Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Carpentry Level 1 BC 2022 > G-7 Place and Finish Concrete > Flashcards

G-7 Place and Finish Concrete Flashcards

1
Q

how could vibration cause a form to fail?

A

over vibrating near a stressed tie

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the environmental concerns associated with concrete treatments?

A

streams and ground water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what tools used to transfer flexible patters

A

tamper boards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what’s the minimum slump of repair concrete ?

A

50mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

concrete that has only been cured for 0 days, 3 days, or 7 days will only have which percent strength?

A

50%, 70%, 90% of it 28 day strength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

if two coats of curing compound are used, how is the second one applied?

A

at 90 degrees or perpendicular to the first coat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Trowel blades

A
  • typically 8” wide - made from thin steel - each pass will increase density of the slab surface
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Discolouration in concrete

A

Prevented by :- clean formwork - maintaining uniform consistency of the concrete mixture - using uniform aggregate types and colour - proper placement of concrete- adequate vibration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

screeding or striking off

A
  • levels the survace of concrete to elevation set by screeds-
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is and edger?

A

used too round the outside corners of the surface of the slab, and create a decretive boarder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

how far apart are external vibrators placed?

A

1200mm apart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

wall patches

A

usually has opening in top to allow placement of patching material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is a white crystalline growth on the surface of concrete called ?

A

efflorescense

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Curing

A

process of keeping concrete moist. - concrete not sured at all will only get 50% strength- cured for three days will get 70%- cured for 7 days will get to 90%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Bull float

A

used for large areas very large wooden or metal float with long handle attached

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the minimum and maximum slope of a walkway

A

2% to 8%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what does flaking mean?

A

very thin flakes of concrete separating from the surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what’s considered a favourable air temperature for concrete curing ?

A

15-20 degrees Celsius

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is Efflorescence?

A

As water from the interior of the concrete migrates to the surface and evaporates, salts are deposited on the surface, usually as a white stain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Fresno

A

long handled steel trowel used to flatten out the ridges left by the bull float -

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Broom finish

A

NAME?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

when are external vibrators used?

A

metal forms for precast, 1200mm apart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

sodium silicate

A

common hardening agent that is applied to new or existing concrete surfaces to increase hardening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

how far into a preceding layer of concrete should a vibrator penetrate?

A

6” or 150mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Bond breakers

A
  • chemicals used to break bond between layers of concrete-
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what’s the maximum aggregate size that should be used when repairing concrete ?

A

1/2 depth of patch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

how does the aggregate size affect concrete placement?

A

large aggregates limit pumping

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what stages of finishing is an edger used and why?

A

after bull floating, pushes large aggregate away from surface and form rounds over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what does dusting mean?

A

fine loose powder caused by the deterioration of a weak surface.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what’s the minimum curing time required to allow the concrete to gain 70% of its 28day strength ?

A

3 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

edger

A

used to round corners of the surface of slab . - done after concrete is floated to remove large aggregates away from forms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what are concrete buckets used for?

A

moving concrete on tall buildings hoisted by a crane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what’s the max spacing of vibrator insertion points when vibrating a wall?

A

1/2 the radius of influence, 600mm if unknown

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Preventing rapid evaporation

A

NAME?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Cold weather concrete

A

formwork left in place to help concrete cure.- once compressive strength reaches 3.5MPa damage caused by freezing is reduced.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

list 4 methods of curing concrete

A

water coating, wet covering, curing compound, mechanical barrier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

what’s the difference between dampproofing and waterproofing materials?

A

dampproofing meant to repel moisture and waterproofing is mean to repel hydrostatic pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

explain the stripping process for foundation forms.

A

orderly and safely, remove cleats, 2x4s, walers, ties, sheathing, de-nail, stack lumber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

riding power trowels

A

for large projects- two or three separate trowels are assembled into one - operator rides on top and is able to control movement and rake of blades

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

list 5 guidelines for placing concrete

A

check forms & falsework, uniform lifts, place within 120 min of batching

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

what are 2 ways to keep concrete moist for an extended period of time?

