COMPOSITION OF GLASS

WHAT IS GLASS MADE OF?

Glass as we know has been used in the construction business for a long time. Moreover, from the original use of glass as window panes and partitions, it is now being used as a mainstream construction material, thanks to technological advancements.

In this post, let's look at the composition of glass.

• Silica: Known as the major component of glass, silica content ( also known as silica dioxide ) makes up about 72% of the glass. Silica needs a very high temperature to fuse. To prevent that, it is mixed with sodium carbonate or potassium carbonate. 
• Potash: Potash increases the thermal expansion properties of glass, making it fire resistant. 
• Soda: Soda/Sodium oxide increases the fusion capability of glass hence, excess of it is harmful. 
• Lime: Lime imparts durability and toughness of glass.
• Lead oxide: Lead is responsible for the coloration of glass. However, in large quantities, it can increase the density of glass, giving it a yellow color, so it should be avoided. 
• Cullet: Cullet acts as a flux to prevent the loss of alkali by volatilization. 

TYPES OF LIME

 Lime and its types

Lime:- Lime is a versatile material that is commonly utilized in building construction. Lime is produced from the calcination of its ore which is limestone. Calcination is the process in which limestone is heated up to redness, causing the loss of carbon dioxide and moisture from it and resulting in the creation of lime. Lime which is produced from relatively pure limestone is called Quick lime. 

Types of Lime:- There are three types of lime used in construction i.e. 

1.  White/ pure/ fat/ rich lime:- This lime is made from moderately pure limestone having percentage purity 90-95% and clay concentration 5-10%. This is termed as Pure Lime. This lime possesses high plasticity and moderate setting time, hence is generally used in work where strength is not required.
2. Water/ hydraulic lime:- This lime is made from impure limestone having percentage purity 70-85% and clay concentration 15-30%. This form of lime does not show slaking and sets rapidly, hence is generally used for those works where strength is required.
3. Impure/ poor lime:- This lime is made from moderately impure limestone possessing high percentage of impurity and clay concentration greater than 30%. This form of lime does not slake, hardens slowly, therefore it is generally used for inferior construction like brick walls.

STEEL AND IT'S TYPES

STEEL AND IT'S TYPES

Steel is another most common used component in civil engineering projects. It is pure form of iron containing 1.5% carbon along with small percentages of Sulphur, silica, phosphorous and magnesia. 

TYPES OF STEEL

Steel is an intermediate stage between cast iron and wrought iron, meaning it has a difference of carbon content from other two types and this difference of carbon makes it convenient for us to categorize steel into different types. Classification depends on the percentage of carbon increasing or decreasing because it is the reason steel has it's characteristic strength. 

• VERY LOW CARBON STEEL/MILD STEEL: This type of steel has carbon in the range of 0.05% - 0.1% and is used in wires, nails, pipes, tubes, etc.
• MILD STEEL: Carbon percentage in this type ranges from 0.1% - 0.2% and is used on lightly stressed machine fittings, structural shapes, bars, rivets, etc.
• MEDIUM CARBON STEEL: This particular type has different ranges which collectively fall into this type i.e. 0.2% - 0.3%, 0.3% - 0.4%, 0.4% - 0.5% and 0.6% - 0.7%. Based on these ranges they are used in gears, axles, spring wires and rails respectively.
• HIGH CARBON STEEL: Steel in this particular type does has different ranges i.e. 0.7% - 0.8%, 0.8% - 0.9%, 0.9% - 1.0%, 1.0% - 1.1%, 1.1% - 1.2%, 1.2% - 1.3% and 1.3% - 1.4%. Based on these ranges, steel is used in clutch plates, hand tools, large turning tools, drills, slotting tools and stone cutting tools respectively. 

PLASTERING

 PLASTERING

A thin layer of plastic mortar is put to the ceiling and walls to provide an even, smooth, uniform, and clean surface. This thin layer of covering is called as Plaster. Plastering is the technique of applying this layer to the surfaces. Plastering is done with plastic mortar, which is made by mixing some binding ingredient (like lime, cement, or mud) with fine aggregate and water in an appropriate proportion.

Some Commonly used Plaster:-

1. Lime Plaster:- Lime plaster refers to the use of lime as a binding material. Lime plaster is a form of plaster made of hydrated lime, sand, and water.

2. Cement Plaster:- It is a combination of portland cement, fine aggregates, and eater in appropriate proportions that is often applied to the interiors and exteriors of masonry to provide a smooth surface.

