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Monday, June 18, 2018

Definition, causes and remedies of efflorescence in masonry & other building surfaces

Efflorescence stands for a fine, white or greyish, powdery deposit of water-soluble salts that is present on brick, concrete, stone, stucco or other building surfaces when the water vaporizes. Besides, efflorescence also exists on floors and walls and requires special attention. It is often mentioned as "whiskers”.

These efflorescent salt deposits is found at the worst times, normally about a month as soon as the building is developed, and sometimes as long as a year after finishing of structure.

Efflorescence is found in both indoors and exterior, and it can differ in frequency and intensity because of the existence of moisture and temperature.

The efflorescence happens for the following three factors :-

• Existence of water-soluble
• Salts are converted into a soluble solution because of moisture content.
• The transmission of salts through a material to its surface that leads to vaporization of the moisture and cause the salts to crystallize and thus efflorescence is formed.

Moisture is mainly formed due to water, rain and snow and may affect the extent of efflorescence. Condensation, groundwater tapering and interior activities also may influence the extent of moisture formation.

In several cases it is found that efflorescence may happen throughout home construction. If masonry units are left behind all through the night during construction, they can consume moisture from damp soil and rain. It is recommended that masonry units should be wrapped and left in pallets to reduce the risk of efflorescence during a construction project.

The following installation issues associated with building surface result in creating efflorescence

• Improper application of through-wall flashing
• Utilization of masonry devoid of adequate ventilation
• Utilization of masonry in areas where a perfect moisture barrier does not exist
• Joint material failure
• Imperfect ground storage

How to get rid of efflorescence - The following measures should be taken to avoid efflorescence:

1) Hydrophobic Sealant: Use a saturating hydrophobic sealant to a building material surface to resist the immersion of water. The sealant also will resist water from passing through a building material.

2) Capillary Breaks: Set up capillary breaks like polyethylene sheeting among a building material and soil to reduce the risk of salt penetrating the material.

3) Standard Masonry Construction: Apply overhanging copings, eaves and flashings will help in reducing the risk of entering water into a wall.

4) Better Emphasis on Landscaping and Sprinklers: Give concentration to landscaping and sprinklers will guarantee to avoid water from reaching permeable building materials.

5) Set up Grout with Mechanical Vibration: Compile grout with mechanical vibration will control the occurring of voids in the grout.

6) Apply Dense Tooled Mortar Joints: Provide dense tooled mortar joints to minimize the permeable nature of a wall, making it strong for salts to pass through it.

7) Utilizing Grout Admixtures: Various grout admixtures like chemical additives should be used since they can make flow of a grout mix better and minimize its water content all together to lessen voids in grout.

8) Preserve Masonry Materials Properly: Retain masonry materials off the ground and wrap them with water-resistance materials to safeguard these materials from groundwater and precipitation.

Article Source:

Definition, causes and remedies of efflorescence in masonry & other building surfaces

Published By
Rajib Dey

Saturday, June 16, 2018

Some vital methods for concrete curing

METHODS OF CURING :- Based on the type of construction work, the curing of concrete is done with the use of the following processes :-
1) COVERING: Under this method, wet gunny bags or hessian are utilized to wrap the newly developed concrete surface. This process is very effective for horizontal and vertical surface.
2) PONDING: Under this process, the entire surface is segregated into rectangular or square cages with the development of tiny clay bunds and these cages are filled with water occasionally building small ponds. This process is ideal for curing horizontal surfaces like floor, pavements etc.
3) SUBMERGING IN WATER: Pre-cast concrete members are over and over again cured by submerging them under water.
4) STEAM CURING: With this process, steam under pressure is sprinkled over the concrete surface. This process is very useful for pre-cast members.
5) SPRINKLING: Under this process, the water is sprinkled repeatedly over the concrete surface to keep the surface wet.
6) CURING WITH CHEMICAL: Under this process, water is sprayed over the surface as soon as specific amount of hygroscopic salt like NaCI, CaCletc are added. It helps to engross moisture from the atmosphere.
(7) MEMBRANE CURING: Under this process, concrete surface is wrapped with water proof membrane like wax emulsion, bitumen emulsion etc. The membrane stops the vaporization of water from concrete surface.
Some vital methods for concrete curing

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Rajib Dey

Friday, June 15, 2018

RCC Column Design – An exclusive mobile based app for civil and structural engineers

RCC Column Design is an exclusive app for civil and structural engineers. This app is available in google play store. It can only work in windows platform.

