Unit 4 – Highway Construction Material & Practice

CE 6504

TEST ON AGGREGATES: Various tests which are done on aggregates are listed below. a) Water Absorption b) Aggregate Impact Value c) Aggregate Abrasion Value d) Aggregate Crushing Value WATER ABSORPTION This test helps to determine the water absorption of coarse aggregates as per IS: 2386 (Part III) – 1963. For this test a sample not less than 2000g should be used. Apparatus: Wire basket – perforated, electroplated or plastic coated with wire hangers for suspending it from the balance,  Water-tight container for suspending the basket,  Dry soft absorbent cloth – 75cm x 45cm (2 nos.),  Shallow tray of minimum 650 sq.cm area,  Air-tight container of a capacity similar to the basket and Oven. Procedure to determine water absorption of Aggregates:  The sample should be thoroughly washed to remove finer particles and dust, drained and then placed in the wire basket and immersed in distilled water at a temperature between 22 and 32oC.  After immersion, the entrapped air should be removed by lifting the basket and allowing it to drop 25 times in 25 seconds. The basket and sample should remain immersed for a period of 24 + ½ hrs afterwards.  The basket and aggregates should then be removed from the water, allowed to drain for a few minutes, after which the aggregates should be gently emptied from the basket on to one of the dry clothes and gently surface-dried with the cloth, transferring it to a second dry cloth when the first would remove no further moisture.  The aggregates should be spread on the second cloth and exposed to the atmosphere away from direct sunlight till it appears to be completely surface-dry. The aggregates should be weighed (Weight ‘A’).  The aggregates should then be placed in an oven at a temperature of 100 to 110oC for 24hrs. It should then be removed from the oven, cooled and weighed (Weight ‘B’). Formula: Water absorption = [(A – B)/B] x 100%. Two such tests should be done and the individual and mean results should be reported.

AGGREGATE IMPACT VALUE V Sem – PEC – by L.Ranjith Kumar/AP Civil

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This test is done to determine the aggregate impact value of coarse aggregates as per IS: 2386 (Part IV) – 1963. Apparatus:  Impact testing machine conforming to IS: 2386 (Part IV)- 1963,  IS Sieves of sizes – 12.5mm, 10mm and 2.36mm,  A cylindrical metal measure of 75mm dia. and 50mm depth,  A tamping rod of 10mm circular cross section and 230mm length, rounded at one end and Oven.

Preparation of Sample  The test sample should conform to the following grading: Passing through 12.5mm IS Sieve – 100%  Retention on 10mm IS Sieve – 100%  The sample should be oven-dried for 4hrs. at a temperature of 100 to 110oC and cooled.  The measure should be about one-third full with the prepared aggregates and tamped with 25 strokes of the tamping rod.  A further similar quantity of aggregates should be added and a further tamping of 25 strokes given.  The measure should finally be filled to overflow, tamped 25 times and the surplus aggregates struck off, using a tamping rod as a straight edge.  The net weight of the aggregates in the measure should be determined to the nearest gram (Weight ‘A’). Procedure to determine Aggregate Impact Value: V Sem – PEC – by L.Ranjith Kumar/AP Civil

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Unit 4 – Highway Construction Material & Practice

CE 6504

The cup of the impact testing machine should be fixed firmly in position on the base of the machine and the whole of the test sample placed in it and compacted by 25 strokes of the tamping rod. The hammer should be raised to 380mm above the upper surface of the aggregates in the cup and allowed to fall freely onto the aggregates. The test sample should be subjected to a total of 15 such blows, each being delivered at an interval of not less than one second.

