How to estimate cement bags in 1 cubic meter

Suppose the proportion of nominal mix is 1:2:4 (one part cement, 2 part sand and 4 part aggregate)

Wastage of cement is taken as 2%
Output of mix is provided as 67%.

For 1 cum output, the requirement of dry mix is 1/0.67 = 1.49 say 1.50 cum.
After including the wastage (2%), the output will be (1.50 + 0.02) = 1.52 cum.
Volume of cement = (cement/cement+sand+aggregate) × Total material

= (1/1+2+4) × 1.52
=0.2171 cum
The density of cement is 1440 kg/cum and
Weight of 1 bag cement = 50 kg.

So, volume of 1 bag cement = 50/1440
=0.0347 cum.
No. of cement bags essential in 1 cubic meter = 0.2171/0.0347
= 6.25 bags.
The above formula can be utilized for measuring cement for other nominal mixes.

To get more details, watch the following video tutorial.

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A wide array of reinforced concrete design examples

This construction article is based on various reinforced concrete design examples. You will be familiar with flexural analysis of beam.

Given below, various examples and their solutions :-
Make proper calculation for the following reinforced concrete sections :-

Example 1 : The balanced steel reinforcement: The maximum steel reinforcement area for a tension-controlled and transition section per ACI code 318-11.

The location of the neutral axis and the depth of the equivalent compressive Whitney stress block for the tension-controlled section in B.

Here, the compressive strength is given as f’c = 4 ksi and yield strength is given as Fy = 60 ksi

ACI code 318-11 is followed

Example 2 : Examine the adequacy of a rectangular tension controlled section on the basis of dead and live loads.

A 10 ft long cantilever beam contains a rectangular section and reinforcement. The beam bears a dead load of 2 k/ft (along with self weight) and a live load of 1 k/ft.

The compressive strength is provided as f’c = 4 ksi and yield strength is fy = 60 ksi, verify if the beam has sufficient strength to bear the provided loads with ACI Code 318-11.

Example 3 : Work out the design moment strength and the location of the neutral axis of a rectangular section containing two rows of tension reinforcement.

b (width) is given as 13 inches
d is given as 23.5
h (through depth of the section) is given as 27 inches
dt (distance from the extreme compression fibre to the location of the extreme tension reinforcement) is given as 24.5

f’c (the compressive strength) is given as 4 ksi
fy (the yield strength) is given as 60 ksi

Example 4 : Work out the design moment strength and the position of the neutral axis of a rectangular section with compression reinforcement that yields.

The following properties are included in the rectangular section :-
Width = b = 12″
Effective depth = d = 22.5″
Tension reinforcement = (6) no. 9 bars
Compression reinforcement = (2) no. 6 bars

Compute the design strength of the beam if f’c = 4 ksi and fy = 50 ksi with ACI Code 318-11.

To get the solutions of the above-mentioned problems, go through the following link. www.engineeringexamples.net

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Cause of errors in flat concrete surface

While concreting is going on the job site, construction errors may happen because of failure to certain methods, improper practice as well as casual attitude.

All of these errors do not contribute to failure or impairment of concrete, but they may provide harmful effect on the structure in due course.

These errors are not present throughout new construction, but also occur throughout repair or recondition works.

Given below, mostly found inappropriate finishing methods which can significantly affect the strength of flat concrete surface:

a. Adding water to the surface: It is found that the water is included to the surface and it is verified with the existence of a large paint brush, together with the other finishing tools. The brush is soaked in water and water is heaved onto the surface that is already completed.

b. Timing of finishing: Final finishing operations should be carried on as soon as the concrete has accommodated its initial set and bleeding does not occur. The waiting period is based on the amounts of water, cement, and admixtures in the mixture but mainly the temperature of the concrete surface. On a incompletely shaded slab, the portion in the sun will normally be prepared to finish prior to the part in the shade.

c. Inclusion of cement to the surface: It is frequently performed to dehydrate bleed water so that finishing can be started and it produces a thin cement-rich coating to craze or flake off easily.

e. Use of tamper: A tamper or “jitterbug” is utilized on several jobs needlessly. This tool drives the coarse aggregate far from the surface and the finishing becomes smooth. This method, however, forms a cement-rich mortar surface layer having the ability for scale or craze. A jitterbug should be un-allowed with a well designed mixture. If it is required to complete a rough mixture, a jitterbug could be useful by applying it sensibly.

e. Jointing: If the joints are placed and located improperly, it may lead to cracking in flatwork frequently.

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How concrete is mixed in different ways

Concrete belongs to a composite material formed by cement, sand, coarse aggregate, water and chemical admixtures (if necessary). To maintain the superior quality of concrete, the materials of the concrete should be blended properly so that the quality of concrete is not impacted.

