CT Flashcards
(214 cards)
1
Q
concrete composition
A
lime-based materials
+ pozzolans (fly ash, silica fume) + bitumen
2
Q
3 stages of Portland cement creation
A
proto, meso, portland
3
Q
clinker composition
A
alite
belite
4
Q
alite and belite chemical formulas
A
C3S and C2S
5
Q
how was hydraulic lime originally fabricated
A
artificially by burning limestone to create a highly reactive powder
6
Q
two sectors of construction industry
A
public and private
7
Q
which sector provides the majority of the construction industry
A
public
8
Q
the ____ sector dominates housing developments
A
private
9
Q
why is the construction industry necessary (list a few)
A
habitat for human activity
infrastructure and utilities
shelter and protection
environmental considerations
cultural and architectural expression
economic development
safety and security
10
Q
how should materials be selected
A
Ashby diagram
11
Q
Modern clinker burns _____ and ____ quicker
A
faster, cools
12
Q
How do the grain sizes of alite and belite compare between the older aspdin and modern clinker
A
alite = larger in aspdin, belite = larger in modern
13
Q
what constituent is not present in aspdin but is in modern clinker
A
alpha belite
14
Q
list the 4 main raw materials for cement production
A
calcareous materials
argillaceous materials (clayey)
gypsum (regulator)
ground limestone/ fly ash
15
Q
if gypsum is not added, what will happen
A
the concrete will flash set
16
Q
what types of enhanced cement can you get
A
geopolymer, high alumina, magnesium
17
Q
different cements have different important properties such as:
A
strength, setting time, durability, dimensional stability/ resistance to shrinkage and creep)
18
Q
Why are aggregates added
A
increase strength and reduce past volume
19
Q
how are gravel aggregates classified
A
by mean particle size
20
Q
aggregates must be ________ and can be sourced by _________________________.
A
inert
quarrying, manufacturing or recycling
21
Q
a higher water to cement ration indicates ___________
A
lower strength
22
Q
why is water required to make concrete
A
it hydrates the cement chemical reaction
23
Q
what additives can be included in cements
A
water reducers
air en trainers
shrinkage reducers
pumping aids
corrosion inhibitors
24
Q
list some factors used to classify concrete
A
self-compactability
structural performance
density
structural form
reinforcements
25
what is pre-stressed concrete
internal compression reduces the tensile stresses
26
concrete stress properties
strong in compression
weak in tension
27
what are the two methods of pre-stressing concrete
pre: steel strands stressed and released in set concrete
post: concrete cast with duct gaps and the strands are then inserted, stressed and sealed
28
what does LC mean
lightweight concrete
29
C45/55, what does each number mean
45 = cylinder strength
55 = cube strength
30
what safety precaution should be taken when casting concrete? why?
PPE
calcium oxide and water react to create calcium hydroxide which can cause burns (+harmful to the environment)
31
examples of emerging concrete technologies
3D printed concrete
polymer microfibre reinforcement
32
what properties links steel and concrete as a good pair for reinforcements
similar expansion rates (proportional)
33
what function do steel rebars provide as reinforcement
resist tension and bending
34
what are other types of reinforcement for concrete (separate to composition)
foundations, columns, beams
35
what 4 stages are considered by a structural engineer for steel fixings
area of steel required
steel grade
no. of bars and their sizes
verifying safety/ design checks
36
what are the three types of steel bar layouts
mesh
fabric
links
37
describe the mesh layout for steel fixings
cross hatched, laid over each other
38
describe the fabric layout for steel fixings
welded cross-hatch
39
describe the link layout for steel fixings
overlapping of the circular bent bars
40
what do steel grades indicate
ductility, diameters
41
How are steel bar shapes conveyed
shape codes - standard (bar marks)
42
5 H16 - 01
explain what this steel scheduling means
5 bars
steel grade H
16mm diameter
shape code 01
43
what are temporary works for
supporting existing structures during construction and demolition
stabilising structural elements
securing the construction site
supporting excavations
44
why might temporary works require a specific supervisor
legal obligations
complex site safety
maintenance to temporary works
reports and inspections
45
legal obligations of temporary works include:
stability of structures
demolition