The app is very user-friendly. There are several fields in the app which range from Factored Axial Load (kN), Length (mm), Width (mm), Concrete Strength (M15, M20 and M25), Steel Strength (HYSD 415, HYSD 500).
Just enter the values in these fields and click on calculate button to get the desired values.
This app is designed on the basis of the Limit State Method with adherence to Indian standard code IS 456:2000. This app takes into account the axial load on a column to recommend a secure design depending on input of column size, concrete strength and steel strength. The app is also very useful for Uniaxial and biaxial bendings.
This app can design a rectangular slender RCC column that contains standard height. It works out necessary reinforcement for a specified axial load for the assumed inputs.
This app is developed for educational purposes only. The answers should be double checked manually.
To download the app, click on the following link
RCC Column Design – An exclusive mobile based app for civil and structural engineers

Published By
Rajib Dey

Thursday, June 14, 2018

How to select perfect scaffolding material towers in construction project

Prior to start any construction project, the most important task is to obtain clear ideas on various types of scaffolding material towers. Improper selection of scaffolding material towers may lead to severe injury to the workers as well as loss of life.

Given below, the detailed lists of commonly used towers in construction site :-

MS Scaffolding Tower

This tower is mostly recognized in the industry due to its well-built design, stability, flexibility & rust resistance. It is built up with the superior quality raw material & cutting technology with regard to established industry standards. The size of the tower can also be customized according to the requirements of the clients. It is normally utilized throughout the formation of the building.

Some useful features of the tower

Perfectly designed, Rugged, Strong resistance capacity against decay

MS Scaffolding Movable Tower: MS Scaffolding Movable Tower is just an extension to MS Scaffolding tower that contains wheels. It is very flexible and can be easily shifted from one place to another without difficulty and huge man power. It also has good longevity & lock system. It is built up with approved hinges and castor wheels with adherence to industry standards.

Features: Strong load bearing capacity, Hassle free movement, Rust proof finish

H Frame Scaffolding Tower: H Frame scaffolding manufactured with superior quality steel having sound tensile strength. Its height is modifiable. There are scissor braces in the tower which are attached through gravity locks to avoid any breakage or mishap. By applying the combination of changing sizes of H Frame, towers can be structured to proper heights.

H Frame Structure: H Frame structure is a part and parcel of H Frame scaffolding. Different types of H Frame structures are combined to form a scaffolding tower. Due to its powerful locking skill, the tower can stand as tall as necessary.

Scaffolding Staircase: There are different types of scaffolding staircases. The size of the staircase can be easily customized as per requirement. Usually, the engineers visit the location of the construction site and offer solutions and build up custom structure as per requirement.

How to select perfect scaffolding material towers in construction project

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Rajib Dey

Wednesday, June 13, 2018

Types and properties of bricks

Bricks is produced from well clay molding, that is dried and then burnt. The size of the brick varies from 90 mm × 90 mm × 90 mm and 190 mm × 90 mm × 40 mm. With mortar joints, the size of brick varies from 200 mm × 100 mm × 100 mm and 200 mm × 100 mm × 50 mm.

Types of Bricks: Bricks are categorized as -
(i) Building bricks, (ii) Paving bricks, (iii) Fire bricks, (iv) Special bricks.
Properties of Bricks: The standard quality bricks should contain the following properties -
(i) Colour: The color should have been identical and clear.
(ii) Shape: Shape of the bricks should have been sharp and genuine rectangular angles.
(iii) Size: There should be standard dimensions for bricks with adherence to codes.
(iv) Texture: A standard brick should contain a fine, solid and consistent texture. They should be free from fissures, cavities, loose grit and unburned lime.
(v) Virtue: If the brick is hit with another brick, there should be a metal sound.
(vi) Hardness: If scratches are made with finger on a brick, there should not be any mark on the brick.
(vii) Strength: The breaking strength of brick should not be under 3.5 N / mm2. A field test is conducted to check the strength by dropping the brick from a height of 0.9 m to 1.0 mm on a hard surface. If the brick has good strength, the stone should not be broken into pieces.
(viii) Water absorption: Once the brick is drowned in water for 24 hours, the water absorption rate should not exceed 20 percent by weight. For class I bricks, this limit remains 15 percent.
(ix) Efficiency: There should not be any white patches in bricks when they are drenched in water for 24 hours and then allowed to dry in the shade. White stains may appear because of the existence of sulfate of calcium, magnesium and potassium. They retain masonry in wet and humid conditions.
(x) Thermal conductivity: Bricks should contain low thermal conductivity, so the buildings developed with bricks should have cold temperature in summer and warm temperature in winter.
(xi) Sound insulation: Bigger bricks have poor sound insulators whereas light and hollow bricks have superior sound insulation.
(xii) (xii) Fire resistance: Normally, the fire resistance capacity of brick is good. Actually, bricks are utilized to trap steel columns to safeguard them from fire.
Types and properties of bricks

