Retaining Wall

1.1:-Introduction

            A retaining wall is a wall constructed for the purpose of retaining vertical or nearly vertical bank or slope. The retaining wall is the most important structure in hill road construction. It provides sufficient stability to the roadway and to the slope at hillside as well as the valley side. The retaining wall provided at the valley side is called the toe wall and provided at the hillside is called the breast wall.

1.2:-Function of retaining wall

1)Retained soil or other materials at the location having an abrupt change in elevation.

2)Break the steepness of the slope.

3)Provide stability to the slope at the valley side as well as hillside and retained backfill.

1.3:-Type of retaining wall

A)Based on structure

1)Gravity retaining wall

2)Semi gravity retaining wall

3)Cantilever retaining wall

4)Counterfort retaining wall

1)Gravity retaining wall

-It depends upon their weight for stability.

-Construction of plane concrete or masonry

-Not  economical for greater height

-Take a large space

2)Semi gravity retaining wall

The size of the section of the gravity wall is reduced by the provision of a small amount of reinforcement.

3)Cantilever retaining wall

Made up of reinforced cement concrete.

-Consists of thin steem and base casted monolithically.

-Economical up to the height of 6-8 meter

4)Counterfort retaining wall

-It has a thin vertical slab called counterfort.

-The counterfort ties the vertical stem with the base slab.

-Counterfort is on the side of backfill.

-They are economical for height more than 6 meter

B)Classification based on material 

1)Dry stone masonry

2)Stone filled gabion wire crates

3)Stonemasonry with cement sand mortar

4)Composed retaining wall

5)PCC retaining wall

6)RCC retaining wall

C)Classification based on location

1)Hill or valley side retaining wall

2)Cut off wall

3)Revetment wall/ breast wall

4)Toe wall

1.4:-Suitable site for retaining wall

1)At the place of partly cutting or partly filling of hill section.

2)At the place where the road crosses a drain.

3)At a valley side and hillside of the roadway.

4)At the toe of an embankment.

5)At the base of the cut slope.

1.5:-Practical features of retaining wall

1)The retaining wall of height less than 6 meters have a minimum base width of 0.5 H and top width 0.45 to 0.6 meter.

2)The rare side of retaining wall is vertical, while the front is batter of 1 in 4 (1:4).

3)In the case of height greater than 6 meters, the base width is (0.4+0.3) to (0.5+0.6)meter with top width o 0.75 meters.

4)The rear face is kept vertical while the front face is batter of 1:2.5 to 1:4.

5)In case of the dry retaining wall of height greater than 6 m of the band of cement mortar at the horizontal and vertical interval of about 3 meter, each is constructed.

Door & Types

INTRODUCTION

The door is generally swinging or sliding barrier by which an entrance is closed and opened which is made up of a similar part of a piece of furniture.

Types of Doors Used in Building Construction

Types of the door based on the arrangement of door components

1. Battened and Ledged Doors

  • Battens are vertical bonds having channels attached to each other by horizontal supports called ledges.
  • General Dimensions of batten are 100-150mm width and 20-30mm thick.
  • The general dimension of ledges is 100-200mm width and 25-30mm thick.
  • This type of battened and ledged doors are good for narrow openings.

2. Battened, Ledged and Braced Doors

  • To make more rigid, braces are provided diagonally in additional to battens and ledges.
  • Braces having 100-150mm width and 25-30mm thickness are mostly used.
  • Braces should place upwards from the handing side, then they work as struts and hold compression.
  • These types of doors can be utilized for wider openings.

3. Battened, Ledged and Framed Doors

  • For the simple battened and ledged door, a framework is provided in the form of two verticals, known as stiles.
  • Stiles is generally 100mm wide, the thickness of stile should be equal to the combined thickness of ledge and batten. Preferably 40 mm.

4. Battened, Ledged, Braced and Framed Doors

  • In this type,  battens, ledges, stiles, and braces are constructed. So, it is more rigid.
  • The braces are connected diagonally between the ledges, at about 40mm from the stiles.