A well-mixed concrete is formed on the basis of the following conditions:

• The color of the concrete should be consistent.
• Admixture of all concrete materials like cement, fine aggregate, coarse aggregate and water should be uniform.
• Cement paste should wrap all the surface of the aggregate.
• Segregation should not happen as soon as the mixing of concrete is completed.

Mixing concrete is dependent on the following three options:

• Hand mixing (Mixing concrete devoid of a mixer)
• Machine mixing (Mixing concrete with a mixer)
• Ready mix concrete

Hand mixing (Mixing Concrete without a Mixer): Hand mixing stands for the method of mixing the different materials of concrete by hand. Mixing concrete devoid of a mixer is suitable for small works. Mixing of materials is executed on masonry platform or flat iron sheet plates.

The hand mixing concrete is performed as follow:

• Expand the measured quantity of sand on the platform, and then unload the cement on the sand.
• The sand and cement should be blended thoroughly with the help of shovels in the dry state.
• The measured amount of coarse aggregate should be extended, and the mixture of sand & cement should spread on it and mixed in an exact manner.
• Depression is provided at the centre of the mixed materials.

• Include 75% of the required quantity of water in the depression and blend well by the shovels.
• Include the leftover amount of water and the mixing method should be carried on unless a uniform colour and consistency of concrete is procured. Time of mixing concrete should not be in excess of 3 minutes.
• The mixing platform should be washed at the end of the day’s work.

Machine Mixing (Mixing Concrete with a Mixer): Machine mixing is mostly suitable for bigger projects where huge masses of concrete are necessary. The machine mixing can retain the persistent uniformity of concrete. Besides, the machine mixing can significantly reduce the mixing time. In recent times, different types of concrete mixers are available which run with petrol/diesel or electricity.

The machine mixing is performed in the following ways:

• Initially, the concrete mixer should be drenched inside of the drum.
• After that Cement, sand and coarse aggregate should be arranged in the portable concrete mixer in desired ratio.
• The dry materials should be blended in the mixing machine. After this, exact quantity of water should be added slowly when the machine is running.
• The concrete should be blended for minimum two minutes after placing all materials in the drum.
• If segregation occurs, the concrete should be remixed after unloading from the mixer.

Ready Mix Concrete: Ready Mixed Concrete (RMC) is developed in the factory or in a batching plant and supplied in a ready-to-use manner. The quality of the consequential concrete is superior as compared to the site-mixed concrete.

Less time is necessary for ready mix concrete as compared to site mixing (hand or machine mixing) and quality of concrete is also greater than the site mixing.

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Basic differences among Prismatic Compass and Surveyors Compass

Compass belongs to an instrument that plays an important role to workout the direction of a survey line relative to magnetic north-south.

The magnetic north-south direction is treated as the reference direction and it is known as meridian (reference direction) and the angle among the line and the meridian is known as bearing. The compass is applied for calculating the direction of a line to simplify the surveying process significantly.

The variations among prismatic and surveyor’s compass are given below :-

Prismatic Compass

1. Graduation circle is attached to a broad type needle. Therefore, it will not revolve with the line of sight.
2. A prism is situated at viewing end.
3. Sighting and reading are performed concurrently.
4. The magnetic needle does not perform like an index.
5. The graduations are in whole circle bearing.
6. Graduations are pointed inverted as its reflection is examined via prism.
7. The reading is captured through a prism.
8. Tripod may or may not be applied. It can be persisted with a stretched hand also.

Surveyors Compass

1. Graduation circle is attached to the box. Si, it revolves with the line of sight.
2. No prism exists at viewing end except for a slit.
3. It is not possible to perform sighting and viewing all together.
4. Magnetic needle functions as index at the time of reading.

5. The graduations remain in quadrantal system.
6. Graduations are pointed directly. They are not inverted.
7. The reading is captured by directly viewing from top glass.

8. Tripod is necessary for being applied.

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How to examine verticality of structure throughout building construction

The verticality works should be examined at the time of building up construction at various stages like during setting up vertical formworks of columns and transmitting levels up successive floors of multi storey structures.

Some useful processes to check verticality of structure throughout building construction
1. Plumb-bob technique
2. Spirit level
3. Theodolite
4. Optical plummet

1. Plumb-Bob Technique: The purpose of this technique is to make sure that constructions are plumb or vertical. It’s application is also found in surveying to set up the nadir regarding gravity of a point in space.

Plumb-bob comprises of a weight with pointed tip on the bottom that is tied to the end of a string. The heavy weight will cling under gravity and produce a precise vertical line that is known as plumb line.

This method is very effective for examining or managing vertical line of structural elements especially indoors like lift shaft. Besides, it is also utilized to check the verticality of foundation, walls, and columns.

