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Questions and Answers
Silicone is used for ______ joint.
Silicone is used for ______ joint.
water tightness
Epoxy is typically used for concrete ______.
Epoxy is typically used for concrete ______.
spalling
There are three types of systems in curtain wall: Stick System, Unitised System, and ______ System.
There are three types of systems in curtain wall: Stick System, Unitised System, and ______ System.
Semi-Unitised
The position of each pile in the installation procedure is set out using a ______.
The position of each pile in the installation procedure is set out using a ______.
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The assembly of mild steel helmet and dolly serves to cushion the pile from hammer ______.
The assembly of mild steel helmet and dolly serves to cushion the pile from hammer ______.
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The boring will continue until the desired depth of the ______ is reached.
The boring will continue until the desired depth of the ______ is reached.
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The most popular displacement pile in Hong Kong is the ______ H Pile.
The most popular displacement pile in Hong Kong is the ______ H Pile.
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If the pile founding level is in a rock stratum, a reversed circulation ______ may be used to bore into the rock.
If the pile founding level is in a rock stratum, a reversed circulation ______ may be used to bore into the rock.
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A ______ is used for bored pile installation.
A ______ is used for bored pile installation.
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The minimum depth of penetration of the ______ is usually 300 mm.
The minimum depth of penetration of the ______ is usually 300 mm.
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Concrete is poured using ______ pipes to prevent segregation.
Concrete is poured using ______ pipes to prevent segregation.
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Predrilling is necessary for piles founded on ______.
Predrilling is necessary for piles founded on ______.
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Excavation is carried out within the ______ slurry to support the trench.
Excavation is carried out within the ______ slurry to support the trench.
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Hydrofraise/hydromill cutters will be used to cut through rocks or other ______.
Hydrofraise/hydromill cutters will be used to cut through rocks or other ______.
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The excavation of the trench is usually done in alternate ______ between the guide walls.
The excavation of the trench is usually done in alternate ______ between the guide walls.
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Dynamic load test and static load test are examples of common pile ______.
Dynamic load test and static load test are examples of common pile ______.
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The bentonite used in the excavation is treated (desanded) and will be re-circulated continuously during excavation by pumping from the trench to an elevated ______.
The bentonite used in the excavation is treated (desanded) and will be re-circulated continuously during excavation by pumping from the trench to an elevated ______.
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Vertical tubes (stop-end) are placed at each end to form a semicircular recess at the end of the ______.
Vertical tubes (stop-end) are placed at each end to form a semicircular recess at the end of the ______.
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Once the concrete is hardened, the ______ will be removed in preparation for bonding to adjacent panels.
Once the concrete is hardened, the ______ will be removed in preparation for bonding to adjacent panels.
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The top-down construction method can reduce the construction time for the ______.
The top-down construction method can reduce the construction time for the ______.
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Ground floor slab is ______ as part of the construction procedures.
Ground floor slab is ______ as part of the construction procedures.
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When the first level of basement is reached, beam and ______ will be constructed.
When the first level of basement is reached, beam and ______ will be constructed.
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Steel stanchions are punched through the concrete at bored piles’ ______.
Steel stanchions are punched through the concrete at bored piles’ ______.
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Excavation takes up a lot of time, but the top-down method allows for the basement and the ______ to be constructed at the same time.
Excavation takes up a lot of time, but the top-down method allows for the basement and the ______ to be constructed at the same time.
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The beam and slab system will act as the lateral support to the ______ wall.
The beam and slab system will act as the lateral support to the ______ wall.
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Temporary openings made in slabs provide access for the excavating ______ and allow the removal of soil.
Temporary openings made in slabs provide access for the excavating ______ and allow the removal of soil.
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For depths more than 20 meters, we should use diaphragm wall + ______ method.
For depths more than 20 meters, we should use diaphragm wall + ______ method.
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Continuous excavated to 4 meters, which is to +8m______.
Continuous excavated to 4 meters, which is to +8m______.
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A potential risk for building basements includes soil ______.
A potential risk for building basements includes soil ______.
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Precast concrete allows for reliable ______ control due to quality checks in factory settings.
Precast concrete allows for reliable ______ control due to quality checks in factory settings.
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Using robots and machinery in precast concrete production ensures consistent ______.
