Construction technology and environmental services

Question 1

What is Substructure?

Answer 1

Lower part of the building which is constructed below the ground level

Question 2

What are the factors to be considered while planning site layout?

Answer 2

Safety, Site accessibility, Security, Offices, Accommodation, Material Storage, Parking, Hard standing of heavy equipment, Pump station, Batching plant, Fabrication, etc shops

Question 3

What is the purpose of Site Investigation?

Answer 3

“To determine the suitability of the site for the proposed works and determine
adequate and economic foundation design (or route of an infrastructure project).
 To determine potential construction difficulties.
 To determine any drainage or soil improvement requirements.
 To prevent building failure due to subsidence, settlement or seismic activity.
 To mitigate impact on environment.
 To determine costs and duration of the project.
 The method chosen will depend on type of building, anticipated depth of
foundations and expected type of sub-soil.”

Question 4

What is the purpose of Soil Investigation?

Answer 4

“ To find seasonal volume changes in the soil
 To determine the nature and composition of the sub soil
 To determine the physical properties of the sub-soil
 To determine the bearing capacity of the sub soil
 To predict the likely behavior of the subsoil under seasonal and ground water level changes
 To ascertain the possibility of ground movement”

Question 5

How do you decide about most suitable construction method for a building?

Answer 5

“It depends on cleinet brief, budget, time, cost, ease of installation, sustainability, type of project, risk etc.
Location - if the construction site is near to beach, I will recommend to RCC building, For temporary building as part of dissaster management, I will recommned to use fabricated buildings, modular, if the project in the city center, I will recomment to use steel structure, it will faster and less pollution, less noisy.
“

Question 6

Advise interpretation of soil investigation report ?

Answer 6

“There are several purpose of the soil investication report.
1. Design the foundation
2. Identify the esiting existing utilities
3. Soil types
4. Water table”

Question 7

What is the ground improvement?

Answer 7

Ground improvement is improving poor soil condition, increase the bearing capacity of the soil. Ground improvement techniques are Vibration, Dynamic Compaction, Jet Grouting.

Question 8

What are the soil compaction methods available in construction projects and explain those?

Answer 8

The method of compaction is primarily of four types such as kneading, static, dynamic or impact and vibratory compaction

Question 9

What are the dewatering methods available?

Answer 9

“A process of removing water and/or lowering the Water Table within a construction site to provide a dry working platform: -
If the Water Table is above the working platform; Option:
1. Keep water out
2. Let water in & remove it
3. Combination

There are different types of dewatering methods used in different scenarios.
Most common types of dewatering methods will be;
 Well point system
 Shallow wells with pump
 Deep wells with pump
 Gravity drainage”

Question 10

What are the foundation types used in Dubai, Bahrain and KSA?

Answer 10

“Types of pad foundation;
* Isolated pad foundation
* Combined pad foundation
* Continues pad foundation
* Pad foundation with continues beam
There are benefits by using draft foundation in UAE
* Soil in the UAE is fine particles, air cap is less, therefore less settlements with draft foundation.
* Use as basement car park”

Question 11

What are the soring method available?

Answer 11

There are 5 shoring methods, H or I beam shoring ceacant plie, contingency pile, sheet piles, Diapramwall.

Question 12

What are the different types of pad foundations available in the construction industry? What are the advantages in UAE soil condition by using a raft foundation?

Answer 12

“Types of pad foundation;
* Isolated pad foundation
* Combined pad foundation
* Continues pad foundation
* Pad foundation with continues beam
There are benefits by using draft foundation in UAE
* Soil in the UAE is fine particles, air cap is less, therefore less settlements with draft foundation.
* Use as basement car park”

Question 13

Can you explain some of the techniques to waterproofing a basement?

Answer 13

”- Tanking - Materials such as asphalt, polythene sheeting, bitumen, etc are applied internally or externally to provide a continuous membrane to the base slab and wall.
- Drained Cavity - This method accepts a small amount of water seepage will occur, Cavity wall are formed, the water seepage is collected in the cavity and drained or pumped away.”

Question 14

What is nominal mix and design mix of concrete ?

Answer 14

“Nominal mix concrete is basically calculated by volume cement, sand, water and aggregate based on required ratio.
Design Mix can be calculated based on weight or ready mix plant mix proportion.”

Question 15

What are types of piles?

Answer 15

“Based Structural behaviour Friction pipe and End bearing pile,
Based on method of construction cast in-situ pile and driven pile.
Based on material, Timber, metal sheet, Concrete”

Question 16

Explain the mechanism of end bearing piles and friction piles?

