amardeep singh sohal

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

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

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Cold Weather Concreting – Any operation of concreting done at about 5 O C atmospheric temperature or below. EFFECTS OF COLD WEATHER ON CONCRETE Delayed Setting – When the temperature is falling to about 5 o C or below, the development of concrete strength is retarded compared with the strength development at normal temperature. Freezing of Concrete at Early Ages – When concrete is exposed to freezing temperature, there is a risk of concrete suffering irreparable loss and other qualities that is, permeability may increase and durability may be impaired. Repeated Freezing and Thawing of Concrete – If the concrete is exposed to repeated freezing and thawing after final set and during hardening period, the final qualities of concrete may be impaired. Stress Due to Temperature Differentials – It is a general experience that large temperature differentials within the concrete member may promote cracking and have harmful effect on the durability. Such differe...

California bearing ratio (CBR).  A simple test that compares the bearing capacity of a material with that of a well-graded crushed stone (thus, a high quality crushed stone material should have a CBR 100%).  CBR is basically a measure of strength.  It is primarily intended for, but not limited to, evaluating the strength of cohesive materials having maximum particle sizes less than 0.75 inches (AASHTO, 2000).  It was developed by the California Division of Highways around 1930 and was subsequently adopted by numerous states, counties, U.S. federal agencies and internationally.  Most agency and commercial geotechnical laboratories in the U.S. are equipped to perform CBR tests. Resistance value (R-Value).  A test that expresses a material's resistance to deformation as a function of the ratio of transmitted lateral pressure to applied vertical pressure.  It is essentially a modified triaxial compression test.  Materials tested are assigned an ...

The downward force of gravity is opposed by an outward centrifugal force due to the planet's rotation, which is greater at the equator than at a higher latitudes. (The centrifugal force is "fictitious" in the sense that the real force caused by rotation is the centripetal force; however, it is a convenient fiction for the sake of calculations.) By itself, this effect would result in a range of values of g from 9.789 m/s2(32.116 ft/s2) at the equator to 9.823 m/s2 (32.228 ft/s2) at the poles. This discrepancy is further accentuated because of the Earth's equatorial bulge, which causes objects at lower latitudes to be further from the planet's center than objects nearer the poles and hence subject to a slightly weaker gravitational pull. Overall these two effects result in a variation of 0.052 m/s2 (0.171 ft/s2) in the value of g, which leads to a variation in the weight of an object by about 0.5% depending on whether it is weighed at the equator or at one of the...

Maximum size. The smallest sieve through which 100 percent of the aggregate sample particles pass.  Superpave defines the maximum aggregate size as "one sieve larger than the nominal maximum size" Nominal maximum size. The largest sieve that retains some of the aggregate particles but generally not more than 10 percent by weight.  Superpave defines nominal maximum aggregate size as "one sieve size larger than the first sieve to retain more than 10 percent of the material"