HIGHWAY CONSTRUCTION MATERIAL & PRACTICE

Highway construction material and properties

1. Highwa y cons t ruc t ion ma t erials and prac t ice Presented by: Vijayvenkatesh.C CIVIL DEPARTMENT OF CIVIL ENGINEERING FINAL YEAR. ST.JOSEPHS COLLEGE OF ENGINEERING & TECHNOLOGY.

2. Highway construction can be characterized by large right-of-way having length of considerable amount. Due to this Highway construction constitutes materials that are needed in large quantum. Depending upon the type of highway pavement, flexible or rigid the material required for highway construction is decided . These items of major importance which are used in normal highway construction  are: 1. Bituminous Materials 2. Soil 3. Aggregates 4. Portland Cement Concrete 5.  Admixtures 6. Pavement Marking Materials 7. Structural Steel 1.Highway construction materials and properties

3. Bituminous Materials Bituminous material, or bitumen in the form of asphalt, is one of the major highway construction materials used . Asphalt is normally a residue product from the distillation of crude oil and, as refined, is a heavy, viscous material that is semisolid at normal atmospheric temperatures. By controlled processing or blending desired viscosity and hardness  characteristics can be produced . This product is called asphalt cement and is also known as paving grade or penetration grade asphalt . Bituminous Materials, of the Highway Materials Manual contains the test procedures, sampling requirements, and test equipments.

4. Soils Major works of man since the beginning of time have depended on the use of soils. Not only does soil form the foundation, or supporting surface for buildings, bridges, roadways and culverts, but it is the most common constituent, in the form of aggregate. Soils are the most basic abundant material in highway engineering and as such, are well characterized by the expression "common as dirt." The steps taken to prepare foundations manipulate and transport soils and prepare them for use as aggregates accounts for well over 70 percent of the total cost of construction for a normal highway project . Aggregates The surface, base, and sub base of pavements consist of aggregates or a mixture of aggregates with cement and water (Portland cement concrete) or a bituminous material (bituminous concrete).

5. The strength properties of a layer are a function of both the quality and the proportions of ingredients. Aggregates are hard, durable, mineral materials obtained by mining or quarrying operations of deposits of sand, gravel, talus or ledges, and may be defined as "granular material of mineral composition Portland Cement Concrete Portland cement concrete is a mixture of portland cement, water, air , sand and gravel or crushed stone. It is formed when the cement and water (paste) combine chemically and binds the entire mixture into a rock-like mass. It may be thought of as a two component material; paste and aggregate. The paste is comprised of cement, water, and entrained air.

6. The aggregate portion is generally composed of sand and gravel and comprises 70 to 80 percent of the volume of the concrete. Aggregates both fine and course, should be selected for their quality, strength, durability and resistance to environmental affects. Admixtures Number of additives developed to improve various characteristics of concrete in both the plastic and hardened states.Other additives gaining in usage are known as water reducing admixtures and set retarding admixtures . Water reducing additive is intended to impart more workability into a plastic concrete with less water, thereby increasing its strength through a reduced water/cement ratio. Set retarding additive is intended to slow the setting characteristics of the mix and thereby allowing more time for placing and finishing

7. Pavement Marking Materials Pavement markings have important functions in providing guidance and information to drivers. Pavement markings convey important information to drivers without diverting their  attention  from the road . In some cases they supplement regulations or warnings given by other devices. In other cases they are used alone and produce results that cannot be obtained by any other device . Many materials can be used for pavement marking. The choice depends on cost, durability, reflectivity, pavement surface, and drying time.

8. These are Pavement Marking Materials, Paint Water-based paint, applied either cold or hot, is the most commonly used pavement marking. It is low cost with a short drying time, but its visibility on wet nights is just moderate. Thermoplastics These pavement-marking materials are made of thermoplastic heated to about 400° F and spread onto the pavement surface Epoxy   Also applied as a liquid with special equipment, epoxy has good visibility and reflectivity, and cost is moderate. Markings remains 3 to 4 years.