Answer 16

Frictional Piles works on the static friction developed between the surface of the pile and soil where it is placed. Where as End-Bearing Piles are driven till hard strata of soil is achieved.

Question 17

In what senario might a pile foundation be the best solution for the Project?

Answer 17

“1. Where the structure is heavy and the underlying soil is weak.
2. In areas where settlement issues are common.
3.Where the sub-soil water table is high.
4.Where the load distribution of the structure is not uniform.
5.Presence of horizontal forces.”

Question 18

Can you explain how end bearing and friction pile transfer the load to the building.

Answer 18

“End bearing piles - The bottom of the pile rests on a layer of stong soil or rock, the load of the building is transferred through the pile onto the strong layer.

Friction piles - Friction piles work on a different principle, friction piles developed most of the pile bearing capacity by shear stresses along the sides of the pile. In other words, the surface of the pile works to transfer the forces to the soil.”

Question 19

What are the difference between bored pile and driven pile?

Answer 19

The fundamental difference lies in their point of the manufacture. A driven pile is formed off site under factory-controlled conditions and a bored pile is manufacture on site.

Question 20

What are the key advantages and disadvantages of driven pile?

Answer 20

“Advantages
1. Pile can be precast to the required specifications.
2. Piles of any size, lenth and shape can be made in advance.
3. A pile driven into granular soil compacts the adjacent soil mass, the bearing capacity of the pile may increase as a result.
4. Fast, neat and clean installation.
Disadvantages
1.Required heavy equipment for handling and delivery.
2.Increased noise and vibration generated by driving the piles.
3.Can be costly if piles are too short.”

Question 21

What are the key advantages and disadvantages of bored pile?

Answer 21

“Advantages
1.Any size or shape of pile can be formed on site.
2. No risk of damage during delivery and handling.
3. Reduced vibration and noise.
Disadvantages
1. Significant spoils are generated that need to be handled.
2. Reliance and coordination on multiple trades ( reinforcement crew, piling crew, and concrete suppliers)
3. Unlike driven piles, bored piles do not improve the bearing capacity of the ground.”

Question 22

What are secant pile walls?

Answer 22

”- A wall is formed by installing interlocking piles which create a soil barrier free of gaps.
- Typically used to forms retaining wall.”

Question 23

What is underpinning any why might it be required?

Answer 23

“Underpinning is a method for repair and strengthing the foundations.
- Stabilising foundation undergoing settlement.
- Stabilising foundation that have moved because of landslips or unstable slope.
- Stabilising foundation affected by erosion, subsidence, or heave,
- Stabilising foundation affected by vibration damage.
- To increase the load capacity of the existing foundation.
- To accommodate a new adjoining building, new basement, or deep sewer.”

Question 24

What are the NDRC types?

Answer 24

Non Disruptive Road Crossing

Question 25

What are Two way slab and one way Slab?

Answer 25

“Both slab are designed with a reinforcement. However, reinforcement arrangment is a key difference.
In two way slab main reinforcement bar in both side shorter and longer, and it is supported by the beam on four sides of the slab.
In one way slab, The main reinforcement bar is a bottom bar laying shorter span, and distribution reinforcement in longer span. one way slab is supported by beam in longer span.”

Question 26

What is the difference of post-tension and pre-tension concrete?

Answer 26

Pretension is the technique in which we are imparting tension in tendons before placing the concrete. Post tensioning is done by forming a duct in which tendons are pulled (tensioned) after the concrete gains it’s full strength

Question 27

What are the advantages and disadvantages of PT slabs?

Answer 27

“Advantages;
1. Reduced cost: Post tension slabs are excellent ways to construct stronger structures at an affordable price. There are many structures like parking garages as well as stadiums, since they are required to hold much more weight than average buildings, this slab becomes a viable option.
2. Flexibility in design: The designs made with this slab are sleek, require lesser space and give way to dynamic contours. All this makes them ideal for the expression of creativity in the building design.
3. Lesser usage of materials: Since the post tension slab is thin, the materials used with it are also lesser. Be it the thin beams, walls or supporting pillars of buildings, this compact concrete slab does not need bulky materials.
4. Durability: Being a very strong substitute of the normal concrete, it lasts longer.

Dis-Advantages;
1. Corrosion - Since there are a number of tendons and wires spread inside the post tension slab, it can result in corrosion. But largely, this tendency to corrode depends on the quality of the material used.
2. Complexity of work: The post tension slab can be made only by skillful professionals. The local workers may not have the necessary skills required to prepare this complex slab.
3. Poor workmanship can lead to accidents: The main problem with using post tension slab is that if care is not taken while making it, it can lead to future mishaps. Many a times, ignorant workers do not fill the gaps of the tendons and wiring completely. These gaps cause corrosion of the wires which may break untimely, leading to some untoward events.
4. Skills”

Question 28

Comparison about steel and concrete structure ?