Types of Doors based on Method of Construction:

Based on the method of construction, the doors are  classified as;

1. Framed and Panelled Doors

  • These are very strong and will provide the best appearance when compared to battened doors. These are the most used doors in almost all types of buildings.
  • Stiles, vertical members and rails, horizontal members are grooved along the inner edges of the frame to receive the panels.
  • The panels are built up of timber or plywood or A.C. sheets or by the glass.
  • These doors can be single leaf for narrow openings and double leaf for outspread openings.
  • The minimum width of the stile should be 100mm and a minimum width of the bottom and locked rail should be 150mm.

2. Glazed Doors

  • Glazed doors are usually kept in interior wall openings or in hospitals, colleges, banks, etc.
  • The interior of the room is visible through glazed doors and light also passes through a glazed portion of the door.
  • These may be fully glazed or partly glazed and partly paneled. Glass panels are provided for glazed doors.

3. Flush Doors

In flush doors, a semi-solid or solid, the core portion is coated on both sides with plywood or face veneer. Nowadays these type of doors is widely used because of good appearance, economic, ease of construction and greater durability.

4. Louvered Doors

  • The louvers permit natural ventilation when the door is closed and also provides privacy in the room.
  • These are usually utilized for toilets of residential and public buildings.
  • The door may be louvered fully or partly.
  • Louvers are made up of timber or glass or plywood and these may be either fixed or movable.

5.Wire Gauged Doors

Wire gaged doors authorize natural ventilation and regulate the entrance of flies, mosquitoes, insects, etc inside the building. These doors are mostly utilized in hotels, restaurants and for cupboards containing eatables.

6. Revolving Doors

Revolving doors are usually provided in public buildings like museums, banks, libraries, etc., because of constant visitors came morely. It contains mullion at its center to which four radiating shutters are connected.

7. Swing Doors

In this door, the shutter is connected to frame by double action spring which helps the shutter to move internally as well as externally.

8. Mild Steel Sheet Doors

  • The door frame is made up of angle or T-sections.
  • The shutter is made up of a frame of the angle of iron, having 2 verticals and at least 3 horizontal.
  • Mild steel plates are connected to the shutter frame.

9. Hollow Metal Doors

Hollow steel sections are utilized to manufacture these doors. The rails and stiles etc., are strengthened by welding small T or I sections inside.

Transparent concrete

                                INTRODUCTION

Transparent concrete is also called as translucent concrete. The bonding material in transparent concrete may be capable to transmit light by utilizing clear resins the concrete mix. Utilize of optical fibers and fine concrete also utilized as transparent concrete.

Transparent concrete was initially developed in 2001 by a Hungarian architect Aronlosonzi by utilizing glass fibers. Transparent concrete is manufactured by mixing 4% to 5% by volume of optical fibers in the concrete mixture. This concrete has low weight compared to the initial concrete.

Materials for Transparent Concrete

Transparent concrete is manufactured by using a combination of fiber optics and fine concrete. Like any other aggregates, These fibers blend into the concrete. The main reason for using optical fiber in concrete is that it can transmit light even an incident angle is greater than 600.

Optical fiber consists of three layers called core, cladding and buffer coating or jacket. The light is transmitted through the core of the optical fiber.

Transparent concrete is produced by utilizing fine materials only. It does not contain any coarse aggregates. This concrete can have a compressive strength of that of huge strength concrete around 70 MPa ( 10,000 psi).

Materials used:

Cement: As the optical fiber is only responsible for the transmission of light, there is no special cement required. So, normal Portland cement is utilized for transparent concrete.

Sand: Since the transparent concrete is produced only by utilizing fine materials, the size of sand should move through 1.18mm sieve. The sand should be free from impurities such as vegetation, large stones, etc.

Water: Water to be utilized for transparent concrete should be good of drinking water quality and free from other impurities.

Optical fibers: Optical fibers in the range of 4 to 5% by volume is used for transparent concrete. The thickness of the optical fibres can be varied between 2 µm and 2 mm to suit the particular requirements of light transmission.

Advantages of Transparent Concrete:

The major advantage of transparent concrete is that it can transmit light through it. Therefore, it can be utilized to construct green buildings. Since it can transmit light from natural as well as artificial sources, the building can have not as many lights to meet its demand for lighting. Thus saving more energy costs.

