geotechnical, Retaining wall

Crib retaining walls, Bin retaining walls & Gabion Walls

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Retaining walls are rigid walls used for supporting soil laterally so that it can be retained at different levels on the two sides. The soil got a natural angle of repose and when it exceeds the range a retaining wall structure has to be provided.

They are vertical or near vertical structures constructed to hold soil between two terrains when the slope exceeds the natural one. The slope can be vertical or steep or much above the range of angle of repose.

Also read : Retaining walls – All Types, Materials, features and uses

In this article we are mentioning about some special type of retaining walls

Gravity retaining walls are made of stone, bricks, concrete or any other heavy material.  Gravity walls are made with or without mortar They are designed to counter the earth pressure by their self weight. Following are the special types of gravity retaining walls.

a) Crib retaining wall

b) Bin retaining wall

c) Gabion retaining wall

Crib Retaining walls

Crib retaining wall or crib lock retaining wall is one of the oldest types of retaining wall. They consist of cribs or cells made of timber, concrete, and plastic/fibres. The cribs or interlock areas are filled with free-draining materials or earth back-fill, eliminating the hydro-static pressure and enabling a free escape of water.

Most common materials used for crib wall construction is 

  • Timber crib retaining walls
  • Precast crib retaining walls

Timber crib retaining walls

Timber crib walls use timber to form the cells of the crib. The cells are filled with free-draining stone materials for maintaining the mass of the wall. Water drainage can happen freely through the cribs. The timber sections are interlocked to make the walls.
They can also be planted with trees to create a natural appearance. These types of walls are ok up to a height of 5-6 mtrs and mostly used for landscape walls etc.

Timber crib retaining walls
Timber crib retaining walls

Precast concrete crib retaining walls

This system consists of a precast concrete header and stretcher units. They are erected to form precast crib retaining walls.
Precast concrete cribs are the cheapest form of earth-retaining systems and are used for landscaping structures, plant terraces, and other works with heights around 10- 20 mtr with proper professional design.
They do not require any skilled labour to do the erection. Trees or shrubs are planted to give natural and excellent looks. Crib walls are erected for small curves and are considered a very flexible material.

Precast Concrete Crib retaining walls
Precast Concrete Crib retaining walls

Bin retaining walls

Steel bin walls are made from corrugated steel sheets and are usually bolted together and then filled with crushed rock or other free-draining material. They are mostly used for bank erosion protection, holding encroaching slopes, breakwaters, etc. They can resist unforeseen ground movements that may cause failure to other types of retaining walls.

Gabion Retaining walls

Gabion retaining wall systems are one of the oldest forms of gravity wall. Gabion walls are manufactured by factory fabricating a galvanised hexagonal wire mesh of varying diameters into box cages. These box cages are site filled with locally available stones and fully closed and laid in a pattern as per design. They are used in areas where the foundation conditions are not favourable for adopting any other retaining structures. The concept of a gabion wall is to increase the shear capacity of rock by providing the box cages. They can accommodate substantial ground movements without failures. Gabion boxes are free-draining structures that can reduce hydro-static pressure drastically.

Gabion Retaining walls
Gabion Retaining walls

The main advantage of these types of systems is that they do not need an exclusive foundation structure. Gabion walls are installed directly over the surface in specified patterns according to design requirements.
The mesh is PVC protected or coated with special coatings to protect from rusting in areas subjected to continuous water flow.
These walls provided a Good visual appeal of the product and the satisfying rock finish look.
Gabion walls are erected mainly for soil stabilisation behind the wall. They can also act as a cover wall. The gabion boxes are stacked in layers with a proper design. They are a very economical alternative for concrete retaining walls and rock anchors for soil stabilisation works and slope protection works.

Also read : MSE retaining walls or Mechanically stabilised Earth walls

CONCRETE

Self Healing Concrete ||Bacterial Concrete -Preparation and Advantages

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Self healing concrete is a mind-blowing innovation in civil engineering. It can potentially contribute to ensure a longer lifespan of a structure. In this article, we will find out the details about bacterial concrete. A bacterial concrete is most effective in this category.

Let’s start from scratch.

What is self healing concrete?

The type of concrete that uses the process of self-filling up of cracks by the help of bacterial reaction in the concrete, after hardening is known as Self-healing concrete.