3. Mud Plaster:- It is composed of the proper proportions of clay and sand. This is the cheapest kind of plaster and is commonly used in case village and temporary kutcha buildings.

DESIRABLE PROPERTIES OF MORTAR

 DESIRABLE PROPERTIES OF MORTAR

A mixture of cement, lime, fine aggregates and water makes up mortar. Cement and lime act as binding agents and fine aggregates are known as matrix. Their combined effect makes up the perfect binding agent which is also capable of providing strong joints.

Apart from the above mentioned facts, mortars are required to project certain properties:

• WORKABILITY: As the name suggests, mortar should be fluid and easy to work with. This includes being able to reach and fill the joints properly without any gaps. 
• RATE OF STIFFENING: As the amount of water reduces in mortar due to evaporation, it starts to become stiff and hard.  As stiffening accelerates, so does the rate of early strength development. Hence, mortars should have a high rate of stiffening.
• VOLUME CHANGE: Mortar is required to undergo minimum change in volume as this sets the standard of strength of bond. Higher the volume change, poor is the initial bond, hence poor strength.
• GOOD ADHESION: Since mortar is a binding agent, it is natural to expect good adhesion property because it will decide the strength of bond.
• COMPRESSIVE STRENGTH: As the structure undergoes compression, naturally mortar should have the desired compressive strength to counter the forces.
• DURABILITY: Higher durability means low maintenance and high strength.

PHYSICAL REQUIREMENTS FOR PORTLAND CEMENT

 PHYSICAL REQUIREMENTS FOR PORTLAND CEMENT 

Indian Standards has issued certain requirements which need to be fulfilled, to ensure quality control of Portland cement. These requirements are based on certain tests:

• Fineness
• Setting time
• Soundness
• Heat of Hydration
• Compressive strength 

FINENESS: The amount of fineness determines, the rate of reaction of cement. So with that it makes the relation between fineness and rate, inversely proportional. Finer the grading, more is the rate of reaction and vice versa. Fineness of cement is determined using Blaine's Air Permeability method.

SETTING TIME: There are two setting times of cement

• initial setting time
• final setting time

Determination of these times involves the use of Vicat's test.

SOUNDNESS: Soundness refers to the ability of cement to maintain a constant volume. Cement having greater volume of lime and magnesia lead to cracking. This is known as unsound cement. Soundness is determined using Autoclave test.

HEAT OF HYDRATION: Cement, on coming in contact with water causes a chemical reaction. This reaction is called hydration and in this, tremendous amount of heat is generated. It needs to be ensured that the heat of hydration does not exceed a certain amount because it can develop cracks in concrete.

COMPRESSIVE STRENGTH: This property of cement is determined using Concrete Cube Test in which cubes of cement are tested for failure under a compression testing machine. This test is carried out for cement cured for 7 days and 28 days.

Today's New Word #1

 Word of the Day 

Coping

Meaning:- The capping placed on the exposed top of a wall (or parapet), generally made of stone, to prevent rainwater from soaking in.

PLANE TABLE SURVEYING

 PLANE TABLE SURVEYING

Plane table is a method of surveying, which involves graphically plotting and carrying out observations at the same time. In a nutshell it is a way to make a manuscript map in the field. It can deploy both topography control and triangulation/traverse as per requirement. 

INSTRUMENTS USED

Plane table surveying uses the following instruments:

• A plane table with leveling head 
• An alidade for sighting
• Plumbing fork and plumb bob 
• Spirit level 
• Compass
• Drawing paper 
• Masking tape 

PROCEDURE FOR SURVEYING

Plane table involves three steps to carry out survey:

• FIXING
• SETTING
• SIGHTING THE POINTS

FIXING: It involves fixing the plane table on tripod stand and making sure it is parallel to the ground with the help of spirit level and plumb bob. 

Care must be given to ensure that the table is levelled from all it's corners.

SETTING: After table is levelled, it should be placed over the station on the ground so that the point plotted on the sheet corresponding to the station occupied comes exactly over the station on the ground. 

This specific step is known as centering of plane table. 

ORIENTATION: Orienting involves, placing the plane table in a fixed direction to make sure the line representing a certain direction on the plan is parallel to the direction on the ground. There are 2 ways of orientation:

• Orientation with the help of compass 
• Orientation by backsighting

SIGHTING THE POINTS: After the table has been set and orientation is carried out, points to be located are sighted with the help of alidade. Alidade is pivoted about the plotted location of the instrument station  and turned to make sure the line of sight passes through the signal at point to be plotted. 

