Classification of Surveying

Surveying may be classified on the basis of nature of the survey field, object of survey, instruments used and the methods employed.

1. Classification Based on Nature of Survey Field

This basis survey may be classified as land survey, marine or hydraulic survey and astronomical survey.

Land Survey
It involves measurement of various objects on land. This type of survey may be further classified as given below:

(a) Topographic Survey: It is meant for plotting natural features like rivers, lakes, forests and hills as well as man made features like roads, railways, towns, villages and canals.

(b) Cadestal Survey: It is for marking the boundaries of municipalities, villages, talukas, districts, states etc. The survey made to mark properties of individuals also come under this category.

(c) City Survey: The survey made in connection with the construction of streets, water supply and sewage lines fall under this category.

Marine or Hydrographic Survey
Survey conducted to find depth of water at various points in bodies of water like sea, river and lakes fall under this category. Finding depth of water at specified points is known as sounding.

Astronomical Survey
Observations made to heavenly bodies like sun, stars etc., to locate absolute positions of points on the earth and for the purpose of calculating local time is known as astronomical survey.

2. Classification Based on Object of Survey

On the basis of object of survey the classification can be as engineering survey, military survey, mines survey, geological survey and archeological survey.

(a) Engineering Survey: The objective of this type of survey is to collect data for designing civil engineering projects like roads, railways, irrigation, water supply and sewage disposals. These surveys are further sub-divided into: Reconnaissance Survey for determining feasibility and estimation of the scheme. Preliminary Survey for collecting more information to estimate the cost of the project, and Location Survey to set the work on the ground.

(b) Military Survey: This survey is meant for working out plans of strategic importance.

(c) Mines Survey: This is used for exploring mineral wealth.

(d) Geological Survey: This survey is for finding different strata in the earth’s crust.

(e) Archeological Survey: This survey is for unearthing relics of antiquity.

3.  Classification Based on Instruments Used

Based on the instruments used, surveying may be classified as:
(i) Chain survey
(ii) Compass survey
(iii) Plane table survey
(iv) Theodolite survey
(v) Tacheometric survey
(vi) Modern survey using electronic distance meters and total station
(vii) Photographic and Aerial survey
The survey is taught to civil engineering students mainly based on this classification.

4. Classification Based on Methods Employed

On this basis surveying is classified as triangulation and traversing.
(i) Triangulation: In this method control points are established through a network of triangles.

(ii) Traversing: In this scheme of establishing control points consists of a series of connected points established through linear and angular measurements. If the last line meets the starting point it is called as closed traverse. If it does not meet, it is known as open traverse.

Garage Building Tips

What is a garage

Garages are used to park cars. This can be a private lot at an airport or a mall, or a storage shed with a garage door at a private home. A car garage can be used strictly for model cars at wealthy homes, or it can be a place for car repair at a car shop. With or without car covers, a garage is always a place for storage, and usually for cars and other vehicles. In the next paragraph, we will talk about how to build a garage for your private house.

Garage Building Guide

Here are four steps for building a garage:

• find a suitable location,
• lay the foundation,
• frame the garage,
• install the roof.

A garage is an unheated space that is used to store a car or other equipment. Garages are usually located fairly close to a primary residence, for the convenience of the homeowner. Using a garage increases the life of a vehicle and can be used to store equipment and supplies securely.

The first step before you even start to build a garage is to obtain permission. If you live in an urban area, there are specific zoning rules and regulations that must be met in order to build a garage. Complete the required forms and make sure that all the legal requirements are met before you begin. The government can tear down an illegally built garage, costing you time and money. In a rural setting, there are fewer restrictions, especially if the land is yours.

The most suitable location for a garage has a straight path to a road or driveway, is close to the primary residence, and does not require the removal of any trees or large shrubs. Take the time to determine the location of any gas, electrical, water, or sewer lines on your property. This information is very important. Although the foundation does not require deep drilling, if the garage is built over any pipes or cables and there is a problem, it may be necessary to dig up the floor.

To lay the foundation, rent a bulldozer and survey equipment. Measure the space required and dig down to create a level surface with the required dimensions to create a foundation when you build a garage. Use the survey equipment to ensure that it is as close to level as possible. Install boards around the perimeter and base, creating a box to hold the concrete. Lay down a layer of gravel and then arrange for the concrete to be poured.

Framing the garage requires the use of wood or prefabricated walls to create the structure. Most people use a team at this stage, as the work moves faster with more people helping. Make a large mark on the floor to indicate where the garage door(s) will be. This will ensure that they are not accidentally closed in.

Cold Weather Concreting

Introduction of Cold Weather Concreting

Concrete placed during cold weather will develop sufficient strength and durability to satisfy intended service requirements only if it is properly produced, placed and protected.

