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Embankment Materials

Earth-fill materials

(1) Whereas most types of soils can be utilized for earth-fill construction development procedures until and unless they are unsolvable and significantly inorganic, the average shake flours and kinds of clays with fluid limits which is greater than 80 ought to for the most part be steered clear away from. The word “soil” as utilized in this article incorporates different kind of materials like the very delicate sandstone or other assortment of rocks that separate into soil during the process of handling and compaction.
(2) In the cases where the fine-grained soil has to be brought promptly inside the scope of water proportions necessary for compaction and for procedures of construction development tools and equipment, additionally can be utilized for other construction projects like embankment development. Some moderate drying impenetrable soils might not be suitable for utilization like the embankment fill due to high degree of dampness, and the decrease of dampness substance will be not very feasible in different kind of climatic zones due to expected level of development amid construction development. In different cases, soils may need necessary additional water content for compaction. Alongside ponding or sprinkling in the borrow regions might be fundamental. The utilization of fine-grained soils having high water proportions might bring about high pore-water weights to create in the dike under its own particular weight. Dampness penetration into dry hard get material can be contributed by tearing or furrowing beforehand the process of sprinkling or ponding operations.
(3) As it is basically complex to diminish generously the water proportion of the impenetrable soils, hollow territories comprising impermeable soils more than around 2 to 5 percent wet of ideal water content (contingent on their plasticity attributes) might be complex to utilize in an embankment construction. But, this depend on on nearby climatic conditions and the size and format of the work, and should be surveyed for every venture on an individual premise. The cost of employing drier material necessitating a more drawn out pull ought to be compared and the economic cost of utilizing wetter substances and compliment slants. Other varying components being equivalent, and if a decision is conceivable, soils having an extensive variety of grain sizes (all around reviewed) are desirable over soils having generally uniform molecule sizes, since the previous as a rule are more grounded, less helpless to funneling, disintegration, and liquefaction, and less compressible. Cobbles and rocks in soils may add to the cost of development since stone with most extreme measurements more prominent than the thickness of the compacted layer must be evacuated to allow appropriate compaction. Bank soils that experience significant shrinkage after drying ought to be secured by satisfactory thicknesses of non-contracting fine-grained soils to lessen dissipation. Dirt soils ought not be utilized as refill in contact with cement or workmanship structures, aside from in the impenetrable zone of a bank.
(4) The majority of the earth appropriate for the impenetrable regions of an earth dam are likewise practical for the impenetrable zone of a stone filled dam. At the point when the loss of the water must be kept to a base (i.e., when the water reserve is utilized for long haul stockpiling), and fine-grained material is hard to come by, bringing about a thin zone, the material utilized as a part of the center ought to have a low porousness. Where drainage loss is less essential, as in some surge control dams not utilized for capacity, less impenetrable material might be utilized as a part of the impenetrable zone.

Ductility of Bitumen

Objective
(i) To compute the ductility of a specific specimen of bitumen
(ii) To assess the suitability of bitumen for its application in road construction.

Apparatus

The apparatus as per IS: 1208-1978 comprises of
  1. Briquette mould: It is created out of brass. Circular holes are made at ends known as clips to grasp the stationary and mobile ends of the testing machine. The mould when correctly amassed produce a briquette sample of the given dimensions.
Total length 75.0 ± 0.5 mm
Distance between clips 30.0 ± 0.3mm
Breadth at mount of slip 20.0 ± 0.2mm
Width at minimum cross-section
(half way between clips) 10.0 ± 0.1mm
Thickness throughout 10.0 ± 0.1mm
2. Water bath: A bath preserved within the temperature of 27.0° ±0.1 °C of the specified experimentation temperature comprising minimum of 10 litres of water, the sample which is being immersed to a deepness at least minimum of 10 cms and reinforced on a punctured shell and additionally minimum 5 cms from the foot of the bath.
3. Testing Machine: For the process of pulling the briquette of bituminous substances separately, any apparatus could be utilized which is so built that the sample would be constantly partially immersed in the water while the two clips are being drawn separately parallel at a constant speed of 50 ± 2.5 mm per minute.
4. Thermometer: Range 0-44°C and decipherable up to 0.2°C

Theory

The ductility provides the extent of adhesive nature or the properties possessed of bitumen and its capacity to stretch. In elastic pavement design, it is important that binder has to create a shrill ductile film round aggregates so that physical interconnecting of the aggregates is amended. Binder material having inadequate ductility gets broken when exposed to recurrent traffic loads and it delivers penetrable pavement surface. Ductility of a bituminous substances is computed by the distance in centimeters to which it will lengthen prior to breaking when two ends of ordinary briquette sample of the material are pulled separately at a stated speed and stated temperature.