Reporting of Results:  The sample should be removed and sieved through a 2.36mm IS Sieve. The fraction passing through should be weighed (Weight ‘B’).  The fraction retained on the sieve should also be weighed (Weight ‘C’) and if the total weight (B+C) is less than the initial weight (A) by more than one gram, the result should be discarded and a fresh test done.  The ratio of the weight of the fines formed to the total sample weight should be expressed as a percentage. Aggregate impact value = (B/A) x 100% Two such tests should be carried out and the mean of the results should be reported. AGGREGATE ABRASION VALUE To determine the abrasion value of coarse aggregates as per IS: 2386 (Part IV) – 1963. Apparatus  Los Angles abrasion testing machine  IS Sieve of size – 1.7mm, Abrasive charge – 12 nos.  Cast iron or Steel spheres - 48mm dia. and each weighing 390 and 445g.

Procedure to determine Aggregate Abrasion Value:  The test sample and the abrasive charge should be placed in the Los Angles abrasion testing machine and the machine rotated at a speed of 20 to 33 revolutions/minute for 1000 revolutions.  At the completion of the test, the material should be discharged and sieved through 1.70mm IS Sieve. Reporting of Results:  The material coarser than 1.70mm IS Sieve should be washed dried in an oven at a temperature of 100 to 110oC to a constant weight and weighed (Weight ‘B’).  The proportion of loss between weight ‘A’ and weight ‘B’ of the test sample should be expressed as a percentage of the original weight of the test sample.  This value should be reported as, Aggregate abrasion value = (A-B)/B x 100%.

Sample Preparation: The test sample should consist of clean aggregates which has been dried in an oven at 105 to 110oC to a substantially constant weight and should conform to one of the gradings shown in the table below:

AGGREGATE CRUSHING VALUE: To determine the aggregate crushing value of coarse aggregates as per IS: 2386 (Part IV) – 1963. Apparatus  Cylindrical measure and plunger  Compression testing machine  IS Sieves of sizes – 12.5mm, 10mm and 2.36mm Procedure to determine Aggregate Crushing Value:  The aggregates passing through 12.5mm and retained on 10mm IS Sieve are ovendried at a temperature of 100 to 110oC for 3 to 4hrs.  The cylinder of the apparatus is filled in 3 layers, each layer tamped with 25 strokes of a tamping rod.

V Sem – PEC – by L.Ranjith Kumar/AP Civil

V Sem – PEC – by L.Ranjith Kumar/AP Civil

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The weight of aggregates is measured (Weight ‘A’). The surface of the aggregates is then leveled and the plunger inserted. The apparatus is then placed in the compression testing machine and loaded at a uniform rate so as to achieve 40t load in 10 minutes. After this, the load is released. The sample is then sieved through a 2.36mm IS Sieve and the fraction passing through the sieve is weighed (Weight ‘B’). Two tests should be conducted.

Aggregate crushing value = (B/A) x 100%. VARIOUS LAB TEST ON BITUMEN Bitumen is a mixture of organic liquids that is black, highly viscous, sticky product used for paving roads, waterproofing products (used in sealing roofs). There are many tests which are conducted to check the quality of bitumen. Bitumen is very important component of many construction sites like roads, highways. Many tests are done to ensure the quality of bitumen. Some of these are given below : Ductility of Bitumen  Penetration of Bitumen  Softening Point Of Bitumen  Flash And Fire Point Of Bitumen  Viscosity Test DUCTILITY OF BITUMEN This test is done to determine the ductility of distillation residue of cutback bitumen, blown type bitumen and other bituminous products as per IS: 1208 – 1978. The principle is : The ductility of a bituminous material is measured by the distance in cm to which it will elongate before breaking when a standard briquette specimen of the material is pulled apart at a specified speed and a specified temperature. The apparatus required for this test: i) Standard mould ii) Water bath V Sem – PEC – by L.Ranjith Kumar/AP Civil

