Brick Bonds Types And Patterns

A brick bond belongs to a pattern where the bricks are placed. The applications of brick bonds are found on the walls as well as for brick paving for paths & patios, concrete blocks and different types of masonry construction.

Brick Bonds can improve the strength & stability of the structure, retain consistency to the structure and composition, and increase the visual appeal. Given below, the details of commonly used wall brick bonds :-

1. Stretcher Bond / Running Bond: It is also known as running bonds. The process is very simple to place this type of bond. Stretcher bond is useful when the walls of half brick thickness are required to be constructed. This bond is applied to build up several types of wall construction as follows :

• Sleeper walls
• Partition walls
• Division walls (internal dividers)
• Chimney stacks

Stretcher bonds should not be used for self-sustaining structural walls, but it is effective for building up the walls of less thickness. Remember, this bond can collapse when the thickness of the walls remains greater than half of the total length of the brick applied.

2. Header Bond: A header stands for the shorter face of the brick. In header bond brick masonry, all the bricks are built up in the header course. Under this type of bond, the overlap is done according to a half width of the bricks. The three-quarter brickbats are used as quoins in alternative courses. This bond is primarily applied for the erection of one brick thick walls.

3. English Bond: This bond contains alternating courses of headers and stretchers. Headers are placed in center position on the stretchers in the course underneath and each alternate row is arranged vertically. To rupture the continuity of vertical joints, a quoin closer is utilized at the start and end of a wall once the first header is provided.

A quoin close belongs to a brick that is cut into 2 halves according to length and applied to the corners in brick walls. This type of bond is useful for building up strong one brick thickness walls.

4. Flemish Bond: Under this type of bond, alternate headers and stretchers are contained in each course. Each header remains on the center of a stretcher over and below and each alternate course is started with a header in the corner. To rupture the vertical joints in the sequential courses, quoin closers are provided with alternate courses alongside the header.

5. Stack Bond: In a stack bond, all the bricks are simply loaded on top of each other and retained with mortar where all bonds are arranged properly. Due to its poor masonry structure and less strength, stack bonds are effective for decorative purposes.

As this bond is a non-structural bond, therefore it should not be used for the walls which need to transmit loads.

6. Dutch Bond: It is a customized form of the English cross bond that includes alternate courses of headers and stretchers. In this arrangement of the brick bond, each single stretching course is started at a quoin containing a 3-quarter bat. Each alternate stretching course contains a header set alongside the 3-quarter bat brick placed at the quoin. This bond is suitable for developing strong corners of the wall that is susceptible to extra loads.

7. Common Bond / American Bond: This bond contains courses of headers provided with each five or six courses. Header courses are placed in center position of the previous header course. This header bond usually functions as a tie brick among the fronting and the backing. To attain the plenty offset in a standard common bond, queen closers are provided at both ends of the header courses. The common bond is generally applied in outside load-bearing walls.

8. Facing Bond: This bond is effective for thick walls, where the facing and backing are selected for construction with bricks having different thickness. Normally, this bond comprises of heading and stretching courses which are provided in such way that one heading course comes after quite a lot of stretching courses. The load distribution of walls of this bond is irregular due to the variation among the facing and the total number of joints in the backing. It can also result in unequal settlement of the 2 thickness of the wall.

9. Diagonal Bond: It is perfect for walls with two to four brick thickness. This bond is generally provided at each 5th or 7th course along the height of the wall. Bricks in this bond are arranged end to end in such a way that extreme corners of the sequence gets in touch with the stretchers.

10. Rat Trap Bond: Under this bond, bricks are placed on edge or in a vertical location rather than the conventional horizontal position. It produces a cavity (hollow space) inside the wall as a result superior thermal comfort is maintained and the inside becomes cool as compared to the outside and vice versa. Because of the internal cavity, a little amount of materials is required for this type of walls.

