Whole circle bearing (WCB) and Quadrantal Bearing System (QBS) in Surveying

The whole bearing system (WBS) and the quadrantal bearing system (QBS) are two bearings systems used in the compass survey. With a simple calculation, the WCB system can be converted to QBS.

The article briefly explains the different bearings used in the survey and classification of bearings (WCB and QB system).

Bearing and Angles:

You may measure a survey line in relation to another survey line or in relation to the meridian. The first method provides the line angle. The second one is giving the bearing The bearing can, therefore, be defined as the line's direction for the given meridian.

There are mainly three types of meridian: 

1. True meridian 
2. Magnetic meridian 
3. Arbitrary meridian

1. True Meridian:

A line passes through a point, with a plane passing through the point and the north-south poles forming the true meridian.

In other words, it forms the line that passes through the true north and the south poles.

The true bearing of a given line is the horizontal angle made with the true meridian through one of the extremities of the line.

2. Magnetic Meridian

The magnetic meridian is the direction shown by a freely suspended and floating balanced magnetic needle. To determine the magnetic meridian, a magnetic compass can be used. For this purpose, the magnetic compass used must be free of other attractive forces. 

The magnetic bearing of a given line is the horizontal angle that it makes with the magnetic meridian that is passing through one of the extremities of the line.

3. Arbitrary Meridian

In some situations during the survey, a convenient direction is set for a permanent or common mark or signal in the area. These are called arbitrary meridians which help determine the survey line's relative positions.

The horizontal angle made by a line with the arbitrary meridian passing through one of its extremities is called as an arbitrary bearing.

Whole Bearing and Quadrantal Bearing Systems:

A WCB bearing system measures an angle in the clockwise direction from the magnetic north or to the south.

hence, the bearing value varies between 0 degrees and 360 degrees. A WCB system graduates from a prismatic compass. 

The Quadrantal Bearing or Reduced Bearing System (QB):

The bearing angle is measured in the QB system either from the north or from the south, whichever is nearer. In either clockwise or anti-clockwise, this can be measured Here it is necessary to mention the quadrant at which the line lies. The Q.B lines vary from 0 to 90 degrees.

Also Read  What Is Leveling And Types Of Leveling? Surveying & Leveling

Quantity Of Cement And Sand Calculation In Mortar CFT

A quantity of cement mortar is required for a building or structure to analyze the rate of brickwork and plaster or to estimate the masonry work. Cement mortar is used in different proportions,  i.e. 1:1, 1:2, 1:3, 1:4, 1:6, 1:8 etc.

Calculation Of Quantity Of Cement Mortar In Brickwork And Plaster:

Let's assume that the volume of masonry work is 20cft. and we assume the ratio of mortar 1:4.

When we estimate the mortar quantity for any masonry work, we just get the wet volume of mortar.

Now we will see how to calculate the dry volume of mortar and then we will calculate the cement and sand quantity in 20cft.

Grains of sand in dry conditions include air voids. Therefore, by adding water to the dry sand, the sand volume will be reduced This happens because of the presence of air voids in particles of sand. The percentage of air void sand compressibility is between 20% and 27%. 

Normally, when converting the wet volume into the dry volume, we take the highest percentage of air void compressibility of sand. That's 27% of it. 

So when we calculate the dry volume of mortar, we just multiply the wet volume by 1.27.

Dry volume= 20 x 1.27 = 25.4 cft

So now we have the dry volume of mortar which is 25.4 Cft

Now we will calculate the quantity of sand and cement in 25.4 Cft. 

first, we will calculate the sum of ratio and our mixing RATIO IS 1:4.

Sum of ratio= 1+4= 5 

Also Read  Quantity Of Cement And Sand Calculation In Mortar meter cube

The volume of cement will be calculated as:

(1 ÷ 5) x 25.4 = 5.08 cft

Since the volume of 1 bag of cement is 1.25 Cft, so the number of a bag of cement will be calculated as:

5.08 ÷ 1.25 = 4.064 bags

The volume of Sand will be calculated as:

(4 ÷ 5) x 25.4 = 20.32 cft

Quantity of cement in 20 Cft  masonry mortar = 4.064 Bags say 4.5 or 5 bags

Quantity of cement in 20 Cft  masonry mortar = 20.32 cft

Conclusion 

To calculate the dry mortar volume, you simply need to estimate your work item's wet mortar volume and then multiply it by 1.27.