The plumb line or vertical line of plumb-bob is affected by wind force and the perfectness is not maintained. It is possible to minimize small to medium lateral movement of plumb-bob efficiently by moistening it in oil or water.

In case the height of structural member is broad, then the string can be substituted with a long wire, but precautions should be plasticized to get rid of imposing risks to the personals functioning under.

2. Spirit Level Method: This tool is used for managing verticality of small scale works; as for instance inspection of formworks and door frames. If spirit level is applied for guess verifications, then it is necessary to examine the verticality with more precise method.

3. Theodolite Method: Theodolite is considerably robust instrument that is utilized to examine verticality works throughout construction providing proper preciseness.

It is useful for examining or managing verticality of towers, wall, foundation and columns specially large number of columns along a one grid line.

The slope can be calculated out of plumb line of the member with Theodolite in conjunction with a tape.

The following methods are utilized to examine column verticality:

Install the digital Theodolite to the center on a peg that is set up 500 mm from the column grid.
Once the Theodolite is installed perfectly the laser beam will be activated and put it to the steel tape that is retained to the formwork.
The reading of the steel tape is captured via the telescope.
Capture the readings of two positions at the equivalent level on both top and bottom levels of the formwork. Any curvature on the surface is easily found by capturing two readings at the same level.

4. Optical Plummet Method: It belongs to an instrument that sight directly down or directly up. Optical plummet contains an automatic compensator that considerably enhances its perfectness with regards to other methods which are applied for managing verticality.

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Combined Pad Foundation Design Spreadsheets

Combined Pad Foundation Design Spreadsheets comprise of a series of spreadsheets which can be used for stability analysis and structural design of a combined rectangular pad foundation.

The spreadsheets evaluate the loadings input by the user and work out the best possible pad size to transmit these loads into an tolerable bearing pressure into the soil.

Unique Pad Sizing and Eccentricity Charts simplify the process for the designer to opt for the best pad dimensions.

As soon as the pad size is set, the spreadsheets then workout the design bending moments and the necessary reinforcement in both X and Y directions for sagging and hogging. The designer can then indicate the perfect reinforcement arrangement with unique recommended reinforcement chart which demonstrates graphically the existing reinforcement arrangements to fulfil both necessary cross sectional area and spacing requirements.

Then a summary page is formed and a reinforcement drawing is produced to provide the perfect reinforcement arrangements which the user has indicated.

The suite comprises of a total of 4 spreadsheets :

• A simple combined pad design spreadsheet to make analysis of a simple combined pad foundation depending on two axial loads where the consequential load must operate through the centroid of the base.

This spreadsheet is ideal for most cases and facilitates making design rapidly for straight forward situations.

• A complex integrated pad design spreadsheet that can easily analyze any combined rectangular pad foundation on the basis of axial, horizontal or moment loadings.

These spreadsheets contain all the tools to design complicated issues or where close attention should be given to detail. It can deal with any size rectangular pad and rectangular columns to where space is restricted in one direction. The spreadsheet also arranges the base for being loaded eccentrically in any arrangement required by the designer.

It comprises sliding analysis to rationalize any horizontal loads. It involves design charts to make brief analysis of shear and punching shear loads, and comprises of bending moment and shear force diagrams to facilitate the designer to design the reinforcement in as much detail.

Both simple and complex spreadsheets are available to abide by either British Standards BS8110 & BS8004 or Eurocodes BS En 1992 & BS En 1997.

Download Combined Pad Foundation Design Spreadsheets civilweb-spreadsheets.com

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Details of tendering method in construction

Tendering: Tendering stands for the procedure of making an offer, bid or proposal, or revealing interest in providing respond to an invitation or request for tender. With tendering, interested contractors can send their bids to execute certain packages of construction work.

Organization will look for other businesses to make response to a specific requirement, like the supply of goods and services, and will opt for an offer or tender that fulfill their requirements and offers the best value for money.

Types of tendering:

a. Competitive tendering
Open – Selective

b. Negotiated tendering
Serial – Nominative

Open tender: Open tendering is the primary tendering procedures which are implemented by both the government and private sector. The client publishes the tender offer in the local newspaper as an advertisement. It provides the detail and essential information concerning the projected works as well as invite interested contractor to tender. In legal term such tender recognizes constitute invitation to treat, a simple request made by the employer for appropriate contractor to tender their bids or offers.

If the pre-requisite to tendering on the form of possession of the obligatory registration has been recognized in the tender notice, then the advertisement is conducted to only that specific class of the public with the stated qualifications. With the purpose of decreasing the number of enquirers, earnest money is paid in (for private project).