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Details about Ultrasonic Pulse Velocity

This test is conducted for the purpose of evaluating the concrete quality with ultrasonic pulse velocity method with adherence to IS: 13311 (Part 1) — 1992. The underlying principle of this test is –

Under this method, testing is done by sending an ultrasonic pulse through the concrete and time of movement is calculated. Relatively, greater velocity exists if the quality of concrete is good with respect to density, consistency, homogeneity etc.

The following method is applied to ascertain the strength of hardened concrete with Ultrasonic Pulse Velocity :-

i) Making it ready for use: Prior to changing to the ‘V’ meter, the transducers should be attached to the sockets leveled as “TRAN” and ” REC”.

The ‘V’ meter is activated with either: a) the internal battery, b) an external battery or c) the A.C line.

ii) Set reference: A reference bar is arranged to examine the instrument zero. The pulse time for the bar is inscribed on it. Prior to set it on the opposite ends of the bar, provide a coat of grease to the transducer faces. Fine-tune the ‘SET REF’ control unless the transit time of reference bar is captured on the instrument read-out.

iii) Range selection: For greater precision, it is suggested that the 0.1 microsecond range should be chosen for path length upto 400mm.

iv) Pulse velocity: After detecting the exact test points on the material to be tested, thorough measurement of the path length ‘L’ should be done. Provide couplant to the surfaces of the transducers and press it firmly onto the surface of the material.

It is suggested not to shift the transducers at the time of taking a reading since noise signals and errors in measurements may occur. Keep on retaining the transducers onto the surface of the material unless a reliable reading is shown on the display that is the time in microsecond for the ultrasonic pulse to pass through the distance ‘L’. The mean value of the display readings should be captured while the units digit follows among two values.

Pulse velocity=(Path length/Travel time)

v) Partition of transducer leads: It is recommended to avoid the two transducer leads from getting in touch with each other at the time of taking the transit time measurements.

If it is not performed, the receiver lead will pick-up unnecessary signals from the transmitter lead and it leads to an wrong display of the transit time.

Interpretation of Results

The quality of concrete with regard to consistency, occurrence or nonexistence of internal faults, cracks and segregation, etc, indication of the level of workmanship provided, can thus be examined with the following guidelines which are changed for defining the quality of concrete in structures with regard to the ultrasonic pulse velocity.

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Major responsibilities of a contractor in construction project

In this civil engineering article, you will get the details about the role of a contractor and the liabilities of him.

Normally, a contractor has to plan, implement, supervise, examine and direct a building construction project from beginning to completion devoid of the scope of the project. The contractor verifies that the project abides by all the specifications as provided in the contract documents.

1. Role Of A Contractor In Project Planning

The project management team develops a master schedule for the project depending on the completion date of the project.

To finish the project on scheduled time according to master schedule, the contractor has to take the following responsibilities :

• Plan for all the important project development and execution details beforehand.
• Specify and evaluate different project issues like the necessary materials, equipment, and personal requirements.
• Anticipate any probable changes.
• Execution of a trustworthy communication strategy between all concerned stakeholders.
• Focus on all legal and regulatory issues and requirements.
• Draft an efficient safety policy.

2. Role Of A Contractor In Project Management

Since the contractor is responsible to finish the project on scheduled time, he should bear the following responsibilities in project management.

• Making funds to accomplish construction tasks.
• Organize the materials for different tasks as projected.
• Arrange necessary construction equipments.
• Appoint required subcontractors to finish the job.
• Submit bills for the completed tasks as mentioned in the contract.

3. Role Of A Contractor In Project Monitoring

To finish the project according to specifications and minimize different issues in the project, a contractor has to take a vital role in project monitoring. He has to perform the following key responsibilities in this field.

• Track time schedule.
• Apply cost-effective methods.
• Check work quality.
• Execution of materials management system.
• Monitor problems associated with safety.