From there, a ray is drawn from the instrument station along the edge of alidade. Following this, rays over other points to be sighted are drawn. 

Finally, the points are plotted on sheet. 

TRAFFIC ENGINEERING

 TRAFFIC ENGINEERING

Traffic engineering is a separate branch of engineering dealing with improving traffic performance of roads and terminal links set up over the city. A part of it involves, studying the traffic patterns, analysis along with engineering applications.

Besides this, traffic engineering involves planning and studying geometric designs of locations to better plan the flow of traffic in the future. Because of this, it deals with the applications of scientific tools and principles for safe, convenient and economic movement of people and goods.

Traffic engineering is that phase of engineering which deals with planning and geometric design of streets, highways, abutting lands, and with traffic operations thereon, as their use is related to the safe, convenient and economic transportation of people and goods.

Definition given by Institute of Traffic Engineers, U.S.A.

SCOPE?

Traffic engineering aims to achieve efficient and rapid flow of traffic across the city and other locations linked through roads. Studying the traffic patterns along with factual observations provide the necessary information for improving traffic conditions along with minimizing accidents. 

Study of traffic engineering is divided into six parts:

• Traffic characteristics
• Traffic studies and analysis 
• Traffic operation - control and regulation
• Planning and analysis 
• Geometric design
• Administration and management 

NOTE:- Study of traffic patterns is one of the most important factors in city planning.

MINE SURVEYING/UNDERGROUND SURVEYING

 MINE SURVEYING/UNDERGROUND SURVEYING

In general the principles of underground surveying are similar to surveying on the surface with a few exceptions. For starters, the work settings and conditions differ from those of surface. Other than that, the instruments used for underground surveying are also different. 

To put them together, changes experienced in underground surveys are:

• Having limited working space, we make use of smaller instruments of special design, fitted with extension tripod legs.
• Having limited sight/vision, it is necessary to adopt special observation methods. Extra care is needed to ensure limited errors in making observations.
• For traversing, the transit is placed on the roof which means there is alteration in traversing as well. 
• Because there is limited/no light as we proceed underground, extra care is given to ensure proper illumination on the work site. 
• Just like general surveying, we have to ensure three points to set up a triangulation from where we can measure the distances on slopes. 

EQUIPMENT USED FOR MINE SURVEYING

Primary instrument used for mine surveying is called Mine Transit. It is smaller in size than the ordinary total station. However, there are instances where the sight can be too steep. In that case, an auxiliary telescope is attached to the transit or the main telescope. 

This type of attachment serves an advantage. With this, the auxiliary telescope becomes interchangeable between top and side positions. And last but not least, we have the eye-piece and tripod attachment at the bottom. 

 Types of Wall in Building Construction

Wall:- Walls are necessary components of every structure. A wall is a structural component that divides a space into two spaces while simultaneously providing safety and shelter from the rain, sun, wind, theft, and other hazards.

• Different Types of Walls are as follows:-

1) Load Bearing Wall:- As the name suggests, the complete structure is supported by walls rather than columns. In general, loads travel from the slab to the beams, then to the columns, and finally to the foundation. Load bearing walls support the entire structure's weight, including the self weight of structural parts. There are also different types of load bearing walls such as: retaining wall, precast concrete wall, masonry wall, stone wall, etc.

2) Non-Load Bearing Wall:- Non-load bearing walls solely hold their own weight and do not support any structural components like beams or slabs. The joists and rafters identify non-load bearing walls. These walls are only used as partitions or to divide rooms from the outside world. It is also referred as internal wall that does not support any other load but its own. There are also different types of load bearing walls such as: hollow concrete block, hollow brick, brick wall, etc.

3) Cavity Wall:- A wall made of two skins of masonry, the outermost part of which can be brickwork or blockwork and the innermost part of which is usually blockwork. A cavity wall provides superior thermal insulation than any other solid wall.

4) Partition Wall:- A partition wall is a non-load bearing internal wall that divides a large space into small spaces. It can be solid, made of brick or stone. It is a framed structure. The partition wall is both a sound barrier and a fire barrier.

5) Panel Wall:- It is a non-bearing wall that is supported by columns or pillars. It is used for aesthetics of the buildings both inside and outside. It remains totally supported at each storey but subjected to lateral loads.