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CE 6504

Testing machine Thermometer – Range 0 to 44oC, Graduation 0.2oC

Procedure to determine the Ductility of Bitumen:  Completely melt the bituminous material to be tested by heating it to a temperature of 75 to 100oC above the approximate softening point until it becomes thoroughly fluid.  Assemble the mould on a brass plate and in order to prevent the material under test from sticking, thoroughly coat the surface of the plate and the interior surfaces of the sides of the mould with a mixture of equal parts of glycerine and dextrin.  While filling, pour the material in a thin stream back and forth from end to end of the mould until it is more than level full.  Leave it to cool at room temperature for 30 to 40 minutes and then place it in a water bath maintained at the specified temperature for 30 minutes, after which cut off the excess bitumen by means of a hot, straight-edged putty knife or spatula, so that the mould is just level full.  Place the brass plate and mould with briquette specimen in the water bath and keep it at the specified temperature for about 85 to 95 minutes.  Remove the briquette from the plate, detach the side pieces and the briquette immediately.  Attach the rings at each end of the two clips to the pins or hooks in the testing machine and pull the two clips apart horizontally at a uniform speed, as specified, until the briquette ruptures.  Measure the distance in cm through which the clips have been pulled to produce rupture. While the test is being done, make sure that the water in the tank of the testing machine covers the specimen both above and below by at least 25mm and the temperature is maintained continuously within ± 0.5oC of the specified temperature. V Sem – PEC – by L.Ranjith Kumar/AP Civil

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Reporting Of Results:  A normal test is one in which the material between the two clips pulls out to a point or to a thread and rupture occurs where the cross-sectional area is minimum.  Report the average of three normal tests as the ductility of the sample, provided the three determinations be within ± 0.5 percent of their mean value.  If the values of the three determinations do not lie within ± 0.5 percent of their mean, but the two higher values are within ± 0.5 percent of their mean, then record the mean of the two higher values as the test result. DETERMINING PENETRATION OF BITUMEN This test is done to determine the penetration of bitumen as per IS: 1203 – 1978. Principle The principle is that the penetration of a bituminous material is the distance in tenths of a mm, that a standard needle would penetrate vertically, into a sample of the material under standard conditions of temperature, load and time. Apparatus:  Penetrometer  Water bath  Bath thermometer – Range 0 to 44oC, Graduation 0.2oC Sample Bitumen should be just sufficient to fill the container to a depth of at least 15mm in excess of the expected penetration.

Unit 4 – Highway Construction Material & Practice

CE 6504

 Record the dial reading.  Repeat the above procedure thrice. Reporting Of Results: The value of penetration reported should be the mean of not less than three determinations expressed in tenths of a mm. DETERMINING SOFTENING POINT OF BITUMEN This test is done to determine the softening point of asphaltic bitumen and fluxed native asphalt, road tar, coal tar pitch and blown type bitumen as per IS: 1205 – 1978. Principle The principle behind this test is that softening point is the temperature at which the substance attains a particular degree of softening under specified condition of the test. Apparatus:  Ring and ball apparatus  Thermometer Preparation of Sample:  The sample should be just sufficient to fill the ring. The excess sample should be cut off by a knife.  Heat the material between 75 and 100oC. Stir it to remove air bubbles and water, and filter it through IS Sieve 30, if necessary.  Heat the rings and apply glycerine.  Fill the material in it and cool it for 30 minutes.  Remove excess material with the help of a warmed, sharp knife.

Procedure to determine the penetration of bitumen:  Soften the bitumen above the softening point (between 75 and 100oC). Stir it thoroughly to remove air bubbles and water.  Pour it into a container to a depth of at least 15mm in excess of the expected penetration.  Cool it at an atmospheric temperature of 15 to 30oC for 11/2 hours. Then place it in a transfer dish in the water bath at 25.0 + 0.1oC for 11/2 hrs.  Keep the container on the stand of the penetration apparatus.  Adjust the needle to make contact with the surface of the sample.  Adjust the dial reading to zero.  With the help of the timer, release the needle for exactly 5 seconds.

Procedure to determine Softening Point Of Bitumen: A) Materials of softening point below 80o C:  Assemble the apparatus with the rings, thermometer and ball guides in position.  Fill the beaker with boiled distilled water at a temperature 5.0 ± 0.5oC per minute.