9. Moisture Condition Value (MCV) Test California Bearing Ration (CBR) Test Dynamic Cone Penetrometer Ground Penetrating Radar ( GPR) Penetration Test on Bitumen : Softening Point Test on Bitumen Los Angles Abrasion Value Test Flakiness Index Test 2.Testing methods on Highway Materials

10. The   California bearing ratio  ( CBR ) is a penetration test for evaluation of the  mechanical strength  of natural ground,  subgrades  and basecourses beneath new carriageway construction . Subgrade soil is the integral part of the road pavement structure which provides support to the pavement. The subgrade and its different properties are very much important in the pavement design structure. The major function of the subgrade is to provide the support to the pavement against traffic loading and for this the subgrade should possess sufficient stability under adverse climate and heavy loading conditions. 3.CBR Test for subgrade

11. The strength of a soil or subgrade can be determined by using a test known as California Bearing Ratio Test which was developed in California in the year 1930's and it is way to determine the standard soil properties such as density Subgrade performance A subgrade characteristics mainly depends on the following three factors such as, Load bearing capacity : The subgrade resists loads which are transmitted from the pavement structure. Various factors such as degree of compaction, moisture content, and nature of soil affect the load bearing capacity of soil. A subgrade without excessive deformation sustain heavy loading is considered good. Moisture content: Properties such as load bearing capacity, shrinkage and swelling etc. are mostly affected by the variation of moisture content. Various things such as drainage, groundwater table elevation, infiltration, or pavement porosity etc. Influence the moisture content. Highly wet subgrades deform more under loading..

12. Shrinkage and/or swelling: Shrinkage or swelling mainly depends on moisture content. Additionally, in frost conditions (in northern climate) soils with excessive fine content may be susceptible to frost heave. Shrinkage, swelling and frost heave are the factors whose tendency is to deform and crack any pavement structure construed over them. The desirable properties of sub grade soil as a highway material are Withstand capability (Stability) Ease of compaction. Strength permanency Low change in volume during adverse conditions of weather and ground water table. Superior drainage Incompressibility

13. Aggregate plays an important role in pavement construction. Aggregates influence, to a great extent, the load transfer capability of pavements, following tests are carried out: Crushing test Abrasion test Impact test Soundness test Specific gravity and water absorption test Bitumen adhesion test 4.Tests on Aggregates

14. CRUSHING TEST Crushing Test is used to determine the crushing strength of aggregates. The aggregate crushing value provides a relative measure of resistance to crushing under gradually applied crushing load

15. ABRASION TEST Abrasion test is carried out to test the hardness property of aggregates and to decide whether they are suitable for different pavement construction works. Los Angeles abrasion test is a preferred one for carrying out the hardness property and has been standardized in India 

16. IMPACT TEST The aggregate impact test is carried out to evaluate the resistance to impact of aggregates. Aggregates passing 12.5 mm sieve and retained on 10 mm sieve is filled in a cylindrical steel cup of internal dia 10.2 mm and depth 5 cm which is attached to a metal base of impact testing machine. The material is filled in 3 layers where each layer is tamped for 25 numbers of blows. Metal hammer of weight 13.5 to 14 Kg is arranged to drop with a free fall of 38.0 cm by vertical guides and the test specimen is subjected to 15 numbers of blows . The crushed aggregate is allowed to pass through 2.36 mm IS sieve. And the impact value is measured as percentage of aggregates passing sieve ( W2 ) to the total weight of the sample ( W1 ). Aggregate impact value = (W1/W2)*100

17. Soundness test is intended to study the resistance of aggregates to weathering action, by conducting accelerated weathering test cycles. The Porous aggregates subjected to freezing and thawing is likely to disintegrate prematurely. To ascertain the durability of such aggregates, they are subjected to an accelerated soundness test Aggregates of specified size are subjected to cycles of alternate wetting in a saturated solution of either sodium sulphate or magnesium sulphate for 16 – 18 hours and then dried in oven at 105 to 110 C to a constant weight. After  five cycles , the loss in weight of aggregates is determined by sieving out all undersized particles and weighing. The loss in weight should  not exceed 12 percent  when tested with  sodium sulphate  and  18 percent  with  magnesium sulphate  solution. SOUNDNESS TEST