Process

  1. Melt down the bituminous test substance totally at the maximum temperature of 75°C to 100° C overhead the estimated moderating point until and unless it transform thoroughly into fluid.
  2. Strain the fluid with the help of IS sieve 30.
  3. After the process of stirring the fluid, we will now pour it into the cast assembly and position it on a brass plate. For preventing the substance exposed to test from sticking, double coat the exterior of the plate and internal sides of the mould with utilization of mercury or by a blend of identical portions of glycerine and dextrine.
  4. After letting in still for approximately 40 minutes, put the plate assembly alongside the specimen in a water bath. Preserve the temperature of the water bath at 27° C for another 30 minutes.
  5. Detach the sample and the cast assembly from the water bath and trim the sample by levelling the surface with help of a hot knife.
  6. Substitute the mould assembly in water bath for 80 to 90 minutes.
  7. Detach the sides of the mould.
  8. Hook the clips cautiously on the device without leading to any kind of initial strain.
  9. Regulate the pointer to read nil.
  10. Initiate the machine and pull clips parallel at a speed of 50 mm per minute
  11. Mark down the distance at which the bitumen thread of specimen breaks.
  12. The mean of the two observations rounded to the closest whole number is ductility value.
  13. Note: Machine might have provision to attach two or more moulds so as to test three samples concurrently.

Precautions

(i) The plate assembly on top of which the mould is positioned should be effortlessly flat and horizontal so that the base surface of the mould tads it throughout the process.
(ii) During the process of filling the mould, we should be very careful not to change the briquette and to comprehend that no air pocket is inside the moulded specimen.

Observations

(i) Bitumen Grade =
(ii) Pouring Temperature =
(iii) Test Temperature =
(iv) Period of cooling in minutes
(a) In air =
(b) In water bath before trimming =
(c) In water bath after trimming =
    1     23
(a) Initial Reading   
(b) Final Reading   

Result:

Ductility Value=
Recommended value:
The extend of suitability of bitumen is assessed based on its kind and suggested application. Bitumen with low ductility value may get cracked especially in cold weather. Minimum values of ductility stated by ISI for numerous grades are as follows.
Source of paving bitumen and penetration gradeMin ductility value (cms)
Assam Petroleum     A255
                                 A3510
                                 A4512
                     A65, A90 & A20015
Bitumen from sources other than Assam Petroleum                                       S3550
                        S45, S65 & S9075
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Dry Density of Soil By Water Displacement Method

Aim: To determine the dry density of a soil specimen by water displacement method

Theory

A soil sample of normal contour is layered with paraffin wax to so that it becomes resistant to water. The aggregate volume (V1) of the waxed sample is ascertained by defining the volume of water evacuated by the sample. The volume of the specimen (V) is expressed by:
Where,  = mass of waxed solid
M= mass of the specimen without wax
 = density of paraffin.
Dry density of specimen= 

Equipment

  1. Water Displacement apparatus
  2. Weighing balance, accuracy 1g
  3. Paraffin wax
  4. Heater
  5. Cutting knife
  6. Oven
  7. Brush
  8. Measuring Jar
  9. Water Content container1.

Process

1. Take the soil sample. Trim it to a normal shape. Stay away from re-participant corners. Take the measurement of sample.
2. Now take some paraffin wax and soften it on a warmer. Apply a layer of softened paraffin wax to the sample with a brush. When it has solidified, once again put another coat. Take the weight of the waxed specimen (Mt).
3. Fill up the water displacement device with water. At the point when the overflow happens, shut the valve.
4. Put a measuring jug underneath the overflow container of the device. Open the valve.
5. Submerge the waxed example gradually into the water in the mechanical assembly. Water floods. Gather the flooded water in the jug. Decide the volume of the water gathered (Vt)
6. Eliminate the waxed sample from the mechanical apparatus. Let it from the exterior part.
7. Expel the paraffin wax by peeling it off
8. Cut the specimen into two pieces. Take a representative specimen for the water content determination.

Data sheet for water displacement method

Density of paraffin (  )= 0.91 g/ml.
Sl. No.Observations an CalculationsDetermination No.
123

Observation

1Mass of specimen (M)   
2Mass of waxed specimen (Mt)   
3Volume of waxed specimen by weight displacement (Vt)

Calculations

4Mass of wax = Mt – M   
5Volume of wax (Vp) = (Mt – M)/     
6Volume of specimen (V) = Vt – Vp   
7Water content   
8Dry density =  

Result:

Dry density of soil = _______g/ml.
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Double Shear Test on Mild Steel

Objective: To ascertain the shear strength (ultimate shear stress) of the mild steel specimen supplied using double shear method.

