Guidelines for making perfect structural design

This civil engineering article focuses on the least standards which should be maintained for the design of various RCC structural elements like the columns, beams, slab and foundation as well as the least safe standards for the reinforcing bars to be applied for making the design of the above mentioned structural elements.

Minimum cross-sectional dimension for a Column should be 9″x 12″ (225 MM x 300 MM). It is the minimum approved size.

It is always recommended to utilize M20 grade concrete for construction as per IS 456:2000. The least steel in a 9″ x 9″ column should be 4 bars of 12 MM with stirrups of 8 MM steel rings at a spacing of 150 MM centre to centre. In a 9″ x 12″ column, more bars (6 bars with 12 mm diameter) should be added to sustain the total efficiently.

Least RCC beam size should not be lower than 9″x 9″ (225MM X 225MM), with an supplementary slab thickness of 125 MM.

Normally, there should be minimum of 4 bars, with 2 bars having 12 MM thickness in the bottom of the beam, and 2 bars having 10 MM at the top of the beam.

A concrete cover of 40 MM should also be provided. It is suggested to utilize M20 grade of concrete (1 part cement : 1.5 parts sand : 3 parts aggregate : 0.5 parts water).

Minimum thickness of RCC slab should be 5″ (125MM) since a slab may comprise of electrical pipes which are implanted into them which could be 0.5″ or more for internal wiring and as a result the depth of slab is decreased at specific places that lead to cracking, weakening and water leakage throughout rains. Therefore, a least thickness of 5″ should be retained.

Minimum size of foundation for a single storey of G+1 building should be 1m x 1m, where safe bearing strength of soil is 30 tonnes per square meter, and the anticipated load on the column does not surpass 30 tonnes.

The depth of footing should be minimum 4′under ground level. It is suggested to get to depths up to had strata.

Minimum Reinforcing bar details:

1. Columns: 4 bars of 12mm steel rods FE 500.
2. Beams: 2 bars of 12 mm in the bottom and 2 bars of 10 mm on the top.
3. Slab

a) One Way Slab: Main Steel 8 MM bars @ 6″ C/C and Distribution Steel of 6 mm bars @ 6″ C/C
b) Two Way Slab: Main Steel 8 MM bars @ 5″ C/C and Distribution Steel of 8 mm bars @ 7″ C/C

4. Foundation: Initially, there should be 6″ of PCC layer. Over it, a tapered or rectangular footing with minimum 12″ thickness should be arranged. Steel mesh of 8 mm bars @ 6″ C/C should be placed. In a 1m X 1m footing, there should be 6 bars of 8 mm on both segments of the steel mesh.

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Segregation of Concrete- Causes and prohibition

Concrete is a paste of sand and cement which helps to bind the building, but sometimes this concrete gets segregated due to some reasons which can be prevented easily.

According to popular belief, concrete and cement is not the same thing; cement is actually just a part of concrete. So basically concrete or Portland cement concrete is a compound material of fine and coarse aggregate bonded together with a fluid cement or cement paste that become hardens over time. It is distinguished from other, non-cementations types of concrete all binding some kind of clumped together, including asphalt concrete with a bitumen binder which is frequently used for road surfaces and polymer concretes that use polymers as a binder. When clumped is mixed together with dry Portland cement and water, the mixture forms a fluid slurry which can be easily poured and molded into shape, then the cement ill reacts with the water and other ingredients to make a hard matrix that binds the materials together into a durable stone-like material that can be used in many ways.

Concrete is a popular building material which often known for its toughness; Concrete is made up with three basic things which are: water, aggregate (rock, sand or gravel) and Portland cement. It is known as a very versatile and reliable material though some construction faults and imprudence can lead to the growth of defects in a concrete structure. These failings can be seen as per poor construction practices, poor quality control or for poor structural design and detailing.

Segregation of concrete is the division of cement paste and groups of concrete from each other during handling and placement. Separation also occurs due to over-vibration or compression of concrete where cement paste comes to the top and aggregates settles at the bottom. This separation affects strength and endurance in structures. While in a good concrete, all concrete separates are equally coated with sand and cement paste and creates a homogeneous mass.

While handling, transporting and placing for the jerks and vibrations the cement-sand paste may gets separated from rough aggregate. But it can be mixed again properly before depositing but it is recommended not to use a concrete where initial setting is over.