Transparent concrete utilized sunlight as a source of light instead of electrical energy and decrease power consumption. This concrete can also be utilized in cold countries to transmit heat with sunlight.

Fiber Reinforced Concrete

INTRODUCTION:

Fiber Reinforced Concrete is defined as a composite material containing mixtures of cement, mortar or concrete and discontinuous, discrete, uniformly dispersed good fibers. Fiber-reinforced concrete is of various types and properties with huge advantages. Continuous meshes, woven fabrics and long wires or rods are not taken to be discrete fibers.

Some of the substances made by chemical synthesis fibers are utilized in concrete are carbon, nylon, polyester, polypropylene, and polyethylene.

 i) Huge fiber volume micro-fiber system.

 ii) It can remove asbestos fiber. 

 iii)It improves toughness and impact strength.

The necessity of Fiber Reinforced Concrete

  1. It arises the tensile strength of the concrete.
  2. It decreases the air voids and water voids.
  3. It arises the durability of the concrete.
  4. Fibers such as graphite and glass can withstand to creep, while the same is not good for most resins. Therefore, the inclination and volume of fibers have a notable impact on the creep performance of rebars.
  5. Reinforced concrete is a composite material, where the reinforcement work as the strengthening fiber and the concrete as the matrix, therefore this imperative that the behavior under thermal stresses for the two materials be the same so that the differential buckling of concrete and the reinforcement are smaller.
  6. It has been acknowledging that the sum of small, closely spaced and uniformly dispersed fibers to concrete would work as a crack catcher and would substantially revamp its static and dynamic properties.

Factors Affecting Properties of Fiber Reinforced Concrete

Fiber-reinforced concrete is the compound material containing fibers in the cement matrix in a proper manner or randomly distributed manner. Its properties would depend upon the efficient transfer of stress between the matrix and the fibers. The factors are briefly discussed below:

1. Relative Fiber Matrix Stiffness:

The modulus of elasticity of the matrix must be much lower than that of fiber for efficient stress transfer. Less modulus fiber such as nylons and polypropylene are, therefore, dissimilar to provide the strength improvement, but they help in the soaking up of huge energy and therefore, impart a more degree of toughness and withstand to impart. Huge modulus fibers such as steel, glass, and carbon impart strength and stiffness to the composite.

The associate bond between the matrix and the fiber also calculates the effectiveness of stress transfer, from the matrix to the fiber. A better bond is important for improving the tensile strength of the composite.

2. The volume of Fibers:

The strength of the composite largely depends on the number of fibers used in it. Show the result of volume on the toughness and strength. It can arise in the volume of fibers, arise approximately linearly, the tensile strength and toughness of the composite. The use of a more percentage of fiber is similar to cause segregation and harshness of concrete and mortar.

3. Aspect Ratio of the Fiber:

Another essential factor that impacts the properties and behavior of the composite is the aspect ratio of the fiber. It has been noted that up to an aspect ratio of 75, an arise in the aspect ratio arise the ultimate concrete linearly. Beyond 75, relative strength and toughness are decreased.

4. The orientation of Fibers:

 The differences between conventional reinforcement and fiber reinforcement are that in conventional reinforcement, bars are positioned in the direction desired while fibers are properly oriented. To look at the effect of randomness, mortar specimens reinforced with a 0.5% volume of fibers were tested.

5. Workability and Compaction of Concrete:

The incorporation of steel fiber decreases the workability considerably. This situation adversely affects the consolidation of a fresh mix. Even prolonged external vibration is unsuccessful to compact the concrete. The fiber volume at which this problem is reached is conditional on the length and diameter of the fiber.

6. Size of Coarse Aggregate:

The maximum size of the coarse aggregate should be restricted to 10mm, to remove an appreciable reduction in strength of the composite. Fibers also in effect, act as aggregate. Although they have a normal geometry, their impact on the properties of fresh concrete is difficult. The inter-particle friction between fibers and between fibers and aggregates controls the orientation and distribution of the fibers and consequently the properties of the composite.

7. Mixing:

Mixing of fiber reinforced concrete requires careful conditions to remove balling of fibers, segregation and in general the difficulty of mixing the materials uniformly.