BUILDING FRAMES

 BUILDING FRAMES

The framing of a multistorey building varies on the basis of it's type and function. Typically multistoried buildings consist of offices, residential flats, hospitals, etc. For these types of buildings RCC is preferred as the catalyst for construction reason being it provides good strength and is economical ( if the building is less than 20 storeys ).

However, if a building has more than 20 floors, then it's debatable if RCC or steel will be used as a means of construction. Exceeding 20 floors, steel becomes more cost efficient than RCC and can also be used to lay down the framing in a lesser time frame than RCC. Hence for multiostorey buildings, steel is used to lay down the frames for columns, beams and girders. 

FRAMING OF A BUILDING

A building frame consists of columns, beams and girders which support floor and roof load. This type of building frame is known as Beam and Column frame. From storey to storey, the columns remain consistent with beams and girders attaching to them as we proceed. 

For the flooring we use wood, concrete or steel ( if required ) and this in turn is supported on the floor beams. 

NOTE: BEAMS WHICH SUPPORT THE EXTERIOR WALLS ARE KNOWN AS WALL BEAMS OR SPANDREL BEAMS.

ABILITY TO WITHSTAND LOADS

In general the ability of a multistorey building to withstand all kinds of loads depends upon the rigidity of connections between the columns, beams and girders. Apart from the vertical loads which consists of the dead loads ( weight of the individual components of the building ), the building is subjected to lateral loads. To resist these, requirement arises for the components to be completely rigid. 

To achieve this, columns can be continuous for upto 2-3 storeys, beyond which they may be spliced and connected to the beams and girders. 

For optimum utilization, the columns are arranged with flanges, parallel to the longitudinal axis of the structure, since that is the best way to resist the transverse loads.

 Post-Tensioning

Post-tensioning is a technique used to produce prestressed concrete, masonry, and other structural components. In this process, steel tendons are tensioned after the concrete has been placed. The tendons are stretched between sturdy bulkheads that can bear external stresses before being surrounded by concrete. 

When is the structural element is heavy, the post-tensioning method is recommended. Construction that would normally be unfeasible due to site limitations or architectural requirements has become possible due to this technique. It is a technique that needs specific expertise and well-trained personnel. This procedure could be used on any structure, whether residential, commercial, or office buildings. It is widely used in bridges, floor slabs, silos, and other concrete structures.

HIGHWAY PROJECT

 HIGHWAY PROJECT

In general a highway project involves an engineer to plan, design and construct either a road network ( new roads linking each other ) or a simple road link. 

Other than this a project can also include redesigning or relinking older projects.

STAGES OF HIGHWAY PROJECT 

A highway project consists of the following stages:

• route selection, finalization of highway alignment and geometric design details
• collecting construction materials and testing them 
• carrying out the construction along with necessary quality checks

Route Selection

Selection of a project location involves going over the geographic, topographic and other features of the desired area. Following that, special care should be given to creating room for renovation and relocation if required in future. With the location selected, the plans and drawings for the project are prepared. 

Materials and Testing 

With the location decided, soil samples are collected from the desired route and tested in laboratory to check their properties are ideal to carry out construction. Since highway construction involves both pavement and embankment slopes, it is very important to carry out soil testing to check it's ability to withstand the loads from all kinds of traffic. 

However keeping the desired quality in mind, efforts should also be made to make the construction as cost effective as possible. 

NOTE: In India, the CBR method has been recommended by the India Roads Congress for designing the thickness of flexible pavements. 

Carrying out Construction

The construction is divided into two steps

• earth work
• pavement construction

Earth work consists of excavation of land and construction of embankments. During excavation, extra care must be given to provide enough space for construction of slopes and installation of drainage alongside the highway. For points where embankment is high, it is important to give special care to that particular foundation and to the slope following. 

Pavement construction eventually takes over starting with preparation of subgrade and construction of sub-base, base and surface courses of pavement.

HIGHWAY ALIGNMENT

 HIGHWAY ALIGNMENT

Positioning or the layout of central line of highway on the ground is known as alignment. A horizontal alignment includes straight paths, horizontal deviations and curves. Vertical alignment involves changes in vertical curves of roads.