Why self healing concrete is important?

  • Unrepaired cracks lead to a reduction in the service life of the structure. Therefore, it is worth giving attention to.
  • Epoxy resins and other synthetic mixtures are alternatives. (But they are not good for human health)
  • Self healing concrete does not require human intervention

Let’s dive in deep now.

Bacterial Concrete

Concrete which is made by adding bacteria that precipitate calcite is called bacterial concrete.

  • It is microbiologically induced calcite precipitation.
  • Bacterial concrete heals cracks around 0.5 mm thickness.
  • It has improved Compressive & flexure strength than ordinary concrete.
  • Bacterial concrete is well suited for Small & Medium-Sized building
  • It is used on a limited scale & not commercially wide-spread.

We learnt the general details. Let’s be a bit technical now?

Bacteria Used in the self healing concrete

Bacteria used in bacterial concrete
Source : alchetron.com
  • “Bacillus pasteurii ”  is a common soil bacterium which is used in bacterial concrete.
  • Precipitates impermeable calcite layer over the surface of concrete.
  • Acid producing bacteria
  • Remains dormant & be viable for over 200 years under dry conditions

In the next section, let me quickly walk you through the mechanism of the self healing concrete.

Mechanism of Bacterial Concrete

  • Bacillus pasteurii is used along with Calcium Lactate. 
  • Both are added in the wet concrete when the mixing is done.
  • Water seeps in the cracks (or exposure to moisture)
  • Spores of the bacteria germinate & feeds on calcium lactate ,consuming oxygen.
  • The soluble calcium lactate is converted to insoluble limestone.
  • limestone starts to harden, filling the crack automatically
  • The advantage is that oxygen consumed helps in the prevention of corrosion of steel.

That’s it. Now, we will move on to the chemical process in bacterial concrete.

Chemical process of this self healing concrete

The steps in the process are as follows.

  • Water comes in contact with the unhydrated calcium.
  • Calcium hydroxide is produced by the help of bacteria, it acts as a catalyst.
  • This calcium hydroxide reacts with CO2 to form limestone and water.
  • This extra water molecule keeps the reaction going.
  • The limestone then hardens and seals the cracks.

Figure below shows the self healing concrete.

Source: sciencedirect.com

self-healing-concrete
bacterial-concrete

What about us study about the preparation of bacterial concrete now?

Preparation of Bacterial Concrete

There are mainly two methods.

  • By Direct application
  • By Encapsulation

Without delay, let’s meet each of them.

Direct Application

  • Bacterial spores and calcium lactate is added directly when mixing of concrete is done.
  • This doesn’t change the most properties of concrete.
  • When water comes in contact with this bacteria
  • They germinate & feeds on calcium lactate and produces limestone.

Encapsulation Method

  • The bacteria and its food (calcium lactate), are placed inside treated clay pellets.
  • Concrete is prepared.
  • Clay pellets break when crack occurs.
  • Bacteria germinate and eat down the calcium lactate & produce limestone.

Time to chill. Sit back and enjoy the advantages and disadvantages of what we have made through the process.

Advantages of bacterial concrete

  • Increase in compressive and flexural strength compared to normal concrete.
  • Self-repairing
  • Reduction in permeability of concrete
  • Resistance towards freeze-thaw attacks.
  • Low maintenance
  • Improves the durability of steel reinforcements.
  • Bacillus bacteria are harmless to human life.

Disadvantages of bacterial concrete

  • High Cost
  • Growth of bacteria is not suitable in some environment.
  • The clay pellets comprise 20% of the volume of the concrete. This may become a shear zone.
  • Design of mix concrete with bacteria  is not available in any IS code

We have reached the shore. Let’s wind this up with the conclusion.

Conclusion

  • Self healing concrete appears to be much more efficient
  • It has more advantages than disadvantages.
  • So far, Bacterial Concrete is the best approach in the field of self healing concrete

Hope the article served its purpose to quench your thirst to know about self healing concrete. Share your thoughts on this in comments.

geotechnical, Retaining wall

Types of Retaining walls – All types,materials,features and uses.