protecting sides of excavations
cofferdam and caisson (used to create dry working environments)
46
false works vs form works
false works: support until self-supporting
form works: similar but help mold shape and structure more than support
47
CDM
construction and design management regulations
48
caisson, explain
closed concrete storage - precast
area pumped and joints grouted
49
what components make up scaffolding
ledgers, ties, bracings, toe board, guard rails,
50
according to what policy is scaffolding designed
permissible design stress philosophy
51
reasons for demolition of a building
redundancy - demolished before completion
partial demolition/ removal
complete demolition
52
Who is responsible for complete demolition
specialist contractors
53
when a building reaches the end of its intended lifecycle, ________________
to refurbish or demolish, that is the question
54
what factors must be considered before demolition (3)
structural stability
health and safety
environmental considerations
55
list some reason why a building may be demolished
structural condition/ instability
durability/ maintenance issues
end of intended life
energy usage/ carbon efficiency
urban regeneration/ infrastructural change
56
what is passive housing/ infrastructure
structures which consume no energy (net zero buildings)
57
why might refurbishment or partial demolition be considered?
increasing lack of space for new constructions
economic constraints
58
what is the green belt
protected green spaces in the UK (protected from construction)
59
what is the difference between deconstruction and demolition?
in deconstruction the parts can be recycled/ repurposed
60
explain the whole building stock approach
demolition policy based on the age, condition and energy efficiency
61
explain the individual building approach
demolition policy based on cost-benefit analysis of demolition against refurbishing
+ expenditure appraisals
62
outline the responsibilities of the client in building design and demolition
appoint a competent designer and contractor as well as a principal designer
allow and provide sufficient time, resources and finances for execution
63
outline the responsibilities of the principal designer in building design and demolition
identify risks and ensure mitigating measures for entire project lifecycle
ensure quality of design/ contracting work
64
outline the responsibilities of the designer in building design and demolition
produce safe, feasible designs
ensure the project is easy to maintain and easy to demolish
manage and address risks
65
outline the responsibilities of the (principal) contractor in building design and demolition
develop the construction phase plan, execute efficiently and to the client's requirements/ designs
66
outline pre-contract planning steps
explain sufficient information about structures to tenderers
identifies existing utilities, previous structural detail, associated risks, site environment survey
67
what is a tenderer
contractor who submits a bid for a project
68
what is a common hazard identified in pre-contract planning
asbestos
69
what are the 4 parts of an 'invitation to tender'
instruction for tendering
description of the works
conditions of contract
tender response form and practical equipment
70
decommissioning
making potentially contaminated structures safe for demolition
71
partial demolition
selective removal of elements, may precede complete demolition
72
soft strip
removing all the non structural elements of a building (initial stage), from bottom to top
73
safe demolition
procedures and resources used protect the local area, public and operators/ contractors
74
environmentally-friendly demolition
fully addresses any and all potential impact and manages this (includes demolition aftermath)
75
what are the four basic steps to demolition
inspect the facility
obtain an inventory list of materials and components
create demolition plan including methods
implement these safely
76
why is a soft strip done from bottom to top
fire safety
77
a refurbishment and demolition survey identifies
hazards and contaminants
78
for a small project, a demolition survey will be
approx a page
contains project info
program of works and method + risk assessment
79
for a large project, a demolition survey will
describe operations, outline the sequenced plan of works, = hazards and risk assessments, waste management plan
80
what factors influence demolition type choices
location, budget, time, materials , expertise
81
mechanical and hand demolition must be executed
top to bottom
82