Reasons of Segregation of Concrete:

• Using of high water-cement ratio in concrete makes concrete segregation and it happens when concrete is mixed at site by unskilled workers.
• Extreme vibration of concrete with mechanical needle vibrators creates heavier particles resolve at bottom and lighter cement sand paste comes on top.
• When concreting is done from high for underground foundations and rafts, which causes concrete to separate.

Way to prevent Segregation of Concrete: When the depth of concrete is more than 1.5 meters it should be located through temporary inclined chutes. The delivery end of chute should be as close as possible to the point of deposit. When Segregation in deep foundations and rafts of thickness is more than 1 meter, there is chance of presence of segregated concrete near bottom or in center without proper supervision. This segregation can be detected by advanced method of testing such as ultrasonic testing.

Source www.theconstructor.org

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7 kinds of Construction failings in Reinforced Concrete Structures

There can be happen several concrete defects in Reinforced Concrete structures which lead the concrete structures weak and make the building defective.

Concrete is a popular building material which often known for its toughness; Concrete is made up with three basic things which are: water, aggregate (rock, sand or gravel) and Portland cement. It is known as a very versatile and reliable material though some construction faults and imprudence can lead to the growth of defects in a concrete structure. These failings can be seen as per poor construction practices, poor quality control or for poor structural design and detailing.

In this article we will discuss about some known defects in concrete structures and the types are written here:

1. Honeycomb and Rock Pockets: This kind of defect can be seen on the concrete structure where gaps are left for the failure of cement mortar to pour spaces around and among coarse aggregates. It happens when poor quality control is mixed during mixing; transporting; or laying of concrete, under or over-compression of concrete, lack of space between bars and low cement content or improper mix design. This kind of defect may reduce durability and make the concrete weak; but if they are minor can be repaired by cement mortar within 24 hours or it can’t be repaired.

2. Poor Formwork Installation: This error includes misalignment, movement, and loss of support, failure of forms which can be lead to cracking and structural failure. The loss of support during construction can increase settlement cracks; while insufficient formwork support and premature removal of formwork are main reasons of loss of support in the construction. These errors can be repaired with surface grinding to maintain the prop of the structure if the error is minor; for major errors, it shall be repaired by removing the concrete in defective area and then building that portion again.

3. Concrete Dimensional Errors: These errors happen when there is poor entering of a structural member or for deviation from the specifications.

4. Finishing Errors: They include over-finishing of the concrete surface or addition of more water or cement to the surface while finishing of the concrete which makes the concrete permeable and makes concrete less durable.

5. Shrinkage Cracks: It happens due to the evaporation of water from the concrete mixture; the intensity of this problem is depended on some reasons like the amount of water in concrete, weather conditions and curing regime.

6. Poor Reinforcement Placement: Defects during reinforcement installation can cause serious concrete deterioration; also insufficient chair bars and lack of tying of reinforcement would cause rebar movement which may cause to insufficient concrete cover and reduction in effect depth of the concrete section. As a result, the durability of the concrete structure is compromised and the structure would be exposed to chemical attacks.

7. Bugholes: Bugholes or surface voids are small regular or irregular cavities made due to the entrapment of air bubbles in the surface during placement and consolidation. They commonly found in vertical cast-in-place concrete like walls and columns. Both the size and number of bugholes vary and depend on form-facing material and condition, release-agent type and application thickness, concrete mix characteristics and placement and consolidation practices.

Source www.theconstructor.org



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Some useful tips to restore active cracks in concrete

Active cracks in concrete stand for live cracks which are broaden in length, width, and depth in due course. Because of overloading & thermal enlargement, these cracks are developed e.g. cracks owing to freeze-thaw. There are different types of processes to restore active cracks which range from drilling and plugging, stitching, external pre-stressing and flexible sealing of cracks.

Because of unrestrained growth, there is chance for a new crack to be developed next to the restored active cracks. So, primarily, it is essential to settle reason of crack formation.

How to restore active cracks in concrete

The following processes are commonly used for restoring active cracks in concrete structures.

1. Drilling and Plugging through Crack: This process is suitable for the cracks which are found in straight lines. Under this process, a hole is drilled adjacent to the crack and stuffed with grout. This grout builds the key to lock the crack so that it can’t expand further. The grout avoids leakages and loss of soil. This method is inexpensive and less time is required for that.

Another useful process for plugging the drilled hole is stuffing it with epoxy mortar or any epoxy formulation with reinforcement bars which are arranged in the drilled hole. The bars applied contain predetermined length and size to fasten the cracks across.

The method includes drilling a hole of 50 to 75mm diameter based on the width of crack following the position of crack. The hole should be must be sufficiently big to bisect the crack along its full length and arrange adequate repair material to structurally bear the loads enforced on the key.