Using robots and machinery in precast concrete production ensures consistent ______.
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An advantage of precast concrete is lower labour costs due to the wage gap between ______ and China.
An advantage of precast concrete is lower labour costs due to the wage gap between ______ and China.
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To ensure safety on site, it's important to minimize work at ______.
To ensure safety on site, it's important to minimize work at ______.
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Using ______ machinery can help reduce the demand on a tower crane for lifting materials.
Using ______ machinery can help reduce the demand on a tower crane for lifting materials.
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Internal access roads need to be designed to allow vehicles to turn around on site for ______ operation.
Internal access roads need to be designed to allow vehicles to turn around on site for ______ operation.
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Prefabricated materials must be stored in an area that considers the ______ speed for quick access.
Prefabricated materials must be stored in an area that considers the ______ speed for quick access.
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Using ______ integrated methods can help minimize weather exposure during the construction process.
Using ______ integrated methods can help minimize weather exposure during the construction process.
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A ______ chamber provides a controlled environment for curing concrete.
A ______ chamber provides a controlled environment for curing concrete.
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The application of a waterproofing layer to the floor slab lowers the risk of water ______.
The application of a waterproofing layer to the floor slab lowers the risk of water ______.
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Having fewer separate operations in construction helps reduce conflicts among ______.
Having fewer separate operations in construction helps reduce conflicts among ______.
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Using precast elements guarantees a steady supply of ______ components.
Using precast elements guarantees a steady supply of ______ components.
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Precast construction methods are ______ friendly as they help reduce material wastage.
Precast construction methods are ______ friendly as they help reduce material wastage.
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Pre-tensioning of concrete can be more efficiently carried out in ______.
Pre-tensioning of concrete can be more efficiently carried out in ______.
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Using hollow units in construction can save materials and reduce the ______ load.
Using hollow units in construction can save materials and reduce the ______ load.
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The design of a thinner slab can lead to savings in ______ costs.
The design of a thinner slab can lead to savings in ______ costs.
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Study Notes
Pile Types
- Two main types of piles exist: displacement piles (e.g., steel-H piles) and replacement piles (e.g., barrettes).
Tremie Pipes
- Tremie pipes prevent concrete contamination during pouring.
Formwork Removal
- Walls and columns can be removed first as they support themselves.
- Beams and slabs require longer removal time due to lower support.
- Wall formwork needs removal within 24 hours.
- Beam and slab formwork removal takes about 2 weeks.
Dewatering Pumps
- Submerged pumps and suction pumps are used for dewatering.
Self-Compacting Concrete
- Self-compacting concrete is highly workable and pumpable.
- Superplasticizers are added to achieve this.
Fly Form/Table Form
- Fly forms are used for tall buildings.
- Relocation is time-consuming with fly forms.
- Telescopic extension legs can be lowered and removed.
- External perimeter allows for obstruction-free work.
- Fly forms are lifted to higher levels by tower cranes.
RC Beam Steels
- Continuous beams need top and bottom steel (cantilever and span).
- Columns need top steel (over columns) and possibly over multiple spans.
- Simply supported beams need only bottom span steel.
Precast Joints
- Two main joint types exist in precast construction: dry (sealant and gasket) and wet (Monolithic joint).
- Wet joints are better for preventing water leakage.
- Construction of an in-situ concrete topping gives a monolithic joint, better than relying on gaskets or sealing.
Construction Equipment
- Hydraulic vibrator machines provide a quieter work environment.
Fire Damage
- Structures lose half their strength at 600°C.
Material Handling
- Material hoists can be used for moving wall tiles between floors.
- Epoxy is suitable for concrete repairs, while silicone is suitable for sealing.
Formwork Cover Materials
- Plastic is suitable for covering formwork spaces.
Curtain Wall Systems
- Three curtain wall systems exist: stick, unitized, and semi-unitized.
- Unitised systems are more effective and economical.
Displacement Pile Installation
- Pile position is set out, and verticality is checked.
- Mild steel helmet and dolly are installed to the top of the pile to cushion the blows and distribute dynamic stresses.
- The first pile is then hoisted and placed in position.
- Regular checks on verticality are important during driving.
- Lengthening, if required, is achieved through welding.
- Installation continues until the required bearing capacity is reached.
- Steel H piles are the most common type in Hong Kong.