Answer 28

Steel building is quicker, easy to erect, less manpower required but concrete building will take more time, and possible to build different type of shape and façade, no sustainability, it give an aestetic appearance. Concrete structure more fire resistance.

Question 29

For a project in city Centre (within the city area), what do you recommend concrete structure or steel structure, why?

Answer 29

in the city area, there will be heavy traffic flow and the space issues to handle the materials and equipment’s. Therefore, I suggest to go for the pre fabricated steel work which will expedite the construction process.

Question 30

What is Lean concrete?

Answer 30

Lean concrete is used for leveling the surface and this is the thin concrete. Also, it is call as a screed.

Question 31

Explain about the concrete test?

Answer 31

“There three type of concrete test available
1.Slump Test 2. Cube Test 3. Thermal Test”

Question 32

what is green concrete and its purpose? are you recommend green concrete?

Answer 32

“Green concrete is sustainable concrete produced using low Portland cement
component and replaced it with the fly ash, which is by product of the iron and
steel manufacturing. The green concrete will be more sustainable as the
production of the cement will be reduced and it is co2 emission will be
drastically reduced.

I will highly recommend the product to be used in the constructing industry as
the carbon foot print is one of the highest in KSA. Hence as a professional I will
have to contribute he sustainable measures within my capacity”

Question 33

What is GGBS?

Answer 33

“Ground Granulated Blast Slag - Supplementary Cementing Materials.
SCM to OPC ratio is a mixture made of 64 per cent GGBS and 34 per cent OPC.”

Question 34

What are the disadvantages of steel frames?

Answer 34

”- Typically, steel frames have a lower load bearing capacity compared to concrete frames.
- Fire protection may be required.
- Price of steel can be volatile.
- Steel frames do not have the same accounting and thermal properties of a concrete frame.”

Question 35

What are the key advantages of concrete frames?

Answer 35

”- Fire protection is inherent in hte structure.
- Cladding and other finishes can be fixed direct the the frames.
- Provide good sound and heat insulation.
- High compressive strength.”

Question 36

What are the key disadvantages of concrete frames?

Answer 36

”- Require formwork.
- Slower to construct on site
- Required by bulky structure
- Concrete does not span as wll as steel.
- Long curing time - maximum strength is typically achieved after 28 days.”

Question 37

What is dynamic compaction?

Answer 37

This is a method of soil improvement which consists of dropping a heavy weight through a considerable vertical distance to compact the soil and thus improve its bearing capacity and is especially suitable for granular soils.

Question 38

What are the type of Slab available?

Answer 38

“There are various types of using I the construction industry depend on
the design requirements.
The most popular types of slab is conventional slab which is having two variants one way slab and two way slab.
The other popular type of slab is flat slab which is having four variants
depending on the drop panels and column heads.
Other than that there are hollow core slab, post tension slab, pre tension slab and
composite slab are used in the industry.”

Question 39

What is the best partition type for the meeting room?

Answer 39

Dry wall partition with acoustic sound proof is more ideal as it have a great sound proof, it is flexoible to make parts.

Question 40

What are the key considerations when designing external walls?

Answer 40

”- Weather protection
- Fore resistance
- Accounting requirements
- Thermal performance
- Structural performance
- Appearance /aesthetics.
- Expected lifespan
- Future maintenance.”

Question 41

What is double skin glazing? What is the standard size of a brick?

Answer 41

“The glazing includes double layer of glass with void in between.
Generally external glass are tempered glass for reduce thermal conductivity and inner glass will be clear glass.”

Question 42

What is rainscreen cladding used for?

Answer 42

”- A system which manages the flow of rainwater on a building.
- The system is not necessarily waterproof itself but services as a screen and protection against rain for the rest if the building.
- Two key types of system:
a. Drained & ventilated system.
b. Pressure - equialised systems.”

Question 43

Can you explain how siphonic drainage system works?

Answer 43

”- Siphonic drainage systems contain an anti-vortex plate which acts as a baffle and prevents air (and debris) from entering the piping ststem a full flow, allowing the pipes to completely fill up with water.
- The water is sucked or siphoned from the roof down into the drain at high velocity. The lack of air and the downward pull of the water creates a vaccum, making the drainage process fast and efficient.”

Question 44

What is the difference between dead loads and live loads on a structure?