Shape test on coarse aggregates constitutes flakiness Index and elongation index tests. The particle size and shape of aggregate is one of the major factors affecting the quality of the concrete.
Shape test on coarse aggregate – Flakiness index test
The particle shape of aggregates is determined by the percentages of flaky and elongated particles contained in it. for concrete and construction of bituminous works the presence of flaky and elongated particles are not suitable and cause failures and breaking during heavy loads.
The Flakiness index of aggregates is the percentage by weight of particles whose least dimension (thickness) is less than three- fifths (0.6times) of their mean dimension. This test is not applicable to sizes smaller than 6.3mm
The Elongation index of an aggregate is the percentage by weight of particles whose greatest dimension (length) is greater than nine-fifths (1.8times) their mean dimension. This test is not applicable for sizes smaller than 6.3mm.
Flake materials may cause voids in concrete and has to be kept under limit to ensure the quality of the concrete.
Relevant IS codes:
IS:2386(PartI)-1963
Apparatus used
Weighing machine
Metal gauge
IS sieve
Test procedure
First we have to find the flakiness index.
Dimensions of thickness and length gauges
For finding the flakiness index, we have to test at least 200 pieces of any fraction and weigh them.
Then sieve the sample through IS sieves according to the table below.
After that to determine the flakiness index separate the aggregate retained in the sieve.
Then pass each aggregate through the corresponding slot in the thickness gauge.
Finally, we calculate the flakiness index.
The flakiness index is the total weight of material passing through the gauge to the total weight of the sample. It is expressed in terms of percentage. Weigh the flaky material passing the gauge to an accuracy of at least 0.1 per cent of the test sample.
The formula for flakiness index is
F.I = (Weight of aggregate passing through the slot of the thickness gauge / Total weight of the sample) * 100
Shape test on Coarse Aggregates- Elongation index test
The presence of elongated particles in the aggregate is undesirable for construction. Also, this shape test is made in coarse aggregate. The elongation shape test is not applicable for aggregates with a smaller size than 6.3 mm.
Relevant IS codes:
IS:2386(PartI)-1963
Apparatus used
Weighing machine
Metal gauge
IS sieve
Test procedure
For finding the flakiness index, we have to test at least 200 pieces of any fraction.
Then sieve the sample through IS sieves according to the table below.
After that pass, each fraction through the gauge individually.
Now using a weighing machine, weigh the total amount of fraction retained.
Finally, we calculate the elongation index.
The elongation index of an aggregate is the weight of the particle whose greatest dimension is greater than 1.8 times its mean dimension.
The formula for elongation index is
Shape test on aggregates
E.I = Weight of the aggregate retained on length gauge / Total weight of aggregate x 100
Conclusion
The shape tests give only a rough idea of the relative shapes of aggregates. Flaky and elongated particles should be avoided in pavement construction, particularly in surface course.
Timber is wood suitable for construction purposes. In order to find the quality and sustainability of the Timbers, Various Quality tests are performed.
They are natural polymeric material that nearly does not age. Moreover, the structure of the wood ensures efficient strength and load capacity. Wood can be split into two classes. They are natural and man-made. Hence some examples of man-made timber are plywood, fibreboard, impregnated wood, etc.
PROPERTIES OF GOOD QUALITY TIMBER
The timber should posses the following qualities.
It should have a good uniform dark colour.
Timber should be free from defects such as shakes, flaws, dead knots, etc.
It should possess regular annual rings.
The freshly carved surface of the wood should have a sweet smell.
Moreover, It should have a heavyweight.
The cellular tissue and fibres should be compact and hard.
A good timber should be durable and possess elasticity.
It should be resistant to fungus, insect, etc.
Also, timbers with compact texture have good resistance to fire.
It should be inert from mechanical, chemical and physical agencies.
A good quality wood should hold loads from structures.
In order to find the quality and sustainability of the Timbers, Various Quality tests are performed. In this article, we have listed a few test procedures.
Moisture content test
Tensile strength test
Compressive strength test
Shear strength test
Bending test
MOISTURE CONTENT TEST OF TIMBER
This test determines the moisture content in wood. However, wood contains a small amount of moisture content. A weighing machine and a drying oven are important apparatus for the water absorption test.
moisture content test of timber
Relevant IS codes:
IS I 2380 ( Part VI ) – 1977
Test procedure
Initially, Take the specimen with a size of 5cm x 5cm x 2.4cm.