Published By
Rajib Dey

Tuesday, June 12, 2018

How to start marking for foundation

This construction video provides detailed guidelines on foundation marking. In the video, the plan of building is given for living room and kitchen room. The center line marking is also provided with 6 numbers of columns. Initially, you have to set the base point as it is very crucial for marking. After that, a base line is arranged from that base point with a thread for fixing the second point.

The centre line of the wall perpendicular to the long wall, is marked by making a proper angle. Right angle is arranged by creating triangles with sides 3,4 and 5units long. If we set the two sides of the right angles triangle to be 3 m, and 4 m, then the third side i.e. the hypotenuse is assumed at 5 m. A steel tape should be used to fix all the dimensions.
The formula is used here as √(L2+B2).

The right angle can be fixed by applying a theodolite. This instrument is very useful in fixing acute or obtuse angles. Small right-angled Projections are generally laid out with mason’s square.

Proper marking of the foundations is specifically important for new walls to make sure that the foundations contain the exact size and are in the perfect position to bear the load of the wall. Good foundations are essential to make sure that no movement can occur because any movement can lead to cracks and problems in the building that is supported with the foundation.

To get the complete instructions, watch the following video.

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Published By
Rajib Dey

Monday, June 11, 2018

Some crucial factors a civil engineer should follow

This construction video tutorial sifts through some vital factors which should be abided by a civil engineer to apply them in the jobsite.
The factors are discussed in below :-
Compressive strength of bricks should be 3.5 N/mm2
Water immersion of bricks should not surpass 15%
Free fall of concrete is permissible up to 1.50 m
Lowest thickness of slab is 125 mm
Longitudinal reinforcement should not be under 0.8% and over 6% of gross C/S
Lowest bars required for square column is 4 Nos and for circular column is 6 Nos
If the bars contain diameter over 36 mm., lapping is not permissible
Compressive strength of bricks is 3.5 N/mm2
Earthwork excavation toward basement over 3 m should remain in stepped form
Cement should be preserved in dry places on a raised platform roughly 200 mm
Electrical conduits should not be set in column
For more information, watch the following construction video.

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Rajib Dey

Friday, June 8, 2018

New technology in earthquake engineering to resist collapsing of the structures

It is the big challenge for the structural engineers to develop earthquake resistance structures.
An Earthquake resistant structure should have the capacity to resist abrupt ground shaking to reduce the damages to the structure.
Though the reinforced Concrete contains sound earthquake resistance capacity of buildings but owing to the substandard mix design of concrete and improper curing the reinforced concrete lost it’s desired compressive strength and it leads to collapsing of structure during an earthquakes.
Recently, a new innovation is launched in earthquake engineering where the curtain of cables is affixed to ground to significantly enhance the earthquake resistance strength of the building.
In these technology threads are used which are created with thermoplastic carbon fibre composite. These threads are fastened and knotted to produce a strong flexible rod which is 90% lighter as compared to reinforcement bars and contain the equivalent strength.
To resist earthquake successfully, these composite rods are fastened & secured from the roof to the ground and set up around the building. Rods are also set up inside the building to make the interior walls stronger.
These Composite threads are formed with textiles so that the rods can expand and pull the structure back in opposite direction to withstand shaking of the structure.
When an earthquake occurs, in case the building is pushed towards left side, the threads or rods located on right side pulls it back to retain the building in exact position and significantly reduces the structural damage and human death.
For online demonstration of this new technology, go through the following video tutorial.
Video Source: TomoNews US

Published By
Rajib Dey

Thursday, June 7, 2018

Various types of notations used in the construction of concrete culvert design

The following notations are used in the drawing of concrete culvert design.

With notation, it is possible to make clear communication among various project stakeholders. Notation helps in avoiding mistakes in any construction project.