18. The specific gravity and water absorption of aggregates are important properties that are required for the design of concrete and bituminous mixes. The specific gravity of a solid is the ratio of its mass to that of an equal volume of distilled water at a specified temperature . Water Absorption:  The difference between the apparent and bulk specific gravities is nothing but the water permeable voids of the aggregates. We can measure the volume of such voids by weighing the aggregates dry and in a  saturated surface dry condition , with all permeable voids filled with water. The difference of the above two is M W . M W  is the weight of dry aggregates minus weight of aggregates saturated surface dry condition. Thus, Water Absorption = (M W /M D )*100   SPECIFIC GRAVITY AND WATER ABSORPTION

19. Bitumen adheres well to all normal types of road aggregates provided they are dry and free from dust. In the absence of water there is practically no adhesion problem of bituminous construction. Adhesion problem occurs when the aggregate is wet and cold. This problem can be dealt with by removing moisture from the aggregate by drying and increasing the mixing temperature . Further, the presence of water causes stripping of binder from the coated aggregates. This problem occurs when bitumen mixture is permeable to water. Several laboratory tests are conducted to arbitrarily determine the adhesion of bitumen binder to an aggregate in the presence of water. Static immersion test is one specified by IRC and is quite simple . The principle of the test is by immersing aggregate fully coated with binder in water maintained at 40 C temperature for 24 hours. BITUMEN ADHESION TEST

20. Penetration test Ductility test Softening point test Specific gravity test Viscosity test Flash and Fire point test Float test Water content test Loss on heating test 5.Tests on bitumen

21. Penetration test It measures the hardness or softness of bitumen by measuring the depth in tenths of a millimeter to which a standard loaded needle will penetrate vertically in 5 seconds It may be noted that penetration value is largely influenced by any inaccuracy with regards to pouring temperature, size of the needle, weight placed on the needle and the test temperature. In hot climates, a lower penetration grade preferred.

22. DUCTILITY TEST Ductility is the property of bitumen that permits it to undergo great deformation or elongation. Ductility is defined as the distance in cm, to which a standard sample or briquette of the material will be elongated without breaking. Dimension of the briquette thus formed is exactly 1 cm square. The bitumen sample is heated and poured in the mould assembly placed on a plate. These samples with moulds are cooled in the air and then in water bath at 27 C temperature .

23. The excess bitumen is cut and the surface is leveled using a hot knife. Then the mould with assembly containing sample is kept in water bath of the ductility machine for about 90 minutes. The sides of the moulds are removed, the clips are hooked on the machine and the machine is operated. The distance up to the point of breaking of thread is the ductility value which is reported in cm. The ductility value gets affected by factors such as pouring temperature, test temperature, rate of pulling etc. A minimum ductility value of 75 cm has been specified by the BIS..

24. SOFTENING POINT TEST Softening point denotes the temperature at which the bitumen attains a particular degree of softening under the specified condition of test. The test is conducted by using Ring and Ball apparatus. A brass ring containing test sample of bitumen is suspended in liquid like water or glycerin at a given temperature. A steel ball is placed upon the bitumen sample and the liquid medium is heated at a rate of 5 C per minute. Temperature is noted when the softened bitumen touches the metal plate which is at a specified distance below. Generally, higher softening point indicates lower temperature susceptibility and is preferred in hot climates.

25. SPECIFIC GRAVITY TEST The specific gravity of bitumen is defined as the ratio of mass of given volume of bitumen of known content to the mass of equal volume of water at 27 C. The specific gravity can be measured using either pycnometer or preparing a cube specimen of bitumen in semi solid or solid state. In paving jobs, to classify a binder, density property is of great use. In most cases bitumen is weighed, but when used with aggregates, the bitumen is converted to volume using density values. The density of bitumen is greatly influenced by its chemical composition. Increase in aromatic type mineral impurities cause an increase in specific gravity. The specific gravity of bitumen varies from 0.97 to 1.02.

26. WATER CONTENT TEST It is desirable that the bitumen contains minimum water content to prevent foaming of the bitumen when it is heated above the boiling point of water. The water in bitumen is determined by mixing known weight of specimen in a pure petroleum distillate free from water, heating and distilling of the water. The weight of the water condensed and collected is expressed as percentage by weight of the original sample. The allowable maximum water content should not be more than 0.2% by weight.