A

spray-on acrylic curing liquid or plastic sheets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

describe how sealers and hardeners also act as curing compounds

A

coat surface to stop moisture loss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

explain the hydration process

A

chemical reaction of water and cement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

what are 2 purposes of chemical sealants?

A

durable waterproof finish, improves looks, cleanable surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

how long should formwork be left in place during cold weather ?

A

minimum 3 days or untill it reaches a strength of 3.5mpa or greater

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Super plasticizing

A

Superplasticizers transform stiff, low-slump concrete into flowing, pourable, easily placed concrete. They can improve workability, speed finishing, increase strength, conserve cement and help reduce shrinkage and thermal cracking.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

what’s the purpose of hand floating or bull floating ?

A

push aggregate down and allow bleed water to escape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What does a bull float do?

A

used too push larger aggregates under the surface and level and smoothen large slabs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

what’s the minimum temperature for curing concrete?

A

10 degrees celcius internal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

floating

A
  • after concrete has been placed and screeded level- the surface is floated - this pushes any large aggregate below the surface of concrete slab-
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

describe how to reduce the segregation of the aggregate from the cement paste

A

don’t drop through, don’t over vibrate, don’t use wrong rake, don’t slide too far at wrong angle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

what causes “plastic shrinkage cracking”?

A

rapid water evaporation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

why are metallic aggregates used in some grouts?

A

so that metal expansion makes up for concrete shrinkage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Hand floats and kneeboards

A

tops of walls and small concrete slabs can be done with hand float - if hand floating larger job kneeboards are used

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

what is a main powdered hardener?

A

Sodium Silicate, sprinkled over concrete and bull floated in reacting with the lime creating a hard dust-proof surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Hydration

A

the chemical reaction that takes place when water reacts with cement. this allows it to harden. must be kept wet so it can get hard.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

how can you tell when consolidation is adequate ?

A

bubbles stop, sheen forms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

list 4 problems that can cause formwork to fail

A

improper stripping, improper rate of placement, improper vibrating, improper bracing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

what is curing?

A

to keep concrete moist as long as possible for maximum strength growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

what are advantages of using pre mixed grouts?

A

contains chemical bonding agents, just add water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Honeycomb

A

occurs at the base of concrete columns when concrete is dropped through reenforcing steel and not vibrated adequately- can result is rebar being exposed - no not over vibrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

how soon after the mix water is added to the concrete mixture must the concrete be placed in the forms ?

A

maximum 120 minutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

how are liquid grouts used ?

A

forms and poured in

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

what causes efflorescense

A

salts amd chemicals in water or aggregate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Presoaking

A

once surfaces have been swept and vacuumed clean, it should be kept wet for at least two hours to ensure old concrete will not absorb water from patching material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

wooden hand floats must be made of?

A

NAME?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

what is the effect on concrete of using fossil fuel burning heaters in an unventilated enclosure?

A

CO2 weakens concrete and causes dusting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Damp proofing

A

concrete foundations that are below grade should be coated on the outside with a damp proofing agent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

what are 2 required conditions for proper concrete curing?

A

moisture and favourable temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

what’s the purpose of a screed

A

elevated guide for strike off

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

Accelerators

A

speed up hydration, which releases more heat warming the concrete.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

divider

A

used to create decretive divisions in walkways an patios- used to create control joints joints-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

what does segregation mean?

A

excessive vibration causing the course course aggregates to settle to the bottom.

74
Q

concrete voids

A

spaces caused by trapped air under window bucks and blockouts.must vibrate properly around bucks - drill holes in bottom of bucks to allow air to escape

75
Q

how far apart, and how far down does the pencil vibrator get placed when vibrating concrete walls?

A

not more than 600mm apart and 150mm into the previous layer

76
Q

Chemical Hardeners

A

NAME?