Unless the receipt of a bone fide tender is chosen then it will be refunded. The price is very crucial in taking the decision on which the tender or bid should be received. The benefits and drawbacks of open tender are described below:

a. It empowers any concerned contractor to submit tender. So, it provides scope for an unfamiliar contractor to bid for the work.
b. The tender list becomes lengthy because too many contractors submit their tender for one job.

c. It facilitates the tender list to be created neutrally. Client will acquire the bargain possible. No favor should be provided for choosing any contractor.
d. Wasteful application of source.
e. Make sure that there is good competition not obliged to accept any offers.
f. The interrogation can be made for public accountability may be questioned if the lowest offer is not accepted.
g. Conventional method of tendering, recognized to all segment of the engineering and construction industry.
h. The reputable and established contractor is not allowed unless they are compelled because of the shortage of water.

Selective tender: The objective of selective tendering is to deal with the constraints of the open tendering process. Under this method, a short list of contractor is made and they are invited to present tenders. The objective of the elective tendering is to make the quality of the received bids better, to make sure that contractors who have required experience and skill get the scope to present the required bids, owning to urgency work involved, for certain reasons of the employer, as for instance security reasons in government projects, Etc. and to make the tendering procedure more simplified and reduce the burden on the associated parties. Such list is made by the suggestions from the Client’s professional adviser having knowledge of the Contractors undertaking the work earlier or advertisement via the newspaper (pre-qualification).

To get more information, go through the following page basiccivilengineering.com

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How to check quality of concrete in jobs site

The following precautions should be taken during preparation of good quality concrete:

To build up a quality, durable and strong structure, the concrete that is used should contain standard quality. A good quality concrete should be stable, condensed, workable and cost-effective.

The following properties should be maintained to produce a good quality concrete :-

1. The quality of aggregate should have been rigid and long-lasting.

2. The grading of the aggregates should be done perfectly and consistently.

3. Adequate quantities of cement should included in concrete to maintain necessary strength and water-resistance capability.

4. The water does not contain any organic or deleterious materials.

5. The quantity of water should be maintained in such a manner so that the uniformity is retained properly.

6. The proportion of water-cement should keep as minimum as possible.

7. To keep up conformity, mixing of concrete should be performed systematically.

8. To eliminate air bubbles and voids, the freshly arranged concrete should be compacted properly.

9. While transmitting the concrete to the job site, no segregation of or separation of materials should happen in concrete.

10. Concrete that is provided at the point of placing should have been homogeneous & contain right symmetry.

11. Ensure that the concrete is not thrown from a distance of high point to prevent segregation.

12. Curing of concrete should be done perfectly for minimum 28 days.

13. The temperature of concrete should be retained over the freezing point unless it gets rigid enough.

14. It should be stored in even horizontal layer having invariable thickness. Concrete should fill each section in this form.

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What should be the qualities for becoming a successful civil engineer

In order to become a successful civil engineer, the following qualities are essential :-

1. TESTS OF BUILDING MATERIALS: An efficient civil engineer should be well versed with various test methods of building materials. Given below, the details of some crucial test methods :-

Concrete Test: Slump test, compression test, split tensile test, soundness etc.
Soil Test: Core cutter test, compaction test, sand replacement test, tri axial test, consolidation test etc.
Bitumen Test: Ductility test, softening point test, gravity test, penetration test etc.

2. EXAMINATION OF SOIL: Prior to build up a construction, different types of soil tests are accomplished to define the settlement and constancy of soils. Therefore, as a civil engineer, one should possess adequate knowledge with these tests to carry on at the job site.

3. APPLICAIONS OF SURVEYING INSTRUMENTS: Each civil engineer should have clear conception on how to apply various surveying instruments like the total station, theodolite etc. These instruments are specifically designed for marking and measurements.

4. STANDARD CODES USED IN CONSTRUCTION: Each country should contain their standard safety specifications (eg: Is Code) for construction associated works. The construction works of new buildings should abide by the rules and processes indicated in the standard codes. if not, there are chances for collapsing of the structure any time.

5. BAR BENDING SCHEDULE: Bar bending schedule is a vital chart for civil engineers. It offers the reinforcement calculation of RC beam like cutting length, type of bending, the length of bending etc.

6. DRAWING AND DESIGN: Drawing and design are considered as the elementary part of a running project. It offers all the necessary specifications of that project. Each site engineers should possess the quality for evaluating such drawings and designs.

7. COMPUTATION AND BILLS: A civil engineer should have the skills to produce the estimation and bills in a construction project.

8. QUALITY CONTROL: With proper quality control, the profit of the project is raised and the cost is decreased. Therefore, a engineer should be well versed with quality control process.

9. ON SITE MANAGEMENT: A engineer should have adequate knowledge with form-work, concreting, safety measures etc.

10. COORDINATION WITH LABOR: As a civil engineer, one should know how to manage the labors in a job site.

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