A’ = The valid contact area of a footing, measuring unit is in square metres
A = A detailing dimension for culverts that contains skewed ends, measuring unit is in mm
B = Depth of the bottom slab of a box culvert, measuring unit is in mm
B = Gapping among adjoining bars with reference to detailing tables, measuring unit is in mm
C = A coefficient that is applied in finding out the quantities of reinforcing bar.
CANBAS = Canadian Bridge Analysis System
c’ = the valid cohesion among the base of the footing and the soil at the ULS, with reference to CHBDC. kPa
CHBDC = Canadian Highway Bridge Design Code, 2000 Edition
CGSB = Canadian General Standards Board
F = Width of footing for open footing culverts, measuring unit is in mm
F1 = A reinforcing bar spacing factor, measuring unit is in mm-1
HULS = maximum factored horizontal reaction at the level of the base of the footing at the ULS, kN
Lc = Culvert length that is calculated the longitudinal axis, measuring unit is in m
OCPA = Ontario Concrete Pipe Association

OMBAS = Ontario Modular Bridge Analysis System
OPSS = Ontario Provincial Standard Specifications
S = Culvert distance that is calculated perpendicular to the longitudinal axis of the culvert, measuring unit is in mm
SLS = Serviceability limit states, in accordance with CHBDC

T = Depth of top slab of culvert, mm tan φ’ effective friction coefficient for concrete cast against soil.
ULS = Ultimate limit states, with reference to CHBDC
V = Unfactored vertical reaction because of the dead load of cast-in-place concrete and soil fill, at the level of the base of the footing, kN
VSLS = Maximum vertical reaction at the level of the base of the footing at SLS, kN

VULS = Maximum factored vertical reaction at the level of the base of the footing at ULS, kN
W = Depth of wall of culvert, measuring unit is in mm
Γ = The extreme angle among the normal to the longitudinal axis and the end of the same culvert, degrees
φ’ = The valid angle of internal friction, with reference to CHBDC, measuring unit is in degrees
θ = Skew angle of culvert, degrees

Various types of notations used in the construction of concrete culvert design

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Rajib Dey

Wednesday, June 6, 2018

Get some useful tips to conduct your leveling survey at home

While going to layout something for road, bridge, dam or pipe line, land surveying plays an important role. Surveying is done to find out the legal boundaries among the parcels of property, the position of current infrastructure, the topography as well as slopes of the land.

Traditional measurement tools like a tape measure and protractor are not suitable for accomplishing large civil structures and public works projects.

In this construction video tutorial, Mr. Grady shows some useful tips which will help you to conduct your own topographic or leveling survey at home with fairly elementary and cost-effective tools. You don’t require any knowledge with sines, cosines, or tangents.

To learn the complete process, go through the following video tutorial.

Video Source: Practical Engineering

Published By
Rajib Dey

Tuesday, June 5, 2018

Basic differences between Development length and Lap Length

Development length is treated as specific minimum length of the bar that is needed on either side of a point of maximum steel stress, so as to transmit the bar force to encompassing concrete through bond devoid of slip, so that the bar is not pulled out under tension. Hooks, bends, mechanical anchorages are applied to supplement.

Lap length: When the steel is arranged in RC structure, if the necessary length of a bar is not suitably obtainable to produce a design length, then lapping is highly recommended.

Lap length stands for the least length that should have been arranged if two bars are attached together in order that forces are transmitted securely.
As for instance, while going to construct a tall column with height 100 feet. But, it is not possible to find a 100 ft long bar practically for caging. So, it is useful to slice the bars in each second story. Now, the tension forces are transmitted from one bar to the other at the location of discontinuity of bar.
Therefore, it is required to arrange the second bar nearer to the first bar that is suspended and overlapping should be provided. The amount of overlapping among two bars is defined as lap length.
1. For flexural tension – Ld or 30d either is larger.
2. For direct tension – 2Ld or 30d either is larger.
The straight length of lapping should not remain under 15d or 20 cm.
LAP LENGTH IN COMPRESSION: The lap length in compression should be similar to the development length in compression already worked out but not under 24d.
FOR DIFFERENT DIAMETER BARS: In case of bars with various diameter should have been cut off, the lap length is computed based on shorter diameter bar.
Article Source:
Basic differences between Development length and Lap Length

Published By
Rajib Dey

Monday, June 4, 2018

Different types of grades of concrete as per 456 : 2000 standard

This construction video tutorial from learning technology demonstrates the grades of concrete on the basis of IS 456 : 2000 standard. As per this standard the grades are categorized in three groups like ordinary concrete, standard concrete and high strength concrete. Here grades range from M10 to M80.