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Retaining walls are rigid structures used for supporting soil laterally and retained at different levels on the two sides. These structures are vertical or near-vertical. They are constructed to hold soil between two terrains when the slope exceeds the natural angle of repose. The slope can be vertical or steep or much above the range of angle of repose. Understanding retaining wall types is crucial for selecting the right wall based on soil conditions, load requirements, and project design.

Key retaining wall types include gravity retaining walls. These rely on weight for stability. Buttress retaining walls provide extra support. Elements like retaining wall heel and toe enhance stability, making these walls effective and durable solutions.

This article is about the types of retaining walls, materials used and features.

  1. What is a retaining wall?
  2. Design criteria of retaining wall
  3. Retaining wall types
    1. Gravity Retaining walls
    2. Cantilever retaining walls
      1. The loads induced on various components
    3. Counter-fort retaining walls
    4. Buttressed retaining walls
    5. Sheet piled retaining walls
    6. Piled retaining walls
    7. Anchored retaining walls

What is a retaining wall?

Retaining walls are critical engineering structures designed to stabilize and support terrain by restraining soil mass at different elevations. These versatile architectural elements are essential in landscape design, civil engineering, and construction projects. They prevent erosion, manage slope stability, create usable spaces on uneven terrain. Retaining walls provide critical structural support in areas with significant elevation changes.

Engineers and landscape architects utilize various types of retaining walls, each with unique characteristics and applications. The selection depends on factors such as soil conditions and load requirements. Other considerations include site topography, budget constraints, aesthetic considerations, and project design. These factors ensure long-term durability and safety. Common retaining wall types include gravity walls, cantilever walls, and anchored walls, each using distinct methods to provide stability.

Design criteria of retaining wall

The main criteria behind the design of the retaining wall are to counter the downward slope movement of back filled soil by gravity. The lateral pressure developed behind the wall depends on the angle of internal friction & cohesive strength of retained materials. The lateral pressure can also be liquid (hydro-static pressure), and pressure from any type of back-fill material like sand, granular material, fly ash, etc. A proper drainage system is to be provided to reduce the hydro-static pressure.

Retaining wall types

There are several types of retaining wall depends on the nature and type of soil and situations they are to be used.

  • Gravity retaining wall
  • Cantilever retaining walls
  • Counter-fort retaining wall
  • Buttressed retaining wall
  • Sheet pile retaining wall
  • Bored pile retaining wall
  • Anchored retaining wall

There are a lot of innovative and alternated methods used for retaining walls

Retaining wall Types

Gravity Retaining walls

Gravity retaining walls are executed with stone, bricks, concrete, or any other heavy material. They are done with or without mortar and are designed to counter back-fill soil pressure by their self-weight.
Dry retaining walls do not require rigid footing. However, they must be designed to counter sliding. They also need to address overturning and bearing loads acting on the structure.
These types of retaining walls are mainly adopted in landscape areas and also in locations with height is around 2-3 meters.

Gravity retaining wall
Gravity retaining wall

Gravity retaining walls are used for larger heights using composite gravity walls. Composite gravity walls include precast crib walls or timber walls filled with granular materials, Gabion walls, Geowalls, etc.
The gravity wall when provided with a small amount of reinforcement is known as semi gravity retaining wall. The load transfer mechanism remains the same as that of gravity retaining walls.

Gabion wall

Cantilever retaining walls

Cantilever retaining walls are the most common retaining wall type. They are reinforced concrete structures wherein the lateral earth pressure is countered by the cumulative action of total structural members.
Cantilever retaining walls consist of a stem, a base slab which is divided into toe slab and heel slab as shown in the figure.

Cantilever retaining walls
Cantilever retaining walls
Cantilever retaining walls


The vertical stem wall is extended to the back fill side or heel side and is called a heel slab and the slab on the other side is a toe slab as shown in the figure.
The stem wall, toe slab, and heel slab act as cantilevers fixed injunction and spanning to other ends. The back filling of soil over the heel slabs imposes additional stability against lateral pressure and stabilises the wall against overturning and sliding.

The loads induced on various components

a) Heal slab and toe slab = Upward soil pressure from the bottom and tends to bend upward. Rebar is placed in a tension zone.
b) stem= Lateral earth pressure tends to bend in the opposite direction of back-fill.
These types of walls are economical and can be used for heights around 5-7 mtr. They are much lighter than gravity walls and require comparatively small foundations. These types of walls can be constructed as to cast in situ and precast and prestressed concrete depending on the site requirements.

