BDC - Masonry & Concrete

Question 1

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

Answer 1

pozzolana or volcanic ash

Question 2

who developed portland cement?

Answer 2

Joseph Aspdin on 1824

Question 3

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

Answer 3

Robert Maillart & designed bridges and industrial buildings.

Question 4

who designed the exhibition hall in Turin?

Answer 4

Pier Luigi Nervi

Question 5

name 3 different types of forms?

Answer 5

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

Question 6

what is a tie hold in conc forms?

Answer 6

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

Question 7

what is a flying form?

Answer 7

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.

Question 8

what is the max tolerance for a concrete column?

Answer 8

1/4” / 10’

Question 9

what is the max tolerance for a concrete floor?

Answer 9

1/8” / 10’ for intended flat slabs

Question 10

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

Answer 10

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

Question 11

what is a vapor barrier?

Answer 11

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

Question 12

what is a vapor retarder?

Answer 12

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

Question 13

what is a perm & how is it measured?

Answer 13

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.

Question 14

what is the grade mean in rebar?

Answer 14

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

Question 15

what are the basic components of concrete?

Answer 15

Cement, aggregate & water

Question 16

What is portland cement?

Answer 16

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.

Question 17

what are the 5 types of concrete?

Answer 17

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.

Question 18

what is the minimum water-cement ratio for concrete?

Answer 18

.35 to .40 by weight.

Question 19

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

Answer 19

70 to 75%

Question 20

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

Answer 20

pumice or cinders. Light weight concretes = better insulating concretes

Question 21

what is the typical ratio of cement to sand to gravel

Answer 21

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

Question 22

what are 6 different types of concrete additives?

Answer 22

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.

Question 23

how does concrete cure?

Answer 23

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,

Question 24

what is the slump test

Answer 24

it measures consistency of the concrete.

Question 25

what is the cylinder test

Answer 25

it measures compressive strength.

Question 26

what is a core cylinder test

Answer 26

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

Question 27

what is the Kelly Ball test?

Answer 27

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

Question 28

What is the impact hammer test?

Answer 28

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

Question 29

what is the calcium chloride test?

Answer 29

its a common test that test for moisture in concrete.

Question 30

what is the electrical impedance test?

Answer 30

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.

Question 31

what is the typ pH level of concrete?

Answer 31

12 to 13 making it alkalinic.

Question 32

what is a tremie?

Answer 32

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

Question 33

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

Answer 33

5'

Question 34

what is a control joint?

Answer 34

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

Question 35

what is a construction joint?

Answer 35

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

Question 36

what is an expansion joint?

Answer 36

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

Question 37

what is an isolation joint?

Answer 37

it allows two adjacent sections to move independently.

Question 38

whats the difference between surface sealers and penetrating sealers?

Answer 38

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

Question 39

What are the components of mortar?

Answer 39

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

Question 40

what are the 4 types of Mortar?

Answer 40

M: S: N: O:

Question 41

what is the most common brick size?

Answer 41

7 5/8"x 3 5/8" x 2 1/4"

Question 42

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

Answer 42

20:1

Question 43

what is the typical spacing for horizontal brick reinforcement?

Answer 43

16" vertical

Question 44

what is a reinforced grouted masonry wall?

Answer 44

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

Question 45

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

Answer 45

24" o.c.

Question 46

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

Answer 46

Width x Height x Length WHL

Question 47

what type of construction is best to limit vibration?

Answer 47

conc slab and beam

Question 48

what is composite steel deck?

Answer 48

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

Question 49

what does the grade of rebar stand for?

Answer 49

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

Question 50

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

Answer 50

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

Question 51

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

Answer 51

seepage

Question 52

what is Self Consolidating Concrete?

Answer 52

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.

Question 53

what is it called when conc heats during curing?

Answer 53

heat hydration.

Question 54

what does a slump test test?

Answer 54

measure consistency and the amount of water in the mox.

Question 55

what does a cylinder test measure?

Answer 55

compressive strength.

Question 56

what is the impact hammer test in concrete?

Answer 56

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,

Question 57

how is high Alkalinity a problem for concrete?

Answer 57

it can damage finish installation.

Question 58

why is generally dropping concrete longer than 5' bad?

Answer 58

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

Question 59

how is lime used in mortar?

Answer 59

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

Question 60

![]() What is this pattern?

Answer 60

Cross Bond

Question 61

![]() what is this pattern?

Answer 61

Common Bond

Question 62

![]() what is this bond pattern?

Answer 62

Flemish bond