REQUIREMENTS FOR HIGHWAY ALIGNMENT

A conventional highway alignment should satisfy the following requirements to fulfil the need of an ideal alignment:

• short: A short alignment serves ground for practical applications keeping aside the fact that while designing there are certain factors which do not allow the laying down of the shortest path.
• easy: An ideal highway alignment should be easy to construct and must allow easy operation of vehicles on gradients.
• safe: The highway alignment should be safe for construction and functioning of gradients and slopes more particularly for areas with mountain slopes and embankments.
• economical: And last but not least, the alignment should be economical for construction which is only considered if the overall cost of construction is the lowest.

FACTORS CONTROLLING ALIGNMENT

The following factors are responsible for controlling the alignment of a highway:

• Obligatory points
• Traffic
• Geometric Design
• Economics 
• Others

Obligatory points: Obligatory points are referred as control points which help in governing the alignment of highways. They are broadly classified in two categories:

• Points through which the alignment is to pass
• Points through which the alignment should not pass

Traffic: The alignment should be done to satisfy the traffic conditions in that particular area. Origin and destination points should be laid down in accordance with the desired lines showing the trend of traffic flow and must also keep in mind the future trends.

Geometric design: Geometric factors play a huge role in determining the alignment of a highway. Traditionally the idea is to provide an alignment as straightforward as possible. In that case the geometric design is supposed to be as straight and simple as possible. If necessary, adjustments should be made to the horizontal alignment of the road keeping in view the minimum radius of curve and transition curves.

Economics: Alignment is finalized on the factor that the overall design is economical. Economy as a whole takes into consideration, the cost of construction, maintenance and transportation. 

Others: Other factors usually undertake drainage conditions, politics or other hydrological factors. 

TYPES OF ROADS

TYPES OF ROADS

Roads have been the oldest mode of transport since ancient times and serve an important role in connecting different parts of a city, state and the entire country.  

CLASSIFICATION OF ROADS

Based on whether they can be used during different seasons of the year:

• ALL WEATHER ROADS: as the name suggests these types of roads are built to handle any and all types of weather conditions.
• FAIR WEATHER ROADS: these roads are permissible for all weather conditions in exception to river crossings. At the river crossings these roads are interrupted during monsoon season because of rise in water level hence posing a threat to the vehicles passing by. 

Based on the type of carriage way or the road pavement:

• PAVED ROADS: if the road is equipped with a hard pavement course at the least having a water bound macadam (WBM) layer are called paved roads.
• UNPAVED ROADS: if the road is not provided a hard pavement course or a WBM layer, then those roads are classified as unpaved roads. Earth roads and gravel roads are examples of unpaved roads.

Based on the type of pavement surfacing provided:

• SURFACE ROADS: the roads which are provided with a bituminous layer or cement concrete surface are classified as surface roads. The roads with a bituminous are also called black toped roads.

• UNSURFACED ROADS: the roads which are not equipped with a bituminous layer or cement concrete surface are called unsurfaced roads.

METHOD OF CLASSIFICATION OF ROADS

Roads are generally classified on the following basis:

• Traffic volume
• Load transported or tonnage
• Location and type of function served by the road

Pre-stress in concrete

 PRE-STRESS IN CONCRETE

Pre-stress can be defined as the initial stress deliberately introduced in a particular structural element by mechanical means. 

OR

It can be defined as the process of deliberately developing stress in an element is known as pre-stressing. 

However, plain cement concrete does not have any strength in tension which is why it is susceptible to crack under tension. This is why it cannot be used for economical design of structures. Because of this plain cement concrete is reinforced by embedding steel bars in tension zone. This steel embedded cement concrete is known as Reinforced Cement Concrete  ( RCC ).

Advantages of Pre-Stressing:

• Pre-stressed members can resist of impact, shock, and reversal stresses more efficiently than RCC structures hence they remain free from cracks.
• Life of pre-stressed elements is more than RCC elements reason being that reinforcement remains unaffected from external agents.
• Section of any member is considerably reduced because of which smaller sections can be used for longer spans.
• There is complete utilization of high compressive strength of concrete resulting in an economical section.

Disadvantages of Pre-stressing:

• Pre-stressing requires special equipment like jacks, anchorage, etc. This restricts the complete use of the pre-stressed member.
• Majority of the steel used is high tensile steel which is difficult to procure and costs more than plain mild steel.
• It requires expertise to exercise control during preparation of high cement concrete.

TYPES OF JOINTS IN A STRUCTURE

TYPES  OF JOINTS IN A STRUCTURE

In any type of structure, consideration is given towards structural damages. These damages can be either sudden or over the course of time. Either way, it is to be ensured that the damage is minimized by any means. For all these dimensional changes, the structure is broken down into different components which when joined together form a joint.

