Construction

Technology

Presentatio

n I

CONTENT

1. BLACK TOP• 1.1 INTODUCTION• 1.2 CONSTRUCTION TECHNIQUES OF BITUMINOUS CONSTRUCTION

2. CONCRETE PAVEMENT• 2.1 INTRODUCTION• 2.2 CONSTRUCTION STEPS FOR CEMENT CONCRETE PAVEMENT SLAB

3. EQUIPMENTS USED FOR ROAD CONSTRUCTION• 3.1 INTRODUCTION• 3.2 EQUIPMENTS

4. HILLY ROAD• 4.1 INTRODUCTION• 4.2 FEATURES OF HILLY ROAD

1. BLACK

TOP

1.1 Introduction

The black top construction is in extensive use in developing nations like India, where the cement as a construction material is in great demand for large number of other engineering projects. Depending on traffic demands , stage development is also possible in the case of bituminous roads. Bituminous pavements are in common use in India and abroad. It is possible to construct relatively thin bituminous pavement layers over an existing pavement. Therefore, these are commonly adopted as wearing course. Flexible pavement could be strengthened in stages by constructing bituminous pavement layers one after another in a certain period of time unlike the cement concrete pavement construction.

1.2 Construction Techniques Of Bituminous Construction

The following construction techniques are in use:-

Interface treatments like prime coat and tack coat.

Surface dressing and

Seal coat.

Surface of the existing pavement layer is to be cleaned to remove dust and dirt and a thin layer of bituminous binder is to be sprayed before the construction of any type of bituminous layer over this surface. This treatment with bituminous material is called interface treatment which is necessary to provide the necessary bond between the old and the new layers. The interface treatment may either be a prime coat or tack coat and in some cases, the prime coat followed by a tack coat.

Interface treatment

PRIME COATBituminous prime coat is the first application of a low viscosity liquid bituminous material over an existing porous or absorbent pavement surface like the WBM base course. The main object of priming is to plug in the capillary voids of the porous surface and to bond the loose mineral particles on the existing surface, using a binder of low viscosity which can penetrate into the voids. The bituminous primer is sprayed uniformly using a mechanical sprayer at a rate of 7.3 to 14.6 kg/m2 area, depending on the porosity of the surface. The primed surface is allowed to cure for at least 24 hours, during which period no traffic is allowed.

TACK COATBituminous tack coat is the application of bituminous material over an existing pavement surface which is relatively impervious like an existing bituminous surface or a cement concrete pavement or a pervious surface like WBM which has already been treated by a prime coat. Tack coat is usually applied by spraying bituminous material of higher viscosity like the hot bitumen at the rate of 4.9 to 9.8 kg/m2 area depending in the type of the surface.

BITUMINOUS SURFACE DRESSINGBituminous Surfacing Dressing (BSD) is provided over an existing pavement to serve as thin wearing coat. The single coat surface dressing consists of a single application of bituminous binder material followed by spreading of aggregate cover and rolling. The principal of this method is illustrated in fig:

When the surface dressing is similarly done in two layers, it is called ‘two coat bituminous surface dressing’. Where better adhesion is required, aggregates pre-coated with bituminous binder are used instead of conventional surface dressing and this technique is called ‘Bituminous Surface Dressing with Pre-coated Aggregates’. The main functions of BSD are:-• To serve as a thin wearing course of pavement and to protect the base

course.• To water proof the pavement surface and to prevent infiltration of

surface water.• To provide dust-free pavement surface in dry weather and mud-free

pavement in wet weather.

SEAL COATThe seal coat is a very thin surface treatment or a single coat surface dressing which is usually applied over an existing black top surface. A premixed sand bitumen (hot mix) seal coat is also commonly used over the premixed carpet .Seal coat is usually recommended as a top coat over certain bituminous pavements which are not impervious, such as open graded bituminous constructions like premixed carpet and grouted macadam. Seal coat is also provided over an existing bituminous pavement which is worn out. The main functions of seal coat are: To seal the surfacing against the penetration of water. To develop skid resistance texture. To enliven an existing dry or weathered bituminous

surface.

2.CONCRETE PAVEMENT

INTRODUCTION

The cement concrete pavement maintains a very high recognition among the engineer and the road users alike. Due to the excellent riding surface and pleasing appearance, the cement concrete roads are very much preferred. It is also a matter of fact that the life of cement concrete road is much more than any other type of construction. This is why the engineers have inherent confidence in the use of cement concrete for any kind of construction project.

Construction procedure of concrete slab

 Preparation of subgrade and sub-base: The subgrade or sub-base for laying of the concrete slabs should comply with the following- that no soft spots are present in the subgrade or sub-base.

that the uniformly compacted subgrade or sub-base extends at least 30cm on either side of the width to be connected.

that the subgrade is properly drained.

that the minimum modules of subgrade reaction obtained with a plate bearing test is 5.54 kg/cm2.

Placing of forms: The steel or wooden forms are used for this purpose . The steel forms are of M.S. channel section and their depth is equal to the thickness of the pavement. When set to grade , the maximum deviation of the top surface of any section from a straight line is not exceeded by 3mm. wooden forms are dressed on side ; these have minimum base width of thickness of 10 cm for slab thickness of 20 cm and minimum base width of 15 cm for slabs over 20 cm thick. They should not deviate more than 3 mm from a straight edge of 3 m in length.