ACI 306 “Cold Weather Concreting” defines cold weather concreting as a period when for more than three consecutive days, the following conditions exist:

•The average daily air temperature is less than 5°C (40°F) and,
•The air temperature is not greater than 10°C (50°F) for more than one-half of any 24 hour period.

Even though not defined as cold weather, protection during Spring and Fall is required during the first 24 hours to avoid freezing.

What Happens When Concrete Freezes?

•Pore water in concrete starts to freeze around -1°C (30°F)
• As some water freezes the ion concentration in the unfrozen water goes up, further depressing the freezing point.
• At around -3 to -4°C (25 to 27°F), enough of the pore water will freeze so that hydration will completely stop, and depending on the extent of hydration, and thus the strength of the concrete, the forces generated by the expansion of ice (ice occupies ~9% more volume than water) may be detrimental to the long term integrity of the concrete.

Objectives of Cold Weather Concreting

The objectives of cold weather concreting are to:

•Prevent damage to concrete due to freezing at early ages
• Assure that concrete develops the required strength for the safe removal of forms
• Maintain curing conditions that foster normal strength development without using excessive heat
• Limit rapid temperature changes in the concrete to prevent thermal cracking
•Provide protection consistent with the intended serviceability of the structure

For every 10°C (18°F) reduction in concrete temperature, the times of setting of the concrete double, thus increasing the amount of time that the concrete is vulnerable to damage due to freezing. It should be noted that warm concrete placed on cold sub-grade will lose heat and its temperature will drop. It is important to understand that having the concrete reach the specified 28-day strength is irrelevant if the structure is damaged by inadequate curing and protection.

Concrete that is protected from freezing until it has attained a compressive strength of at least 3.45 Mpa (500 psi) will not be damaged by exposure to a single freezing cycle. Concrete that is protected and properly cured will mature to its potential strength despite subsequent exposure to cold weather.

Except in heated, protective enclosures, little or no external supply of moisture is required for curing during cold weather.

RCC Mix Design

Mix design proportioning methods for Roller Compacted Concrete RCC:

ACI 207.5R (chapter 2.4) and ACI 211.3R extensively described the mix design proportioning methods for no slump concrete applicable forRoller Compacted Concrete RCC

Materials Used in RCC mix design

a) Cementitious materials:

Cement content is generally low (typically 70 to 130 kg/m3). Any kind of Portland Cement (but low heat cement is a preferred type when its is available)

Fly Ash: Class F pozzolans are preferred. When used pozzolans, may replace up to 80 % of cement content.

b) Aggregates:

Selection of aggregates and control of aggregates quality is essential. Aggregates shall meet ASTM C33 standard.

Coarse aggregates:
Most of project use a coarse aggregates with a Nominal Maximal Size Aggregate (NMSA) between 37.5 and 75mm. The thickness of placement layer shall be more than 3 times the NMSA.

Fine aggregates:
The grading of fine aggregates strongly influence paste requirements and compactibility of RCC. It also affects water and cementitious material requirements needed to fill the aggregates voids and coat aggregate particles.

Other aggregates: Fines (crusher fines…):
In low cement content mixtures, supplements fines (material passing 0.075 mm sieve) are usually required. Fines quantities is generally 5% of total aggregates

c) Admixtures:

Admixtures for RCC needed mostly for set retardation (and plasticizing) effect. Water Reducer Type D (WR + retarder)
WR use is beneficial for strength gain, and retardation which can be required very extended. Main Sika Product for RCC: Plastiment TM 25 specifically designed for RCC.

Mix design considerations:

a) Workability / Consistency:

Measured with a Vebe vibrating table (ASTM C 1170).
The test principle is to measure the time for the concrete to be consolidated by vibrating in a cylindrically shaped mold. The longer the time, the drier/lesser workable is the concrete. Vebe times of RCC mixtures is generally from 10 to 40 seconds. Comparison of concrete consistency measured by slump and Vebe apparatus. ACI 211.3R

Consistency	Slump (mm)	Vebe (s)
Extremely dry	-	32 to 18
Very Stiff	-	18 to 10
Stiff	0 to 25	10 to 5
Stiff Plastic	25 to 75	5 to 3
Plastic	75 to 125	3 to 0
Very plastic	125 to 190	-

b) Strength:

Design strength of RCC dam is often based on long term strength (90 days, 120 days or even 1 year!). The strength of RCC is a function of w/c ratio only for mixture with Vebe time of ~ 15 to 20 sec. range. For drier mix, the strength is more controlled by the moisture-density relationship.

If water content is less than optimum => voids in structure, poorly compacted concrete with loss in density and strengths.

Compressive strength of RCC is usually measured by testing cylinder (15cm diameter,30cm long).

