Work Shop - Construction Materials Quality Control
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Transcript of Work Shop - Construction Materials Quality Control
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www.unops.org
Construction Materials
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1. Fulfillment of Requirements
Material Requirements
Process Requirements Equipment Requirements
End Product Requirements
2. Fitness for Purpose
Riding comfort at design speed Ability to serve till the end of design life at design level of
serviceability
What is Quality in Construction?
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Quality is generally to mean compliance withspecified requirements
Quality control is a means to control quality i.e.to verify compliance of materials, equipment,process and final product to predetermined
requirements.
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Fine Aggregates (Sand)No. Inspection and TestingDescription
Testing
method
Acceptance criteria Frequency of Test
1
Grading
AASHTO T-27 Sieve(mm) % pass
10 100
4.76 95-100
2.38 68-861.19 47-65
0.59 27-42
0.3 9-20
0.15 0-7
0.075 0-2.5
One sample per 1500 m3
2 Soluble chlorides BS 812
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Rapid field Technique to Estimate silt content
River or pit sand shouldbe sharp, angular, hard,clean uncoated particles
free from clay andorganic impurities.
Well graded sand must beused for all cement work.
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Coarse Aggregate (Gravel)No. Inspection and Testing
Description
Testing method Acceptance criteria Frequency of Test
1Grading
AASHTO T-27 Different for different
nominal sizes
One sample per 1500 m3
2 LAA AASHTO T-96
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WaterNo. Inspection and Testing
Description
Testing method Acceptance criteria Frequency
of Test
1 Chloride content ASTM D 512
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Cement
No. Inspection and
Testing Description
Testing
method
Acceptance criteria Frequency
of Test
1cement
AASHTO T-
131
AASHTO M-85 Every lot
1.1 Consistency test AASHTO M-85 Every lot
1.2 Initial setting time AASHTO M-85 Every lot
1.3 Final setting time AASHTO M-85 Every lot
The cement to be used in the work should be ordinary Portlandcement complying with ASTM C-150 or BS-12.
Both Roads and Building specifications of UNOPS specify OPC,not PPC
Hardened cement will not be permitted in the works and is tobe removed from site at the contractors expense.
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Brick
Brick must have correct size, shape and sharp edges.
Bricks shall not break when dropped from 1m height, shall give ringingsound when struck with each other and leaves no impression withfinger nail
1. Mortar joint thickness shall not exceed 10mm in the class bricksand 12mm in second class bricks
2. Crushing strength (shall not be less than 35kg/sqcm for ordinarybricks) and water absorption (shall be less that 20%) waterabsorption dry the bricks and weigh (w1), immerse in water for24 hours and weigh again (W2). Then WA=(w2-w1)/W1*100 orA Brick shall not absorb more than 1/6th of its weight ofwater after being soaked for one hour
3. Bricks shall be soaked at least for 1 hour before use
4. Bricks work should be raised uniformly and height of work in a dayshall be less than 1.5m. Difference in height between two different
portions shall be less than 1m
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Shall be regular and uniform in size and shape with sharp square edges andparallel faces.
They shall be free from flaws, cracks and chips.
should have the following dimensions: 400mm x 200mm x 200mm.
There should be a longitudinal groove with 10mm depth and 20mm width oneach block in order to provide place forhorizontal steel reinforcement for themasonry work.
Sample shall be collected randomly and tested every 10m3 of blocks produced.Three samples (blocks) shall be selected at random from every batch.
The crushing strength of blocks shall be tested in a laboratory and the averagecrushing strength of blocks shall not be less than 15MPa (10 MPa) ??? (N/m2)and the water absorption of the blocks shall be not more than 240kg/m3 ofconcrete.
Blocks
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Timber shall be free from twists, knots, splits and other visual or physicaldefects
TIMBER
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Examples of Poor Materials
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Process Control
The assistant engineers shall always be at site to inspect and control thecontractors work processes.
Contractors always give priority for profit than for quality. Therefore, willgo for cheaper materials .
When you do process control, strictly ad
here to t
he Specifications
A number of factors should be controlled during construction as a vital partof process Control:
Material - is the contractor using approved material?
Mixing is the contractor using proper mix ratios? Proper mixingtechniques?
Moisture content is the contractor applying proper water content?Thickness / Lift what is the maximum thickness or lift specified forearth work, brick work, concreting etc?
Compaction what equipments are used during compaction?Whatare the number of passes?What is the sequence/direction passingduring compaction? etc
General finish what is the quality of the final product?
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Examples of Poor Process Control
Top soil and Overburden were notremoved properly due to weakness inprocess Control
Removal of overburden of the sameborrow pit after PM and ME instruction
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Poor Process Control Excessive material spreading with outclearing the road bed
The maximumallowed thicknesswas 200m
The road bedshould have beencleared properlybefore dumping
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Poor workmanship, Substandard work, and poor Masonrystones due to Poor Process Control during Culvert apron
construction
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Excessive Back Fill and Dry Compaction byContractor Lack of Process Control
Maximum allowed thickness of compaction at a time was 150mm butcontractor is filling 1000mm at a time
Contractor is supposed to apply optimum moisture to the back fill, but
prefer to compact it dry
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Improper Soaking of CBR test specimens Poor
Process Control
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End Product Specification
e.g. RoadIs the surface free from compaction planes, ridges, cracks, loose material andmovement under construction equipment?
Has the loose, segregate and otherwise defection areas made good to full depth?
Is the thickness of the layer in limits?The size of the coarse material does not exceed 2/3 of layer thickness?
Does the rolling pattern confirm to specification?