If water tightness is mainly required over structural load transmission, then the drilled hole is stuffed with a flexible material having low modulus. If both properties are necessary, the first hole is stuffed with grout and the second hole is stuffed with a flexible material.

2. Stitching of Cracks: Under this process, holes are drilled in such a manner that entry and exit points are provided across the cracks. Through the holes, several U-shaped metallic staples are provided through the holes and the holes are secured firmly at the end with grout or epoxy.

3. External Prestressing: Post-tensioning method is used to close flexural cracks in reinforced concrete. It will stop the cracks to be expanded further or fixed entirely. The process offers compression force so as to correct the tendons and then supplementary residual compressive force.

This process needs anchorage of the tie-rods to the anchoring device tied to the beam.

4. Flexible Sealing: Under flexible sealing method, bond breaker is utilized for repairing active cracks.

Prior to apply a repair method for active cracks, it should be checked that whether it is essential to make the flexural or tensile strength better across the crack. To sustain the strength, it is required to set up an expansion joint close to the repaired crack so that further cracking can’t happen adjacent to the corrected one in due course of time.



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LIMIT STATE DESIGN: (A Text-book of Reinforced Concrete Structures)

Dr. Ram Chandra, M.E. (Hons.), B.E., M.I.E., Ph.D (Roorkee), Professor of Structural Engineering has written an exclusive e-book alias LIMIT STATE DESIGN: (A Text-book of Reinforced Concrete Structures).

In this book, the author briefly explains each basic concept, elementary method, equation or theory of interest to the student of reinforced concrete design in simple manner. S.I. system of units and new code IS: 456-1978 are fully utilized in the text.

The book is specifically designed for degree, diploma and A.M.I.E. students in different branches of engineering. This book on ‘Limit State Design’ is based on the provisions of code IS: 456-1978. Both the topics of this subject, ‘Limit State of Collapse’ and ‘Limit State of Serviceability’ are clearly explained to design the reinforced concrete structures and the structural elements.

Given below, some exclusive features of the book :-

a. Each topic presented is described in detail.
b. This book is entirely composed of SI system of units and with adherence to the Indian Standard specifications (IS: 456-1978) all through the text.
c. The text of this subject is started, presented and explained in such a manner that is suitable for the students.
d. The different notations applied all through throughout this text book adhere to code of practice IS: 456-1978.
e. A number of design examples are provided in each chapter to demonstrate the theory and practice. Unsolved design problems are also provided in each chapter.
f. The diagrams clearly demonstrate the detailing of reinforcement.
g. This book abides by the current design practice.

To access the book online, click on the following link. www.amazon.in



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How to measure superimposed loads on a column

The objective of a column is to withstand axial and lateral forces and transmit them securely to the footings in the ground.

In this exclusive article, you will learn how to work out the superimposed loads on a column in a structure with some easy-to-follow steps.

Columns provide support to the floors in a structure. Slabs and beams transmit the stresses to the columns. So, it is crucial to make a strong column.

A column stands for a compression member, the effective length of which surpasses three times the minimum lateral dimension. Compression members whose lengths remain under three times the minimum lateral dimension, are constructed with plain concrete.

The axial load bearing strength of a column is derived from the follwoing formula :-



Besides, axial loads, the column design is dependent on several other factors. Because of beam spans, wind loads, seismic loads, point loads and various other factors, the bending moments and tortional forces are produced.

A column is categorized on the basis of various factors :-

1. Depending on shape
• Rectangle
• Square
• Circular
• Polygon

2. Depending on slenderness ratio: The ratio of the effective length of a column to the minimum radius of gyration of its cross section is known as the slenderness ratio.

• Short RCC column, =< 10
• Long RCC column, > 10
• Short Steel column, =<50
• Intermediate Steel column >50 & <200
• Long Steel column >200

3. Depending on the type of loading
• Axially loaded column
• A column subjected to axial load and unaxial bending
• A column subjected to axial load and biaxial bending

4. Depending on pattern of lateral reinforcement
• Tied RCC columns
• Spiral RCC columns

Least eccentricity
Emin > l/500 + D/30 >20
Where, l denotes unsupported length of column in ‘mm’
D = lateral dimensions of column

The following types of Reinforcements for columns are found :-

Longitudinal Reinforcement
• Least area of cross-section of longitudinal bars should be minimum 0.8% of gross section area of the column.
• Maximum area of cross-section of longitudinal bars should not be in excess of 6% of the gross cross-section area of the column.
• The bars should not be below 12mm in diameter.
• Least number of longitudinal bars should be 4 in rectangular column and 6 in circular column.
• Distance of longitudinal bars measured along the perimeter of a column should not go above 300mm.