4. Role Of A Contractor In Legal And Regulatory Issues

The contractor also plays an important role in legal and regulatory issues. Besides, he has to check that the project isn’t breaching any legal terms.

• Ensure that the project is in accordance with all the required legal and regulatory issues.
• Obtaining all the required permits prior to progressing with the project.
• Paying or making sure to disburse all the fees and taxes essential to finish the project.

5. Role Of A Contractor In Health And Safety Issues

The contractor has to undertake the following liabilities for health and safety issues.

• Maintain health and safety in the workplace.
• Execute a safety method and standards for the project.
• Apply the proper safety equipment in the project.
• Execution of well organized risk management and communication strategies.
• Provide safety awareness among workers.

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How to measure concrete mix design

Concrete mix design refers to the method utilized for finding out the exact ratios of cement, sand and aggregates for concrete so that the target strength of concrete can be obtained.

For concrete mix design, different types of laboratory testing and calculations should be accomplished to get exact mix ratios. This method is suitable for Building structures where superior grades of concrete are required like M 25 and over as well as large construction projects where quantity of concrete consumption is extreme.

The main objective of concrete mix design is to arrange the proper ratios of materials so that the application of concrete becomes cost-effective to maintain perfect strength of structural members. In a project, large quantity of concrete & construction work are required and saving in quantity of materials like cement makes the construction project cost-effective.

Concrete Mix design of M – 20, M – 25, M – 30 and superior grade of concrete are measured from following steps:

Concrete Mix Design:

Necessary data for Mix Design of Concrete:

• Concrete Mix Design Date:-

(a) Characteristic compressive strength of concrete necessary at end of 28 days = M 25
(b) Nominal maximum size of aggregate applied = 20 mm
(c) Shape of Coarse Aggregate = Angular
(d) Necessary workability at site = 50-75 mm (slump Value)

(e) Quality control is performed as per IS: 456
(f) Type of exposure condition of concrete (as specified in IS: 456) = Mild
(g) Type of cement applied = PSC as per IS: 456 – 2000
(h) Method of providing Concrete on Site = pumpable concrete

(ii) Material testing data (set in the laboratory):

(a) Specific gravity of cement = 3.15
(b) Specific gravity of FA = 2.64

(c) Specific gravity of CA = 2.84
(d) The surface of aggregates is supposed to be in dry condition.
(e) Fine aggregates are abided by Zone II of IS – 383

To get details on the method of M-25 grade concrete mix design, click on the following link. civiconcepts.com

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Methods of concrete cube test

In concrete compression test, generally the concrete cube samples with dimensions 150mmx150mmx150mm are utilized. But, in place of 150mmx150mmx150mm concrete cube samples, 100mmx100mmx100mm concrete cube samples are applied for the test.

Fundamentally, the force produced through a concrete compression machine is a definite value. For the use of normal concrete strength, suppose under 50MPa, the stress provided by a 150mmx150mmx150mm cube is adequate for the machine to smash the concrete sample.

However, when the intended concrete strength is 100MPa, under the equivalent force (about2,000kN) delivered by the machine, the stress under a 150mmx150mmx150mm cube is inadequate to crush the concrete cube.

So, 100mmx100mmx100mm concrete cubes are used in place of 150mmx150mmx150mm cubes to raise the used stress to crush the concrete cubes. For normal concrete strength, the cube size of 150mmx150mmx150mm is already sufficient for the crushing strength of the machine.

Cube Test:

Instrument And Material.

Concrete cube mould with size 150mm or 100mm is applied for aggregate size of not more than 40mm and 25mm. Cube mould for test should be formed into steel or cast iron containing smooth inner surface. Each mould should contain steel plate to support and avoid leakage.

Compacting steel rod should be used with 16mm diameter and 600mm length.

The test should be conducted by compression test machine.

Method: Mould and base plate should be cleansed and employed with oil so that the concrete can’t fix to the side of the cube. Base plate is affixed to the mould with bolt and nut.

