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Tuesday, October 17, 2017

How to settle density of various masonry walls in buildings

On the basis of loads and other factors, the density of masonry walls in a building is designed. Given below the details of perfect thickness of masonry walls necessary at the design phase :-

As for instance, it is suggested to utilize invariable masonry wall thickness among lateral supports. The lateral support for masonry is arranged with cross walls, pilasters, and structural frame members.

Concerning deviation of masonry in vertical direction, the distance among floors, structural frames and roofs should be taken into consideration if the density of masonry wall is different.
Masonry wall thickness modifies among floor and roof as well as various floors that is generally imposed to attain thermal, sound and fire requirements.
If the density of masonry wall is modified, it is suggested to expand the thicker wall to the lower support level.
Building code requirements and specifications for masonry structure (ACI 530-11) affirms that, when the density of masonry wall is developed hollow masonry units is modified, then it is necessary to arrange a layer or various layers of solid masonry units or entirely grouted hollow masonry units among the thicker masonry wall and the thinner masonry wall.
The objective of arranging solid masonry course among thicker and thinner masonry wall should be transmitting loads perfectly from the above wall (thin wall) to the wall underneath (thick wall).
There are various constraints and limitations which should be taken into consideration for masonry walls apart from the case where the walls are designed for reinforcements on the basis of the engineering principles.
The constraint related to masonry thickness for various masonry walls types are explained in detail.
Thickness Requirements for Load Bearing Masonry Wall: The density of load bearing masonry wall should have been minimum 304.8 mm (1 ft.) dense for maximum wall height of 10.668m (35 ft.).
Besides, the density of masonry wall should be raised by 101.6 mm (4in.) for each consecutive 10.668m (35 ft.) height or fractions of this height calculated from the top of the masonry wall.
There are different cases in which the above conditions are not applicable for load bearing masonry walls which range from stiffened masonry wall, top storey masonry wall, residential masonry wall, masonry wall of penthouses and roof structures, plain concrete and grouted brick masonry wall, hollow masonry wall, faced masonry wall, nonbearing masonry wall.
How to settle density of various masonry walls in buildings

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Published By
Rajib Dey

Friday, October 13, 2017

Different types of concrete mixes

Nominal Mixes: Earlier, specifications for concrete are set the ratios of cement and fine course aggregates. This mixes of fixed cement & aggregate ratio makes sure sufficient strength in concrete and it is termed as nominal mixes.

The strength of the nominal concrete for a specified workability fluctuates significantly because of the difference of mix components. In this type of mix, all the ingredients are prearranged and their proportions are given.

Nominal mix contains volumetric batching. It is mainly utilized for comparatively insignificant and simpler concrete works. Nominal mix concrete generally utilized for concrete of M-20 or lower.

Standard Mixes: The nominal mixes of fixed cement-aggregate ratio (by volume) differentiate greatly in strength and may leads to under or over-rich mixes. Due to this the least compressive strength is contained in various specifications. These mixes are described as standard mixes.

As per IS 456-2000 standard, the concrete mixes are divided into several grades like M10, M15, M20, M25, M30, M35 and M40. Here M denotes the mix and number to the number to the stipulated 28 day cube strength of mix in N/mm2.

The mixes of grades M10, M15, M20 and M25 conform roughly to the mix proportions (1:3:6), (1:2:4), (1:1:5:3) and (1:1:2) correspondingly.

Design Mixes: In these types of mixes, a designer indicates the performance of the concrete but the ratios of mixes are defined by the producer of concrete irrespective of the minimum cement content is set.

It is the most appropriate method for choosing the mix ratios with certain materials which contain comparatively distinct characteristics.

This method facilitates the formation of concrete keeping the proper properties most inexpensively. But this type of mix does not ensure the exact mix ratios for the standard performance.

Different types of concrete mixes

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Published By
Rajib Dey

Thursday, October 12, 2017

About the Efflorescence on Brick masonry, its causes and treatment techniques

About Efflorescence on Brisk Masonry: It is often a white or a brown green or yellow powdery material which can be observed mainly in the winter season and it is produced from the mix of soluble salts and water.

The salt would drop on brick masonry and palpable itself as efflorescence when the water disappears and the color of the efflorescence is based on type of created salt. This efflorescence might vanish in summer but remains for the whole year.

Cause of Efflorescence on Brisk Masonry: There is a unique condition of occurring efflorescence and all the conditions should be met otherwise the brick masonry would suffer. There are three main three conditions offering the best conditions for efflorescence formation on brick masonry wall which are discussed here:
• The wall should be contained with soluble salts and that could be presented in masonry brick, mortar, adjacent soil and backing material.
• Water has to present in the brick masonry wall with the contact with soluble salt for the surface where water can be evaporated and left the salt.
• This wall will acquires pore structure for permitting the migration of soluble salt for dissolving it.
• And last of all, all the above conditions should be present for creation of efflorescence.