- Bored pile installation requires temporary steel casing, hydraulic oscillator, chisel, RCD, roller bit, underway mark, steel reinforcement cage, and a trim pipe and hopper.
Machine Dug Piles
- Predrilling is essential for piles founded on rock.
- The boring rig (rotary auger) is used to bore the initial hole.
- Temporary steel casing is inserted to prevent collapse.
- Rotary auger excavates soil and the temporary steel casing can be extended.
- A bellout at the base and cleaning of the hole are usually done.
- Steel reinforcement cage is placed and concrete is poured using tremie pipes.
Pile Testing
- Dynamic and static load tests, sonic logging tests, standard penetration tests, core drilling, vibration testing, lateral load testing, and tension testing methods are used.
Diaphragm Wall Construction
- Guide walls act as guides for the machinery excavating the trench.
- Hydrofraise/hydromill cutters are used to cut through rocks.
- Bentonite slurry is used to support the excavation and prevent soil collapse.
- Excavation proceeds in alternate panels between the guide walls.
- Panel width is typically from 4 to 6 meters.
- Bentonite is re-circulated.
- Concreting uses tremie pipes.
Top-Down Method
- Excavation takes a lot of time.
- The top-down method speeds up construction.
- Construction of the basement and superstructure can be simultaneous.
- Advantageous weather-tight working conditions.
Top-Down Construction Procedures (3 Levels Example)
- Drive steel sheet piles all around.
- Excavate to 1 meter.
- Install level 1 wailing and strut.
- Excavate to 4 meters (12m divided by 3 levels).
- Install level 2 wailing and strut.
- Excavate to +4mPD.
- Install level 3 wailing and strut.
- Excavate to basement bottom 0mPD.
- Start constructing basement.
Basement Risks
- Soil collapse, worker safety, disruption of underground utilities, neighbouring building settlement, and ground water/flooding.
Prefabricated Concrete Advantages
- Labour demand reduction, lower labour costs, consistent and higher quality control, standardized quality in factory.
Precast Concrete Benefits
- Faster construction, less separate operations, improved continuity of operation, fewer trades during construction.
Site Plan Considerations
- Tower crane capacity in relation to pick-up radius & material storage area adequacy according to the speed of construction.
- Internal access for material movement & turnaround space for vehicles.
Steel Bar Types
- High yield steel bars are used as main reinforcement & are deformed to increase adhesion.
- Mild steel bars are usually used as stirrups (links) for beams.
- They are smooth round bars.
- Steel work sections
- Common type structural steel sections: Universal Beam (UB), Universal Column (UC), Joist, Structural Tee, Channels, Angles, and Hollow sections (SHS, CHS, RHS).
Corrosion Protection
- Hot-dip galvanizing coats iron or steel with zinc to resist corrosion.
- Cathodic protection makes a metal work as a cathode in an electrochemical cell to control corrosion.
Cement Admixtures
- PFA (Fly Ash)
- A1) PFA/Fly Ash: replaced up to 15-30% of cement, improving workability, ultimate strength, and chemical resistance ,but slower initial strength development. It has some radioactive materials.
- A1) PFA: Slows down chemical reactions, useful in hot climates, provides added time to pour large concrete amounts.
- B2) Water Reducing Admixtures: reduce water content, increase workability, improve concrete strength.
- B1) Set Retarding Admixtures: slow down setting time, useful in hot weather, allow concrete placements longer.
- A2) GBS (ground-granulated blast furnace slag): replace cement, improves durability, chemical resistance and lower permeability reduces cement replacement level around 40%.
- A3) Condensed Silica Fume (CSF): provides extra bonds in concrete, increasing strength.
Other Materials
- Grit blasting: Process to remove unwanted materials from a surface.
- Tempered Glass: Stronger glass created through a cooled process, more resistant against breakage, used for safety/security.
- Laminated Glass: Glass panels are sandwiched by a protective layer, like polyvinyl butyral (PVB), improving toughness, strength, and sound insulation.
- Low-E glass has a transparent coating that reflects infrared energy, essential in windows.
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Description
Test your knowledge on construction techniques and materials used in civil engineering. This quiz covers essential concepts related to pile installation and curtain wall systems, as well as the various types of systems and tools utilized in these processes.