The cube should be filled with concrete in three layers.

Each layer should be consolidated for 25 times. This process should be accomplished systematically and compaction should be finished equally to all the surfaces of the concrete. Compaction is also done with machine.

The surface of concrete should be leveled to retain the equivalent level with the upper side of the mould.

Cubes which are produced at construction site should be wrapped with plastic cover for a period of 24 hours prior to remove the moulds.

After remoulded, the concrete cubes should be drowned in water for curing.

Compression strength test should be conducted for concrete at age 7, 14, and 28 days through compression test machine.

Result: The Strength value of each cube should be noted and compared with the targeted strength value. The reason for conducting the concrete test on 7 th day and the 14 th day is to anticipate whether the concrete could attain the targeted 28 th day strength. Normally, concrete can obtain 70% strength on the 7 th day.

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Definition of building substructure and its constituents

The primary constituents of a building substructure belong to the foundation and plinth beam. These components securely transmits the load from the superstructure to the ground.

Foundation: The foundation means the structure situated under the ground level that gets in touch with the superstructure directly. The foundation transmits the dead loads, live loads and all other loads operating on it to the foundational soil.

The construction process of foundation is done in such a manner that the soil over which it stands is stressed inside its safe bearing strength. Any failure of foundation leads to the failure of the building structure.

Therefore, different building structure requires various types of foundations like shallow or deep foundations.

Preliminary, the soil profile is checked with a geotechnical engineer prior to complete a proper foundation for the building structure. The following types of foundation are normally utilized for building structure:

1. Strip Foundation (Shallow Foundation)
2. Raft Foundation (Shallow Foundation)
3. Pile Foundation (Deep Foundation)

1. Strip Foundation: Strip foundation or strip footing offers support for linear structures like a wall or tightly spanned column, in the shape of strips. It is suitable for the soils having strong bearing strength as well as ability to support light structural loading. The size and location of the strip foundation are based on the width of the wall.

2. Raft Foundation: Raft foundation is also known as a mat foundation. It expands over the total building area and combats severe structural loads.

A raft foundation transmits the total load from the building area to the total floor area. As a result, the stress operating on the soil is significantly decreased that results in lessening the scope for shear failure of soil.

3. Pile Foundation: Pile Foundation stands for a type of deep foundation that transmits heavy loads from the superstructure to hard strata underneath the ground. Pile in a pile foundation refers to a deep reinforced concrete column that meets the hard rock strata far below the ground.

Plinth Beam: Plinth beam belongs to a beam that is developed in the plinth level among the wall and the foundation.

The purpose of this type of reinforced concrete beam is to resist the circulation of cracks from the foundation to the walls.

A plinth beam can allocate the load uniformly from the walls to the foundation. These are essential for construction projects planned in the areas susceptible to earthquake.

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How to create exact building plan for a G+1 storey building

In this exclusive civil engineering video tutorial, you will get some vital information on how to develop perfect building plan for any G+1 story building. Besides, you will also get details about section, elevation and 3D model.

The area of the building = 14.9 x 14.5 square meter. The building contains space for car parking, hall room, one bed room, kitchen & dining, bathroom as well as staircase.

The buildings should have firmly interconnected beams and columns which are known as building frames.

The loads from walls and beams are transmitted to beams and consequently rotation of beams occurs. As beams are firmly attached with column, the rotation of column also occurs. Therefore, any load enforced to anywhere on beam is distributed by entire network of beam and columns.

The building design involves the following steps :-

Step 1: Plan the fairly accurate layout of the building.
Step 2: Workout dead and snow load.
Step 3: Design steel roof decks:
Step 4: Choose open web steel joists
Step 5: Design beam.
Step 6: Design column.
Step 7: Design steel column bore plates.
Step 8: Design footing
Step 9: Create engineering drawing.
Step 10: Final check and submission.

To get more detail, go through the following video tutorial.