V Sem – PEC – by L.Ranjith Kumar/AP Civil

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With the help of a stirrer, stir the liquid and apply heat to the beaker at a temperature of 5.0 ± 0.5oC per minute.  Apply heat until the material softens and allow the ball to pass through the ring.  Record the temperature at which the ball touches the bottom, which is nothing but the softening point of that material. B) Materials of softening point above 80oC: The procedure is the same as described above. The only difference is that instead of water, glycerine is used and the starting temperature of the test is 35oC. Reporting Of Results: Record the temperature at which the ball touches the bottom. DETERMINING FLASH AND FIRE POINT OF BITUMEN This test is done to determine the flash point and the fire point of asphaltic bitumen and fluxed native asphalt, cutback bitumen and blown type bitumen as per IS: 1209 – 1978. Principle Flash Point – The flash point of a material is the lowest temperature at which the application of test flame causes the vapours from the material to momentarily catch fire in the form of a flash under specified conditions of the test. Fire Point – The fire point is the lowest temperature at which the application of test flame causes the material to ignite and burn at least for 5 seconds under specified conditions of the test. Apparatus: The apparatus required for this test is i) Pensky-Martens apparatus ii) Thermometeriii) The sample should be just sufficient to fill the cup upto the mark given on it.

Unit 4 – Highway Construction Material & Practice

CE 6504

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Fill the cup with the material to be tested upto the filling mark. Place it on the bath. Fix the open clip. Insert the thermometer of high or low range as per requirement and also the stirrer, to stir it.  Light the test flame, adjust it. Supply heat at such a rate that the temperature increase, recorded by the thermometer is neither less than 5oC nor more than 6oC per minute.  Open flash point is taken as that temperature when a flash first appears at any point on the surface of the material in the cup. Take care that the bluish halo that sometimes surrounds the test flame is not confused with the true flash. Discontinue the stirring during the application of the test flame.  Flash point should be taken as the temperature read on the thermometer at the time the flash occurs. B) FIRE POINT:  After flash point, heating should be continued at such a rate that the increase in temperature recorded by the thermometer is neither less than 5oC nor more than 6oC per minute.  The test flame should be lighted and adjusted so that it is of the size of a bead 4mm in dia. Reporting Of Results:  The flash point should be taken as the temperature read on the thermometer at the time of the flame application that causes a distinct flash in the interior of the cup. The fire point should be taken as the temperature read on the thermometer at which the application of test flame causes the material to ignite and burn for at least 5 seconds. VISCOSITY TEST: Viscosity is defined as inverse of fluidity. Thus it is a fluid property of bituminous material. The degree of fluidity at the application temperature greatly influences the ability of bituminous material. Objective: To determine the viscosity of bitumen by Tar Viscometer. Apparatus: Tar viscometer (4mm and 10mm orifice) – the main parts are Cup, Valve, Water bath, sleeves, stirrer, receiver and thermometers.

Procedure to determine the Flash and Fire Point of Bitumen: A) FLASH POINT:  Soften the bitumen between 75 and 100oC. Stir it thoroughly to remove air bubbles and water. V Sem – PEC – by L.Ranjith Kumar/AP Civil

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Unit 4 – Highway Construction Material & Practice

CE 6504

Procedure:  The tar cup os levelled and water in the bath is heated to specific temperature.  The sample material is heated at temperature 20oC above specified test temperature and allowed to cool.  During this the material is continuously stirred.  When material reaaches alsightly above the test temperature, the same is pout in the tar cup.  In the receiver 25ml of mineral oil is poured.  The receiver is placed under the orifice.  When material reaches specified temperature it is maintained for 5min.  The valve is opened.  The stopwatch is started when cylinder records 25ml.  The time is recorded for flow upto a mark of 75ml (i.e 50ml through orifice) Results: The time in seconds for 50ml of test sample to flow through orifice is defined as the viscosity at a given test temperature. WATER BOUND MACADAM ROAD: Excavation:  The box cutting shall be done in such a way, that the width of cutting is exactly that of the sub-base width.  The depth of cutting shall be total thickness of sub-base, consolidated soling, road metalling and bituminous wearing course.  The formation shall have the same profile and camber as shown on the drawings. Preparation of soil sub-grade: After the box cutting is completed the formation shall be watered and rolled to a proper gradient and camber with a road roller of 8 to 10 tonnes weight minimum, for thorough compaction, care shall be taken to avoid excessive rolling of the formation. Preparation of sub-base:  After rolling of the subgrade is completed, the granular sub-base material shall be laid in two separate layers of 150mm and 200mm respectively.  The first layer of 150mm shall be laid over the compacted sub-grade between the edges of box-cutting, watered and rolled to a proper gradient and camber with a road roller of 8 tonnes weight minimum for thorough compaction to achieve a CBR value greater than 20%.  Subsequently the second layer of 200mm shall also be laid over the first layer, watered and rolled to a proper gradient and camber with 8 tonnes road roller and thoroughly compacted with a CBR valve of 10% is achieved.  Excessive rolling shall be avoided.

