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2012 AIN SHAMS UNIVERSITY
[CONSTRUCTION ENGINEERING II REVISION]
Made By: Ahmed Fathy Abdel-Azeem
Supervised By: Dr.Amgad Talaat
[CONSTRUCTION ENGINEERING II REVISION] January 14, 2012
Dr. Amgad Talaat Page 1
1) Draw a flow diagram showing the typical activities involved in the inspection and repair
of concrete structures?
Solution
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2) What are the two groups of concrete deficiencies? Explain briefly.
Solution
Structural Failure
Usually result from a design deficiency or an overloading condition. Overloads may
be either manmade or natural. An example of a man made overload is a load that
exceeds the allowable floor loading in a building. An example of a natural overload is
an earthquake.
Lack of Durability and Serviceability
It may be caused by material, production, or environmental factors. These three
factors were discussed in the three previous modules and will not be covered again.
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3) What are the reasons of conducting inspections?
Solution
To determine the present condition of the structure.
To determine the type, extent, rate and causes of deterioration.
To estimate the time remaining before repair or replacement.
To estimate the effects of deterioration on serviceability if repair or replacement is
deferred.
To determine if the proposed changes to the structure will affect the structure‟-s safety
and service life.
[CONSTRUCTION ENGINEERING II REVISION] January 14, 2012
Dr. Amgad Talaat Page 2
To estimate the most cost-effective means to prevent further deterioration to the structure.
To study the performance of a material under a specific exposure condition.
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4) Draw the general flow-chart of inspection?
Solution
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5) What are the conditions indicate the need for detailed inspection?
Solution
When the information gathered during a preliminary inspection indicates a need for
closer examination.
When either the inspectors or plant operators note potentially serious deterioration.
When there is a plan to increase significantly the loads on a structure.
When the condition of the structure has changed significantly since the last inspection.
[CONSTRUCTION ENGINEERING II REVISION] January 14, 2012
Dr. Amgad Talaat Page 3
6) What should field measurements include?
Solution
Delamination, voids, crack mapping.
Corrosion activity/potential mapping.
Carbonation.
Concrete cover, spacing of rebars.
Concrete strength and variability.
Concrete quality.
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7) Explain briefly what is meant by crack survey?
Solution
It‟s a function of crack length, direction, width, and depth.
Types: active or passive.
o Active Crack: a crack caused by;
Atmospheric variations- Temperature changes- Moisture drops- Settlement-
Loading conditions
o Passive Crack (Dormant) (Inactive): a crack caused by;
Construction errors _ Shrinkage _ Dead loads _ Internal temperature variations _
Shock waves
A good crack survey includes the following steps:
o Locate all cracks.
o Measure or estimate the widths and lengths of all cracks and then record the
results. (using comparator or crack microscope) (Tell-tale).
o Record the size and location of the cracks on a structural plan.
o Classify each crack as active (A) or passive (P).
o Determine the causes of all cracks, if possible.
o Locate internal cracks by sounding, impact echo testing, or ultrasonic pulse
velocity methods.
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8) How can you evaluate the crack enlargement?
Solution
Make a “tell-tale” of two thin glass or metal strips and position them side-by-side over the
crack. Bond the two plates on opposite sides of the crack, and make aligned marks across
each plate. Any changes in the distance between these two marks indicate relative movement
of the parts separated by the crack
[CONSTRUCTION ENGINEERING II REVISION] January 14, 2012
Dr. Amgad Talaat Page 4
9) Explain what is meant by concrete non-destructive tests? Choose one of them and
illustrate it in details.
Solution
Non-destructive tests:-
They are necessary tests done after the concrete has hardened to determine whether the
structure is suitable for its designed use (used also for quality control). Ideally such
testing should be done without damaging the concrete.
Examples: Pachometer (Cover) Survey _ Chloride Content Determination _ Moisture
Content Determination_ Ultrasonic Testing (Pulse Velocity Test) _ Rebound Hammer
Test _ Impact-Echo Test _ Concrete Core Extraction.
Ultrasonic Testing (Pulse Velocity Test):-
Applications
o Testing uniformity and relative quality
of concrete.
o Indicated the presence of crack and
voids.
Concept: Measuring the velocity of an ultrasonic
pulse through concrete.
Types of measurement: Direct _ Semi-direct _
Indirect
Factors: Density _ Voids _ Cracks _ Coarse
aggregates _ Rebars.
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10) Explain what is meant by concrete components’ tests? Choose one of them and
illustrate it in details.
Solution
Ensuring that all concrete materials are satisfied with specifications and well stored.
(i.e. Raw materials must be with the contracted conditions).
Components are mixing water, cement, aggregates, and admixtures.
Types: Initial _ Periodic _ Additional Tests.
For Example: Testing of Cement
o The fineness of cement
o The initial and final setting time of cement
o Soundness of cement
o Compressive strength of cement
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[CONSTRUCTION ENGINEERING II REVISION] January 14, 2012
Dr. Amgad Talaat Page 5
11) What are the reasons of applying a load test on concrete element/elements? Explain the
procedure of applying the load test?
Solution
Reasons:
o Changing the type of structure usage.
o If listed in project specification.
o Having doubts in efficiency of structural elements.
o Presence of irregular settlement during construction.
