amardeep singh sohal

Diameter of mandrel for providing L shape - bend and c shape - hook d is the dia of bar As per IS 2502 1963 For upto 25 mm dia bars - 8d Above than 25 mm dia bars - 12d As per BS 8666 2005 For upto 16 mm dia bars - 4d Above than 16 mm dia bars - 7d

Example of SDBC In SDBC blending on 9.5 mm IS sieve the passing should be 90 to 100 Practically we have two aggregates 10 mm passing 89.4 percent and stone dust passing 100 percent from 9.5 mm IS sieve P =              A-B    * 100                    -------                     A-C Where P = proportion percent required of fine agg for blending A = percent passing of coarse agg B = percent passing required of coarse and fine agg C = percent passing of fine aggregate         P = 89.4 – 95  * 100                ----------------             ...

Take the sample passing 25 mm and retaind on 12.5 mm IS sieve. Heat the aggregate at 150oc and Binder at 160oc and then mix it according to yhe percentage then allow it to cool for 2 hours Put the mix in beaker with Distilled water.Then place it in water bath for 24 hours at temp of 40oc and cover the beaker with glass sheet or any other suitable device. After 24 hours saa the stripping visually while specimen in beaker with water not touching the specimen. As results cames the antistripping agent will required for according to percentage of stripping. The Stripping value depends on the nature of aggregates.as the water absorbption is more stripping is more and if the aggregates are with smooth surface the stripping will be more. As specific gravity is more the stripping is less. Secondly use the Distilled water to perform the test.If we use normal water the salts present in water will give more stripping.

Hot the Bitumen at 75oc – 110oc above softening point say at 90oc + softening point and place it in testing moulds. Pour it in the Moulds Place the moulds at room temp. for 30 – 40 min. Keep the in water bath for 27 oc for 30 min then attach them in apparatus. The rate of pull of the sample in appatatus is 50 mm per min at temp of 27oc. When low temprature Ductility is required, the temp should be 4oc the rate of pull will be 10 mm per min. For Grade S35 Ductility is 50 in cm (min) For Grade S55 Ductility is 75 in cm (min) For Grade S65 Ductility is 75 in cm (min) For Grade S90 Ductility is 75 in cm (min) For Grade S200 Ductility is 75 in cm (min) If Ductility is above 75 cm then report it Above 75 cm

It is the lowest temp when bitumen catches sparks is called the Flash point and when the bitumen catches the fire for 5 sec is called the fire point at the temp from bitumen starts heating. Generally the Bitumen CRMB 60 has Flash point is 220oc

Hot the bitumen in oven or on hot plate at 75oc – 110oc above softening point say at 90oc + softening point of bitumen and pour it in the rings Balls weights 3.5 gms and dia of Ball is 9.5 mm After 30 min in air place it in beaker 600 ml and keep it in apparatus the temp of Distilled water should be 0oc and heat it at the rate of 5oc /min place the thermometer and note down the temp when balls touched the lower plate. For CRMB 55 the Softening point is 55oc For CRMB 50 the softening point is 50oc And For CRMB 60 the Softening point is 60oc For Bitumen having the Softening point above 80oc use Glysrine in place of water and the starting temp should be 35oc In IS 1205 1978 the water bath is written to perfotm the test first keep the beaker with sample in water bath for 15 min at 5oc and then allow to rise the temp at 5oc per min.

Hot the Bitumen in oven 90oc + Softening point and pour in in bowl, approx 10 mm more than expacted penetration. Use bowl depth 35 mm, dia 55 mm size for penetrations below 225 Then keep it in room temp for 1 – 11/2 hours (75 min) Then in water bath at temp 25oc for 1 – 11/2 hours (75 min) Use bowl depth 45 mm, dia 75 mm size for penetrations from 225 to 350 Then keep it in air for  11/2 -2 hours (105 min) Then in water bath at temp 25oc for 11/2 -2 hours (105 min) Then place it under the apparatus Wt of assembly should be 100 g (if 50 gm wt + needle + assembly) Wt of assembly should be 200 g (if 150 g wt + needle + assembly) For CRMB 60 penetration will be <50 Penetration ratio = Penetration at 4oc 200 gm for 60 sec ---------------------------------------------- x 100 Penetration at 25oc 100 gm for 5 sec