Equipment

  1. UTM
  2. Shear attachment to the UTM
  3. Shear dies
  4. Venire Calipers.

Theory and Principle

Shear strength of the material refers to the ultimate shear stress achieved by the sample which under double shear shown by:
Where,
F = Maximum load at which the specimen breaks, and
A = cross-sectional area of the specimen.
The load range to which the machine is to be set for the experimentation is chosen bases on the expected maximum load F to be exerted on the sample. This is premeditated from the yield stress fy and the factor of safety     , as follows:
Permissible shear stress t for mild steel is,
Thus,

Process

Measure and mark down the dimensions of the sample. Compute the greatest load expected to be exerted on the sample utilizing the equation (2) and choose the load range to be utilized. Set the UTM for the chosen load range. Set the accurate set or dies to amass the shear attachment with the correct set of dies in it. Enclosure the sample in to the dies so that it projects correspondingly on both of the sides. Position the total bear assembly with the sample in it centrally over the baring plate on the lower table. Transport the lower cross- head close to the highest surface of the assembly. After that, float the lower table and then set the load pointer to nil. Exert the load slowly until the specimen breaks. Mark down the ultimate load exerted on the sample.

Observation

The observation is tabularized

Calculations

Range: Utilizing the equation (2) and assuming taking fy = 250 N/mm2 and =3 and, expected maximum load to be applied on the sample is,
F’ = 3×0.45×250/2A
Using equation (1) the ultimate shear stress is= F/2=___________

Result

Ultimate shear stress of the material be N/mn^2

Questions

1. State the differences between single shear and double shear.
2. State the differences between average shear stress and maximum shear stress.
3. Explain why Modulus of rigidity is not computed from shear test?
4. Give reasons for why structural component is designed chiefly by considering double shear strength?
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Determination of Modulus of Elasticity Concrete

Objective: To ascertain the modulus of elasticity of concrete
Sample: Concrete calendar 15 cm diameter and 30 cm long
Process
Setting up of the Compressometer
(i) Assemble the top and base casing by keeping the spacers in position.
(ii) Put the pivot rod on the sinks and bolt them position.
(iii) Put the tightning screws of the base and top casing unscrewed (however not totally).
(iv) Place the example on a level surface.
(v) Keep the compressometer halfway on the sample so that the tightning screw of the base and top casing are at equivalent separation from the two closures.
(vi) Tighten the screws so that the compressometer is hung on the example.
(vii )Remove the spacers by unscrewing the spacer screws.
Test procedure
(I) Put the sample with compressometer in the compression testing machine and center around it.
(II)  Put the load incessantly devoid of stock at a rate of 140 kg /cm²/minute until a stress of (c+5)kg/cm² is obtained where c is the one third of standard compact strength of cubes computed to the closest 5kg /cm²(a load of 12.4T)
(III) Uphold the load at this stress for minimum of one minute and decrease steadily to an usual stress of 1.5 kg/ cm²(a load of 0.3 T)
(IV) Put the load once again at the same rate till the average stress of (c+ 1.5) kg/cm² is obtained(a load of 11.8T)
(V) Mark the compressometer reading at this load point
(VI) Lessen the load steadily and take readings at a period of 1T up to 0.3T(11.8T,10.8T,9.8T,8.8T,7.8T,…………,1.8T,0.3T)
(VII) Once again put the load for the third time and mark the compressometer readings at the time interval of 1T (0.3T,1.8T,2.8T,………….11.8T).
Note
  1. The readings have to be undertaken promptly
  2. If the in general strain witnessed on the second and third readings vary exceeding by 5%,the loading the loading has to be carried out again and again until the disparity in strain between successive readings of (c+1.5)kg/sq.cm. (11.8T) is not greater than 5%.
  3. To obtain the actual deformation, split the marked readings of the dial gauge by 2.
Graph
A load – deflection graph is then plotted for the loading and nu loading requirements. Now draw the tangents at the first segment of the loading curve and at the load matching to the working stress of the mix. Link the first point and the point on the loading curve equivalent to working stress.
Calculation
Initial tangent modulus = stress/ strain
(Take load & deflection from the initial tangent )
Tangent modulus at working stress= stress/ strain
(Take load and deflection from the tangent drawn at working stress)
Secant modulus = stress/strain
(Take load and deflection from the line joining initial point and the point at working stresses)
Report
The subsequent information has to be incorporated in the report.
(i) Identification mark
(ii) Date of test
(iii) Age of specimen
(iv)  Shape and nominal dimensions of the sample
Result
Initial tangent modulus of given concrete = ………………N / mm²
Tangent modulus at working stress =……………….N / mm²
Secant modulus (Modulus of elasticity of given concrete) = ………….. N / mm²

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