Then using a weighing machine weigh the specimen. Mark it as W1.
After that oven-dry the timber at a temperature of 103-degree celsius.
Later, take out the specimen when becomes dry.
Again weigh and mark the weight of the dry specimen as W2.
Finally, calculate the percentage of moisture content by
% of moisture content = Weight of moisture in sample/ Dry weight of sample = (W1 – W2)/ W2
TENSILE STRENGTH TEST OF TIMBER
The tensile strength test defines the strength and ability to withstand breaking. Also, we can determine the load-carrying capacity of the wood.
Relevant IS codes:
IS I 2380 ( Part VI ) – 1977
Test procedure
Tensile test on timber
Firstly, take a specimen with 5cm x 5cm and 20cm in length.
Then place the specimen on the base plate of the instrument.
After that apply load either parallel or perpendicular to the grains.
Mark the load at which the wood breaks.
Finally, calculate the tensile strength of the wood.
Tensile strength = Maximum load applied / Cross sectional area
COMPRESSIVE STRENGTH TEST
The compressive strength test defines the crushing strength of the timber. Furthermore, this test determines the load which the wood can support over a period.
Relevant IS codes:
IS I 2380 ( Part VI ) – 1977
Test procedure
Compressive test
Initially, take a specimen with a size of 5cm x 5cm x 20cm.
Then place the specimen in the compressive testing machine.
Following this, apply load parallel to the grains.
The specimen should be free from defects. Gradually increase the load.
Then note down the load at which the timber breaks.
Lastly, calculate the compressive strength from the below formula.
Compressive strength = Load at which the specimen breaks/ Total area of the specimen
SHEAR STRENGTH TEST
The shear strength is important when timber is used as slabs. The load should be applied parallel to the grains.
Relevant IS codes:
IS I 2380 ( Part VI ) – 1977
Test procedure
Shear test apparatus
The size of the specimen for shear strength is 5cm x 5cm x6.25 cm.
Then cut the corner of the specimen.
Thus it produces failure on 5cm x 5cm surface.
However, this failure occurs tangentially or radially.
BENDING STRENGTH TEST
The Bending strength test is necessary when we use timber as a beam. Through this test, we can find the modulus of rupture and modulus of elasticity.
Relevant IS codes:
IS I 2380 ( Part VI ) – 1977
Test procedure
Bending test on timber
For this, take a specimen of 5cm x 5cm x 7.5 cm in size
The specimen should be free from defects and deterioration.
Then drop a hammer with specific weight from a certain height.
Thus we get the impact bending.
Lastly using the load and deflection, calculate bending strength.
Prefabricated construction, or “prefab,” is a method of construction that uses components made off-site in a factory, which are then transported put together on-site to create a structure. Prefabrication is an amazing technology that helps to reduce time and have many more benefits.Construction has always been about the speed and efficiency that can be ensured with the materials and techniques of construction.
In this blog, we will find out all the details about the same.
Let’s start from the definition.
What is prefabrication?
Prefabricated construction, or “prefab,” is a method of construction that uses components made off-site in a factory, which are then transported put together on-site to create a structure.
With different advantages to offer, there are a few different common types of prefab. You may want to consider incorporating any of these solutions, depending on your particular building project.
So, that’s the basic details. We will discuss about the benefits in next section.
It is already difficult for contractors to find labour, but construction still needs to take place.
It decreases labour productivity much more as on-site building continues piecemeal.
Therefore, prefabrication helps businesses speed up timelines, make the most of their on-site labour, improve efficiency, and succeed in the marketplace.
It also costs less to transport partial assemblies from a factory than to move pre-production resources to each site.
Plus, as labour efficiency increases, personnel-related costs decline.
3. Time savings:
Time is the essence of the rainy season, and prefabrication will help you manage tighter timelines.
4. Quality control:
Factory tools can provide added quality assurance as opposed to repetitive construction on-site.
In addition, consistent factory indoor environments remove much of the weather effects on manufacturing, while streamlined manufacturing and production improve job site safety on the whole.
Accelerated offsite production of parts results in reduced emissions and work disruption.
This preserves wetlands or protected areas nearby and minimises local flora and fauna disturbance.
