In general, a very good presentation for learners and young engineers to start with except a few points which may have some contradiction. Let me explain one by one. 1) W/C selection - The general curve given in IS 10262, actually based on normal slump concrete and not for SCC. So calculation of w/c ratio from that curve may be not sufficient. It will always be on the higher side than what is actually needed lower value for SCC. For example, with the same w/c ratio of 0.42, one may not have same strength for normal concrete as well as SCC for M30 grade. M30 SCC will always show lesser strength than normal M30 grade concrete because of higher paste content and in other words comparatively with lower A/C ratio. So in this case some margin is to be considered at least (-) 0.02. say the w/c ratio may be considered as 0.40 in place of 0.42. Now the only cement content will be = 190/0.40 = 475 kg in place of 452 kg. 2ndly, while calculating only cement content through w/c ratio, we need to increase total cementitious fines at least 10% of the cement content as per IS 10262, in case of SCM addition like PFA.That means final cementitious content should be at least = 475*1.10= 522 kg. Therefore , final w/c ratio now will be 0.36 (190/522). It is done because of getting equivalent strength in comparison with only cement mix. Blended mix is little prone to Shrinkage cracks and carbonation of concrete.and hence these two effects are compensated with lowering w/c ratio little lower. Considering all above, we can finalize the cementitious content as follows.... Cement = 340 kg PFA = 182 kg Free water = 190 kg W/C = 0.36. 3rdly, W/P ratio by volume (0.85 to 1.10) may be applicable for lower or moderate strength of concrete but certainly not applicable in high strength Concrete like grade M60 and above. In such cases we already observed that this ratio is always less than 0.85. we generally get this ratio in such grades very close to 0.70. Powder content (400 to 600 kg) also may not be applicable in such high grades where we all saw that it ranges between 650 to 700 kg in such grades. So in SCC design IS 10262 alone is not sufficient to follow. It needs some revisions immediately. Thanks Mr. Kamal to deliver a good presentation on SCC in general.
Thank you very much for your explanation. True, SSC is special type of concrete and it is a vast subject. One can go deeper and deeper on this subject. I always try to give some basic ideas for the new comer. Thank you very much for liking my presentations. Above all , your suggestion is always special to me and it helps me to grow.
No, it is only cement content & not totally cementitious content. 0.42 was evaluated from the graph mentioned & this graph is based on cement content. Therefore, 190/0.42 is the cement content only and not as a cementitious content.
Good one sir , keep updating more.🎉🎉
Thank you very much.
In general, a very good presentation for learners and young engineers to start with except a few points which may have some contradiction. Let me explain one by one.
1) W/C selection - The general curve given in IS 10262, actually based on normal slump concrete and not for SCC. So calculation of w/c ratio from that curve may be not sufficient. It will always be on the higher side than what is actually needed lower value for SCC. For example, with the same w/c ratio of 0.42, one may not have same strength for normal concrete as well as SCC for M30 grade. M30 SCC will always show lesser strength than normal M30 grade concrete because of higher paste content and in other words comparatively with lower A/C ratio. So in this case some margin is to be considered at least (-) 0.02. say the w/c ratio may be considered as 0.40 in place of 0.42. Now the only cement content will be = 190/0.40 = 475 kg in place of 452 kg.
2ndly, while calculating only cement content through w/c ratio, we need to increase total cementitious fines at least 10% of the cement content as per IS 10262, in case of SCM addition like PFA.That means final cementitious content should be at least = 475*1.10= 522 kg. Therefore , final w/c ratio now will be 0.36 (190/522). It is done because of getting equivalent strength in comparison with only cement mix. Blended mix is little prone to Shrinkage cracks and carbonation of concrete.and hence these two effects are compensated with lowering w/c ratio little lower.
Considering all above, we can finalize the cementitious content as follows....
Cement = 340 kg
PFA = 182 kg
Free water = 190 kg
W/C = 0.36.
3rdly, W/P ratio by volume (0.85 to 1.10) may be applicable for lower or moderate strength of concrete but certainly not applicable in high strength Concrete like grade M60 and above. In such cases we already observed that this ratio is always less than 0.85. we generally get this ratio in such grades very close to 0.70. Powder content (400 to 600 kg) also may not be applicable in such high grades where we all saw that it ranges between 650 to 700 kg in such grades.
So in SCC design IS 10262 alone is not sufficient to follow. It needs some revisions immediately.
Thanks Mr. Kamal to deliver a good presentation on SCC in general.
Thank you very much for your explanation. True, SSC is special type of concrete and it is a vast subject. One can go deeper and deeper on this subject. I always try to give some basic ideas for the new comer. Thank you very much for liking my presentations. Above all , your suggestion is always special to me and it helps me to grow.
Thanks Mr. Kamal.
The presentation was indeed very good and explanatory.
@@nirmalendukargupta201 Your word is my inspiration. Thank you.
In your trial proportion you are taking cement 452 kg and Flyash 158 kg ( 452 kg is the total cementitious material na )
Yes , 452 kg is total cementitious materials.
No, it is only cement content & not totally cementitious content.
0.42 was evaluated from the graph mentioned & this graph is based on cement content.
Therefore, 190/0.42 is the cement content only and not as a cementitious content.