Building Pathology Flashcards
Describe 101 NCS?
Explain Carbonation
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.
Can you name some deleterious concrete materials?
RAAC, HAC, Calcium Chloride Concrete Additive
Can you name concrete defects
chloride attack, sulpate attack, carbonation, honey combing
What is RAAC?
Reinforced areated autoclave concrete. lightweigth precast concrete panels typically used in floor construciton.
What is HAC?
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.
What is calcium chloride additive
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.
What is chloride attack?
chlorides can diffuse throught the concrete pores and attache the passive protection layer to the steel rebar leading to corrosion.
What is Sulphate Attack?
atmopsheric sulphate diffuses into the cocrete and destroys the chemcial bond if the concrete paste and forms ettringite.
what is honey combing?
Honeycombing is the airpockets created in concrete due to poor distribution of the aggregate and poor vibration compaction.
What is nickel sulphide inclusion?
is an imperfection in tempered or toughened glass whihch can cause spontaneous breakageof the pane. Panels are now heat soaked to avoid this.
What is ASR?
alkali-silica reaction is a swelling reaction, which creates a map-like cracking pattern.
Describe the construction of a victoria terrace (overstone rd)?
Why did you approach a structural engineer for the crack at victorian terrace in hammersmith?
I refered to the BRE digest 251 and determined that this was significant structural movement.
what was your specification and why? why did you no use helical bars?
where you concerned about the breathablitiy of the resin mortar?
Describe the construction of the warehouse in bedford?
What is the difference between built-up and composite panels?
How can you identify the different cladding systems?
What are the risks of built-up cladding systems?
what is and how do you identify UV degradation to Glass reinforced plastic roof lights?
What was the tenant liable for? What did you recommend? (bedford)
Did you consider any interim measures due to health and safety risks?
what is sick nail sydrome?
what part L considerations did you need to undertake?
can you name 5 approved documents?
Can you describe the roof structure?
What is the difference between settlement and subsidence?
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.
What type of trees cause subsidence?
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.
