T4-x4: Quality Control of the Works Flashcards
(14 cards)
What are some common pitfalls in repair specifications (x5)?
- Access
- Cleaning surfaces
- Removal of concrete
- Profile restoration (e.g. poor mixing, poor compaction)
- Surface protection systems (e.g. thickness of coats)
Name the different components of the bills of quantities
- General items (e.g. access, trial sample repairs)
- Surface cleaning, inspection, testing
- Repair process
.
What standards is used for the site application of products & systems, and quality control of the works?
BS EN 1504-10
For substrate concrete, what tests would be used for:
a) compressive strength
b) surface tensile strength
c) roughness
a) core
b) pull-off strength
c) sand area
For substrate concrete, what test would be used for:
a) chloride penetration
b) depth of carbonation
c) crack width and depth
d) crack movement
a) dust drilling
b) fracture face
c) visual (ultrasonics)
d) visual (monitoring)
For reinforcement, what test would be used for:
a) size
b) section loss
c) degree of corrosion
d) resistivity meter
e) surface electrode potential
f) cover
a) visual
b) visual
c) visual
d) resistivity meter
e) half-cell
f) covermeter
[NAQ] bond coat and rebar coat tests
[NAQ] high-strength concrete and plain cement concrete tests
For factory vs site production:
a) how do you know if a factory product is prequalified?
b) how must a site-mixed produced is compliant?
a) it is CE-marked
b) it must prove compliance (ie. site compliance testing) with performance requirements for the actual materials to be used in the works
What are six watchpoints in quality control?
- Break-out (e.g. chase back until uncorroded steel is found)
- Priming the concrete (cement-based)
- Priming the concrete (epoxy)
- Mixing the repair mortar
- Placing the repair mortar
- Applying the SPS
Describe the components of a detailed condition survey
Describe the preventative maintenance and repair principles (x3)
- Remove the corrosion initiator (e.g. chloride contamination)
- Replace cracked/delaminated material with new concrete/mortar
- Enhanced protection [(e.g. SPS to prevent ingress, extra cover (e.g. sprayed, recast)]
What are two protection systems in BS EN 1504
Hydrophobic system
- prevents water, harmful substances from penetrating (more durable)
Cathodic protection
- prevents steel corrosion, makes steel cathode of an electrochemical cell
What are two problems with hydrophobic treatment?
- Doesn’t impact structure of concrete; no barrier
- Carbonation can increase