Procedure:
o Subjecting the different elements with additional loads
o Record deflection readings before and after loading
o Compare noticed deflections with the max accepted limit
o If unsatisfied; repeat test after 72 hours, otherwise element will be unaccepted.
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12) What are the different methods of strengthening an RC element?
Solution
Crack‟s Treatment: painting with epoxy material.
Horizontal Narrow Crack‟s Treatment
o Open the crack wider
o Fill it with epoxy material from one side only
o Clean the crack ( after concrete hardening)
Deep Crack‟s Treatment ( Injection)
o Open the crack wider
o Fill it with epoxy material from two sides
o Make holes at 25-50 cm spacing, and fill with epoxy material
o Inject the first side through pipes, go on the other side
Wide Crack‟s Treatment
o Clean the crack after opening at V shape
o Fill with Cement, Polymer, and epoxy materials
Building Crack‟s Treatment
o Clean the crack after opening at V shape
o Paint then fill the interior surface with certain materials
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13) Explain the procedure of strengthening a reinforced concrete column in ground
floor using a reinforced concrete jacket?
Solution
[CONSTRUCTION ENGINEERING II REVISION] January 14, 2012
Dr. Amgad Talaat Page 6
Remove the paining layer and clean the surface
Insert bars to fix the new stirrups in both directions at 25-50 cm spacing (By making
holes with the corresponding rebar diameter + 2 mm, and clean them and fill).
Vertical bars are inserted with the same number of that of column and diameter
Vertical bars are inserted before stirrups fixing
Column surface is fully painted with epoxy material ( after cleaning and filling holes)
Pour the concrete of the RC jacket
[CONSTRUCTION ENGINEERING II REVISION] January 14, 2012
Dr. Amgad Talaat Page 7
14) Using neat sketches, explain the main difference between good and bad storage of the
following materials: cement – fine and coarse aggregate – shuttering wood –
reinforcement steel.
Solution
Cement
Aggregates
Reinforcement Steel
GOOD BAD
GOOD/fine GOOD/coarse
e BAD
GOOD
BAD
[CONSTRUCTION ENGINEERING II REVISION] January 14, 2012
Dr. Amgad Talaat Page 8
Shuttering wood
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15) How can we prevent the failure of excavation sides in site?
Solution
Applying safe side slopes with different depths.
Sides strengthening with longitudinal and transverse wood bars.
Using pre-cast barriers
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16) What are the steps of replacement for bad types of soil? And what are the soil
replacement types?
Solution
Steps
o Distinguish the new soil layers
o Compact each layer by compactor (هراس)
o Put a sand layer for leveling
Types
o Fine and Coarse aggregates soil.
o Fine aggregates soil.
o Coarse aggregates soil.
o Plain (weak) concrete soil.
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17) What are the different methods of mixing concrete? And when can we use each of
them?
Solution
Manual (hand-made) Mixing: For small traditional works.
GOOD BAD
[CONSTRUCTION ENGINEERING II REVISION] January 14, 2012
Dr. Amgad Talaat Page 9
Mechanical Mixing
o In-situ Mixer: small mixer availability in site (Traditional Projects)
o Central Ready Mix Stations: in-site or near it (Large Projects)
o Concrete Mix Trucks: site is far away from water resources
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18) What are the precautions of casting concrete?
Solution
Selecting appropriate pump location to ensure reaching all places.
Max casting height for columns is 2.50 m.
Thicker slabs should be casted at layers.
Determining the positions of casting stoppage.
Main beams should be casted first.
For casting on old concrete; its surface must be roughed.
Super Plasticizers could be used to increase workability.
Environmental conditions considerations.
Max time of concrete existence in truck is 2 hours.
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19) What are the different types of concrete joints?
Solution
Casting (Pouring) Joints: for large volume of poured concrete.
Expansion Joints: for buildings of length more than 30-40 m.
Settlement Joints: to avoid differential settlement.
Control Joint: to allow slab to expand in horizontal direction.
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20) What are the different types of concrete curing?
Solution
Submerging in water: like lakes (horizontal surfaces and floors)
Water spraying; keep surface moist and preventing drying
Covering with moist overlaps
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[CONSTRUCTION ENGINEERING II REVISION] January 14, 2012
Dr. Amgad Talaat Page 10
21) State the time after which we can remove the shuttering of the following reinforced
concrete elements: columns, beams, slabs and cantilever elements.
Solution
Columns & Sides: T= 24 hours
Beams & Slabs: T= 2 L + 2 days
Cantilevers: T= 4 L + 2 days
If forms carries additional loads: T = 28 days
If temperatures decreases than 15 c ; postpone removing of forms
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22) What are the types of quality control inspection programs?
Solution
Adjustment of Design‟s Quality (Quality Control):
All required calculations should be done to determine the best proportions in designing
the concrete mix in both cases of fresh and hardened.
Adjustment of Raw materials „Quality (Total Quality Management):
put a plan to good raw materials according to specifications, taking into consideration
that it must be at the required quality level during all the project stages.
Adjustment of Product‟s Quality (Quality Assurance):
It‟s to control quality during the construction stages to ensure satisfaction with
specifications.
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23) State briefly the inspection plan (field inspection) guidelines?
Solution
Structural Design Revision
Technical Inspection for Materials
Periodic Technical Inspection
Out site Technical Inspection
Additional Tests for Technical inspection
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