Different types of joints are provided in a structure:

• Expansion Joint: This type of joint is provided, keeping in mind of the thermal expansion property of concrete. With an increase in temperature, concrete can expand  which in turn can form cracks. To avoid the formation of cracks, expansion joint is provided which allows for free movement of concrete.

• Contraction Joint: This type of joint is inverse in comparison to the expansion joint. Aim is the same as expansion joint ( to prevent the formation of cracks ) the only difference being that this is provided for the case where the temperature drops.

• Sliding Joint: As the name suggests, this joint is provided to allow free movement between two components of a structure. This joint is usually provided under the foundation keeping in mind the horizontal forces ( shear stress ) applied by the subsoil on concrete. 

• Isolation Joint: This joint serves the purpose of isolating one structural component from the other. This joint is usually made from asphalt-impregnated fiberboard, cork, rubber or neoprene. 

CEMENT CONCRETE

         CEMENT CONCRETE

    

                                                   

It is a hardening construction material made up of cement, sand aggregate, and water in a limited proportion. Portland cement is the most often used type of cement in the production of concrete. Concrete Technology is concerned with the study of concrete characteristics and their practical applications.

The Cement Concrete is manufactured by two ways:-                                                         

• Nominal Mix Concrete
• Design Mix Concrete

1) Nominal Mix Concrete: - In a nominal mix, materials like cement, sand, and aggregate are not placed under ideal conditions prior to mixing. It is difficult to determine the assurance of concrete quality and strength corresponding to the desired strength. In this quality control is sacrificed. Skilled workmanship is also sacrificed, resulting in insufficient strength.

2) Design Mix Concrete:- In a design mix, materials like cement, sand, and aggregate are kept under ideal temperature and humidity. In this type of mix concrete is made at a nodal place called a batching plant and then transported to the site through transit mixture. During transportation, the appropriate temperature for the ideal proportion mix is maintained by admixtures such as plasticizers and superplasticizers, which do not change the strength of the mix proportion of concrete but delay its setting time. 

Tests on Concrete

 TESTS ON CONCRETE

There are certain types of tests performed on concrete in order to ensure it's workability, tensile strength, etc. Different types of tests are used to determine different results.

1. Rebound Hammer Test:

Rebound Hammer Test is used to determine the compressive strength of concrete. Apparatus consists of a Rebound Hammer or Schmidt Hammer. Hammer consists of a spring controlled mass contained in a tubular house which slides on a plunger. When the rebounded hammer plunger is pressed against the surface of concrete, the spring controlled mass is released and made to hit the concrete surface and rebound. The amount of rebound is a measure of hardness of concrete surface. This rebound is measured on a graduated scale and the measured value is called the Rebound Number. Concrete with high strength will reveal a higher Rebound number and vice versa.

2. Penetration Resistance Test: 

This test is used to determine the uniformity and assess the in-situ strength of concrete. Test is conducted using Windsor Probe test machine. A steel probe is fired on the surface of concrete sample with a sudden explosion. The amount of penetration is inversely proportional to the strength of concrete. Strength of aggregates and nature of formed surfaces of concrete can influence the result of this test. 

3. Ultrasonic Pulse Velocity Test: 

Idea behind Ultrasonic Pulse Velocity test is to measure the time taken by an ultrasonic pulse to pass through a concrete sample. This test is performed in-situ to assess the quality of concrete ( homogeneity, check presence of cracks and overall imperfections ). The concrete sample is induced with a series of waves. A transducer is placed on the other side to detect the ultrasonic waves. The speed of wave is affected by the shape, size and geometry of concrete. Concrete with homogeneity and uniformity will allow the waves to pass through quickly and vice versa. 

4. Core Sampling of concrete:

Concrete core or core sampling makes use of a rotary cutting tool with diamond bits. This is used to obtain a cylindrical specimen . The cores are documented on site. ( visually observed and photographed ) Next it is soaked in water, made even over it's surface and tested for compression in a moist condition as per BS: 1881: Part 4: 1970. 

5. Water Absorption Test: 

This test is used to determine the durability of concrete. In this 3 cubes of 150mm concrete sample are taken and and placed in a curing tank for 28 days or after 24 hours the concrete is removed from the mold and sent to a third-party laboratory for curing. The testing is done in accordance with BS: 1881-122.