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CE 6504

Preparation of base:  The stones shall be laid closely packed to the profile of the finished road surface in such a way that these shall not move under pressure.  A thin cushion of murrum shall be placed over the sub-base and packed with the stone.  The joints shall preferably be staggered. Soling shall commence from edges and proceed towards the center.  The profile of the soling shall frequently be checked with templates as the laying progresses.  When a sufficient length of soling has been laid this shall be watered and packed with a power road roller of not less than 8 tonnes capacity and the surface shall be evened by blinding with small pieces of stone and chipping during rolling.  A final thin cushioning with murrum shall be spread over the surface and watered and lightly rolled.  Rolling shall be continued till the required compacted thickness is obtained. Preparation of Wearing Course:  Road metal from road side stacks shall be raked on to the carriage way soling course directly.  Spreading shall be done to the specified camber and thickness, but never more than 100mm at a time to make a consolidated thickness of at least 75mm after rolling.  Two such layers shall be spread and consolidated separately but consequently to form a total compacted thickness of 150mm.  The surface so laid in each layer shall be checked up by means of wooden templates and spirit levels placed every 6 to 7 meters.  The top surface being dressed up and hand packed with smaller pieces of stone between successive templates.  Transition strips and curves shall be checked up very carefully Dry Rolling: When spreading has been done for a sufficient length (not less than 15m), dry rolling shall be started with a power road roller of 8 tonnes minimum weight, to obtain perfect inter locking of the adjacent pieces of stones. Adding Screenings When the desired degree of compaction has been obtained by dry rolling screenings of approved stone chippings shall be spread uniformly over the surface by brooming and these shall be pushed into the interstices by rolling. Any unevenness observed shall be rectified by removing stones to a depth of 50 to 75mm, refilling the same, hand packing and re-rolling. No watering shall be done till the process is complete. Spreading and wet rolling:  Approved quality blindage such as murrum or sandy loam shall then be spread uniformly over the surface to a thickness of about 12mm watered and rolled. V Sem – PEC – by L.Ranjith Kumar/AP Civil

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The roller wheels as well as the road surface shall be constantly watered during the wet rolling and nay stone piece picked up shall be replaced by hand.  The rolling shall be continued until slurry is formed over the entire surface and the same moves in a wave in front of the roller wheels as it moves, when rolling may be stopped and the surface allowed drying.  The finished surface shall be smooth and uniform, free from waviness and corrugations and as per specified profile and camber. Finishing, Curing and Open to traffic: After 24 hours of wet rolling, the surface shall be covered with a thin layer of sand (about 12mm thick) for curing. Ordinarily the newly consolidated surface shall not be opened to traffic till it is dry which may take 2 to 4 days depending on weather conditions. As the surface dries up the road maybe opened to traffic. BITUMINOUS ROAD CONSTRUCTION: Preparation of existing WBM surface:  The existing water bound macadam surface shall be brushed, cleaned properly with wire brushes and coir brooms, so as to free from all loose materials, murrum, earth, silt and caked mud etc.  If during the process of cleaning the sub grade (water bound macadam), soft spots and pockets, hollows etc. are found and such spots/pockets will be filled with approved precoated bituminous chips, consolidated and finished to proper level, rolled with power roller if necessary.  The pot holes shall be excavated properly in a rectangular or rhomboidal shape with vertical edges.  The bottom and sides shall be cleaned as stated above.  The sides and bottom shall then be thoroughly painted with heated 80/100 penetration bitumen.  The pot hole shall thereafter be filled with premixed bituminous chips so that after thorough tamping and rolling, the surface is flush with surrounding road surface. Tack Coat:  Bitumen of the grade shall be heated to a temperature of 1630 C to 1770 C in a bitumen boiler and the hot bitumen shall be applied evenly to the thoroughly cleaned and prepared road surface @ 8.5 kg/10 sqm.  Application shall be done by a mechanical pressure sprayer or if permitted, by perforated pouring cans.  The tack coat shall be applied just before the macadam is laid.  Application of tack coat shall be only slightly in advance of laying premixed chips.  In case of surface already asphalted application of tack coat is not necessary.