methods to demolish a building
by hand
mechanically
deliberate collapse
wrecking balls
wire rope pulls
explosives
83
demolition is executed __________
one level at a time
84
hand demolition
slow, hazardous
uses a waste chute into a skip
85
bursters
apply pressure to cracks causing collapse
86
where is mechanical demolition executed from
ground level or sequentially in levels
87
mechanical demolition
fast and efficient for large demolitions
requires external power, slower than ground mechanical
88
outline the exclusion zone for demolition
plan area
predicted debris area
designed drop area
buffer zone
89
where are exclusion zones applied
demolition sites
any machinery
90
what pollutants of demolition should be highly managed
dust
contaminants
waste (recycling)
91
demolition waste create ___% of EU waste
30
92
what two main methods can be used to control groundwater
exclusion or pumping
93
why is controlling groundwater important
allows excavations to be made in dry and stable conditions
94
permeability
measure of ease of water flowing through a soil or rock
95
coefficient of permeability, k
hydraulic conductivity (m/s),
96
draw-down
vertical distance that the groundwater is lowered due to pumping, measured in metres
97
aquifer
permeable water-bearing layers or soil/ rock
98
aquitard
less permeable stratum/ layers of soil and rock (compared to an aquifer)
99
stratum
layers of soil and rock
100
water exclusion
physical cutoff walls to isolate an area
101
pumping
arrays of well/ sumps and pumps
102
sumps
cave/ mine pit that collects water
103
list exclusion methods
steel sheet piles (cofferdams with props)
excavated barriers
104
cofferdam
water-tight zone to permit work below the water table
105
list different types of excavated barrier
concrete diaphragm walls
bored pile walls
bentonite slurry walls and trenches
106
describe how diaphragm walls are constructed
guide wall placed
bentonite slurry added to prevent collapse
excavation (gradual)
metal cage reinforcements installed
concrete by the tremie method
107
tremie method
method to install concrete below water level via submerged water tight delivery pipe (bottom to top)
108
how are bored pile walls constructed
drilling interlocking holes (female and male) and filling these with concrete
109
why are there gaps left in pile walls and how big are they
typically 100-150mm
used for reinforcement purposes to retain soil
110
how are bentonite slurry walls formed
excavation filled with slurry and then back fill replaced with concrete/ bentonite mixture
111
name four exclusion-based techniques for groundwater control
permeation grouting
rock grouting
jet grouting
mix-in-place methods
112
what is grouting (water control)
injecting grouting-concrete mixture to reduce permeability and increase strength
113
what is a temperature related groundwater control method, explain
artificial ground freezing - freeze-holes via pumps and circulation pipes
114
how can water be managed at surface level
intercepting run-off
preventing water generation
water treatment (removing contaminants)
french drains
115
french drains
intercept collector chains and sumps via pumping system
116
name four pumping water control methods
sump pumping
well points
deep wells
ejector wells
117
sump pumping
using a pit to store water
doesn't allow pre-lowering of water before excavation
risk of water pollution
118
wellpoints
collects water from deep wells and transfers by pumps
119
what is the drawdown limit of wellpoints
5-6m
120
deep-wells
submersible electric pumps installed by drilling
121
ejector wells
vacuum-assisted drainage system used to lower groundwater levels
122
what is earthworks (three main types)
removal of soils/ rocks and foundations
handling spoils (waste storage)
importing soil for embankments
123
3 elements of earthworks planning
drainage
modelling
slope stabilization and remediation
124
shoring
temporary works support (safety net) during construction or demolition
125
what factors affect ease of earthworks
density
air voids
moisture content/ voids ratio
(back)fill materials
126
what machinery is used for earthworks
excavators
loaders
earth transporters
bulldozers
graders
compactors
127
list types of excavators and loaders
back actors
drag lines
loading shovel
128
what is required to operate earth transporters
a mass haul plan
129
list types of earth transporters
swivel dumpers
dump trucks
tipper trucks
scrapers
130
compactors
can reduce aeration and water content
static or vibrationary
131
types of compactor
smooth roller
sheep foot
grid
pneumatic Tyre
132
ends area formula