The controlled, dry environment of modular construction saves water consumption and allows scrap and other materials to be recycled.
Plus, fossil fuel consumption plummets with less on-site traffic and streamlined transportation.
6. Better safety and security:
By reducing a construction site’s timeframe, you simultaneously decrease the amount of time that the site is vulnerable to vandalism or robbery.
7. Flexibility:
It is easy to disassemble and move modular construction to various sites.
This greatly decreases the demand for raw materials, minimises the resources spent and overall reduces time.
Modular construction also allows for versatility in the structure’s design, allowing for an infinite number of possibilities.
Since prefabricated building units can be used in various spaces, their neutral aesthetics can be combined with almost any form of construction.
8. Reduced Site Disruption:
There is much fewer truck traffic, machinery and material suppliers around the final construction site as several parts of a building are completed in the factory.
The disturbance of conventional workplaces suffering from noise, emissions, waste and other common irritants is therefore minimal.
This structured design approach offers a much more productive productivity environment and removes unwanted disruptions and interruptions typical of construction sites.
Time to know the challenges of prefabrication.
Challenges of Prefab Construction
Construction site of prefabricated building
The joints to be given should be well-built enough to convey all sorts of stresses, connecting the core structure and the components.
The strength and solidity of the whole building totally depend on the strength of the joint.
Therefore, rather than component-based analysis, it is important to have detailed studies on the whole system.
One of the key challenges in embracing prefabrication technology in construction requiring accuracy and precision is the need for skilled labour on-site and the lack of on-site automation.
Skill development and native automation are also mandatory for prefabricated systems to be installed.
It is likely to get damaged during the erection or transport of heavy machinery units, so the arrangement of the units must be performed precisely and this process in a congested area becomes sloppy.
Labour maintenance is another concern because prefabricated construction requires skilled labour as it differs from in-situ construction, which requires machine-oriented expertise both on-site and in the production process.
Now, let me show you the advantages of prefabrication
Advantages of Prefabrication
Prefabrication technology has several advantages, such as energy efficiency revision, minimal waste and inspection, efficient construction, work speed, protection, sustainability and quality.
As self-supporting ready-made components are used, the need for formwork, shuttering and scaffolding is substantially lowered.
Building time is thereby decreased, resulting in lower labour costs.
Reduced the quantity of waste materials relative to building on site.
Reduction in construction time to allow an earlier return of the invested principal.
Construction guarantees precise compliance with building codes and excellent quality assurance.
Along with quality control and factory sealing, high-energy performance.
It is possible to place prefabrication sites where skilled labour is more readily accessible and the costs of labour, electricity, materials, space and overhead are reduced.
Prefabrication permits building throughout the year, regardless of the weather (related to excessive cold, heat, rain, snow, etc.).
Material waste from the building is less.
Regardless of climatic conditions.
Security and worker comfort levels are higher in the off-site building.
Last, but not the least the disadvantages should be known.
Disadvantages/Limitations of prefabrication
Material assembly for prefab construction
The subsequent constraints are known to have restricted design choices, decreased reselling value, high initial expenditure, non-suitability for foundation and precast unit transport.
There are even more drawbacks. They are the following:
Leakage occurs in joints in prefabricated parts.
For huge prefabricated parts, transportation costs can be high.
To ensure affordability through prefabrication, increased production volume is required.
Initial costs for construction are higher.
The initial production of designs is time-consuming.
Large prefabricated parts require heavy-duty cranes and measurement of precision from handling to position on site.
Local employment can be lost, as skilled labour is needed.
Modular building design and construction requires high levels of cooperation between project parties, particularly architects, structural engineers and manufacturers.
These buildings usually depreciate more rapidly than standard site-built housing due to their shorter economic existence.
Hope the time you spent for the article was worth it. Let me know if you have any doubts in comments.
Aggregate crushing test is done to find out the strength of aggregate which is the fundamental and essential components of concrete, flexible pavements, etc. More than 70 to 80 per cent of the volume of concrete is aggregate. Aggregates are a very important component of concrete, so the quality really matters when it comes to aggregates. Furthermore, their uses include flexible pavements, railway ballast, etc.
Different tests are to be performed to ensure the quality requirements of aggregates for the specific uses.
Tests on aggregates
Different types of tests are done to determine their properties like
Following are the types of aggregate tests conducted to ascertain the suitability of aggregates.