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Unit 4 – Highway Construction Material & Practice

CE 6504

Compaction:  The base bituminous macadam course shall be compacted thoroughly and evenly with 8 to 10 tonne power roller immediately after it is laid.  The surface shall be checked for correct grade during and after rolling.  Any irregularities shall be corrected by adding precoated chips or removing the surplus. The disturbed surface shall be well compacted again. I  If necessary, the roller wheel shall be coated with oil to prevent the coated chip from sticking to the wheels. Rolling shall be continued till no wheel marks are left on the surface. CEMENT CONCRETE ROAD CONSTRUCTION: Preparing the Sub-grade and subbase: Subgrade: earth that has been graded to the desired elevation. (In county and municipal paving projects with low traffic volumes, concrete is often placed directly on the prepared earth subgrade.) Subbase: a course of material that is placed on the subgrade to provide drainage and stability. Granular subbase is the most drainable subbase. It is a mixture of granular material that is uniformly shaped and minimally compacted. It does not provide significant structural support; no construction traffic is allowed on a granular subbase. Placing dowel bars:  Dowel bars transfer heavy loads across joints in the pavement, preventing faulting at the joint that can lead to pavement damage.  Practices vary from state to state, but dowel bars are typically required in eight-inch or thicker pavements.  Dowels must be positioned and aligned perfectly so that, as joints open in winter and close in summer with contraction and expansion of the concrete, the pavement on either side of the joints can move in a straight line along the smooth dowels.

Wetting the grade: A dry subbase draws water from the bottom of the concrete mixture. This can produce stress due to differential moisture levels throughout the slab, causing cracking. To help prevent these stresses, thoroughly spray the subbase with water shortly before V Sem – PEC – by L.Ranjith Kumar/AP Civil

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Unit 4 – Highway Construction Material & Practice

Placing the concrete: Delivering the mix when transporting the mixture from plant to construction site, the goal is to deliver well mixed, workable concrete to the construction site. It is essential that the mixture be uniform and consistent from batch to batch. Placing the concrete To prevent differential compaction that can interfere with good drainage, haul trucks should not be driven on the subbase. If the grade provides adequate space, delivery vehicles should deliver the concrete from a haul road adjacent to the area to be paved. The mix is deposited, from off the grade, in front of the paver. It may be deposited by a belt placer or other method. Setting header joints Header joints are built at the end of a section of pavement where, in the future, pavement construction will continue. Header joints must be constructed at the end of a pour or a day’s run, or if paving is delayed by 30 minutes or more. Header Construction:  A header board is placed just beyond the line where the paver has pulled away from the slab.  Tie-bars protruding through the header board are placed into the fresh concrete and stick out beyond the board. (The protruding ends will be incorporated into the next pavement section.)  The header area is hand-poured, then vibrated, finished, and cured. Concrete should be well consolidated against the header board and finished with an edging tool. Placing tie bars:  When two or more lanes are placed, tie-bars must be placed across the centerline or lane lines to prevent movement along the line.  If the paver does not install tie bars mechanically, a crew member rides on the paver and inserts them manually.  In either case, a timing device—usually a wheel of a specific circumference riding on the paver track—is used to ensure the correct spacing. Finishing Immediately after the paver passes, the surface is normally finished to close holes and create a tight surface. Crews standing along the slab edge run finishing tools (floats and straightedges) across the surface. Curing The importance of managing moisture in concrete immediately after placement cannot be overemphasized. Concrete moisture is managed primarily through proper curing—that is, by applying curing compound uniformly to the entire surface and exposed edges of the concrete to slow the evaporation of water from the concrete. Curing preserves water for hydration, maximizing pavement strength and durability. It also helps prevent the surface from drying out more quickly than the rest of the slab, reducing the possibility of surface damage due to differential shrinkage.

