Civil Inspector Interview / Quality Control Inspector

TYPICAL INTERVIEW ANSWER FOR QUALITY CONTROL CIVIL INSPECTOR

Part-1:

1.      What are the most important elements of soil classification 

a)      Type of soil, Gradation, and Atterberg limits. The inspector should have a general idea of how these limits (liquid limit, Plastic limit, and plasticity index) correlate with selecting approved select fill).

2.        What’s “CBR” 

a)      California Bearing Ration (CBR). It’s a laboratory value that helps determine soil bearing capacity and in classifying soil. It is a design parameter, however is a requirement by our standard to verify and check! Not knowing what it indicates the inspector has poor soil knowledge and experience.

3.      What is the maximum depth of regular fill lift (layer) prior to compactions 

a)      200 mm

4.      What is the maximum depth of a fill lift (layer) when manual equipment is used for compaction (SAES A-114)

a)      100 mm

5.      What are the project conditions and factors that control compaction? 

a)      Proper Moisture Content.

b)      Compaction Equipment used and a number of rolls.

c)      Confinement of soil (for sand) and stepping of layers of marl and select fill.

d)     Type of Soil.

6.       What are the different types of laboratory ASTM soil density tests? And what are the minimum required density values for each of the tests mentioned above?

a)      Proctor                              95%

b)      Modified Proctor              90%

c)      Relative (for sand)             70%

7.      What are the important points to look for in Concrete form prior to pouring concrete?

a)      Tightness, cleanness, plumpness, steadiness, shoring and bracing, rebar cover, concrete tip level mark correctness.

b)      Also, a vapor barrier must be installed prior to pouring on grade.

c)      Also, the grade must receive termite chemical spray protection prior to vapor barrier placement.

8.      What are the essential elements of concrete placement?

a)      Maximum height of concrete drop is less than or equal to 1 meter.

b)      Segregation must be prevented by ensuring transit mixture is approved, has operating revolution counter, no adding water after batching, and concrete is placed in such a manner to prevent segregation (i.e. only shovels can be used to move concrete around inside the forms-no raking allowed. Vibration should not be used for that purpose.

c)      Pooper vibration must be implemented. (Proper vibrating-dropping the vibrator under its own weight until it gets to the desired drop height, then leaving it there for 3-7 seconds pulling at the count of 3-4 seconds. When vibrating sub-sequent layers, the vibrator must penetrate a centimeter into the older layer. ( Any answer close to this indicate experience)

d)     Some laborers must be continuously watching the forms in case of a large/high pout to ensure no forms failure takes place. In case a wall is being poured, proper height (maximum heights) of each concrete lift must be observed, such as the usual 600 mm stated normally in projects specifications. Also, tamping on the wall is necessary to assist in the consolidation process.

e)      The concrete temperature and the slump are two strong indicators of the inspector’s knowledge. A slump between 75mm and 125mm is normal for normal pours. If the inspector has no clue as to even the range, that’s serious! The maximum allowed temperature for concrete when arriving at the project site is 32 degrees Celsius.

9.      Tell me structural steel receiving inspection and Structural Steel Erection  (AISC-American Institute of Steel Construction)?

a)      This is involved experience in structural steel inspection against abuse and damage, proper storage, proper sequencing on job site to minimize damage, etc.

b)      An experienced civil inspector must know about the erection of structural steel based on the AISC 9 (American Institute of Steel Construction) specification for High Strength Bolts A325 & A490. Solid knowledge in the Turn-Of-The-Nut method is extremely essential for proper erection!

10.  What is the minimum and maximum acceptable asphalt temperature range when arriving on-site ( AASHTO)?

a)      139 to 163 degrees centigrade.

11.  What is the required compaction density of asphalt ( AASHTO)?

a)      96%

12.   What is Prime Coat and where is it applied (AASHTO)? What is it curing requirement for the Prime Coat?

a)      It is asphalt bituminous material that is place on the substrate prior to placement of the first asphalt mixture (the binder course). It must be allowed to cure and to soak into the capping layer (usually select fill).

b)      24 hours, a good indication that the material cured is when the colors turn to pitch black, i.e. the brownness is gone.

13.  What is Tack Coat ( AASHTO)

a.       It is asphalt bituminous material that is applied on existing concrete or asphalt surfaces to bond the new subsequent asphalt pavement to them. A tack coat is not necessary to place on new asphalt before placing the next layer of asphalt unless it is solid (dirty).

14.  Which is the tolerance requirement of sub-grade asphalt smoothness prior to placing asphalt ( AASHTO)?

a.       Using a 3 meter straight edge = 6mm

15.  What is a requirement of finished asphalt surface smoothness (SAES Q-006 & AASHTO)?

a.       Using a 3-meter straight edge 4mm longitudinally, 3mm laterally.