Aggregate Crushing test
Abrasion test
Impact test
Water absorption test
Flakiness index test
Elongation index test
Bulk specific gravity test
Polishing test
Aggregate Crushing test (IS 2386(Part 4):1963 & BS 812–110:1990)
Aggregate crushing test values indicates the strength of aggregate and hence it is very significant. Similarly we can say crushing value is the relative measure of resistance of an aggregate under gradually applied compressive loads. Higher crushing strength means lower crushing value and vice versa. If the aggregate crushing value is less than 10, means an exceptionally strong aggregate, Whereas crushing value of 35 and above means a weak aggregate.
Relevant codes for aggregate crushing test
IS 2386(Part 4):1963
BS 812–110:1990
Apparatus required
Compressive Testing Machine
Crushing Mould: A steel cylinder 15 cm diameter with plunger and base plate.
Weighing machine,
Sieve: Size of 12.5 mm, 10 mm and 2.36 mm
Aggregate crushing value test apparatus
Aggregate crushing Test procedure
Oven dry the aggregates
Firstly, sieve the aggregate using Indian standard sieves.
Then collect the specimen passed through 12.5 mm and retained on a 10mm sieve.
Thus is the test sample of aggregate.
Then put the cylinder on the base plate and weight it (W).
The aggregate sample should be filled in 3 layers , each layer is subjected to 25 strokes using tamping rod.
After that weigh the materials with cylinder and record as (W1)
Weight of aggregate will be (W1-W). ie : (Weight of cylinder with aggregates – Weight of cylinder)
Level the aggregate surface carefully before inserting the plunger so that it rests horizontally over the surface.
Place the cylinder with plunger below a compression testing machine.
Apply load at a uniform rate so that a total load of 40T is applied in a span of 10 minutes.
Then release the load and remove the material from the cylinder.
Following, sieve again on 2.36mm IS sieve.
Then weigh the material passing through the sieve and record it as W2.
Finally, calculate the specimen crushing value using the formula below.
Aggregate crushing value = (W2 x 100) / (W1-W)
W1-W = weight of dry sample
W2 = Weight of fraction passing through the sieve after application of load.
For a good quality aggregate, the crushing strength value is low.
Recommended crushing values
Flexible pavements
Crushing value
Soling
50
Water bound Macadam
40
Bituminous macadam
40
premix carpet
30
Dense mix carpet
30
Rigid pavements
Other than wearing course
45
Surface or Wearing course
30
The aggregates used in roads and pavement construction must be strong enough to withstand crushing under roller and traffic. If the aggregate crushing value is 30 or higher’ the result may be anomalous and in such cases the ten percent fines value should be determined instead.
Reservoirs are artificial or natural structures used for collecting and storing for further usages. The reservoir is formed by constructing dams across rivers, valleys, and streams. The Reservoir is located on the upstream side of dams and prevents floods by managing the water flow apart from serving as a storage basin.
Reservoirs are broadly classified into three types.
Valley dammed reservoirs
Back-side reservoirs
Service reservoirs
Valley dammed reservoirs
Valley dammed reservoirs are located between mountain valleys where there is an existing water body. A dam is built in the narrowest portion for holding the water.
Bank-side reservoirs
Bank side reservoirs are made by diverting water from rivers and streams to an existing reservoir. These reservoirs can be located in different geographical locations.
Service reservoirs
Service reservoirs are man made reservoirs located above the ground or below the ground. The huge water towers/ water tanks and sumps are service reservoirs.
Service reservoir
Reservoir components and terms
There are some specific terms for defining the water level and storage capacity of a reservoir
Pool level
The water level at a particular point of time is called the pool level. No water can be collected above the maximum pool level. No water can be drained below the minimum pool level.
Useful Storage
The volume of water within the normal pool level and minimum pool level is known as useful storage.
Dead storage
The volume of water underneath the minimum pool level is known as dead storage.
Surcharge Storage
The volume of water within the normal pool level and maximum pool level is known as surcharge storage.
Reservoir yield
The volume of water discharged within a certain interval of time is reservoir yield.
Reservoir Planning
Accurate planning is necessary for locating a reservoir. For planning a reservoir the following points are taken into consideration.
Topography
A Broad natural valley opts as the site of a reservoirs. The valley can be U- shaped or V-shaped. For reservoirs sites, flatland and plains are not considered.