HIGHWAY DRAINAGE: Typical cross section of urban roads:

V Sem – PEC – by L.Ranjith Kumar/AP Civil

V Sem – PEC – by L.Ranjith Kumar/AP Civil

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CE 6504

Arrangement of Water collection and disposal: a) Catchpit and Drain

b) At Superelevation opening in the median:

c) At superelevation with central drainage system

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Unit 4 – Highway Construction Material & Practice

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Urban drainage system:

Unit 4 – Highway Construction Material & Practice

CE 6504

Typical Crossection of hill road drainage: In stable area:

Side Drains:

Longitudinal and transverse drains:

V Sem – PEC – by L.Ranjith Kumar/AP Civil

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V Sem – PEC – by L.Ranjith Kumar/AP Civil

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Unit 4 – Highway Construction Material & Practice

CE 6504

Construction Machineries: The crawler Tractor: It is a construction vehicle that moves on tracks instead of wheels. The tracks spread the vehicles weight over a larger surface area, enabling the tractor to exert a lower force per unit area on the ground.

This allows the tractor to safely traverse over moister ground. A variety of attachments can be added to the crawler tractor by its usability. When a dozer blade is attached to the front of the crawler it is known as “Bulldozer”. With a loader attachment, it becomes a crawler loader. The Hydraulic Excavator: It is most commonly used for digging rocks and soil but with its many attachments it can aslo be used for cutting steel, breaking concrete, drilling holes in the earth, laying gravel, crushing rocks, steel and concrete and even landscapes. It have an operating weight of 9072 kg or higher.

The wheel loader: It is also known as a front end loader or bucket loader. It is one of the most widely used machines in construction today and is noted for payload capacity to perform multiple tasks at a low cost. Wheel loaders are primarily used in construction applications such as material handling, digging, load-and-carry, road building and site preparation some models even come in waste handling versions. The Motar Grader: It is also known as patrol. It is a piece of heavy machinery used to create a smooth, wide flat surface. The grader is used for road maintenance. Its main function is to flatten surfaces before the application of asphalt presently these machines are also commonly used for fine grading, spreading and earthmoving. They can be used for clearing debris and brush snow removal.

Motor Scraper: It also known as self-propelled scrapers are lare motorized machines used for digging, hauling and levelling out materials in variety of construction jobs. Running on massive rubber tires, these machines quickly move large quantitues of earth around a construction site.

The Rollers: Rollers are used to compact loose foundation such as soil, gravel, asphalt and bituminous material and are primarily used for construction or agriculture applications. The rolling process ensures that foundations are compacted throughly so the materials are solid and do not come loose.

V Sem – PEC – by L.Ranjith Kumar/AP Civil

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The compactors: Compactors are machines frequently used to compact materials such as soil in order to increase its density for construction. In addition, compactors are utilized in landfill tasks. Common varities are plate tampers, vibratory plates.