27. LOSS ON HEATING TEST When the bitumen is heated it loses the volatility and gets hardened. About 50gm of the sample is weighed and heated to a temperature of 163 C for 5 hours in a specified oven designed for this test. The sample specimen is weighed again after the heating period and loss in weight is expressed as percentage by weight of the original sample. Bitumen used in pavement mixes should not indicate more than 1% loss in weight, but for bitumen having penetration values 150-200 up to 2% loss in weight is allowed.

28. Wha t is Bitumen? The primary use (70%) of asphalt/ bitumen  is in  road  construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Preparation of the existing base course layer The existing surface is prepared by removing the pot holes or rust if any. The irregularities are filled in with premix chippings at least a week before laying surface course. If the existing pavement is extremely way, a bituminous leveling course of adequate thickness is provided to lay a bituminous concrete surface course on a binder course instead of directly laying it on a WBM. Application of Tuck Coat It is desirable to lay AC layer over a bituminous base or binder course. A tack coat of bitumen is applied at 6.0 to 7.5 kg per 10 sq.m area, this quantity may be increased to 7.5 to 10 kg for non-bituminous base. 6.BITUMINOUS ROAD CONSTRUCTION

29. Preparation and placing of Premix The premix is prepared in a hot mix plant of a required capacity with the desired quality control. The bitumen may be heated upto 150 – 177 deg C and the aggregate temperature should not differ by over 14 deg C from the binder temperature. The hot mixed material is collected from the mixture by the transporters, carried to the location is spread by a mechanical paver at a temperature of 121 to 163 deg C. the camber and the thickness of the layer are accurately verified. The control of the temperatures during the mixing and the compaction are of great significance in the strength of the resulting pavement structure. Rolling A mix after it is placed on the base course is thoroughly compacted by rolling at a speed not more than 5km per hour .

30.   The initial or break down rolling is done by 8 to 12 tonnes roller and the intermediate rolling is done with a fixed wheel pneumatic roller of 15 to 30 tonnes having a tyre pressure of 7kg per sq.cm. the wheels of the roller are kept damp with water. The number of passes required depends on the thickness of the layer. In warm weather rolling on the next day, helps to increase the density if the initial rolling was not adequate. The final rolling or finishing is done by 8 to 10 tonne tandem roller. Fig: Tandem Roller

31. Quality control of bituminous concrete construction The routine checks are carried out at site to ensure the quality of the resulting pavement mixture and the pavement surface. Periodical checks are made for, a) Aggregate grading b) Grade of bitumen c) Temperature of aggregate d) Temperature of paving mix during mixing and compaction. At least one sample for every 100 tonnes of the mix discharged by the hot mix plant is collected and tested for above requirements.  Marshall tests  are also conducted. For every 100 sq.m of the compacted surface, one test of the field density is conducted to check whether it is atleast 95% of the density obtained in the laboratory. The variation in the thickness allowed is 6mm per 4.5m length of construction.

32. Finished surface: The AC surface should be checked by a 3.0 m straight edge. The longitudinal undulations should not exceed 8.0 mm and the number of undulations higher than 6.0 mm should not exceed 10 in a length of 300 m. The cross-traffic profile should not have undulations exceeding 4.0mm.

33. Cement concrete road construction is one of the types of low volume road construction. We know that the construction of the road is mostly dependent upon the factor like amount traffic that is to be handled by the road after its completion. On most of the village roads connecting small villages in the rural areas of the country, the type of vehicular traffic is quite different from the traffic on other highways. The traffic passing on a road can be categorized into three categories as light commercial traffics, medium commercial traffics and heavy commercial traffics, but the frequency of each class of traffic varies with the road. 7.Concrete Road Construction

34. Materials for concrete cement road construction The materials for the cement concrete road construction may be divided into two parts. These are mentioned as follows:- Selection of basic component materials Mix design and production of pavement quality concrete(PQC) mix required to construct the cement concrete road pavement

35. Subgrade preparation Subgrade preparation involves cleaning,  earthwork  (excavation or filling of soil, replacement of weak soil,  soil stabilization  etc.) and compaction. Where the concrete layer is laid directly over the subgrade, the subgrade is moist at the time concrete is placed. If the subgrade is dry, water could be sprinkled over the surface before laying any concrete course, however, care should taken so that soft patches or water pools are not formed at the surface Construction of Base/ Sub-base A base/ sub-base to the concrete pavement provides uniform and reasonably firm support, prevents  mud-pumping  , and acts as capillary cut-off .

