGSB are the same.
@@SatishIITR Sir please make a video for CTSB design mix ...
@@spiritualmotivation12 There is no mix design for CTSB, It is just adding 2 percent cement to the aggregate base. Please see IRC 37 once.
Sir, is it possible for residual strength of stabilised layer to be higher than 28 days ucs??
what is the meaning of residual strength here? Is it the strength of the layer after design life?
Sir, one video made on FDR( Full Depth Reclamation) please
Ok, noted
Thank6
thanks for watching
Thank you sir
You are welcome Mr. Reddy. Please forward the link to your friends
Yes sir, I am sharing your every concept with my friends and colleagues. Looking forward for more brilliant concepts in Pavement Engineering, Traffic and Highway Engineering.
Please sir upload design mix Excel format.
Sorry, I have not made any excel sheet for design of CTB