Building Pathology

Question 1

Describe 101 NCS?

Question 2

Explain Carbonation

Answer 2

Carbonation is a chemical reaction with the concrete and C02 in the environment. The reaction reduces the PH level so the concrete becomes less alkaline.

The oxide layer protecting the rebar breaks down allowing meaning that the reinbar is vulnerable to corrosion.

When the reinbar corrodes the steel expands, sprawling the concrete.

Question 3

Can you name some deleterious concrete materials?

Answer 3

RAAC, HAC, Calcium Chloride Concrete Additive

Question 4

Can you name concrete defects

Answer 4

chloride attack, sulpate attack, carbonation, honey combing

Question 5

What is RAAC?

Answer 5

Reinforced areated autoclave concrete. lightweigth precast concrete panels typically used in floor construciton.

Question 6

What is HAC?

Answer 6

high aluminim cement. HAC was used in used in precast concrete until 1974. a molecular reaction called conversion or cyrstalline re-arrangement reduces its strenght.

Question 7

What is calcium chloride additive

Answer 7

Is an additive used in increase the rate of the curing process. It can reduce the ph levels in teh concrete and cause sprawing and rebar corrosion.

Question 8

What is chloride attack?

Answer 8

chlorides can diffuse throught the concrete pores and attache the passive protection layer to the steel rebar leading to corrosion.

Question 9

What is Sulphate Attack?

Answer 9

atmopsheric sulphate diffuses into the cocrete and destroys the chemcial bond if the concrete paste and forms ettringite.

Question 10

what is honey combing?

Answer 10

Honeycombing is the airpockets created in concrete due to poor distribution of the aggregate and poor vibration compaction.

Question 11

What is nickel sulphide inclusion?

Answer 11

is an imperfection in tempered or toughened glass whihch can cause spontaneous breakageof the pane. Panels are now heat soaked to avoid this.

Question 12

What is ASR?

Answer 12

alkali-silica reaction is a swelling reaction, which creates a map-like cracking pattern.

Question 13

Describe the construction of a victoria terrace (overstone rd)?

Question 14

Why did you approach a structural engineer for the crack at victorian terrace in hammersmith?

Answer 14

I refered to the BRE digest 251 and determined that this was significant structural movement.

Question 15

what was your specification and why? why did you no use helical bars?

Question 16

where you concerned about the breathablitiy of the resin mortar?

Question 17

Describe the construction of the warehouse in bedford?

Question 18

What is the difference between built-up and composite panels?

Question 19

How can you identify the different cladding systems?

Question 20

What are the risks of built-up cladding systems?

Question 21

what is and how do you identify UV degradation to Glass reinforced plastic roof lights?

Question 22

What was the tenant liable for? What did you recommend? (bedford)

Question 23

Did you consider any interim measures due to health and safety risks?

Question 24

what is sick nail sydrome?

Question 25

what part L considerations did you need to undertake?

Question 26

can you name 5 approved documents?

Question 27

Can you describe the roof structure?

Question 28

What is the difference between settlement and subsidence?

Answer 28

subsidence is the downward foundation movement caused by the change in teh site below the foundations, usually assoucated with volumetric changes if the subsoil i.e. variation in moisture content caused by trees

Settelment is downward foundation movemenbt caused by an application of load immediately after construction or due to poorly compacted ground.

Question 29

What type of trees cause subsidence?

Answer 29

All trees can but there are a number of factors including the tree type, location, soil make up. I would need to refer to the BRE note if I was investigated this issue.