77
Q

explain the sack rubbing process

A

wet the area, rub on sacking, let stand, rub on dry sacking

78
Q

Retarding admixture

A

added to concrete for pumping and are particularly useful in hot weather. lengthens the setting time of concrete but does not have any effects on the strength gain of concrete

79
Q

when is a concrete bucket used to place concrete ?

A

when building is more than a few stories high and a cranes more feasible to use

80
Q

What is the soul purpose of vibration?

A

To remove pockets of air from the concrete

81
Q

formwork failure

A

NAME?

82
Q

Overhead paches

A

patching material must be stiff and must be braced

83
Q

what type of tools should be used to pry forms loose when stripping?

A

wood wedges, wood bars

84
Q

water proofing

A

waterproofing membrane applied to foundation walls to resist hydrostatic pressures

85
Q

Repair concrete Grout

A

NAME?

86
Q

Concrete (patching)

A

NAME?

87
Q

what safety precautions must be taken with concrete treatments?

A

read msds

88
Q

why should additional water not be added to the concrete when placing concrete in hot weather ?

A

it weakens the concrete

89
Q

Curing compounds

A

NAME?

90
Q

What happens when concrete flash sets?

A

concrete hardens too quickly resulting in improper finishing and inadequate strength

91
Q

what does it mean too continually pour concrete within multiple forms or slabs?

A

Monolithic concrete placement

92
Q

when are screeds removed from concrete?

A

after strike off

93
Q

Floor patches

A

more rebar could be drilled and place to allow patch to take better

94
Q

Wall finish

A

after concrete has been vibrated into place the surface of top of wall is finished level strip or chamfer strip set elevation of top of wall. then hand float is used to finish

95
Q

Bonding

A

just prior to patching material, apply bonding material and patch before bonding has a chance to dry

96
Q

Using power trowel

A
  1. make sure concrete is levelled properly 2. should support foot pressure before power trowel 3. make sure bleed water has evaporated 4. move over entire surface evenly 5. allow concrete to harden between passes with trowel
97
Q

Scaling

A

small pieces of concrete flake off the surface of a concrete slab. scaling is dude to lowered concrete strength at the surface.

98
Q

Sealers

A

chemicals that seal the surface of concrete and prevent the formation of dust on a worn concrete surface

99
Q

why would non metallic grouts be used?

A

to avoid rust staining

100
Q

whats the ideal tempurature range for placing concrete ?

A

15-20 degrees Celsius

101
Q

Curing concrete walls

A

NAME?

102
Q

what is the difference between a divider and a control joint tool?

A

a divider is only for decorative purposes where a control joint tool has a deeper cutter for creating control joints

103
Q

Architectural concrete finish

A

NAME?

104
Q

explan when a conveyor is used to transport concrete?

A

onsite, large jobs, protect from weather.

105
Q

what does spalling mean?

A

Spalling is similar to scaling except large chunks instead of just flakes break loose

106
Q

Curing flatwork

A

most efficient way to cure concrete slab is to use curing agent. this is sprayed onto slab after finishing it.b

107
Q

what is sack-rubbing finish mean?

A

concrete low spots can be filled with the use of a flowable sacking mix mortar and burlap pads. fills voids in the concrete and left flush with surrounding surfaces.

108
Q

what can cause a concrete slab on grade to sag and crack?

A

settling or heaving of sub grade

109
Q

what does crazing mean?

A

minute cracking of the concrete surface caused by bleed water not fully evaporated disrupting the water/cement ratio

110
Q

Power trowel

A

used for finishing concrete slabs- have four spinning concrete trowel blades that spin clockwise

111
Q

Float blade

A
  • used for final levelling of concrete surface - usually 10” wide - made from thick gauge steel blades are kept flat for initial passsecond pass kept at 90° (crossover floating)
112
Q

what is a screed/strike off bar and what does it do?

A

long 2X4 the extends beyond the edge of a slab for to level out the concrete

113
Q

why should the edges of the area being patch be sloped inward?

A

to create more surface and bonding area for the patch

114
Q

what should the slump of a concrete patch be?

