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BDC - Masonry & Concrete Flashcards

1
Q

what did the ancient romans add to concrete to make it set under water?

A

pozzolana or volcanic ash

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2
Q

who developed portland cement?

A

Joseph Aspdin on 1824

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3
Q

who advanced concrete for construction in the earth 20th cen?

A

Robert Maillart & designed bridges and industrial buildings.

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4
Q

who designed the exhibition hall in Turin?

A

Pier Luigi Nervi

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5
Q

name 3 different types of forms?

A

1) Plywood (cheep) 2) Pre fab steel (strength and reusability) 3) Glass fiber reinforced plastic

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6
Q

what is a tie hold in conc forms?

A

the round imprint of a disk thats left after formwork is removed.

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7
Q

what is a flying form?

A

typ used in highrise construction, you form up and cast a floor section then fly-out or remove that section to be used in upper floors.

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8
Q

what is the max tolerance for a concrete column?

A

1/4” / 10’

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9
Q

what is the max tolerance for a concrete floor?

A

1/8” / 10’ for intended flat slabs

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10
Q

in fresh conc slabs what is the recommended water content ratio be to accept floor finishes?

A

.45 to .50 & conc slabs should be allowed to cure & dry for a minimum of 6 weeks before flooring is installed

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11
Q

what is a vapor barrier?

A

its placed under a slab (above any subbase) and it stops moisture migration through the slab. A barrier prevents water vapor from passing.

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12
Q

what is a vapor retarder?

A

it only slows the rate of water vapor transmission. Its acceptable permeance is between .04 & 10 mills

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13
Q

what is a perm & how is it measured?

A

Permeance: its a measure of a materials resistance to water vapor transmission, expressed in perms. A perm is the passage of one grain of water vapor per hour threw one square foot of material at a pressure of one inch of mercury between the two sides.

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14
Q

what is the grade mean in rebar?

A

typ used grades 50 & 60, these refer to the yield strength measured in Kipps / square inch.

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15
Q

what are the basic components of concrete?

A

Cement, aggregate & water

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16
Q

What is portland cement?

A

its the bonding agent in concrete, its made from lime, silica, iron oxide & alumina it chemically reacts with water to form a paste that binds with the aggregate.

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17
Q

what are the 5 types of concrete?

A

Type I: called standard its used for most general construction. Type II: is called modified and is used in places where modest amounts of sulfate resistance is needed Type III: is high-early-strength and is used where quick set is needed. Its also suitable for cold weather locations. Type IV: is used in massive structures to minimize cracking and is called low heat. Type V: os sulfate resisting cement, and is used for structures exposed to water or soil with high alkaline content.

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18
Q

what is the minimum water-cement ratio for concrete?

A

.35 to .40 by weight.

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19
Q

what % do aggregates typically occupy of the total volume of concrete?

A

70 to 75%

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20
Q

what kind of aggregate is added to increase insulation in conc?

A

pumice or cinders. Light weight concretes = better insulating concretes

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21
Q

what is the typical ratio of cement to sand to gravel

A

1:2:4 1 part cement, 2 parts sand and 4 parts gravel

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22
Q

what are 6 different types of concrete additives?

A

AIR-ENTRAINING: form tiny dispersed bubbles, increases the workability of concrete & improves resistance to freeze. ACCELERATORS: speed up the hydration process PLASTICIZERS: reduces the amount of water needed (higher strength) RETARDERS: slows down the setting time to help reduce the heat of hydration. WATERPROOFING: agents decrease the permeability of conc. FLY ASH: increases strength & decrease permeability.

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23
Q

how does concrete cure?

A

it gains strength by curing threw a chemical reaction between the water & the cement rather than by drying. Concrete gains ~70% of its strength after the first week of curing. 28 days is for its design strength,

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24
Q

what is the slump test

A

it measures consistency of the concrete.

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25
Q

what is the cylinder test

A

it measures compressive strength.

26
Q

what is a core cylinder test

A

a cylinder is drilled out of a already cast and cured conc. and taken to a lab to determine the compressive strength.

27
Q

what is the Kelly Ball test?

A

a steel ball is dropped onto a slab of freshly laid concrete. The amount of penetration of the ball into the concrete.