Once you get the required dry mortar volume the amount of cement and sand required for the mortar can be calculated based on the proportion of the mixture.

Quantity of Cement and Sand Calculation in Mortar m3

A quantity of cement mortar is required for a building or structure to analyze the rate of brickwork and plaster or to estimate the masonry work. Cement mortar is used in different proportions,  i.e. 1:1, 1:2, 1:3, 1:4, 1:6, 1:8 etc.

Calculation of quantity of cement mortar in brickwork and plaster:

Let us assume that we use 1m3 of cement mortar for the calculation of cement mortar. The calculation method is:

1. Calculate the amount of dry material required for 1m3 cement mortar. Considering the voids in the sands we assume the material is consists of voids of 60%. That is, 1.6m3 of materials are needed for 1m3 of wet cement mortar.

2. Now, based on its proportions, we calculate the volume of materials used in cement mortar.

Let's say, the cement and sand ratio is 1:X, where X is the required sand volume.

Then, the volume of sand required for 1:X proportion of 1m3 cement mortar will be

3. The volume of cement will be calculated as:

Also Read  Types Of Masonry Construction Based On Material

Since the volume of 1 bag of cement is 0.0347 m3, so the number of a bag of cement will be calculated as:

For cement mortar of 1:6, the quantity calculated will be as below:

Sand Quantity:

Quantity of cement (in bags):

The volume of cement = 

There number of bags required =  = 6.58 bags.

Next article= How to find cement and sand quantity in the mortar in Ft3

Types of Masonry Construction Based on Material

A variety of materials may be used in masonry construction, combined with mortar of varying strength. Brick, stones cement, veneer, gabion, etc. are some of the common materials used.
Some of the important masonry construction based on the material used are briefly explained.

1. Brick Masonry Construction

The construction of brick masonry uses first-class burnt clay bricks. Third-class bricks are used in masonry for less important construction. Second-class bricks are best for plastered masonry construction due to lack of finish compared to first-class bricks. 

The overall tensile strength of the brick masonry is lower, regardless of the brick class chosen. Overall performance depends on the size, position, and number of openings provided to the structure of the masonry.

2. Stone Masonry Construction

Stone, relative to any other, is the most durable solid, and weather-resistant construction material. These are less affected by wear and tear from day today. Masonry structures made of stone also last longer. It has a lifetime of between 300 and 1000 years plus years. It is widely used in masonry construction because it is numerous advantageous.

Stonemasonry has two main classifications:

1. Rubble Masonry
2. Ashlar Masonry

Rubble Masonry is again classified into:

• Uncoursed or Coursed Random Rubble Masonry
• Uncoursed or Coursed Square Masonry
• Polygonal Rubble Masonry
• Dry Rubble Masonry

Ashlar masonry is again classified into:

• Ashlar Fine Masonry
• Ashlar Block in Course
• Ashlar Chamfered Masonry
• Ashlar Rough Tooled Masonry
• Rock or Quarry Faced Masonry

also read Quantity Of Cement And Sand Calculation In Mortar M3

3. Concrete Masonry Construction

In the construction of concrete masonry, the blocks of concrete are pressed on top of others similar to the construction of brick masonry. This produces a turbulent formation The scale of concrete blocks is smaller than that of bricks, so it takes less time to lay concrete blocks.

It is, therefore, popular to build concrete blocks as it is affordable and gain high fire resistance. The concrete blocks of masonery come in different sizes, forms, and special designs, making it a flexible medium for building. It is commonly used in factories, universities, and residential building construction.

4. Veneer Masonry Construction

This construction of masonry is a style that is mainly used for remodeling and interior finishing. It gives the appearance of a more economical and isolated stone or brick wall. It is possible to place veneer maçonnery units on the existing concrete wall, giving a better look.