V = d/2 * (first + last + 2(all other sections))
133
prismoidal formula
V = d/2 * (first + last + 4(even sections) + 2(odd sections))
134
the ends area method is accurate if ______________
cross sections are off similar magnitude
135
you are required to analyse a volume of earthworks split into eight sections. how will you approach this
use prismoidal for first 7 and ends area for the last one
(N must be odd for prismoidal)
136
what is d in the earthworks quantifying formulas
separation of cross sections
137
important factors for foundation construction (3)
soil bearing capacity
site geology
construction challenges/ restraints
138
pile foundations (how support)
friction or ends bearing
F: between pile and surrounding soil
E: direct transfer of load to strong soil below
139
how is a site analysed for a foundation
site visit and analysis
active load analysis and design
soil characterisation
geological profiling
140
site review features
site specific issue identification
strength test of soil
locating water table
141
augers
hand-held surface probing for chemicals
OR
drilling tool with helical screw blade
142
test pits
area for lab samples
multiple boring pits
~5m deep
143
SPT value
N value
no. of hammer blows for standard penetration test
144
CPT value
Qc value
cone penetration test
assesses soil conditions and layering
145
two types of pile foundations
displacement and non-displacement
146
piles are classified by
size
147
driven in place piles summarise
hollow steel pipes filled with concrete (CHS)
or precast concrete or timber
148
driven in place piles - advantages
cheaper than bored and sometimes precast
large capacities and sizes
no spoil/ waste
small rigs possible for restricted access sites
149
driven in place piles are driven to set, what does this mean
don't just rely on geotechnical data
150
driven in place piles - disadvantages
noisy
rigs can be heavy
unfilled pipes have low durability
time consuming
concrete burns risk
151
driven preformed piles, summarise
steel sections driven in by hammers
152
driven preformed - advantages
delivered in one rig - efficient for public works and highway structures
can accommodate large horizontal forces
each pile calibrated mitigating risks
no spoil
fast
strong structural sections - appropriate fro most soils
153
driven preformed - disadvantages
big rigs
expensive
must be one long section/ welded
high level noise and vibration issues
154
continuous helical displacement piles, summarise
hard helical bullet screw drilled into the ground
runny (high slump) concret pumped through the stem
screw removed
reinforcement bars added
155
CHD piles - advantages
minimal spoil/ waste
quiter than driven piles
shorter piles than CFA piles
156
CHD piles - disadvantages
expensive
slower than driven
require lots of power/ large rigs
very noisy
lots of equipment required for steps
157
CHD piles limits
13-15m deep or 22m with segmental augers
158
segmental augers
drilling tools composed of individual segments
used to extend depth of CHD piles
159
screw piles, summarise
steel tubes with screw head ends and a capped top
160
screw piles - advantages
minimal spoil
minimal vibration/ quieter than driven
good for restricted access sites
cheap for small projects
safe
161
screw piles - disadvantages
more expensive and slower than precast/ CHS
requires high levels of expertise
162
what are two types of non-displacement piles
continuous flight auger (CFA)
rotary bored piles
163
CFA piles (cont. flight auger)
screw compactor drilled in
withdrawn as concrete is injected
reinforcement cage added
164
CFA piles - advantages
low vibration, less noise
cheaper and faster than rotary bored
165
CFA piles - disadvantages
more expensive and slower than driven piles
much spoil to be disposed of (cost)
concrete supply (large)
166
rotary bored piles, summarise
excavation by bore blows/ drilling and temporary pile casing added (walls)
reinforcement inserted and concrete added
removal of temporary side casing
167
rotary bored piles - advantages
large diameters
placement through hard rock possible - drilling
large depth capacity
168
rotary bored piles - disadvantages
very slow and expensive
creates lots of soil (contaminated)
resource intensive
environmentally dirty
169
non-displacement piles
excavation and then placing piles into hole
170
displacement piles
pile directly inserted into ground without removing soil (therefore does not produce spoil) - soil displaced not excavated
171
what type of piles are used to retain earth or water
preformed or non-displacement
172
