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Cert III Steelfixing study materials
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Cert III Steelfixing practice questions

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Question 1Core units of competency

Which document provides the steel reinforcement details, bar sizes, spacing and lap lengths for a project?

  1. The site diary
  2. The toolbox talk record
  3. The reinforcement placing drawings and schedules Correct answer.
  4. The delivery docket

Explanation

Reinforcement placing drawings and bar schedules are the project-specific documents that specify bar diameters, spacing, cover, lap and anchorage lengths, and the arrangement of bars in each member. Site personnel must work to the current approved revision of these drawings, because they carry the engineer's design intent and any superseded sheet must be withdrawn from use.

Question 2Core units of competency

What is the minimum concrete cover normally specified for reinforcement, measured from the outer surface of the bar to the exposed concrete face?

  1. The cover specified on the drawings for the exposure condition Correct answer.
  2. The distance between parallel bars
  3. The bar diameter plus the lap length
  4. The thickness of the formwork ply

Explanation

Cover is the concrete protecting the steel from moisture, chlorides and fire, and its required value depends on the exposure classification and member type, so it is stated on the drawings and in the specification. Bar spacers and chairs are used to hold the steel at that distance so the cover is achieved consistently over the whole element.

Question 3Core units of competency

Which personal protective equipment is essential when cutting and bending reinforcing bar on site?

  1. A high-visibility vest only
  2. A dust mask and a hard hat only
  3. Hearing protection only
  4. Eye protection, gloves and safety footwear Correct answer.

Explanation

Bar cutting and bending exposes workers to flying scale and wire fragments, sharp cut ends, and heavy bar ends that can crush feet, so eye protection, suitable gloves and steel-capped safety footwear are all required. A task risk assessment and the site PPE rules set the full minimum, which usually also includes a hard hat and high-visibility clothing.

Question 4Core units of competency

What is the main purpose of tying reinforcement with binding wire before concrete is placed?

  1. To provide an electrical earth for the structure
  2. To replace the need for bar chairs and spacers
  3. To hold the bars in their designed position during placing and vibration of concrete Correct answer.
  4. To increase the tensile strength of the bars

Explanation

Tying secures the bars so the cage keeps its shape and stays at the specified spacing and cover while concrete is poured and vibrated, and so workers can walk on or work around it safely. The wire tie itself carries no design load; the structural strength comes from the bars and their correct embedment and laps.

Question 5Core units of competency

Which statement best describes a lap splice in reinforcement?

  1. A bar shortened on site to suit the formwork
  2. A single bar bent through ninety degrees at the end
  3. Two parallel bars overlapped for a specified length so force transfers from one to the other Correct answer.
  4. Two bars placed end to end with no overlap and butt-welded

Explanation

A lap splice works by overlapping two bars over a length calculated to develop the force in the bar through bond with the surrounding concrete, so the two bars act together. The lap length depends on bar diameter, concrete strength, bar type and the amount of other bars lapped nearby, and must match the approved drawings.

Question 6Core units of competency

Before placing concrete, why must the reinforcement be inspected and signed off?

  1. To record the concrete supplier's delivery times
  2. To check the formwork oil has been applied
  3. To confirm the crane has been inspected
  4. To confirm the bar diameter, spacing, laps, cover and cleanliness match the approved drawings Correct answer.

Explanation

Reinforcement is covered permanently once concrete is placed, so a pre-pour inspection verifies bar size, number, position, spacing, laps, cover and that the steel is free of mud, oil, loose rust and ice. The inspection is documented and signed so there is a record that the work complied before it became inaccessible.

Question 7Core units of competency

What does the term 'bar mark' refer to on a reinforcement drawing?

  1. The physical mark left by the bar bender's machine
  2. The paint colour used to identify the steel grade
  3. A unique label linking each bar shape to its schedule entry Correct answer.
  4. The position number of the bundle on the truck

Explanation

Each distinct bar shape is given a bar mark, and that mark ties the drawn bar to a schedule line giving diameter, shape code, dimensions, quantity and bending details. Fixers use bar marks to match delivered bundles to the correct location and to check that the right bar goes in the right place.