Transverse reinforcement
• It may appear in the form of lateral ties or spirals.
• The diameter of the lateral ties should not remain below 1/4th of the diameter of the greatest longitudinal bar and in no case below 6mm.

The pitch of lateral ties should not go beyond
• Minimum lateral dimension
• 16 x diameter of longitudinal bars (small) • 300mm

Helical Reinforcement
The diameter of helical bars should not remain below 1/4th the diameter of largest longitudinal and not below 6mm.
The pitch should not go above (if helical reinforcement is permitted);
• 75mm
• 1/6th of the core diameter of the column

Pitch should not remain under,
• 25mm
• 3 x diameter of helical bar
Pitch should not surpass (if helical reinforcement is not permitted)

Least lateral dimension
• 16 x diameter of longitudinal bar (smaller)
• 300mm



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Different components of super structure

Superstructure stands for segments of the structure that is situated over the surface of the ground. The superstructure is built with different sections of walls, roof, doors, and windows, flooring. The sections of the structure situated on the grounds and underneath the ground floor level are known as the plinth.

The objective of superstructure is to bear different types of loads operating on the structure which range from dead load, live, load, wind load etc. These loads are then transferred to the underlying soil through the substructure.

Each element of superstructure is applied as a specific purpose, but the prime function is to arrange privacy, safety to the inhabitants. Wall and roof safeguards from the surrounding, doors permit entry and give safety, windows arrange requisite sunlight and fresh air and floor provides a leveled surface to live and protection from beneath.

Building superstructure

Column: A column in structural engineering stands for a vertical structural component that disperses the weight of the structure over to other structural components underneath , through compression.

Floor: A floor normally comprises of a support structure known as a sub-floor on top on which a floor cover is placed to arrange a walking surface.

Roof wall :

Flat – Should contain a slight slope for drainage

Shed – A single slope

Gable – Two slopes intersect at a ridge. Two walls expand up to the ridge.

Hip – Two gables, a pyramid is treated as a hip roof.

Gambrel – Four slopes in one direction, the usual barn roof.

Mansard – A four-sided gambrel-style hip roof formed with two slopes on each of its sides with the lower slope, perforated by dormer windows, at a steeper angle than the upper.

Beam: Beam stands for an inflexible structural member formed to bear and transmit transverse loads across space to supporting components.



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Common structural members in a building

In this civil engineering article, you will get detail information on different types of structural members in a building.

Beam: Beam stands for a flexure member of the structure. It is exposed to transverse loading like vertical loads, and gravity loads. With these loads, shear and bending are formed inside the beam. Beams belong to horizontal structural members to bear a load successfully.

Beam is generally applied for withstanding vertical loads, shear forces and bending moments.

Columns: A long vertical member that mostly undergoes compressive loads & buckling loads is known as column. Columns stand for vertical, structural members of a structure. They transmit load from beams to footings. Columns are mostly utilized to support beams or arches on which the upper sections of walls or ceilings rest.

Strut: Strut is a compressive member of a structure. This structural member is driven from opposite ends. The purpose of a strut is to withstand compression.

Ties: A tie stands for a structural member that is extended from opposite ends. A tie mainly deals with tension.

Beam-Column: A structural member that is exposed to compression and flexure is known as beam column.

Grid: A group of beams which overlap each other at right angles and exposed to vertical loads is known as grid.

Cables and Arches: Cables are normally suspended at their ends and are granted to sag. The forces then turn to pure tension and are headed along the axis of the cable. Arches have the similarity with cables apart from they are inverted. They bear compressive loads which are directed along the axis of the arch.

Plates and Slabs: Plates belong to three dimensional flat structural components generally constructed with metal which are frequently utilized in floors and roofs of structures. Slabs are identical to plates apart from that they are normally constructed with concrete.



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POLEFDN – A excel based construction program for pole foundation analysis

POLEFDN is a MS-excel based spreadsheet program that can be used for making analysis of a pole foundation on the assumption of the application of a inflexible round pier that is supposed free (unrestrained) at the top and exposed to lateral and vertical loads. The spreadsheet particularly makes calculation for the necessary embedment depth, the maximum moment and shear, the plain concrete stresses, and the soil bearing pressures.