Batching and mixing : After determining the proportion of ingredients for the field mix, the fine aggregates and coarse aggregates are proportioned by weight in a weight-batching plant and placed into the hopper along with the necessary quantity of cement . The mixing of concrete is done in a batch mixer which will ensure a uniform distribution of the materials throughout the mass, so that the mix is uniform in color and is homogenous. The batch of cement, fine aggregate and coarse aggregate is led together into the mixer. The water for mixing in introduced into the drum within the first 15 seconds of mixing. The mixing of each batch is commenced within 1 and ½ minute after all the materials are placed in the mixer.

Transporting and placing of concrete: The cement concrete is mixed in quantities required for immediate use and is deposited on the soil sub grade or sub-base to the required depth and width of the pavement section within the form work in continuous operation. Care is taken to see that no segregation of materials results while the concrete is being transported from the mixer to its placement. The spreading is done uniformly.

Compaction and finishing: The surface of pavement is compacted either by means of a power-driven finishing machine or by a vibrating hand screed. For areas where the width of the slab is very small as at the corner of road junctions, etc., hand consolidation and finishing may be adopted. Concrete as soon as

placed, is struck off uniformly and screened to the crown and cross-section of the pavement to conform the grade.

The tamper is placed on the side forms and is drawn ahead in combination with a series of lifts and drops to compact the concrete.

CURING OF CEMENT CONCRETE The entire pavement surface of the newly laid cement concrete is cured in accordance with the following methods:INITIAL CURING: The surface of the pavement is entirely covered with burlap ,cotton or jute mates .prior or being placed, the mates thoroughly saturated with water and are placed with the wet side down to remain in intimate contact with the surface.FINAL CURING : The final curing is done with any one of the following methods:Curing with wet soil exposed edges of the slab are banked with a soil berm. A blanket of sandy soil free from stones is placed .The soil is thoroughly kept saturated with water for 14 days.IMPERVIOUS MEMBRAME METHOD: Use of an impervious membrane which does not impart a slippery surface to the payment is used. Liquid is applied under pressure with a spray nozzle to cover the entire surface with a uniform film. It hardens with 30 minutes after its application. The liquid is applied immediately after the surface finishing.

3. EQUIPMENTS USED FOR ROAD CONSTRUCTION

The Crawler Tractor

A construction vehicle that moves on tracks instead of wheels. The tracks spread the vehicle’s 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.. When a dozer blade is attached to the front of the crawler tractor it is commonly known as a "bulldozer". With a loader attachment, it becomes a crawler loader.

The Hydraulic Excavator  

The hydraulic excavator is most commonly used for digging rocks and soil, but with its many attachments it can also be used for cutting steel, The hydraulic excavator are used for breaking concrete, drilling holes in the earth, laying gravel onto the road prior to paving, crushing rocks, steel, and concrete, and even mowing landscapes. Hydraulic excavators have an operating weight of 20,000 pounds (9,072 kg) or higher.

Motor Scraper

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

The Wheel Loader

The wheel loader, also known as a front end loader or bucket loader, is one of the most widely used machines in construction today and is noted for its extreme versatility and 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 Motor Grader

A motor grader, known as patrol, or maintainer, is a piece of heavy machinery used to create a smooth, wide, flat surface. Traditionally, 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, as well as for snow removal. A variety of attachments convert the motor grader into a more versatile machine, enabling the machine to do things such as dig shallow holes.

The Rollers

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

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 varieties are plate tampers (also known as rammers), vibratory plates, compactors (also known as tamping foot rollers), and vibratory pad foot compactors.

Asphalt Road Paver

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

4. HILLY ROADS

4.1

IntroductionHilly regions have steep topography, difficult and hazardous terrain, high altitude areas and extreme climatic conditions. Planning, alignment, design, construction and maintenance of roads in hilly terrain are quite different and pose difficult problems in comparison to those for roads in plain terrain. Roads passing through such hilly terrain and leading to towns and villages located on hills are called ‘hill roads’.

4.2 Features of hilly roads

As far as possible the hill road should be aligned along the stable side of the hill slope in order to prevent future land-slides and related problems after the construction of the hill road.

In order to limit the gradient, the length of the hill road is increased by planning zigzag alignment of the road.

An effective surface and sub-surface drainage system is to be planned, designed and constructed in order to keep the road stretches safe without getting washed out during heavy rains.

Also a large number of cross drainage structures such as culverts and bridges are required to enable the streams and rivers to cross the road, without causing damages to the hill road.

Prepared and presented by- KENEDDY NARZARY(CIT/11/CT/013)

RAJU BRAMHA (CIT/12/CT/020)

PURNA ABHILASH MALLICK (CIT/12/CT/003) MURARI KUMAR (CIT/12/CT/013)

ROSEY BARO (CIT/12/CT/017) JEWMA DAIMARY (CIT/12/CT/024)

SHIVAM CHOUDHARY (CIT/12/CT/ET/029) DEBRAJ DAS (CIT/12/CT/010)

}}}

}

BLACK TOP

CONCRETE PAVEMENT

EQUIPMENTS USED FOR ROAD CONSTRUCTION

HILLY ROADS

Thank you