Factors affect the Efflorescence on Brisk Masonry:
• Temperature: An effect of high temperature falls on the efflorescence as it disappears water prior to reach the brick masonry surface.
• Water: Efflorescence is also frequent in water as water takes some time to reach the surface of the brick masonry.
• Wind
• Humidity

Sources of materials cause Efflorescence on Brisk Masonry:
• Soluble salt: There are a few sources for instance brick masonry, block masonry, mortar constituents like cement, sand, lime and admixture, grout components including cement, sand, aggregates and admixtures, contacting soil and ground water. The salts may be produced as the reactions between various constituents of brisk masonry walls and all soluble salts has the capability of producing efflorescence, like carbonates silicate, sulfate and chloride.
​• Moisture: The main source of it is the rain water especially which are wind driven and penetrate considerable water quality into the well.

Detrimental effects of Efflorescence on Brisk Masonry building: It generally damages the artistic value and the maintenance of the building. But it does not affect too much in the inner side of the building.

Control over Efflorescence on Brisk Masonry: The three conditions that are responsible for this should be controlled and proper action should be taken and as they are removal so can be washed to keep the bricks safe. But the thing is only removal and cleaning is not enough so it is required to seal the wall to avoid the problem permanently.

For more information follow

About the Efflorescence on Brick masonry, its causes and treatment techniques

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Published By
Rajib Dey

Wednesday, October 11, 2017

Illustration of stress-strain curve for concrete and steel

This construction video tutorial will teach you the detailed process for creating the design of stress-strain curve of concrete and steel by adhering to the IS 456:2000. Limit State Method is used here for these curves.

As the tensile strength of concrete as compared to compressive strength is very week, it can only withstand compressive stress. Alternatively, the tensile strength of steel is very strong and it can withstand both tensile and compressive strength.

While going to design a structure located in costal area and as per IS code the minimum grade of concrete for this structure should be M30 and concrete can’t be used below this grade. It is known that 30th characteristic strength of concrete cube of size 150 mm at 28 days. The characteristic strength is represented with the symbol as fck.
The stress-strain curve for hardened cement paste is nearly linear. The aggregate is more stiff as compared to the cement paste and will consequently deform less (i.e. contain a lower strain) under the similar applied stress.
The stress strain curve of concrete remains among those of the aggregate and the cement paste. But this alliance is non-linear over the most of the range. This non-linear behavior occurs because of formation of micro-cracks for the following reasons :-
(i) At the interface among aggregate particles and cement paste due to the differential movement among the two phases, and
(ii) Inside the cement paste itself.

These cracks are developed owing to variations in temperature and moisture and the application of load.
To learn the detailed process, watch the following video tutorial.

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Published By
Rajib Dey


Tuesday, October 10, 2017

Download spreadsheet to assess wind load on solar panels

With wind load on solar Panels Analysis Spreadsheet, it becomes easier for installing Solar Panels on any roof. By applying this spreadsheet, one can verify whether it is reasonable to compute necessary ballast weight / fixings forces / roof loads from wind operating on Solar Panels (also known as solar modules, photovoltaic modules, photovoltaic panels or PV modules). The design adheres to BRE Digest 489.

This spreadsheet is user-friendly. The spreadsheet allows several automatic calculations and with the pop-up UK & Ireland map, it is possible to define the wind pressures on projected solar panels with a single click of the mouse. So, a normal house owner gets the ability to utilize this spreadsheet for making calculation of required ballast weight.

The spreadsheets can deal with the following types of Solar Panels:
Photovoltaic modules with ballast: This type of modules is free from any fixings into prevailing roof structure and therefore, it is not to get through current roof membrane. It makes the process simple for post-installing Photovoltaic arrays. The spreadsheet computes ballast weight necessary to resist uplift, sliding and overturning.
Photovoltaic modules fixed to flat or pitched roof: Pitched roofs are mostly found in UK and Ireland. For utilizing them to support PV modules it is required to settle load bearing components directly inside the roof structure. In this situation, it is necessary to workout fixing forces retaining a PV module and thus loads on a supporting roof. These calculations can be made with this spreadsheet.
The spreadsheet contains the following exclusive features :-
- Completely user-friendly;
- A normal house owner can use this excel sheet without any engineering knowledge;
- A comprehensible and easy to read output (all on a single page);
- Includes three PV classes:
1) PV modules mounted on or above pitched roofs;
2) PV stands mounted on flat roofs - free standing (with ballast);
3) PV stands mounted on flat roofs - mechanically fixed;
- Pop-up window for easy selection of wind loads inside UK and Ireland;
- Automatically works out dynamic wind pressure on the basis of site location, building size etc;
- User may overwrite dynamic wind pressure 'qs' and modify size effect factor 'Ca' if it was computed in another software;
- Automatically measures pressure coefficients for different situations;
- Covers open and enclosed support structures;
- For ballasted PV modules, spreadsheet evaluates sliding, overturning and uplift;
- For fixed PV modules, spreadsheet provides forces for which fixings should be designed;
- Live diagrams;
- Instant summary of results;
- Design is made by adhering to BRE Digest 489: 2004
Click on the following link to download the spreadsheet
Download spreadsheet to assess wind load on solar panels

Published By
Rajib Dey

Monday, October 9, 2017

Specification of M50 concrete mix design

Concrete mix design belongs to the method of determining the ratios of concrete mix in terms of proportions of cement, sand and coarse aggregates.