This program stands for a workbook that comprises of the following six (6) worksheets:

• Doc - Documentation sheet
• Pole Fdn (Czerniak) - Pole foundation analysis for free-top round piers with PCA/Czerniak method
• Pole Fdn (UBC-IBC) - Pole foundation analysis for free-top round piers with UBC/IBC method
• Pole Fdn (OAAA) - Pole foundation analysis for free-top round piers with OAAA method
• Granular Soil (Teng) - Pole foundation analysis in granular soil with USS/Teng method
• Cohesive Soil (Teng) - Pole foundation analysis in cohesive soil with USS/Teng method

Given below, some useful features of the program :-

This program can deal with both horizontally and vertically applied loads. The vertical load may contain an associated eccentricity that leads to an additional overturning moment to be always assumed to add directly to the overturning moment formed with the horizontal load.

This program guesses that the top of the pier remains at or over the top of the ground surface level.

This program guesses that the actual resisting surface remains at or under the ground surface level. It takes into account any weak soil or any soil that is detached at the top.

The "Pole Fdn(Czerniak)" worksheet guesses that the inflexible pier rotates about a point situated at a distance, 'a', under resisting the surface. The highest shear in pier is supposed to be at that 'a' distance, whereas the maximum moment in the pier is supposed to be at a distance = 'a/2'.

The "Pole Fdn(Czerniak)" worksheet works out the "plain" (unreinforced) concrete stresses, compression, tension, and shear in the pier. The corresponding permissible stresses are also set on the basis of the strength (f'c) of the concrete. It is performed to check whether the steel reinforcing is actually necessary or not. The permissible tension stress in "plain" concrete is supposed to be equivalent to 10% of the value of the permissible compressive stress.

The "Pole Fdn(Czerniak)" worksheet measures the actual soil bearing pressures along the side of the pier at equivalent distances to 'a/2' and 'L'. The relevant permissible passive pressures at those locations are set for comparison.

As all overturning loads are protected with the passive pressure against the embedment of the pier, this program guesses that the pier functions in direct end bearing to withstand only the vertical loading. The bottom of pier bearing pressure is measured that contains the self-weight of the pier, assumed at 0.150 kcf for the concrete.

To download the program, click on the following link www.cesdb.com



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Details about various sections of bridge

All the major elements are arranged within three main bridge areas – Foundation (that retains the shallow or deep base of the bridge and transmits it’s load to the bearing strata, it comprises of foundations underneath the primary span of the bridge and the abutments underneath starting points of the bridge), Substructure (piers, abutments, spandrels, caps, bearings, and other elements that retains the top part of construction) and Superstructure (all the segments of the bridge which are assembled on top of the supporting substructure system, it comprises of various components like decking, girders, slab, and everything arranged over the main deck like posts, steel truss system, bridge girder, cable-stayed system, cable suspended systems and more).

The followings are the major elements of the modern bridges:

Abutment – Endpoints of the bridge. They are reinforced to facilitate withstanding extreme lateral pressures.

Pile (also called as beam, footing, and pier) – It stands for reinforced concrete post that is pushed into the ground to function as the leg or support for the bridge. The extent among piles is worked out to provide support to the rest of the structure that will be placed on top of them.

Cap – Cap is located on top of the pile beam that gives extra support and distributes the load to the piles underneath. The amalgamation of Pile and Cap elements is known as Bent.

Girder or Span – It is one of the major components of the bridge that attaches all the Piles beams. It involves several simple spans, a single continuous span that is supported with numerous beams, cantilever spans and cantilever spans with the suspended span among them. They are normally formed with metal or reinforced concrete as well as in the form of haunches girded be bear more load. Girder sections are usually not formed with a simple block of material but built up with truss network (or Orthotropic beams) that enhance their resistance capacity against load. Girders are also utilized as a part of rigid frame network where they are totally attached with frame legs (that may appear as inclined or in V shape).

Superstructure truss network – Truss network that provides supports to travel surface is built with three basic ways – Deck truss where traffic passes on top of truss network, Pony truss where truss network passes among two parallel walls of trusses, and via truss that includes extra cross-braced truss network over and below the traffic.

Deck beam – Simple continuous decks are created with metal or reinforced concrete. They comprise of sub-components like approach slab (attaches main bridge decking with the ground on both sides of the bridge), expansion joint, drainage scupper, curb, running surface, footpath.

Barriers – These are the sides of the bridge decks normally contain extra barrier components like railings, handrails and ground fixtures.