Strength measured on cores is also possible.

d) Segregation:

It is necessary to produce mixture with minimum tendency to segregate => Aggregates (especially with NSMA > 37.5mm) shall be well graded.

Higher cement content mixture are generally more cohesive => less tendency to segregate.

e) Permeability

Mixture with paste volume of 18 to 22% by mass shall provide suitable level of impermeability. Higher cementitious content or high workability mixes that bond well to fresh lift joints will produce watertightness.

For lower cementitious content mix, and/or low workability mix, a bedding mortar between lifts may be needed.

f) Heat Generation:

It is an important factor considering the massive structures. Limitation of cement content, and/or use of fly ash is helping reduce heat generation.

g) Durability:

RCC should be free of damaging effects of alkali-aggregate reactivity

Quality control of RCC concrete:

• Vebe Consistency Test
• Density and air voids tests.
• Moisture/water content tests.
• Cement content evaluation
• Temperature monitoring
• Test (cylinders) specimens:

- Using modified Vebe apparatus (generally for mix with Vebe up to 20 seconds),

- Using of special vibrating hammers

Beware, because of low early strength of concrete specimens are “fragile”.

Lift-Joint sealing systems:

Lift joints shall be kept moist before placing next lift and normally do not require special treatment. In some cases, it is required to apply a “flowable” bedding mortar which need to be retarded with admixtures.

Civil Engineering Branches for Civil Engineer Jobs

Civil engineer job are one of the world’s most important jobs: they build our quality of life. With creativity and technical skill, civil engineers plan, design, construct and operate the facilities essential to modern life, ranging from bridges and highway systems to water treatment plants and energy­ efficient buildings. Civil engineers are problem solvers, meeting the challenges of pollution, traffic congestion, drinking water and energy needs, urban redevelopment and community planning.

There are seven major branches of civil engineering:

Structural Engineering

Structural engineers face the challenge of designing structures that support their own weight and the loads they carry, and that resist extreme forces from wind, earthquakes, bombings, temperature and others. Bridges, buildings, amusement park rides and many other kinds of projects are included within this speciality. Structural engineers develop appropriate combinations of steel, concrete, timber, plastic and new exotic materials. They also plan and design, and visit project sites to make sure work is done properly.

Environmental Engineering

The skills of environmental engineers have become increasingly important as we protect our fragile resources. Environmental engineers translate physical, chemical and biological processes into systems to destroy toxic substances, remove pollutants from water, reduce non­hazardous solid waste volumes, eliminate contaminants from the air and develop groundwater supplies. Environmental engineers are called upon to resolve the problems of providing safe drinking water, cleaning up contaminated sites with hazardous materials, disposing of wastewater and managing solid wastes.

Geotechnical Engineering

Geotechnical engineering is required in all aspects of civil engineering because most projects are supported by the ground. A geotechnical engineer may develop projects below the ground, such as tunnels, foundations and offshore platforms. They analyse the properties of soil and rock that support and affect the behaviour of these structures. They evaluate potential settlements of buildings, the stability of slopes and fills, the seepage of ground water and the effects of earthquakes. They investigate rocks and soils at a project site and determine the best way to support a structure in the ground. They also take part in the design and construction of dams, embankments and retaining walls.

Water Resources Engineering

Water is essential to our lives, and water resources engineers deal with the physical control of water. They work with others to prevent floods, supply water for cities, industry and agriculture, to protect beaches or to manage and redirect rivers. They design, construct and maintain hydroelectric power facilities, canals, dams, pipelines, pumping stations, locks, seaport facilities or even waterslides.

Transportation Engineering

The quality of a community is directly related to the quality of its transportation system. Transportation engineers work to move people, goods and materials safely and efficiently. They find ways to meet our ever-increasing travel needs on land, air and sea. They design, construct and maintain all types of transportation facilities, including airports, highways, railroads, mass transit systems and ports. An important part of transportation engineering is upgrading our transportation capability by improving traffic control and mass transit systems, and by introducing high­speed trains, people movers and other intermodal transportation methods.

Construction Engineering

The construction phase of a project represents the first tangible result of a design. Using technical and management skills, construction engineers turn designs into reality ­ on time and within budget. They apply their knowledge of construction methods and equipment, along with the principles of financing, planning and managing, to turn the designs of other engineers into successful facilities.

Urban and Community Planning

Urban and Community Planners are concerned with the full development of a community. They analyse a variety of information to co-ordinate projects, such as projecting street patterns, identifying park and recreation areas, and determining areas for industrial and residential growth. They employ their technical and people skills to co-ordinate with other authorities to integrate freeways, airports and other related facilities.

Whatever area a civil engineer choose, be it design, construction, research, planning, teaching or management, civil engineering offers him a wide range jobs for his career choices.