A

no less than 50mm

115
Q

patching procedure

A

make test batch and test run a patch, check for discolouration and strength

116
Q

Heated enclosures

A

using heated enclosures concrete can continue as usual. fuel burning heaters must have exhaust vented outside because carbon monoxide causes surfaces of concrete to be weak and dusty

117
Q

explain how-to strip and lift slab tables

A

using fall protection, lower jacks onto dollies, attach lines to core, roll out 1/4 way, attach first pair of slings, roll out and attach second pair, detach line from core, hoist out

118
Q

why is a divider tool not used to make control joints?

A

the groove is not deep enough

119
Q

when placing concrete for a slab, what precaution should be taken with the reinforcing steel?

A

keep off ground using chairs or bricks

120
Q

how are chemical hardeners used?

A

sprayed or sprinkled onto surface and floated In

121
Q

what are pigments used for?

A

colouring concrete or surface

122
Q

why must rustication be removed very carefully ?

A

to not damage green concrete

123
Q

what’re two basic types of concrete pumps?

A

boom ( crane) & line

124
Q

formwork and patching

A

sometimes formwork must be left in place when patching occurs to allow to harden properly

125
Q

Which of the following chemical elements produced by motorized
equipment on a construction site can poison the cement finisher?
a. Carbon dioxide
b. Carbon monoxide
c. Hydrogen
d. Nitrogen

A

B

126
Q

Metallic or aggregate hardeners

A

NAME?

127
Q

what is placed just before the patch goes on?

A

a bonding agent

128
Q

Chemical sealers

A

NAME?

129
Q

What is the capacity of a concrete bucket?

A

Depends on the lifting capacity of the crane, usually able too care between 0.4 - 1.5m cubed

130
Q

why are some curing compounds coloured?

A

to show coverage

131
Q

Dusting

A

when surface of concrete is weakened - caused by early age freezing- adding to much water while placing concrete - using unvented heaters - working bleed water back into the surface

132
Q

Prep for formwork in cold temperatures

A

NAME?

133
Q

chemical hardeners

A

provides a hard-wearing concrete surface and prevent dusting of the concrete

134
Q

what’s the minimum time that concrete should be cured?

A

3 days

135
Q

why should the bleed water be allowed to evaporate ?

A

to not dilute surface concrete, causing dusting and crazing

136
Q

why must your wet the area to be patched?

A

to key the patch

137
Q

what is cementation?

A

use of liquid grout In industrial/ commercial projects

138
Q

Mortar

A

same as grout but cement content is lower. consistency is much stiffermortar is used to bond bricks together

139
Q

Describe concrete finishing

A

top surfaces of cast in place concrete must be finished to a smooth, uniform surface for appearance and durability

140
Q

Concrete is placed in lifts because why?

A

so that the overall height of the fresh concrete does not exceed the rate of placement set by the form design

141
Q

bonding agents

A

epoxies and adhesives are used to create a good bond between fresh concrete placed over old concrete

142
Q

Spalling

A

pieces of concrete chipping off the surface around openings or edges- spalling around rustication strips or window and door bucks is caused by removing forms before concrete s strong enough to resist stripping stresses

143
Q

how are powdered hardeners applied to concrete ?

A

telecast on & floated or troweled In

144
Q

walk behind power trowels

A
  • size determined by diameter of circle it makes- ranges from 24inces to 48 inches in diameter
145
Q

how is the top of the concrete wall finished

A

remove cleats and floats

146
Q

Temperature for curing

A

keeping concrete warm promotes curing.prime curing temperature is overcast skies at 15-20°

147
Q

Bonding compounds

A

used to ensure positive bond between patch and concrete being repaired. woodglue can be used

148
Q

Stamped concrete

A

uses manufactured stamps that are set into the partially set surface of concrete.- done after bleed water is evaporated - surface of slab is covered with fine powdered release agent that is designed to allow the stamps to be removed cleanly from the concrete

149
Q

how long should a patched area be allowed to cure?

A

3 days minimum

150
Q

what precautions should be taken when using hot water in the concrete mixture ?