Prestressed retaining wall & Retaining wall
Prestressed retaining wall & Retaining wall

Counter-fort retaining walls

Counter-fort retaining wall is a cantilever retaining wall used when the height is around 7 mtr or more. For economising the structure, vertical bracing called counter-forts are provided on the back fill side. These counter-forts connect the heel slab and stem as shown in the figure. The stem and heel slabs between counter-fort act as continuous slabs and negotiate the high bending movements. The counter-forts function as tension stiffness and reduce the bending and shear stresses. These types of retaining walls are used for heights ranging from around 8-12 mtr.

Counter-fort Retaining walls
Counter-fort Retaining walls
Counter-fort Retaining walls

Buttressed retaining walls

Buttress retaining walls have the vertical bracing located on the front side of the retaining wall in place of the back-fill side like that of counter-fort retaining walls. The structural action of the stem remains the same as the counter-fort walls.

Sheet piled retaining walls

Sheet pile walls are erected using steel sheets into a slope to be protected or for excavations up to a required depth. Sheet pile retaining wall economical till a height of 6m and cannot negotiate huge loads. Sheet pile acts as a temporary wall that is driven into the excavation area for protecting the area from collapsing. They provide high resistance to driving stresses. They can also be reused and are considered the most economical retaining solutions. They can be bolted and driven easily and do not deform on driving. The problem with sheet piles is the noise it creates while driving.

Sheet pile

Piled retaining walls

These types of retaining walls consist of a sequence of bored piles. The bored piled retaining walls are often accompanied by erection earth anchors, shot-creating the pile gaps, and provision of additional supports depending on the site conditions and designs. Bored pile retaining walls are used in areas where sheet pile tends to create a lot of noise and disturbs the areas.
These types of piles are used for temporary and permanent works. They can hold huge lateral pressure and are used for holding earth for high depth excavations without disturbing the nearby structures. Bored pile retaining walls are classified into contiguous pile walls, tangent pile walls & secant pile walls according to the sequence of piling works.

Piled retaining wall
Piled retaining wall

Anchored retaining walls

Anchored retaining walls, also known as tie-back systems, are essential structural components used in construction. They are mostly used to stabilize earth and as support structures. Anchored Retaining walls deliver lateral support to walls. They prevent soil from shifting or eroding. These walls are commonly used in applications like deep excavations, embankments, and hillside retention etc.

BUILDING CONSTRUCTION

3 d Printing buildings |Concrete Printing & Contour Crafting Methods Full Guide

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3 d Printing buildings are one of the greatest advancements of technology. The rapidity and accuracy with which the work can be completed is the attraction. We will find out all the details about the important methods of 3 d printing which are concrete printing and contour crafting.

What is 3 D Printing?

The 3D printing process builds a three-dimensional object from a computer-aided design (CAD) model, by successively adding material layer by layer.

Unlike conventional machining, casting and forging processes, where material is removed from a stock item or poured into a mold and shaped by means of dies, presses and hammers.

Time to ask the question. Why is it a big deal?

Why 3 D Printing for construction?

  • To avoid construction formwork which accounts for 40% of the total budget for concrete
  • It allows for flexibility and freedom of architectural design
  • To reduce construction and facilities management costs
  • To build a future of sustainable construction

Now, let’s move on to the next section which introduces the 2 printing methods.

3 d printing buildings methods

There are mainly 2 methods for 3 d printing buildings.

  1. Contour crafting
  2. Concrete printing

Let’s dive in deep into each of them.

Contour crafting for 3 d printing buildings

Contour crafting- Schematic of CC extrusion and filling process
Contour crafting- Schematic of CC extrusion and filling process
  • Contour crafting is based on an extrusion and filling process
  • The extrusion process forms the smooth object surface by constraining the extruded flow in the vertical and horizontal directions by the use of trowels.
  • The orientation of the side-trowel is dynamically changed for better surface fit for each decomposed layer.
  • The side-trowel allows thicker material deposition while maintaining the high surface finish.
  • Thicker material deposition cuts down manufacturing time, which is essential for building large-scale parts using the material additive process.
  • Maximum deposition layer thickness is limited by the trowel height.
  • As the extrusion nozzle moves according to the predefined material deposition path of each layer, the rims (smooth outer and the top surface of outside edges) are first created.
  • The towelled outer surface of each layer determines the surface finish quality of the object.
  • The smooth top surface of each layer is also important for building a strong bond with the next layer above.
  • Once the boundaries of each layer are created, the filling process begins and material is poured or injected to fill the internal volume.