Does survey results conform confirm to requirements grade, cross fall, side ,surface levels, slopes etc
Moisture content prior to compaction ok?
Is Degree of Compaction acceptable?
Is the thickness as per the design?
Then Approve the layer!
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How can we control Quality of ConstructionMaterials in Particular and constructionactivities in General?
1. By Inspection and Process Observation
2. By Random sampling
3. By Testing
4. By Measuring
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InspectionInspection of Storage of Construction MaterialsSI. No Material/pr
oduct
Storage Precaution(Do`s and
Donts)`Location Method
1 Rebar open Store on timber
Runners or concretebeam
1. Dont mix different
dais.2. Cover with
polythene sheet in
rainy season
3. Dont block access
to vehicle
2 Cement Bag Shelteredstore Placed on pallets lifted300mm above ground. 1. Dont allow contact withmoisture or side walls
2. Dont exceed 12 bags
stacking
3 Concrete
pipes
Curing tank
for 7 days
Open Stack yard Proper ramp is made for
loading & unloading
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Testing/Inspection Item Yes No
Has the pipe culvert location been excavated as per the drawings
Have the bed levels of the excavation been checked as per the
drawings
Has the type of bedding specified in the drawing or ordered by the
engineer constructed
Is the manufactured or imported pipe culvert is as per the Technical
Specification
Are the installed pipe culverts are free of defects like crack
Have the jointing of the pipes done properly and collars satisfactorilygrouted
Has the pipe culvert invert elevation checked as per the drawings
Does the pipe culvert bed slope conform to the drawings
Have the pipes culvert been backfilled according to the Technical
Specification
Have th
eh
eadwalls constructed as per th
e drawings and inconformance to the Technical Specification
Inspection for Different types of Construction
Pipe Culvert Installation
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Testing/Inspection Item Yes No
Has the foundation location been excavated as per the drawings
Have the bed levels of the foundation excavation been checked as per
the drawings
Have the form works and reinforcements of the Footing, Abutment,
Piers, Girders and slab being properly spaced as per the drawings.
Has the proportion of the concrete mix been as per the mix design
proportion
Have cube and/or cylinder samples taken for concrete compressive
strength
Has slump test taken frequently
Has the minimum compressive strength obtained
Has the slump test satisfactory
Has backfilling at the abutment, piers and footings done properly
Has the bearings, and filter media placed properly
Have the pre cast Concrete beam placed properly on the abutments
and piers
Is the Expansion joint as per the drawings
Inspection for Bridges
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Testing/Inspection Item Yes No
Working drawing checked and approved
Latest revision being used
Bar schedules approved
Reinforcing steel material approved
Bar bending and cutting satisfactory
Corrosion treatment of bars, if required,
satisfactory applied
Bar size and spacing correct
Bar lap length and location correct
Bar tied as specified Bar assembly rigid and adequately supported
Cover to bottom bars correct
Cover to side bars correct
Cover to top bars correct
Cover blocks approved including fixing
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Description Yes No Not available
Method statement approved
Batching plant mixers in working order(separate dispenser for admixture, if required,
available)
Stand by batchers in working order
Water , sand, coarse aggregate, cement, admixture approved
Water, sand, coarse aggregate, cement, cement stock sufficient.
Concrete conveying arrangement (including transit mixers) available in working condition
and of sufficient capacity
Formwork approved
Reinforcement approved
Pre stressing sheathing approved
Concreting equipment in working order
Stand by crane, vibrators present
Tremie in working order (for under water work)
Concrete ganging present, including carpenter, steel fixer, mechanics and electrician
Access provided
Safety arrangements adequate
Lighting provided
Communication between various points provided
arrangements for arranging suspension/stoppage of concrete provided
curing arrangements made
laboratory notified
Inspection for Concrete works
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Description Yes No
Are the site, orientation and plan of the buildings approved?
Is the site layout as per the drawings?
Is the foundation material of the buildings acceptable for the superstructure load or need
improvement?
Is the foundation material compactedsatisfactorily?
Are the materials for masonry work like stone, sand and water approved?
Is the stone for masonry work shaped and dressed satisfactorily?
Is the mortar mix proportion as per the standard requirements of UNOPS?
Is the hardcore and masonry works constructed as per the drawings and site condition?
Is the backfill in foundation construction made with approved material?
Is the back fill material compacted to satisfactory level?
Is the reinforcement arrangement of the grade beam, beams and columns (if any) as per the
drawings?
Is the proportion of cement, sand and coarse aggregates for grade beam and column as per the
UNOPS standards?
Is the walls constructed with fiber cement or other approved material?
Are the walls double and filled with insulating materials?
Is the fittings of the buildings are provided as per the drawings, and UNOPS spec?
Is the floor of the buildings as per the requirements of UNOPS spec?
Is the building painted with approved paint?
Is the paint work maintained regularly?
Inspection for Building
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Procedures
Quantity
Location
Time
Representative sampling?
Sampling
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Testing
Standards Common standards are ASTM, BS,AASHTO
Laboratory management Joint Laboratory,Separate Laboratory, External Laboratory
Contractors will manipulate results to their
interest if there is no proper control duringtesting
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The quantity of the sources
Visual uniformity/variability of the sources
Intended use (more critical materials require exhaustivetesting)
Quality of the sources (more tests will be made on marginalsources)
Type of tests (more number of tests will be made for moreimportant requirements)
The minimum number of tests, however, will not be generallybelow three.
Procedures forM
aterials Source Approval
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Problem soils in Construction
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When we build Let us think that we buildforever, Let it not be for the present
delight!!!
Thank You!