5. Gabion Masonry Construction

Gabions are baskets made of zin-protected steel or galvanized steel, filled with broken stones of medium size. These gabions are working as one unit. This functions as preservation or as retention of walls. These units of masonry are in nature well-drained and flexible. As a result, they have high horizontal pressure resistance such as water floes, surface flow, frost damage and floods. Commonly used gabions are in fact rectangular. The strength of gabions relies on the steel's corrosion resistance properties used in gabion baskets.

6. Composite Masonry Construction

Two or more types of building materials are used for the construction of a composite masonry structure. These masonry buildings are used to increase the building's appearance and to make use of available material resources with the utmost economy.

Bearing Capacity of Different Types of Soil

Bearing capacity values of various soil types like clay, sand, gravel, rocks, etc.
Bearing capacity can be defined as ;

"The maximum load per unit area which the soil will resist safely without displacement."

Types of Soil	Bearing Capacity (Kg/m2)	Bearing Capacity (kN/m2)
Soft, wet clay or muddy clay	5000	50
Soft clay	10000	100
Fine, loose and dry sand	10000	100
Black cotton soil	15000	150
Moist clay and sand-clay Mixture	15000	150
Loose gravel	25000	250
Medium clay	25000	250
Medium, compact and dry sand	25000	250
Compact clay	45000	450
Compact sand	45000	450
Compact gravel	45000	450
Soft rocks	45000	450
Laminated rock such as sandstone & Limestone	165000	1650
Hard rocks such as granite, diorite, trap	330000	3300

Also Read  What Is Soil? Formation And Types Of Soil?

The maximum load per unit area is the soil bearing strength. This is the total soil bearing capacity shown in the table. By dividing the ultimate soil bearing capacity by a safety factor, we obtain the maximum safe soil bearing capacity for foundation design

How to convert?

1 kg = 10 N, so, 1000 N = 100 kg = 1 kN. So, the value of column 1 is divided by 100 to obtain value in kN/m2

What is Soil? Formation and types of Soil?

What is soil?

The term "Soil" has different meanings depending on the field of general professional consideration.
To an agriculturist, Soil is the material on the surface of the earth which grows and produces plant life.
To the Geologist, Soil is the substance in the relatively thin surface area within which there are roots.
To an engineer, Soil is an unconsolidated agglomerate of minerals found on or near the earth's surface with or without organic matter through which and on which engineers build structures.
It covers the entire thickness of the earth's crust that is accessible and feasible for practical use as foundation support or building material.
The behavior of soil as a foundation or building material is heavily influenced by the following:

• Moisture content present in soil pores
• The fluctuation of the groundwater table
• Freezing and thawing phenomena
• Presence of organic matter
• History of the formation of soil
• Seismicity of area

Mechanical or attractive forces bind the particles of the soil together.
The binding strength of the soil is very low compared to the rocks.
The type of soil will differ between clay and gravel and even between cobble and boulders.
The topsoil, normally two feet deep, contains organic matter and is generally considered unacceptable for use in civil engineering.

Formation of soil:

Soil is generally formed by rock decomposition or disintegration (rock weathering) on or near the earth's surface through the action of many natural, physical, and chemical agents that often break them into smaller and smaller particles.

The weathering of rocks may be the following: 

1. Physical/mechanical weathering
2. Chemical weathering 

1.Physical/mechanical weathering:

It is the disintegration of rocks caused by changes in temperature, freezing and thawing, swelling, flowing water erosion, natural disasters (earthquake, land sliding, etc.) and animal activities including people. 

Soils formed by physical weathering retain parent rock minerals.

Coarse-grained soils (gravels, sands and their mixtures) are the physical weathering products

2. Chemical weathering:

Weathering caused by oxidation, hydration, carbonation, desilication, and leaching of rock minerals is known as chemical weathering.

The common soils formed by chemical weathering are different types of clay and organic soils (peat, muck, hummus, etc.).