Now, let’s find out the details of concrete printing.

Concrete printing for 3 d printing buildings

Concrete printing
Concrete printing
  • Concrete printing is similar to contour crafting in the ejection phase of concrete
  • It is able to achieve better 3D printing, because of its resolution of deposition
  •  Concrete printing provides larger freedom printing internally and externally.
  • The method not only enables the production of both high compressive compressive_strength and_tensile_strength concrete mixture, 110 MPa and 10 MPa respectively but improves the overall workability, extrusion and onsite construction methods.

Next, let me show you the advantages of 3 d printing in construction industry.

Advantages of 3 d printing in the construction sector

  • Cost Efficiency
  • Labour efficiency
  • Time and costs savings
  • Environmental/ economic aspects
  • Any complex design can be built

Now, let me quickly show you some examples of 3 d printing buildings.

Implementation examples of 3d printing for construction

  1. Dubai Future Foundation (DFF)
DFF Building Dubai
Dubai Future Foundation (DFF) Building in Dubai

     2. Reinforced concrete printed bridge at Gemert

     3. Yin gChuang, the Chinese company

Conclusion

  • Using this technology is cost, time and quality efficient, through analyzing many theoretical and practical examples of 3D printed structures.
  • According to the literature survey that was conducted, using 3D printing can save up to 80% of manufacturing costs and 40% in materials costs.
  • For future work and application, the detailed economic analysis must be conducted to show the reduction potential of 3D printing, and its impact on the full-scale economy of the country, by applying any of the methods previously mentioned companies use in their work.

Real experiments must be conducted to prove the material, labor and energy reduction. And, you will amaze at the beauty of 3d printing building.

Photo credits: https://www.spentys.com/

Don’t forget to share your views on the innovation in comments.

Happy learning!

BUILDING CONSTRUCTION

Cracks in a Building |3 Types of Cracks in Building Walls Full Guide

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Cracks in a building affect the building’s artistic look and it destroys the wall integrity, affects the safety of the structure and even reduces the durability of the structure.

In this blog, I will show you the important types of cracks in building and example of these cracks to understand them better.

Cracks occur when stress in the components increases beyond its strength.

Stress in the building components could be caused by externally applied forces like,

  • Dead load
  • Live load
  • Wind load
  • Seismic loads
  • Foundation settlement

It could be induced by internally due to temperature variations, moisture changes and chemical actions.

Let’s find out the types of cracks in building now.

Types of cracks in a building

Cracks are classified into three types

  • Structural cracks
  • Non-structural cracks
  • Cracks based on width

Structural cracks

Structural cracks arise due to different reasons such as incorrect design and overloading of the structural components. Structural cracks are a threat to the stability of the building and are difficult to correct.

This type of cracks can’t be corrected. But needs special retrofitting techniques to prevent the structure from collapsing. We will discuss more that in another blog.

For now, see the cracks in different structural members below.

BEAMSCOLUMNSSLABS
Flexural CracksHorizontal CracksFlexure Cracks
Shear CracksDiagonal CracksShrinkage Cracks
Torsional cracksCorrosion cracksCorrosion cracks
Corrosion cracks
Combination of above cracks
Cracks in a building at different structural members

Next let’s know about the structural cracks on beams and columns. An example is always good to understand a concept better.

Cracks on beams and columns

Cracks on beams and columns
Cracks on beams and columns
  • Cracks in beams and columns occur when a material is strained under stress.
  • When two materials of varying elastic properties is joined together under the effect of force, then different shear stresses in these materials create cracks at the junction.
  • Dead and live loads are the main reasons for elastic deformation in any structural components of a building

Preventive Measures

  • To prevent this, you can build slip joints under the support of concrete slab on walls
  • Slip joints are mounted in the brickwork and concrete junctions to allow low friction movement between different materials due to expansion and contraction. And, thereby, prevent the bricks or mortar from cracking.
  • Provide horizontal movement joints between the top of the brick panel and reinforced cement concrete- beam/slab

Now, we will find out the details on non- structural cracks.