Arch – Arches on the bridges are differentiated with the number of hinges they contain (normally among zero or three) which ascertain the volume of stress and load they can bear securely, and the type of material they are built up (solid material, truss system). Arches underneath the bridge are known as spandrel-braced (cantilever) or Trussed deck arch.

Spandrel – Spandrels belong to the almost triangular space among the main pillar of the bridge and decking. Stone bridges employ filled “closed” spandrels deck arches, whereas the modern bridges are constructed with metal having open spandrel deck arch configurations.

Truss – Framework is created by attaching triangles and other forms that disperse load and stress forces across its whole structure. They are generally segregated into various categories like simple truss (King and Queen posts), covered bridge truss (multiple kingpost truss, Howe truss, long truss, Burr arch truss, town lattice truss, Haupt, Smith, Partridge and Child truss), Pratt truss (and it’s many variations), Whipple truss, Warren truss variations, Howe truss, Lenticular truss, Fink truss, multiple Cantilever truss variations, and suspension truss arches.



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How bubble deck technology is used in construction work

Bubble Deck belongs to the original combination method of connecting air, steel and concrete in two-way structural slab. Hollow plastic balls is embedded into the slab and reinforced with steel. The end result eliminates up to 35% of concrete that contains carrying effect at the time of restoring the two-way span strength. It can be used with most of the buildings particularly open floor design : educational, commercial, hospital and other organizational buildings.

Bubble Deck contains the following properties :-

Shear strength - 80% of solid deck slab
Deflection - Similar to solid slab
Weight - 40% below solid slab
Fire Resistance – 65% of solid slab

Bubble Deck slab belongs to a biaxial voided concrete slab in which high density polythene hollow sphere substitute the incompetent concrete in the middle of concrete slab.

Materials for building up the bubble deck

Steel: The steel reinforcement of MS or HYSD is applied.

Plastic Sphere: Void sphere formed with recycled high density polyethylene. It contains adequate strength & rigidity. It does not make any reaction.

Concrete: The concrete is formed with standard Portland cement with highest aggregate size of ¾ inch.

Bubble Deck Manufactured Components: It stands for a structural vacuumed smooth slab system that reduces dead weight of a floor slab by 33% facilitating longer span among column supports and forms an entire range of other cost and construction benefits.

The system acts as an alternative of all other supporting structure like beams or walls. The entire floor slab extents in two directions directly into pre-cast or in-situ reinforced concrete column.

Benefits of Bubble Deck:

Structural:
a. Less weight
b. No beams are necessary
c. Only few columns are essential
d. Make your choice for shape
e. Bigger Span

Construction
a. Fewer work on job site
b. Light weight, less equipment is necessary
c. Simple and does not require heavy jobsite work

Economy:
a. Huge savings for materials (slabs, beams, columns, foundation), up to 50%
b. Needs fewer carrying cost
c. Requirement of concrete is reduced up to 35%
d. Lower workforce, no carpentry, no beams and workers with less skill can be employed

Environmental:
a. Less material consumption (cement, aggregate, steel)
b. Less energy consumption (throughout production, transportation and lifting on construction site)



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Difference Between Flexible Pavement and Rigid Pavement

The pavement designing is complicated task in Transportation Engineering. The most recognized methods for pavement design are Rigid pavement and Flexible pavement. The pavement surface has good longevity and it can resist the load operating from the wheel tyres.

Given below, the functional requirement of highway pavements :-

1. Flexible pavement and Rigid pavement contain superior riding quality
2. It should be less slippery
3. It should be rigid
4. It should contain adequate friction keeping the power of the vehicle unchanged.

Variation among Rigid Pavement and Flexible Pavement

1. Flexible Pavement

a. Load is transmitted from grain to grain to the lower layers
b. The design is totally based on the subgrade strength.
c. IRC 37-2012 code is applied for making the design of flexible pavement
d. The strength of flexible pavement is influenced by the aggregate interlock, particle friction and cohesion.
e. Flexible pavement demonstrates the deflection of subgrade at the surface of the pavement.
f. Design life lasts for 15 years.

Rigid Pavement:

1. Rigid pavement contains a strong flexural strength that is considered as the vital factor of design.
2. Rigid pavement contains a concrete layer at the top, the base course and soil subgrade remain underneath.
3. Rigid pavement disperses the load over a broad area due to its high flexural strength.
4. Load is transmitted through slab action.
5. The total thickness of the pavement remains under flexible pavement.
6. IRC: 58-2011 is utilized for making the designing of Rigid pavement.
7. Design life extends for 30 years



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