Types of Soil Based on Particle Size:

Types of soil based on engineering considerations depend on particle size. As the engineering properties of soil change with particle size change, different names are given for different particle size ranges. The range of particle size defined for each soil type varies among agencies.

clay:

Composed of fine particles with a size of less than 0.002 mm. Flaky in the form with a large area of the surface. Have a strong attraction of inter-particles and therefore have sufficient cohesion. Poor permeability is vulnerable to swelling and shrinking. Typically the color is brown.

silt:

Composed of particles between 0.002 and 0.06 mm in size. Have high capillarity and dry strength very low. The intermediate particle size between clay and sand, therefore, has sand and clay properties, i.e. it shows slight friction and friction as well. The silty soil color is mostly brown.

Sand:

Particle size from 0.06 to 2 mm, in shape, can be rounded to angular in color brown. No plasticity, high resistance in a confined environment and significant resistance to friction. angular particles have a high resistance to friction compared to rounded particles. It is extremely permeable and has low capillarity.

gravel:

The particle size ranges between 2 and 60 mm. Form good material for the foundation. Show high resistance to friction. Angular particles have a high resistance to friction compared to rounded particles. The gravel produced by rock crushing is angular in shape, while those taken from the riverbeds are sub-rounded to rounded.

Cobbles and Boulders:

Particles larger than gravel are commonly referred to as cobbles or boulders. Cobbles vary between 60 and 200 mm in length. Boulders are the material greater than 200 mm.

Soil types According to ASTM and AASHTO:

Difference between Tender and Contract Documents

In order to understand the difference between tender documents and contract documents, we must first understand what they contain.

Tender Documents:

A tender is a written offer to contractors to conduct such specified works or to supply specified materials within a specified time period and in compliance with contract and contractual conditions between the contractor and the owner or department or party. 

The tender documents contain the bill of quantities (BOQ), work specifications to be performed, time frame for completing the work, contract conditions and plans and drawings. On the payment of certain fees, these documents are given to the contractor. The contractor who offers the lowest or appropriate rates for the works as a whole is offering the contract to do the work.

OR

It's a document pre-bidding. This document mainly describes four issues, i.e. 1 Contractor Eligibility Criteria, 2 Project Timeline 3 Contract Working Procedure and 4 Quantity Material Specification(BOQ).


In order to obtain tender papers, there are also some limitations. In some cases, only the tender document is available to the contractor who is eligible.

Once the rate is quoted by the contractor in BOQ, it is sealed in cover and submitted to Tender Inviting Authority Panel. At the date of tender opening, the panel will unseal the cover and start to name L1, L2 & L3 respectively to the contractor, who quoted the lowest or appropriate value of three members. Then the negotiation process will take place, the contractor who comes for the lower price to him the tender will be awarded.

Contract Documents:

Contract documents are the arrangement between the owner or the party or agency and the contractor to conduct the works as stated in the tender documents on the rates quoted by the contractor in compliance with the contract conditions.

OR

It is a Post – Bidding Document. This document is a total of an agreement. Once the bidding is over the contractor and client will undergo an agreement that the Project will be completed in scheduled time, with the same specification and working procedure as mentioned in the Tender document. If the project is delayed due to the contractor, then the penalty will cover some percent of the total project cost. This agreement is documented as a Contract Document.

Tender and Contract Documents difference:

The difference to remember here is that tender contracts are given to as many suppliers as possible to receive the lowest offers for the stated work, whereas contract agreements are only signed with the contractor with the appropriate or lowest bid or rates and technical skils.

While the tender documents include the contract terms and all the information for the stated work, in terms of content, there is not much difference between the two. But it is not possible to send tender documents as Letter of Acceptance (LOA) since these are two different types of documents. While a tender document can not bind the contractor to do the work, the contractor is bound by a contract document to complete the work as per the contract.

Simple Example for understanding the difference between tender documents and contract documents:

When you are selected for a job in a company you are offered an offer letter to join the company. But getting selected in a company does not mean that you join the same company, you may have other offer letters as well. But when you sign the letter of acceptance (LOA) for the job, you are bound to join the company. So, here offer letter from the company is a tender document and LOA is the contract document.