Non-structural cracks in a building (hair cracks)

Non-structural cracks are formed because of internal forces in the structure.

Materials due to moisture variation, temperature changes and suitable remedial measures can be carefully handled to put a curb on the crack. Cracks differ in width largely.

There, she is. The last member. Let’s meet last member in types of cracks in a building.

Cracks based on width

Depending upon the crack width, the cracks can be further divided as,

  • Thin Crack -less than 1 mm in width
  • Medium Crack -1 to 2 mm in width.
  • Wide Crack -more than 2 mm in width.

That’s it about the types of cracks in building.

We have sailed through the important aspects of cracks in building. We missed out the causes of cracks which will be explained in a blog in future.

Stay tuned!

Roads, TRANSPORTATION ENGINEERING

4 Types of Pavement |Difference between Flexible and Rigid Pavement

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Types of pavements play a crucial role in road construction. They determine the performance, durability, and maintenance requirements of highways and streets. There are four primary pavement types: flexible pavements, rigid pavements, composite pavements, and semi-rigid pavements. Each of these serves specific purposes depending on the load-bearing capacity, climatic conditions, and construction needs. It is essential to understand the difference between flexible and rigid pavements. These two major categories vary in material composition, load distribution, and overall performance. Flexible and rigid pavements offer distinct advantages. Flexible pavements are more adaptable to underlying soil conditions. Rigid pavements, made of concrete, provide higher structural strength.

This article covers the four types of pavements and the difference between flexible and rigid pavements

Before we begin, let’s look into what a pavement is.

  1. What is pavement?
  2. Types of Pavements
  3. Flexible pavement
    1. Examples of flexible pavements
    2. Advantages of flexible pavement
    3. Disadvantages of flexible pavements
  4. Rigid pavement
    1. Advantages of rigid pavement
    2. Disadvantages of rigid pavement
  5. Comparison between flexible and rigid pavements
  6. Semi rigid/ composite pavements
  7. Interlocking Concrete Block Pavement (ICBP)

What is pavement?

The pavement is a hard surface that’s built with concrete or asphalt, like a road or a driveway.

Pavement refers to the hard, durable surface layer of roads, walkways, and other transportation paths. These surfaces are designed to withstand the wear and load of traffic. It provides a smooth, stable platform for vehicles and pedestrians, while ensuring safety and comfort. Pavements are engineered for strength, weather resistance, and longevity, typically made from materials like asphalt or concrete. Properly constructed pavements reduce road maintenance and improve traffic efficiency, contributing significantly to infrastructure durability and performance.

Types of Pavements

Pavements are essential for providing a stable and smooth surface for roads and infrastructure. The main types of pavements differ in their structural composition and load-bearing capacities. The top four types of pavements include flexible pavements, rigid pavements, composite pavements, and semi-rigid pavements. Each type serves specific purposes depending on traffic load, climatic conditions, and construction requirements.Based on the structural behavior, road pavements are classified as

  • Flexible pavement
  • Rigid pavement
  • Semi-rigid pavements
  • Composite pavements
  • Interlocking cement concrete block pavement (ICBP)

Without any due, let’s jump onto the first type of pavement.

Flexible pavement

Flexible pavement - Type of pavement
Flexible type of pavement

Flexible pavement is the pavement which possess negligible flexural strength. And,

  • The flexible pavement layer can exhibit non-recoverable deformations of the lower layer. It may also show recoverable deformations. These deformations include the subgrade on the upper layers and possibly affect the pavement surface.
  • The vertical compressive stress is maximum on the pavement surface directly under the wheel load and is equal to the contact pressure under the wheel
  • The lower layers of pavement have to withstand lesser magnitudes of stresses. There is no direct wearing action due to traffic loads. They also do not experience weathering action due to environmental factors. Therefore inferior materials with lower cost can be used in the lower layers.
  • In flexible pavement layers, the top layer has to be the strongest. This layer must sustain the highest compressive stresses. It also endures wear and tear due to moving traffic and varying weather factors.