M10, M15 and M20 belong to Ordinary Concrete. M25, M30, M35, M40, M45, M50, M55 belong to Standard Concrete. M60, M65, M70, M75 and M80 belong to High Strength Concrete (HSC).

Here m denotes mix and number denotes characteristic compressive strength of 150 mm cube at 28 days in N/mm2 (Newton per millimeter square). It means if you take compressive test of a cube having dimensions 150 x 150 x 150 mm for 28 days, the value obtained is 10 N/mm2.

All these concrete grades are suitably for PCC work i.e. plain cement concrete work where rebar is not used.

Standard Concrete is generally used in 10 storied and higher buildings and super structures.

High strength concrete is mostly used for designing heavy structures.

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Published By
Rajib Dey

Saturday, June 2, 2018

Definitions of trade and non-trade cement

This construction video tutorial sheds light on the following topics :-

a. Definitions of trade and non-trade cement
b. Variations among trade and non-trade cement
c. The benefits of non-trade cement over trade cement in big projects as well as governments bodies.

Cement is marketed with two mechanism i.e. trade and non-trade.

The manufacturer directly sells trade cement to the dealers and retailers, who alternately sell to the end consumers. It is a more stable method of vending cement since the manufacturer does not have to take the liability for making sales pitches to the consumer directly. The dealer get incentives to sell the product.

Under this mechanism, all taxes like vat octroi etc are levied when the consumer buys cement with the intension of developing a home and seizing it as his property. Here, the purchaser belongs to a house owner or a petty contractor, whose consumption is insufficient Ex. (200+40vat+30octroi+30profit) = 300/- per Bag in which company earns profit as 30/- and the government earns rest 70/- per bag.

Under non-trade cement mechanism, the manufacturer directly sells to the consumer like a construction company for self usages in project. Here, the cement is not sold to any third party. Here, the dealer is not involved.

It is mostly effective for small scale manufacturers of cement. In non-trade cements, there are not huge overhead costs and for this reason it is economical with regards to trade cements. This type of cement is brought in mass volume from the manufacturer by the consumers like realtors, contractors, etc.

Under this mode, the company only levies the central sales tax on the commodity, borne by the buyer, and provides a form C, that is generally offered to a builder or contractor since he only constructs the projects and delivers to the owner and don’t have to care for its possession after finishing of construction. Generally, in this case the purchaser is a contractor or a builder or developer, whose intake is considerably high as in construction projects.

As for instance if the cost to company for cement is 200/- with zero profit, the non trade price may be (200+20 tax + 15 profit) = 235/- per bag with company making 15/- profit per bag and the government is obtaining 20/- per bag as tax.

To learn more, go through the following exclusive construction video tutorial.

Video Source: Tutorials Tips

Published By
Rajib Dey

Friday, June 1, 2018

Benefits and uses of Light Weight Concrete

Usually, the traditional concrete is made of a heavy material containing density about 2400kg/m3 and strong thermal conductivity. If, the ordinary concrete is used for building up the structure, it can increate the dead weight of the structure and as a result the structure turns out to be heavy. The cost of the structure is also increased significantly.

The light weight concrete is defined as the concrete whose density differs from 300 to 1800 kg/m3.The following methods are applied to build up light weight concrete:

1) By cellular construction.
2) By generating huge quantities of air
3) With the use of no fines concrete
4) With the use of light weight aggregates like expanded clay, shale and slate , fly ash, blast furnace slag etc.

Advantage: The light weight concrete is beneficial for the following reasons :-

a) Because of its low density , it can minimize dead load, enhances the advancement of building and reduces the handling cost.
b) The light weight concrete contains low thermal conductivity. Therefore, in severe atmospheric condition, the type of concrete is mostly recommended.
c) When light weight concrete is used, it provides an opening for industrial wastes like fly ash , slag etc, to get rid of the issue for disposal.

d) It has good resistance capacity against fire.
e) The process for slicing , cutting, drilling or nailing becomes easier for light weight product. It can simplify the construction and repair work.

Uses: Given below, various applications of light weight concrete :-

a) It is extensively utilized as insulator to exterior walls of different types of buildings.
b) It is suitable for erecting load bearing walls, filler wall and partition wall.
c) It is effective for producing pre-cast floor and roof panels and composite walls.

d)It can also be applied for building up in situ composite roof and floor slabs.

Benefits and uses of Light Weight Concrete

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Published By
Rajib Dey