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Different types of concrete admixtures

Instantly before or during mixing concrete, the admixture should be added to the batch of concrete to make the quality of concrete manageability, acceleration, or retardation of setting time better. Now-a-days, several concrete mixes comprise of one or more concrete admixtures that will aid in reducing the cost of pouring method as well as growing the productivity, The cost of these admixtures will differ on the basis of the quantity and type of admixture to be applied. All of these will be added to the cubic yard/meter cost of concrete.

Given below, the details about the different types of concrete admixtures :-

Concrete Admixtures: Set-Retarding: The purpose of set retarding concrete admixtures is to defer the chemical reaction that occurs when the setting process is initiated for concrete. These types of concrete admixtures are generally applied to minimize the impact of high temperatures that can expedite the initial setting of concrete.

Set retarding admixtures are mostly found in concrete pavement construction. They provide sufficient time for finishing concrete pavements, lessen extra costs to arrange a new concrete batch plant on the job site and facilitate removing cold joints in concrete. Retarders are also useful for withstanding cracking due to form deflection that can happen when horizontal slabs are arranged in sections. Most retarders also perform as water reducers and may entail some air in concrete.

Concrete Admixtures – Air-Entrainment: With air entrained concrete, the freeze-thaw strength of concrete is raised significantly. This type of admixture develops a more executable concrete as compared to non-entrained concrete and at the same time the bleeding and segregation of fresh concrete is minimized. Besides, resistance strength of concrete against extreme frost action or freeze/thaw cycles is considerably improved. This admixture provides the following advantages:

• Greater resistance against cycles of wetting and drying
• Superior degree of workability
• Superior degree of stability

The entrained air bubbles function as a physical buffer against the cracking resulting from the stresses owing to water volume augmentation in freezing temperatures. Air entrained admixtures are well suited with almost all the concrete admixtures. Normally, for each one percent of entrained air, compressive strength will be decreased by about five percent.

Water-Reducing Concrete Admixtures: Water-reducing admixtures belong to chemical products which can be added to concrete for producing a required slump at a lower water-cement ratio than what it is generally designed. The purpose of water-reducing admixtures is to retain certain concrete strength with lower cement content. Lower cement contents lead to lesser CO2 secretions and energy consumption per volume of concrete created.

This type of admixture facilitates to enhance the properties of concrete as well as set concrete under tough situations. Water reducers are mainly utilized in bridge decks, low-slump concrete overlays, and patching concrete. Now-a-days, mid-range water reducers are gaining popularity because of the improvements in admixture technology.

Concrete Admixtures – Accelerating: Accelerating concrete admixtures are applied to accelerate the rate of concrete strength formation as well as minimize the setting time of concrete. Calcium chloride is the example of common accelerator component though it may develop the scope of erosion in steel reinforcement. Accelerating admixtures are suitable for altering the properties of concrete in cold weather.

To get more details, click on the following link www.thebalancesmb.com

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Causes of honeycombing in concrete and proper solutions

Honeycombing refers to a structural defect related to a RCC Structure. The areas of the concrete surface where the coarse aggregate are clearly shown known as honeycombed surface that provides an appearance of honey bees nest.

If honeycombed surface is ignored, the RCC structure fails to function properly according to the design (structurally fragile). Besides, it enables penetration of damaging agents like impure water and air through the existing voids which impact the stability of the structure considerably.

Honeycombing happens for the following reasons :-

1. Concrete mix does not remain integral.
2. Existence of more percentage of larger size of aggregate in concrete resists concrete to fill narrow spaces among the reinforcement rods.
3. The workability of concrete is inadequate.
4. Inadequate compaction to concrete.
5. Imperfect vibration throughout concreting.
6. Steel congestion does not permit concrete to flow toward all corner.
7. Concrete is already set prior to placing.
8. High free fall of concrete at the time of pouring

9. Form work is not water-resistant or inflexible.
10. Inappropriate detailing and/or fixing of steel
11. Inferior proportion of cement to water that can minimize the workability of concrete.

