amardeep s

Strength of concrete on perticular required day can be find out by following formula as per SP 24 :- t/(a+bxt) x fck Where, t, is the age in days a, is value = 4.7 b, is value = 0.833 fck, is compressive strength of the concrete Example: To find compressive strength of concrete on 3rd day , fck is 35 N/mm2 Implementing above formula t/(a+bxt) x fck 3/(4.7+0.833x3) x 35 = 14.59 N/mm2 Which is 15/35x100= 41.67% of fck

Since we know weight of a steel bar per meter length in kg is W = D²/162 Where W is the weight of steel bar and D is the dia of bar Cross sectional area of steel bar = ∏r² [D=2r , r=D/2] = ∏D²/4 Vol of steel bar per meter length = ∏D²/4  x 1000 Density of steel = 7850 kg/m³ = 7850 kg/1000 x 1000 x 1000 Now weight of bar per meter = vol of steel bar x Density of steel = ∏D²/4  x 1000 x 7850 kg/1000 x 1000 x 1000 = 3.14 D²/4 x 7850 x 1000 x 1000 = 0.785 D² x 0.007850 = 0.00616225 x D² = 0.00616225 / 1 x D² / 1 = D²/1/0.00616225 = D²/162.28

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