28
Q

What is the impact hammer test?

A

a non destructive way to test conc strength after it has harned. a spring loaded plunger is snapped against a conc surface

29
Q

what is the calcium chloride test?

A

its a common test that test for moisture in concrete.

30
Q

what is the electrical impedance test?

A

it is used proprietary meters to determine the moisture content in concrete by measuring conductance & capacitance. Probes of the meter are placed on the concrete & the percentage of moisture content in the slab is read out directly.

31
Q

what is the typ pH level of concrete?

A

12 to 13 making it alkalinic.

32
Q

what is a tremie?

A

its a long cylinder tube or chute used for distributing concrete for underwater applications.

33
Q

what is the typical vertical distance concrete should be dropped to avoid segregation (the separation of sand, aggregate and water)

A

5’

34
Q

what is a control joint?

A

creates a weak section so that normal temperature & stress cracking occurs along the joint

35
Q

what is a construction joint?

A

its the connection of two successive pours of concrete. Typically there is rebar that dowels the two sections together.

36
Q

what is an expansion joint?

A

it allows entire sections of a concrete structure to move independently.

37
Q

what is an isolation joint?

A

it allows two adjacent sections to move independently.

38
Q

whats the difference between surface sealers and penetrating sealers?

A

SURFACE: dries on the surface and can in time be worn off. PENETRATING: they seep into the tiny pores of the concrete.

39
Q

What are the components of mortar?

A

lime (retains the water), sand (aggregate) , cement & water

40
Q

what are the 4 types of Mortar?

A

M: S: N: O:

41
Q

what is the most common brick size?

A

7 5/8”x 3 5/8” x 2 1/4”

42
Q

on a single wythe wall what is the max ratio of unsupported height or length thickness can’t exceed

A

20:1

43
Q

what is the typical spacing for horizontal brick reinforcement?

A

16” vertical

44
Q

what is a reinforced grouted masonry wall?

A

its a double wythe but the cavity contains the vertical and horizontal reinforcing.

45
Q

What is a proper weep hole spacing in a masonry wall?

A

24” o.c.

46
Q

in masonry what is the order of dimensions a manufacturer will provide?

A

Width x Height x Length WHL

47
Q

what type of construction is best to limit vibration?

A

conc slab and beam

48
Q

what is composite steel deck?

A

In a composite steel deck, the dissimilar materials in question are steel and concrete. A composite steel deck combines the tensile strength of steel with the compressive strength of concrete to improve design efficiency and reduce the material necessary to cover a given area. Additionally, composite steel decks supported by composite steel joists can span greater distances between supporting elements and have reduced live load deflection in comparison to previous construction methods.[5

49
Q

what does the grade of rebar stand for?

A

the grade number refers to the yiel strength in kips/ sq inch

50
Q

what would w wire grid designated as 6x6-W1.4 x1.4 mean?

A

the grid is 6x6 & the size of wire is 1.4 hundredths of a square. the W = smooth wire (A D= deformed wire).

51
Q

the passage of water under pressure through concrete cracks is defined as?

A

seepage

52
Q

what is Self Consolidating Concrete?

A

its a mix that can be placed purely by means of its own weight without vibration. SCC is made possible with the ise of a superplasticizer.

53
Q

what is it called when conc heats during curing?

A

heat hydration.

54
Q

what does a slump test test?

A

measure consistency and the amount of water in the mox.

55
Q

what does a cylinder test measure?

A

compressive strength.

56
Q

what is the impact hammer test in concrete?

A

a spring loaded plunger is snapped against a conc surface & the amount of rebound is measured. this gives an approx reading of the concrete strength,

57
Q

how is high Alkalinity a problem for concrete?

A

it can damage finish installation.

58
Q

why is generally dropping concrete longer than 5’ bad?

A

it can produce segregation which is he separation of the aggregates , water & sand.

59
Q

how is lime used in mortar?

A

Lime helps to retain water in the mortar for hydration, a mortar with a high lime content is appropriate for bricks with a high initial rate of absorption or for summer construction where evaporation is a concern

60
Q

What is this pattern?

A

Cross Bond

61
Q

what is this pattern?

A

Common Bond

62
Q

what is this bond pattern?

A

Flemish bond

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