36. Sub-base for concrete pavement could be constituted with brick flat soling, WBM, granular aggregates, crushed concrete, slag, stabilized soil etc. sub-base could be of three types with ( i ) Granular material (for example, brick soling with one layer of sand under it, WBM, well graded granular materials etc.) (ii) Stabilized soil (iii) Semi-rigid material, (for example, lime burnt clay pozzolana concrete, lime fly-ash concrete, lean cement concrete roller compacted concrete etc.). Compaction and surface finishing Concrete is spread evenly and is rodded with suitable equipment such that formation of  honey-combing  or voids can be avoided. At the same time, over-compacting needs to be avoided, which can cause segregation and loss of  entrained air 

37. Texturing Finished concrete has a smooth surface;  texturing  of concrete surface is done to impart required  skid resistance  to the concrete surface. The texturing is done by means of wire brushing or grooving along the transverse direction. Initial texturing may be done at the time of construction of the paver itself. Final texturing is done no sooner the sheen of the concrete surface goes off.

38. Concrete curing Curing  is a process in which requisite moisture content and temperature is maintained so that concrete achieves its design strength through hydration of cement

39. 8.QUALITY CONTROL MEASURES Study duties responsibilities, Tender specification, standards, codes of practice and work instruction. Evolve effective acceptance/rejection procedures for construction materials in coordination with the project purchase department. Do proper sampling and testing of steel, cement, concrete, aggregates, water, etc., and verify test results in view of standards and work specifications prior to their use in construction. Also control quality of electrodes to their use in welding. Set procedures to control quality at the points of storage for raw materials, mixing and placing of concrete. Follow the prescribed curing and deshuttering schedules. Observe procedures to control quality of welded joints of structural steel members. Evolve a system to check quality of workmanship in all construction activities.

40. Keep all revised Indian Standards and codes of practice available in QC laboratory and have them handy during discussion with client/consultant. Maintain sequence of construction required under any activity. Discuss QA/QC issues as a separate agenda during site review meetings with staff. Observe regular schedule for maintenance, repairs and calibration of plants and equipments. Keep spare parts/materials for laboratory equipments weigh batchers, batching plant, etc., always keep spare vibrators ready at site. Carry work instruction cards in pocket while supervising/inspecting works. Regularly maintain the formats prescribed under ISO 9002 Quality assurance system Practice sound house keeping methods to achieve saving, safety and quality.

41. 9.Highway Drainage It’s purpose is to drain rain water from the highway into the sewerage system. A highway drain is the pipe connecting the highway gully to the surface water sewer. A soakaway is a drainage pit covered by a metal cover or sometimes by soil. Its purpose is to allow rain water from buildings to permeate into the surrounding subsoil. These are sometimes used to drain the highway Highway drainage should fulfil the following objectives: Prevent flooding, ponding and seepage, and keep the carriageway, cycleway and footway as free of standing water as possible. Ensure surface water falling on the highway enters the drainage system or natural watercourse as speedily as possible. Keep the underlying road structure as dry as possible.

42. Prevent injury or damage caused by hazardous surface water. Prevent highway surface water flooding adjacent properties. Prevent blockages in associated highway drainage systems with consequential flooding.

43. Highway drainage is important from various view points: Excess moisture in soil sub-grade causes instability under the road surface. The pavement may fail due to sub-grade failure. In some clayey soil variation in moisture content causes considerable variation in volume of sub-grade. This sometimes contributes to pavement failure. The waves and corrugations formed in case of flexible pavements also play an important role in pavement failure. Sustained contact of water with bituminous pavements causes failure due stripping bitumen from the aggregates like loosening of some of the bituminous pavement layer and formation of pot holes The prime cause of failures in rigid pavements by mud pumping is due to the presence of water in fine sub-grade soil.

44. Well designed and well maintained road drainage is important in order to: Minimize the environmental impact of road runoff on the receiving water environment. Ensure the speedy removal of surface water to enhance safety and minimize disruption to road users. Maximize the longevity of the road surface and associated infrastructures.

45. 10.Highwa y machineries mo t or grader

46. Asphal t mixing plan t

47. Road Roller machine

48. Crawler Excava t or

49. Forklif t t ruck

50. Wheel loader

51. Ruck crane