Sieve Analysis of Coarse Aggregate ASTM : Explanation and Procedure of TEST Step by Step

TO FIND THE GRADATION OF COARSE AGGREGATE BY SIEVE ANALYSIS (ASTM C136-05).

THEORY & IMPORTANCE:

This experiment is conducted to find and check coarse aggregate gradation i.e. crush.  The main bulky component of the concrete is crush; it is used together with its strength-giving properties to increase the volume of the concrete. it calculates its fineness module to find the water ratio to be used, along with the value of the specific crush gravity and its maximum grain size.

The maximum size of the coarse aggregate will be calculated from the modulus fineness table in this experiment. For example, if its maximum size is 3⁄4 inches, it means that all grain size is less than 3⁄4 inches. This can also be expressed by writing it as a crush: 3⁄4 inch down.

APPARATUS DETAILS:

For this gradation, the sieve used is 1 1⁄2 in, 1 in, 3⁄4 in, 1⁄2 in, 3/8 in, and #4 sieve. The distinction is that #4 sieve means that in one linear inch of the sieve there are four holes, while 1 1⁄2 inch sieve means the one side dimension of the sieve hole is 1 1⁄2 inches (not that in one linear inch of the sieve there are one and a half inches). The sieves are stacked with their lengths in ascending order. The crushed sample here is 3000 g.

APPARATUS:

• Sieve Apparatus or sieve set.
• Electronic Balance.
• Brittle brush.
• Empty plate.

Electronic Scale

Sieve Set & shaker

MATERIAL:

Sample of Coarse aggregate

PROCEDURE: 

Ø  Took the digital balance and set the scale reading to zero

Ø  Took and measured the weight of pan.

Ø  Put some crush in the pan and measure 3000 grams of crush with the help of electronic balance.

Ø  Put the crush in a sieve of 1. 5 inches and began shaking until no more seeds could escape it readily. Using the electronic balance, measured the weight retained on the sieve and noted it in the table.

Ø  Some stone had fallen out of the reduced sieve placed it in it and begins to shake the sieve for sufficient time. Noted the sieves read of the retained weight.

Ø  Similarly, placed the entire remaining crush in the below sieve and began shaking for enough moment and noticed the weight retained in all the sieves.

Ø  Calculated the percentage of each sieve's weight retained.

Ø  The percentage of the weight that had passed through each sieve was found in the next phase.  The complete quantity entered will be 3000 grams for 1.5 inch sieve.

Ø  But it won't be the same for the 1 inch sieve because the upper sieve had retained some weight, so the proportion of the passing was calculated relative to the quantity that enters that sieve.

Ø  For a sieve of 3⁄4 inches, the total quantity entering the sieve will be less the value for the upper sieve, similarly, for other sieves, the same method should be used to calculate the percentage of the passed weight

Ø  The cumulative proportion was calculated in the next column.  This was the weight proportion that would be retained if the crush were placed directly on the sieve.  It will be the same as it was for 1. 5 inch sieve, but for 1-inch sieve, it would be the sum of the proportion retained by 1. 5 inch sieve plus the one retained.  Similarly, the cumulative proportion was calculated for other sieves, this was denoted by a1, a2, a3, etc

Ø Then at the end to find the crush's fineness module add each sieve's cumulative proportion and divide it by 100.

Observations and Calculations:

Total weight of natural coarse aggregate = 3kg.

Sieve No	Weight Retained on Sieve (kg)	Percentage of weight Retained (%)	Percentage Of weight Passed (%)	Cumulative Percentage of Retained (%)
1 in	0	0	100	0
3/4 in	0.3594	11.98	88.02	11.98
1/2 in	1.1526	38.42	49.6	50.40
3/8 in	0.9732	32.44	12.16	82.84
#4	0.489	16.30	0.86	99.14

Finess modulus formula= a1+a2+a3+a4+a5 / 100

(Note:- a is the Cumulative Percentage of Retained (%) )

Finess modulus= 244.36/100=2.44