most common earth-retaining structure
sheet piling
173
sheet piling, summarise
vibrators mounted on excavators or large hammers on cranes
drives piles into the ground
174
contiguous bored pile wall, summarise
several bored piles constructed close together to form a wall
175
king post retaining wall, summarise
excavating a hole with piling rig or auger, filling with concrete and inserting steel king post
176
how is a driven pile wall constructed
impact of weights via pulley mechanism
+ guide system for verticality
177
rate of penetration
no. of blows per inch
178
disadvantage of driven pile walls
piles susceptible to damage from weights
noisy
can require large rigs/ transport equipment
179
what powers hammer pulley system for driven piles
steam
diesel
hydraulic
180
four design approaches to piles
geotechnical design
set calculations
design by testing
contractor design
181
set calculations
determining required no. of blows for pile penetration to reach desired depth or load capacity
182
piles approach: geotechnical design
uses ground investigation soil parameters to calculate pile capacity via series of complex programs
183
geotechnical design approach - piles, advantages and disadvantages
favoured by consultants/ academics
analytical
completely reliant on ground investigation analysis
184
piles approach: set calculation method
uses newton's 3rd law
only for driven piles
calculates energy of hammer blow by weight and distance falling + comparison with distance pile moves
185
set calculation method - piles, advantages and disadvantages
every pile is set and tested before full installation
only for driven piles
186
piles approach: design by testing
traditional approach
preliminary piles across site tested until failure
geotechnical designs then modified to match criteria
187
design by testing - piles, advantages and disadvantages
very safe
costly, long process (time delays)
188
the contractor design approach to piles
combines geotechnical design, set calcs and testing
189
technology and pile installation
hammer speed increasing
greener engines/ power sources
remotely controlled rigs
better monitoring and sensors
more accurate ad efficient setting out
more pre-fabricated sections
lower costs and lower risks
190
composite construction
construction involving multiple materials
191
ex-situ elements
per-fabricated / pre-assembled elements
192
advantages of ex-situ elements
time efficient
specific deisgn requirements
quality control = high
cost effective
193
ex-situ elements disadvantages
less flexible/ tight tolerances -> can cause delays
194
substructure vs superstructure
foundations and basement
vs
frame and cladding
195
the majority of the ___________ is in-situ
substructure
196
modular units
sections of ex-situ elements fabricated together in sections
197
portal frames
foundations, preformed columns and rafters to roof
connected to give continuous grid structure
198
what can provide additonal support to portal frames
haunches (additional support bars) - enhance stiffness
199
load path of conventionally framed building
roof/ slab
beams
columns (walls are type of column)
foundation
200
how are framed structures deisgned
based on euro code
permissible stress over a structural grid
201
steps in framed buidling construction (6)
clear site
excavate for foundations/ leveling
compacting
lay binding/ bedding layer over top soil
spacers (grid) and mesh
set out bolt positions
202
types of frame connection
welding
bolting
knee frames (beam and column intersection)
endplates (single or double intersecting beams)
203
how to read de-watering graph
by change in depth required and permeability of soil
204
why must reinforcements overlap
to ensure continuous strength
205
what is cover in reinforcement
wall coverage around the metal wires
206
what is synonym for bar mark
label
207
for steel scheduling calculations, always remember to
consider the plane in which each link/ beam is
208
loose volume =
bank volume x swelling or bulk factor
209
backacters
excavate/ dig and remove materials
210
dumper trucks
transport earthworks
211
after concrete is poured, it must also be
cured to develop reasonable strength and compacted to standard consistence of concrete
212
what temporary works may be required for installing a foundation
form-works - timber board guide panels
213
essential steps in laying foundations (pad)
excavation
compaction
binding layer
form-work/ false-work
bolt setting out
timber form-work guider for bolts
casting an curing concrete
214
pockets function for bolts in foundations
allow minor horizontal adjustments