Ground water condition
The groundwater investigation is done by analysing the water table level and reservoir level.Hence it is an ideal situation for the reservoirs site if the water table level and the top reservoir level is the same. No loss or gain is ensured.
Permeability
Permeability is a default nature as the rocks are porous. It is considered when the water table is below the reservoirs level. It is a significant characteristic for investigation.
Hydrological Investigation
This involves the study of runoff pattern. Leakage quantity should be minimum. Storage capacity calculation and maximum discharge rate are also estimated.
Difference between dams and reservoirs
DAMS
RESERVOIR
Structural barriers built across,rivers valleys,streams etc for the purpose of storing and managing water flow.
Reservoir is a large water body formed behind the constructed dam structure across a river,stream,etc
Dams are reinforced concrete structures or structures made of bricks rubble etc erected across water bodies to control the water flow.
The reservoir is the water that accumulates behind the constructed dam.
Create site for hydro electric power generation. This can improve the industrial development and living standards of people living in that region.
Stores water for later usage, water for human consumption and excess water for agricultural and industrial uses.
Dams fluctuates oxygen levels and restricts migration of fishes in the river.
Reservoirs leads to the displacement of people.
Dams are tourist attraction sites
Helps in water transportation
Reservoir Sedimentation
Rivers transport sediments. During heavy rainfall, sediments are carried by the water to the reservoir. Silts are accumulated due to soil erosion. These get collected in the dead storage. Sedimentation depends on Rainfall intensity, Soil nature, Soil type, topography and vegetation. The sediment deposit replaces the water storage. Thus water supply and flood control are affected. The sediments should be removed eventually. Hydraulic flushing, dredging, Explosive mobilization are methods adopted for sedimentation removal.
reservoir
Environmental impacts of Reservoirs.
The construction of the reservoir prompts severe effects on the environment.
Since the water is stored, the rate of transpiration is high. This changes the moisture concentration.The climate of the surrounding area is affected. It causes natural temperature fluctuation. This causes heavy rainfall and deprives the traditional rainfall patterns.
Reservoirs disturb the flow and composition of the rivers. The water from the downstream has high energy, it enhances the water flow by eroding the river bed.
The change in the river composition affects the upstream and downstream habitats. The reservoirs disturb the fish and birds migration.
Studies show that reservoirs emit greenhouse gases. Anaerobic bacterias are seen in the river bed releases carbon dioxide and methane. This occurs in tropical regions.
They also cause troubles for people living near the reservoir site. Old and failing dams lead to disasters.
Reservoir induced seismicity is a phenomenon of provoking earthquake by reservoirs. This happens when water sweeps into the minor cracks under the bed.
Total station in surveying is used for computing slant distances, horizontal and vertical angles, elevations in topographic and geodetic works, tacheometric surveys, etc. The total station is a pre-eminent contribution to modern surveying and hence the equipment is designed for speed, range, and accuracy. They are a combination of Theodolite and Electronic Distance measurement (EDM). This enables computing the vertical, horizontal as well as slope measurements.
They act as a substitute for theodolite, EDM, Data collectors, and Microprocessors. Moreover, they are lightweight and compact machines and perform like transit stadia and plane table alidades.
The integration of microprocessors helps in the data collection and measurement computation process. Further to that, the inbuilt software helps to generate the maps instantly.
Apart from taking the measurements, the total station helps in computing, interpreting, and documenting the data. Here is a list of activities that are computed, interpreted, and analyzed.
The total station consists of a built-in emitter, capable of emitting microwaves and infrared signals. The wavelength of these emitted waves helps in calculating the distance between the points. Distance = velocity * time
Here the distance is calculated by multiplying the time taken to cover a certain distance by the velocity. However, Triangulation and trigonometry methods are adopted for computing the angles and determining the coordinates.
The Equipment is composed of different parts. Below listed are the major components.
