CHAPTER 1: INTRODUCTION

Question 1

Define CONCRETE

Answer 1

CONCRETE is a mixture of sand and gravel, crushed rocks or other aggregates

Question 2

Define REINFORCED CONCRETE

Answer 2

REINFORCED CONCRETE is the combination of concrete and steel

Question 3

Give at least 5 advantages of Reinforced concrete as a structural material

Answer 3

has a considerable compressive strength
has great resistance to fire and water
it is very rigid
it is a low-maintenance material
it has a long service life
can be cast in different shapes
economical for footing, floor slabs, basement, etc.
inexpensive local material
low grade of skilled labor is required

Question 4

Give at least 3 disadvantages of Reinforced Concrete as Structural Material

Answer 4

It has a low compressive strength
forms are required to hold the concrete until hard
low strength per unit of weight of concrete - Heavy members
members are relatively high
properties vary widely

Question 5

How many weeks does a normal Portland cement need to achieve sufficient strength to permit the removal of forms?

Answer 5

2 weeks

Question 6

Portland cement reach their desired strength after how many days?

Answer 6

28 days

Question 7

It is the common or all-purpose cement

Answer 7

TYPE I (of Portland Cement)

Question 8

It has a modified cement; it has lower heat of hydration compared to Type I

Answer 8

TYPE II (of Portland Cement)

Question 9

It is a high-early-strength STRENGTH CEMENT; it will be produced in the first 24 hours

Answer 9

TYPE III (of Portland Cement)

Question 10

it is a low-heat cement; used for huge concrete structures

Answer 10

TYPE IV (of Portland Cement)

Question 11

It is used for high-concentration of Sulfate

Answer 11

TYPE v (of Portland Cement)

Question 12

These are the materials added to the mixture during or after mixing

Answer 12

ADMIXTURES

Question 13

Identify the common types of Admixtures

Answer 13

Air-entraining Admixtures
Accelerating Admixtures
Retarding Admixtures
Super Plasticizers
Water-proofing materials

Question 14

It increases concrete’s resistance to freezing &thawing; results to less cracking

Answer 14

Air-entraining Admixtures

Question 15

It accelerates early strength development

Answer 15

Accelerating Admixture

Question 16

It is used to slow the setting of the concrete and to retard temperature increases

Answer 16

Retarding Admixtures

Question 17

These are the admixtures made from sulfonates

It is used to reduce water content in the concrete while increasing their slumps

Answer 17

Superplasticizers

Question 18

It is usually applied to hardened concrete surface

Answer 18

Waterproofing material

Question 19

Enumerate the 8 Properties of Concrete

Answer 19

1. Compressive Strength
2. Static Modulus of Elasticity
3. Dynamic Modulus of Elasticity
4. Poisson’s Ratio
5. Shrinkage
6. Creep
7. Tensile Strength
8. Shear Strength

Question 20

Based on your understanding, explain compressive strength

Answer 20

Explain*

Question 21

Based on your understanding, explain the Static Modulus of Elasticity

Answer 21

Explain*

Question 22

What are the different definitions of Modulus of Elasticity?

Answer 22

Initial Modulus
Tangent Modulus
Secant Modulus
Apparent or long-term Modulus

Question 23

It is the slope of the stress-strain diagram at the origin of the curve

Answer 23

iNITIAL MODULUS

Question 24

It is the slope of the tangent to the curve at some point along the curve somewhere in the 50% of the ultimate compressive strength

Answer 24

TANGENT MODULUS

Question 25

It is the slope of the line drawn from the origin to a point somewhere between 25% to 50% of its ultimate compressive strength

Answer 25

SECANT MODULUS

Question 26

It is determined by using stress-strain obtained after the load has been applied for a certain length of time

Answer 26

APPARENT/ LONG-TERM MODULUS

Question 27

Corresponds to small instantaneous strains; usually obtained by SONIC TEST

Answer 27

DYNAMIC MODULUS OF ELASTICITY

Question 28

Generally 20% to 40% higher than the Static Modulus of Elasticity and approximately equal to the initial modulus

Answer 28

DYNAMIC MODULUS OF ELASTICITY

Question 29

used in analyzing structures for seismic or impact loads

Answer 29

DYNAMIC MODULUS OF ELASTICITY

Question 30

the ratio of the lateral expansion to the longitudinal shortening

Answer 30

POISSON’S RATIO

Question 31

ratio used for statically indeterminate structures

Answer 31

POISSON’S RATIO

Question 32

Define Shrinkage

Answer 32

Explain*

Question 33

Additional deformation that occurs after the initial deformation; also called plastic flow

Answer 33

CREEP