Unit 4 – Highway Construction Material & Practice

CE 6504

CBR test on Soil: Definition: It is the ratio of force per unit area required to penetrate a soil mass with standard circular piston at the rate of 1.25 mm/min. to that required for the corresponding penetration of a standard material. The California Bearing Ratio Test (CBR Test) is a penetration test developed by California State Highway Department (U.S.A.) for evaluating the bearing capacity of subgrade soil for design of flexible pavement. Tests are carried out on natural or compacted soils in water soaked or un-soaked conditions and the results so obtained are compared with the curves of standard test to have an idea of the soil strength of the subgrade soil. Apparatus:  Mould  Steel Cutting collar  Spacer Disc  Surcharge weight  Dial gauges  IS Sieves  Penetration Plunger  Loading Machine  Miscellaneous Apparatus

Asphault Road Paver: A paver is an engineering vehicle used to lay asphault on roadways. It is normally fed by a dump truck. A separate machine, a roller is then used to press the hot aphault mix, resulting a smooth, even surface. The sub-base being prepared by use of grader to trim crushed stone to profile after rolling.

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Unit 4 – Highway Construction Material & Practice

CE 6504

Procedure:  Normally 3 specimens each of about 7 kg must be compacted so that their compacted densities range from 95% to 100% generally with 10, 30 and 65 blows.  Weigh of empty mould  Add water to the first specimen (compact it in five layer by giving 10 blows per layer)  After compaction, remove the collar and level the surface.  Take sample for determination of moisture content.  Weight of mould + compacted specimen.  Place the mold in the soaking tank for four days (ignore this step in case of unsoaked CBR.  Take other samples and apply different blows and repeat the whole process.  After four days, measure the swell reading and find %age swell.  Remove the mould from the tank and allow water to drain.  Then place the specimen under the penetration piston and place surcharge load of 10lb.  Apply the load and note the penetration load values.  Draw the graphs between the penetration (in) and penetration load (in) and find the value of CBR.  Draw the graph between the %age CBR and Dry Density, and find CBR at required degree of compaction. Uses and Significance:  The CBR test is one of the most commonly used methods to evaluate the strength of a sub grade soil, sub base, and base course material for design of thickness for highways and airfield pavement.  The California bearing ratio test is penetration test meant for the evaluation of subgrade strength of roads and pavements. The results obtained by these tests are used with the empirical curves to determine the thickness of pavement and its component layers. This is the most widely used method for the design of flexible pavement.  This instruction sheet covers the laboratory method for the determination of C.B.R. of undisturbed and remoulded /compacted soil specimens, both in soaked as well as unsoaked state.

Unit 4 – Highway Construction Material & Practice

CE 6504

Step 1: Plastics waste (bags, cups, thermocole) made out of PE,PP and PS cut into a size between 2.36mm and 4.75mm using shredding machine, (PVC waste should be eliminated). Step 2a: The aggregate mix is heated to 165°c (as per the HRS specification) and transferred to mixing chamber. Step 2 b: Similarly the bitumen is to be heated upto a maximum of 160°c (HRS Specification) to have good binding and to prevent weak bonding. (Monitoring the temperature is very important). Step 3: At the mixing chamber, the shredded plastics waste is to be added. It gets coated uniformly over the aggregate within 30 to 60 seconds, giving an oily look. Step 4: The plastics waste coated aggregate is mixed with got bitumen and the resulted mix is used for road construction. The road laying temperature is between 110°c to 120°c. The roller used is 8-ton capacity. Overall Process: AGGREGATES

170oC

HOT AGGREGATES

Final Stage

Waste Plastics

POLYCOATED AGGREGATES

POLYMER BITUMEN AGGREGATE MIXTURE

PLASTICS: The following types of waste plastic can be used in the construction of rural roads:  Films ( Carry Bags, Cups) thickness up to 60micron (PE, PP and PS)  Hard foams (PS) any thickness  Soft Foams (PE and PP) any thickness.  Laminated Plastics thickness up to 60 micron (Aluminum coated also) packing materials used for biscuits, chocolates, etc.  Poly Vinyl Chloride (PVC) sheets or Flux sheets should not be used in any case. V Sem – PEC – by L.Ranjith Kumar/AP Civil

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V Sem – PEC – by L.Ranjith Kumar/AP Civil

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