As for instance a concrete mix of proportions 1:2:4 signifies that cement, fine and coarse aggregate are in the ratio 1:2:4 or the mix comprises of one part of cement, two parts of fine aggregate and four parts of coarse aggregate.

The concrete mix design proportions are both by volume or by mass. The water-cement ratio is normally stated in mass.
The mix design M-50 grade (with Admixture –Sikament) presented here is for reference purpose only. Actual site conditions may fluctuate and consequently, this should be modified as per the location and other factors.
M50 Grade concrete is mostly suitably in heavily reinforced structures to withstand dynamic loading.
Given below the specifications of M50 Concrete Mix Design
Grade Designation = M-50
Type of cement = O.P.C-43 grade
Brand of cement = Vikram ( Grasim )
Admixture = Sika [Sikament 170 ( H ) ]
Fine Aggregate = Zone-II
Sp. Gravity
Cement = 3.15
Fine Aggregate = 2.61
Coarse Aggregate (20mm) = 2.65
Coarse Aggregate (10mm) = 2.66
Minimum Cement (As per contract) =400 kg / m3
Maximum water cement ratio (As per contract) = 0.45
Mix Calculation: –
1. Target Mean Strength = 50 + ( 5 X 1.65 ) = 58.25 Mpa
2. Selection of water cement ratio:-
Suppose water cement ratio = 0.35
3. Calculation of water: Estimated water content for 20mm max. Size of aggregate = 180 kg /m3 (As per Table No. 5 , IS : 10262 ). As plasticizer is projected, water content is decreased by 20%.
Water content is taken as 180 X 0.8 = 144 kg /m3
For more details, click on the following link
Specification of M50 concrete mix design

Published By
Rajib Dey

Saturday, October 7, 2017

IRCON INTERNATIONAL LIMITED is hiring Civil Engineer, Site Supervisor(Civil)

IRCON INTERNATIONAL LIMITED that falls under a premier Schedule “A” infrastructure government company under the Ministry of Railways. The company is involved in developing the turnkey infrastructure projects in Railways, Highways, Buildings, Power sector, etc.
The Company has a turnover of over 3200 crores in the year 2016-17. The Company has accomplished differ types of railway and highway project with high value over the years in India as well as outside of India like Malaysia, Bangladesh,Algeria, Iraq, Jordan, Saudi Arabia, Indonesia, Turkey, Nepal, Sri Lanka etc.
The Company is seeking candidates for different positions in various disciplines (Civil, Mechanical etc.) on contract basis. Given below, the details of eligibility criterion :
Age relaxations as per Govt. of India guidelines can be obtained upon fulfillment of the necessary qualification, pay & experience criteria etc.
Medical Standards: The health condition of the candidates should be good and there is no color blindness. No relaxation is permissible in health standards.
Selection Process: The Work Engineers have to appear for written exam and/or interview.
The Site Supervisors have to appear for written test.
The above posts are intended for Specific Ircon’s Projects and not for the regular establishment of Ircon. The tenure of position will be initially for one year and it is further extended as per necessity of the Company if the services of the candidates remain satisfactory.
However, the appointment is co-terminus with the project and will not be granted any right to claim absorption in regular establishment of the company or for appointment in other projects of the company.
B-1 compensation for indoor treatment for self at the place of posting only would be allowable.
B-2 Minimum PF as approved under the EPF & MP Act 1952 will be subtracted from the salary and equivalent contribution will be done by Ircon. The perks will be disbursed at the time of termination of contract.
B-3 One leave for each calendar month of service is allowed throughout the contract period. Leave can be carried forward and accrued but no leave payment for un-availed leave is permissible throughout the contract or on resignation or termination of contract. No other type of leave would be allowable.
B-4 One weekly leave and other public holiday are granted if the project office remains closed.
B-5 TA/DA are allowed if assigned on outstation duty.
B-6 Working hours will be identical as for the project.
B-7 No other perks or benefits are provided except the above.
B-8 The ex-employees of Ircon, whose services were terminated because of shutdown of projects, are eligible to apply for these posts upon fulfillment of necessary qualifications and experience. A copy of the termination letter will be delivered along with the application. This appointment will be based on their satisfactory performance and shall be co-terminus with the project. The persons so appointed for this project can’t claim for their absorption in regular establishment of the Company or for appointment in other projects of the company.
To apply online, click on the following link
Civil Engineer, Site Supervisor - Civil

Published By
Rajib Dey