Components
Components of total station
Handle
Handle securing screw
Data input/output terminal (Remove handle to view)
Instrument height mark
Battery cover
Operation panel
Tribrach clamp
Baseplate
Levelling foot screw
Circular level adjusting screws
Circular level
Display
Prism and prism pole
Objective lens
Tubular compass slot
The optical plummet focusing ring
Optical plummet reticle cover
Optical plummet eyepiece
Horizontal clamp
A horizontal fine motion screw
Data input/output connector
External power source connector
Plate level
Plate level adjusting screw
Vertical clamp
A vertical fine motion screw
Telescope eyepiece
Telescope focusing ring
Peep sight
Instrument centre mark
A tripod enables one to affix the equipment onto the ground. A handle is available on the top of the equipment for holding it. There are a Data input and output terminal below the handle enabling the data transfer to the computer. The total station comes with inbuilt software, an operation panel, a keyboard, and a screen. The prism and prism poles help in measuring distances.
Total station applications
The total station consists of an EDM, Theodolite, and a Microprocessor combined into one. They got a memory card for data storage and a battery. A fully charged battery works for about 3 to 5 hrs continuously.
Coordination determination
Distance measurement
Angular measurement
Data processing
Coordination Determination
The total station determines the coordinate of an unknown point. The instrument is placed over a known coordinate. The equipment digitally computes the coordinates.
Distance measurement
As mentioned earlier, the total station got an inbuilt miniature emitter. The emitters release microwave signals. The prism reflector or object under survey at the other end reflects the waves. Onboard data interpreters compute the distance by emitting and receiving multiple frequencies.
Angular measurement
The total station uses the distance between the point and the time taken by the waves reflected for deciding angular measurement.
Data processing
The integration of the microprocessor in a total station helps to read and interpret the survey parameters. Subsequently, the data is stored in the memory card of the instrument and later transferred to a computer. They can compute multiple measurements with high precision with compensation for temperature, pressure, and humidity corrections.
Setting up of a total station
The basic steps involved in setting up are tripod setup, levelling, and instrument focusing.
The tripod legs are placed firmly on the ground with equidistant legs with the head position above the survey point.
The total station is placed on the tripod. It is fixed and secured using a centring screw.
The next step is to sharpen the optical plummet towards the survey point. On sharpening, the optical plummet reticle centres the survey point.
The bubble is adjusted to the centre by levelling foot screws
The time taken for levelling the equipment depend on the skill of the operator. However, levelling is the topmost activity to maintain the accuracy of measurements.
Adjust the plate level by loosening the horizontal clamp. The equipment is parallel to levelling foot screw.
Turn the instrument at 90 degrees and level using a 3rd levelling screw.
Subsequently, turn on the instrument.
Select the tilt function from the opening window followed by adjusting the foot level screw and centre the bubble.
Rotate the instrument at 90 degrees. Repeat the process.
Finally, adjust the ring and focus the telescope on the target point.
Total station prism
Advantages of Total station
There are a lot of advantages of total station as mentioned below
High precision and accuracy.
Requires limited manpower
Perform quick fieldwork
Reduction in manual errors.
Correction for temperature, pressure etc and digitally rectified.
Storage and interpretation of data are easy
Time consumed is less.
Inbuilt GIS software helps in instant map creation
Assists in local languages.
Disadvantages of Total station
The cost of the instrument is high.
Need highly skilled surveyor with AutoCAD knowledge and professional training.
Checking errors during the operation is impossible.
Low battery life.
Key Takeaways
Functionality: Total station integrates Theodolite and Electronic Distance Measurement (EDM) for precise surveying.
Components: Includes emitter, microprocessor, prism, and multiple control interfaces.
Applications: Measures horizontal/vertical angles, distances, coordinates, and calculates areas/contours.
Working Principle: Uses microwaves/infrared signals to compute distances via time and velocity; angles through triangulation and trigonometry.
Advantages: High precision, reduced manual errors, quick data processing, minimal manpower, and inbuilt GIS software for instant mapping.
Disadvantages: High cost, requires skilled operators, limited battery life, and no real-time error checking.
Setup Process: Involves tripod positioning, levelling, centring optical plummet, and adjusting levels and focus.
Conclusion
The total station revolutionizes modern surveying with its advanced integration of theodolite, EDM, and microprocessor technology. It enhances efficiency through precise measurements, quick data processing, and inbuilt mapping capabilities. Despite its high cost and need for skilled operation, the total station’s benefits of high accuracy, reduced manpower, and minimized manual errors make it indispensable in topographic, geodetic, and tacheometric surveys. Its ability to handle multiple functions—angle, distance, and coordinate measurements—streamlines surveying tasks, making it a valuable tool for civil engineering and related fields.