Examples of flexible pavements

  1. Asphalt Pavements – Commonly used for highways, streets, and driveways.
  2. Bituminous Surface Treatment (BST) – Used for lower-traffic roads and rural areas.
  3. Gravel Roads with Asphalt Coating – Often found in rural areas or less populated regions.
  4. Full-Depth Asphalt Pavements – Used in areas with high traffic and heavy loads.
  5. Cold Mix Asphalt – Used in maintenance and patching.

Each of these examples offers flexibility, enabling them to adjust to changes in the subgrade beneath.

Also read: Electronic Toll Collection-4 subsystems of ETC Full details

Next, let’s peep into advantages and disadvantages of flexible pavements.

Advantages of flexible pavement

Flexible pavement is a common choice in road construction. It is designed to distribute loads over a wide area. This allows for movement and adaptation to underlying conditions. This adaptability makes flexible pavements particularly beneficial in various applications.

Types of Road pavements - Flexible pavement
Types of Road pavements – Flexible pavement
  • Initial cost can be reduced by constructing thin bituminous surface layer
  • Standard design load in terms of CSA (Cumulative Standard Axles)
  • Functional deterioration
  • Strengthening by overlay
  • High salvage value
  • Can be open to traffic after 24 hours

Disadvantages of flexible pavements

  • Deterioration under stagnant water
  • Periodic maintenance
  • Patching of pot holes is expensive
  • Thickness is very high
  • Night visibility is very low

That’s it about flexible pavement. Let’s move onto the next type of pavement.

Also read: Classification of roads- 5 types of roads full details

Rigid pavement

Rigid pavements are those which possess noteworthy flexural strength of flexural strength or flexural rigidity.

See more details below.

  • Rigid pavements are generally made of Portland cement concrete hence known as ‘cc pavement’
  • Construction of rigid pavement using high quality plane cement concrete known as ‘pavement quality concrete (PQC)
  • The CC pavement made of PQC are generally expected to sustain up to 45kg/cm2 of flexural stresses
  • In rigid pavements, the stresses are not transferred from grain to grain to the lower layers as in the case of flexible pavement layers.
  • Slab action is capable of  transmitting the wheel load cases through a much wide area below pavement slab

Having the details in back pack, ready to know the advantages and disadvantages of rigid pavements?

Advantages of rigid pavement

  • No deterioration under stagnant water
  • Thickness is less
  • Service life 30 years
  • Life cycle cost is very less
  • Night visibility is high

Disadvantages of rigid pavement

  • Axle load study is required
  • Design should be for 30 years
  • Possible to restore the pavements under crack
  • Surface may become smooth or slippery
  • Long period of 28 days is required to open traffic

Let’s conclude the section with a comparison.

Comparison between flexible and rigid pavements

Flexible pavementRigid pavement
Bitumen is mostly used for construction Otherwise called concrete pavements
Bitumen becomes soft due to low temperature and bleeds leading to failure of pavementHave longer life and is practically maintenance- free
When water enters the pavement during raining, resulting in potholes Can withstand extreme weather conditions
Due to low temperature in winter season, bitumen becomes brittle leading to cracking of pavementInitial cost higher comparatively, but economical in long term
Comparison between flexible and rigid pavements

Now, you know about flexible and rigid pavement. Time to meet some not-so-famous type of pavement.

Also read: Gauges in railway- All Details About Broad, Metre and Narrow Gauges

Semi rigid/ composite pavements

Semi-rigid pavements are an intermediate state between the Flexible and the Rigid pavement. The flexural strength of the pavement is less than a concrete slab. Nevertheless, it finds support by the lateral distribution of loads through the pavement depth as in flexible pavement.

When the intermediate class of semi-rigid materials like soil cement, lean cement concrete are used in the sub-base or base course of layers of pavements, they are called semi-rigid pavement.

Pavement consisting of both flexible pavement layers and one or more semi rigid pavement layers are called composite pavements.

The last member is ICBP or Interlocking concrete block pavement.

Interlocking Concrete Block Pavement (ICBP)

interlocking concrete block pavement
Interlocking Concrete Block Pavement (ICBP)

Interlocking Concrete Block Pavement (ICBP) has been extensively used in a number of countries for quite sometime as a specialized problem-solving technique for providing pavement in areas where conventional types of construction are less durable due to many operational and environmental constraints

That was the trip through the types of pavement. Have any doubts regarding this? Just drop it in comments.

See you there. Happy learning!

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