A

avoid flash set by adding cement last and after scheming mix temperature

151
Q

describe the procedure used to place concrete around bucks in a wall form

A

place on one side only to prevent air entrapment/ vibrate and have holes drilled into buck

152
Q

Preventing dusting

A
  1. maintained designated water/cement ratio2. do not add water to finishing process. protect the fresh concrete from direct exposure to the sun, rain and freezing 3. vent heateres!!!!
153
Q

Mechanical Hardeners

A
  • increase durability of concretes - added at the troweling stage - worked in and bonded to the surface to protect concrete- metal shavings, plastic particles,
154
Q

what is a groover?

A

like a hand divider tool but larger with a long handle for making grooves in slabs

155
Q

explain how to strip and lift gang form panels

A

using fall protection, partially strip leaving top taper ties in but loose, attach tag lines and crane, tension crane, finish stripping take top taper ties off, clear area

156
Q

how should concrete be placed on a sloping surface?

A

start from the bottem work your way up

157
Q

preparing patched surfaces

A

edges of area to be patched should be undercut (cut smooth) to provide a key where new patch concrete is being placed.

158
Q

what are the disadvantages of using liquid grouts?

A

forms required

159
Q

Crazing

A

series of small cracks in surface of concrete. happens due to working the bleed water back into the slab during finishing

160
Q

what is bleed water?

A

excess water in the concrete mixture that is not needed for the chemical reaction with the cement. the bleed water will rise too the surface and evaporate.

161
Q

Pigment

A

coulering agents may be added during concrete mixing or may be shaken onto surface when slab is being finished

162
Q

what is honeycombing?

A

trapped air bubbles from improper vibration that is visible after forms are removed

163
Q

what is the minimum temperature for curing?

A

10 degrees celsius

164
Q

how long should the area being patched stay wet for?

A

2 hours prior to patching

165
Q

Vibration

A
  • slabs must be vibrated like walls or columns - edges must be well vibed to reduce bug holes -
166
Q

how fast should you place the concrete after the water has been added?

A

120 minutes

167
Q

how is an exposed aggregate wall surface created?

A

uniform coat of retardent painted on the surface, don’t slide concrete on surface of treated form, strip after 24hours

168
Q

how is the concrete mixture cooled in hot weather

A

spray aggregate with cold water cool the mix with water

169
Q

what’s the purpose of kneeboards

A

distribute the finishers weight

170
Q

sacking mix

A

sacking is a mixture of portland cement and fine aggregates and admixtures. - used to patch minor defects in concrete like bug holes and honeycomb that can get water in and freeze causing spalling

171
Q

Hot weather conditions

A

when temperatures are above 25°C rapid evaporation of water in concrete occurs. water loss will accelerate setting times and create shrinkage cracks.

172
Q

explain how a broom finish is created?

A

float, edge, trowel, broom, edge

173
Q

how is a suspended concrete slab waterproofed?

A

membrane roofing

174
Q

what happens when dry shrinkage occurs?

A

shrinkage happens mostly because of the reduction of capillary water by evaporation and the water in the cement paste. Tensile stress increases causing stress cracks

175
Q

what is spalling around rustication strips? (keyways)

A

larger bits or chunks of concrete stuck too the strip and pulled off

176
Q

Flatwork finishing

A

NAME?

177
Q

how can scaling be prevented

A

quality concrete, placed and finished correctly, low w:c ratio

178
Q

explain tailgate delivery

A

trucks chute to forms

179
Q

Steel trowel

A

12- 16 inches - longer legnths needed when less pressure is required short is needed hen more pressure is required

180
Q

what causes spallimg ?

A

chipping caused by stripping techniques or stripping too soon

181
Q

when is the placing of concrete completed ?

A

after floating

182
Q

Effloresence

A

white powdery crystal substance that seems to blooms out of cured concrete. dissolved salts in concrete mic - unattractive but generally harmless

Carpentry Level 1 BC 2022 (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions