USQStudyDesk: My home > My courses > Fac of Hlth, Eng & Sciences > 2015 Semester 1 >CIV2605_2015_1 > Course and Assessment Information > ONLINE QUIZ 2

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Construction Engineering

(2 marks)

Which of the following factors does NOT directly influence the workability offresh concrete?

Select one best answer.

Select one:1. Aggregate shape

2. Level of hydration

3. Water content

4. Exposure classification

5. Cement content

(2 marks)

What particle shapes are considered desirable for aggregates used in aconcrete mix?

Select one best answer.

Select one:1. Angular and elongated

2. Rounded, irregular and angular

3. Irregular and elongated

4. Rounded, flaky and elongated

(2 marks)

Which of the following items is NOT one of the key components used inmaking Portland cement?

Select one best answer.

Select one:

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1. Fly ash

2. Alumina

3. Calcium carbonate

4. Silica

5. Iron Oxide

(2 marks)

Which of the following items is included in the cement making process, tocontrol the rate at which the cement hydrates when mixed with water?

Select one best answer.

Select one:1. Gypsum

2. Limestone

3. Magnesium

4. Alumina

(2 marks)

Is the following statement true or false?

Generally, if water is drinkable, it is suitable for making concrete?

Select one:1. True

2. False

(15 marks)

You are a local government Engineer responsible for the design andconstruction of a footpath and bikeway in the local parklands. Your designcalculations indicate a requirement for 25MPa reinforced concrete. Soil testsshow the parklands contain non-aggressive soils, and you will not be using amembrane under the concrete. (Your footpath will not be submerged inwater.)

Using the attached tables, calculate the Target Strength in MPa based on theminimum requirement for Characteristic Strength considering both strengthand durability.

(Round your answer to one decimal place. Do not include the MPa unit orany spaces or commas.)

Table 1: Minimum characteristic strength for durability

Exposure classification Minimum characteristic strength f ' (MPa)

A1 20

A2 25

B1 32

B2 40

C 50

Table 2: Assumed standard deviation

Grade designationCharacteristic strengthMPa

Assumed standarddeviation MPa

Standard grades

25 25 4.8

32 32 5.34

40 40 5.9

50 50 6.2

Flexural grades

F2.5 2.5 0.5

F3.5 3.5 0.6

Indirect-tensilegrades

IT2.0 2.0 0.5

IT2.5 2.5 0.5

Table 3: Exposure classification table

Surface and exposure environment

Exposure classification

Reinforced orprestressedconcrete members(Note 1)

Plainconcretemembers(Note 1)

1.Surfaces of members in contact with theground

(a)Members protected by a damp-proofmembrane

A1 A1

(b)Residential footings in non-aggressivesoils

A1 A1

(c)Other members in non-aggressivesoils

A2 A1

(d) Members in aggressive soils (Note 2) U U

2.Surfaces of members in interiorenvironments

c

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(a)Fully enclosed within a buildingexcept for a brief period of weatherexposure during construction

A1 A1

(b)In industrial buildings, the memberbeing subject to repeated wetting anddrying

B1 B1

3.

Surfaces of members in above-groundexterior environments

In areas that are:

(a)Inland (> 50 km from coastline)environment being

(i)Non-industrial and arid climaticzone (Notes 3 & 4)

A1 A1

(ii)Non-industrial and temperateclimatic zone

A2 A1

(iii)Non-industrial and tropicalclimatic zone

B1 A1

(iv) Industrial and any climatic zone B1 A1

(b)Near-coastal (1 km to 50 km fromcoastline), any climatic zone

B1 A1

(c)Coastal (Up to 1 km from coastlinebut excluding tidal and splash zones)(Note 5), any climatic zone

B2 A1

4. Surfaces of members in water

(a) In fresh water B1

(b) In sea water

(i) permanently submerged B2

(ii) in tidal or splash zones C

(c) In soft or running water U

5.Surfaces of members in otherenvironments

Any exposure environment nototherwise described in Items 1 to 4above

U U

Answer:

(10 marks)

32.92

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Your engineering firm has been awarded a contract to replace an existingtimber bridge with a new concrete bridge over a river crossing in centralQueensland. You will act as the onsite Project Engineer for the constructionof the bridge piers. These piers will be submerged during the wet seasonand above water level during the dry season.

Using the attached tables, calculate the Target Strength in MPa based on theminimum requirement for Characteristic Strength for durability.

(Round your answer to one decimal place. Do not include any spaces orcommas.)

Table 1: Minimum characteristic strength for durability

Exposure classification Minimum characteristic strength f ' (MPa)

A1 20

A2 25

B1 32

B2 40

C 50

Table 2: Assumed standard deviation

Grade designationCharacteristic strengthMPa

Assumed standarddeviation MPa

Standard grades

25 25 4.8

32 32 5.34

40 40 5.9

50 50 6.2

Flexural grades

F2.5 2.5 0.5

F3.5 3.5 0.6

Indirect-tensilegrades

IT2.0 2.0 0.5

IT2.5 2.5 0.5

Table 3: Exposure classification table

Surface and exposure environment

Exposure classification

Reinforced orprestressedconcrete members(Note 1)

Plainconcretemembers(Note 1)

1.Surfaces of members in contact with theground

c

(a) Members protected by a damp-proofmembrane

A1 A1

(b)Residential footings in non-aggressivesoils A1 A1

(c)Other members in non-aggressivesoils

A2 A1

(d) Members in aggressive soils (Note 2) U U

2.Surfaces of members in interiorenvironments

(a)Fully enclosed within a buildingexcept for a brief period of weatherexposure during construction

A1 A1

(b)In industrial buildings, the memberbeing subject to repeated wetting anddrying

B1 B1

3.Surfaces of members in above-groundexterior environments

In areas that are:

(a)Inland (> 50 km from coastline)environment being

(i)Non-industrial and arid climaticzone (Notes 3 & 4)

A1 A1

(ii)Non-industrial and temperateclimatic zone

A2 A1

(iii)Non-industrial and tropicalclimatic zone

B1 A1

(iv) Industrial and any climatic zone B1 A1

(b)Near-coastal (1 km to 50 km fromcoastline), any climatic zone

B1 A1

(c)Coastal (Up to 1 km from coastlinebut excluding tidal and splash zones)(Note 5), any climatic zone

B2 A1

4. Surfaces of members in water

(a) In fresh water B1

(b) In sea water

(i) permanently submerged B2

(ii) in tidal or splash zones C

(c) In soft or running water U

5.

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Surfaces of members in otherenvironments

Any exposure environment nototherwise described in Items 1 to 4above

U U

Answer:

(10 marks)

A concrete retaining wall is being built as part of the construction of anunderground car park below a new high-rise development. TheCharacteristic Strength is 40Mpa. Using the attached tables, calculate thewater/cement ratio for use in the concrete mix design.

(Note: Target strength should be used as the 28-day compressive strength)

(Round you answer to two decimal places. Do not include any spaces ofcommas.)

Table 1: Assumed standard deviation

Grade designationCharacteristic strengthMPa

Assumed standarddeviation MPa

Standard grades

25 25 4.8

32 32 5.34

40 40 5.9

50 50 6.2

Flexural grades

F2.5 2.5 0.5

F3.5 3.5 0.6

Indirect-tensilegrades

IT2.0 2.0 0.5

IT2.5 2.5 0.5

Table 2: Water/Cement ratio v. Strength

40.8

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(5 marks)

The reinforced concrete base slab for a single storey residential house is tobe constructed. The characteristic strength is 25MPa. Using the attachedtables, calculate the water/cement ratio to be used to design the concretemix.

(Note: Target strength should be used as the 28-day compressive strength)

(Round you answer to two decimal places. Do not include any spaces ofcommas.)

Table 1: Assumed standard deviation

Grade designationCharacteristic strengthMPa

Assumed standarddeviation MPa

Standard grades

25 25 4.8

32 32 5.34

40 40 5.9

50 50 6.2

Flexural grades

F2.5 2.5 0.5

F3.5 3.5 0.6

0.47

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Indirect-tensilegrades

IT2.0 2.0 0.5

IT2.5 2.5 0.5

Table 2: Water/Cement ratio v. Strength

Answer:

(15 marks)

Using the following known information, what is the aggregate/cement ratioto be used in the concrete mix design based on a water/cement ratio of 0.4?

Nominal aggregate size: 40mm

Aggregate shape: irregular gravel

Slump: 160mm

Grading curve: 3

(Round your answer to one decimal place. Do not include any spaces orcommas.)

0.65

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(10 marks)

Using the following known information, what is the aggregate/cement ratioto be used in the concrete mix design based on a water/cement ratio of0.6:1?

Nominal aggregate size: 20mm

Aggregate shape: crushed rock

Slump: 40mm

Grading curve: 4

(Round your answer to one decimal place. Do not include any spaces orcommas.)

3.3

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(10 marks)

A concrete design has been completed for an upcoming project, with thefollowing parameters:

Water/cement ratio is 0.62

Aggregate/cement ratio is 5.1

The total aggregate proportions in the blend are as follows:

20 mm aggregate 20%

10 mm aggregate 65%

Sand 15%

Calculate the total mass of concrete mix (in kg) using these proportions,based on a 50kg bag of cement.

(Round your answer to one decimal place. Do not include the kg unit or anyspaces or commas.)

Answer:

(15 marks)

You have an approved mix design for a concrete pour that will be takingplace tomorrow morning. You are in an arid zone of Queensland and havenot had any rainfall for over 2 months. Your 20mm aggregate has been in

4.8

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Cement 428 kg

Water 201.2 kg

20 mm aggregate 1061.4 kg

Sand 650.6 kg

Total 2341.2 kg

The soil laboratory have taken samples from the aggregate stockpiles, andfound that the actual moisture content of the 20mm aggregate is 1.8 %, andthe water absorption is 2.1 %. The sand is in SSD condition.

What is the total quantity of water in kg to be included in the concrete mix,after the adjustment for aggregate moisture content?

(Round your answer to one decimal place. Do not include the kg unit or anyspaces or commas.)

Answer:

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