Guidelines to get rid of Honeycombing in Concrete.

All concrete batches should be integrated; examine the concrete production/cohesiveness frequently. If it is possible to develop “ball” form the fresh concrete, concrete mix is defined as cohesive.

Concrete workability should meet the placement requirement, as for instance, a lightly reinforced column can contain 75mm slump, 150 mm slump is necessary for a highly reinforced column.

Make sure that exact compaction is provided for placed concrete, vibrators should be detached since large air bubbles stop to step out (over vibration will cause bleeding). The sizes of the vibrator needle should remain as 25 mm, 40 mm and 60 mm according to RCC sections.

Concrete should be exhaustively consolidated and fully functional around the reinforcement, around implanted fixtures as well as the corners of the formwork. Precautions should be taken throughout vibration otherwise honey combing may occur.

The strength of concrete is decreased by 30% due to 5% voids in concrete.

Cover to formwork, Pins and spaces bars to layers of reinforcement should be provided to maintain exact compaction.

Concrete should maintain Slump prior to placing. Besides, initial slump, concrete should be designed to detain slump untill the time it is set.

The height from where the concrete is dropped should be minimum, if possible concrete bucket with canvas pipes, concrete hose pipe, should be provided to minimize the concrete free fall height.

Formwork should be water resistant; cement grout should not be wasted at the time of placing concrete.

Steel detailing and fixing should be provided to allow smooth flow of concrete across all corners and depths. To get rid of steel congestion, special concrete formulations like self-compacting concrete, concrete with lower maximum aggregate size (12.5mm) etc should be used.

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ACI 318-14 approved design guidelines of isolated footing

Isolated alias single footing is utilized to provide support to single RCC columns. It is cost-effective and suitable when the columns are placed at comparatively long distances, loads operating on footings are less and the safe bearing strength of the soil usually remains high.

Isolated footing is categorized as pad footing and sloped footing.

The isolated footing is arranged underneath the column to disperse the loads securely to the bed soil.

The design of isolated footing is made for the following purposes :-

Area of footing

Thickness of footing

Reinforcement details of footing with a satisfactory moment and shear force review.

The design of isolated footing is made on the basis of the guidelines set by ACI 318-14.

1. The compressive strength of concrete should satisfy the needs for both strength and stability. As per ACI 318-14, least concrete compressive strength should be 17MPa for normal applications.

2. With adherence to ACI 314-14 section 20.2.1.1, the deformed type steel bars should be used.

3. Factored forces and moments provided at the base of columns are transmitted to the foundation with reinforcement, dowels, anchor bolts, or mechanical connectors.

4. There should be least reinforcement even if the concrete bearing strength is not crossed.

5. Adequate anchorage should be arranged for tension reinforcement if reinforcement stress is not directly relative to the moment like in sloped, stepped or tapered foundation.

6. There should be sufficient anchorage length of both flexural and dowel reinforcement to get rid of bond failure of the dowels in the footing and to resist failure of the lap splices among the dowels and the column bars.

7. As per ACI 318-14 section 13.3, depth of footing over reinforcement should not remain under 150 mm.

8. The depth of the footing should be in such a manner that the shear strength of the concrete remains equivalent or surpasses the critical shear forces (one-way shear and punching shear) developed with factored loads.

9. In sloped, stepped, or tapered foundation, location and depth steps and angle of slope should satisfy design requirements at each section.

10. Concrete cover of 75 mm is necessary when the concrete is cast against soil.

11. With adherence to ACI Code specifications, base area of footing is set from unfactored forces and moments transferred by footing to soil and the permissible soil pressure evaluated through principles of soil mechanics. To get the necessary base area of the footing, the column service loads are divided with permissible net soil pressure of the soil. The net factored soil pressure is equivalent to factored load column loads by the selected footing area.

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