Question 8Core units of competency

Which hazard is most associated with storing bundles of reinforcing bar on site?

  1. Release of toxic gas from the bar surface
  2. Bundles rolling or collapsing onto workers Correct answer.
  3. Electrical short circuit between bars
  4. Spontaneous combustion of the steel

Explanation

Round bars stacked or bundled can roll, and badly chocked or overloaded stacks can collapse, so bundles must be stored on firm level ground with dunnage and restraints. Storage areas also need to be separated from walkways and kept clear of the crane slew zone to control the risk.

Question 9Core units of competency

A slab is drawn with N12 bars at 200 mm centres each way. What does this mean for the fixer?

  1. 12 mm bars spaced 200 mm from the slab edge only
  2. 200 mm diameter bars spaced 12 mm apart
  3. 12 mm diameter bars spaced 200 mm apart in both directions Correct answer.
  4. 12 bars in total spaced 200 mm apart

Explanation

The notation gives bar size in millimetres followed by the centre-to-centre spacing, so N12 at 200 means 12 mm diameter bars at 200 mm centres. 'Each way' indicates a two-way mat, so the same bar size and spacing is repeated in the perpendicular direction.

Question 10Core units of competency

A fixer notices that the delivered bars are bent to a different shape from the bar mark shown on the placing drawing. What is the correct action?

  1. Straighten and re-bend the bar on site to suit
  2. Cut the bar shorter so it fits the formwork
  3. Stop, quarantine the bars and refer the discrepancy to the supervisor before use Correct answer.
  4. Install the bar as delivered and note it later

Explanation

Bars that do not match the approved bar schedule must not be placed, because the wrong shape may not develop the required anchorage or may foul formwork and other steel. The fixer should set the bars aside, keep them identifiable and report the discrepancy so the supplier or engineer can resolve it.

Question 11Core units of competency

Why are bar chairs and spacers placed under and beside reinforcement?

  1. To hold the formwork apart
  2. To stiffen the bars against bending
  3. To connect the bars electrically
  4. To lift the steel so the specified concrete cover is maintained Correct answer.

Explanation

Chairs support the top and bottom mats at the correct depth, and spacers hold the outer bars at the required distance from the form face, so the specified cover is achieved. Correct cover protects the steel from corrosion and provides the fire resistance assumed in the design.

Question 12Core units of competency

What is the purpose of a cranked or bent-up bar in a slab or beam?

  1. To make the bar easier to tie
  2. To allow concrete to flow past more freely
  3. To provide reinforcement where bending moments change, such as over supports Correct answer.
  4. To reduce the weight of the element

Explanation

Bent-up bars are shaped so a single bar can provide bottom tension steel in the span and top steel over the support, where the bending moment reverses. The bend positions place steel where the design requires it, and the anchorage beyond the bend must still meet the specified length.

Question 13Core units of competency

A bundle of reinforcement has been stored on the ground for several weeks and shows loose flaking rust. What should the fixer do before placing it?

  1. Place it, because rust improves the bond with concrete
  2. Reject the whole bundle without inspection
  3. Paint the bars with bitumen to seal them
  4. Wire-brush the loose scale and seek supervisor assessment of the bar section Correct answer.

Explanation

Light surface rust is generally acceptable, but loose flaking scale and pitting may reduce the bar cross-section and bond, so the steel needs cleaning and assessment against the specification. The supervisor or engineer decides whether the bars can be used, and the decision should be recorded rather than assumed by the fixer.

Question 14Core units of competency

When lapping two bars in a column, how should the lapped bars normally be positioned?

  1. Both bars placed side by side in contact over the specified lap length and tied Correct answer.
  2. The bars crossed at right angles
  3. The bars separated by a gap of at least one bar diameter
  4. One bar cut away so the bars butt together

Explanation

A contact lap splice places the two bars side by side in contact over the full lap length and ties them so they stay together while concrete is placed. The lap length must be measured from end to end of the overlap and must match the schedule, and the bars must not be separated by a gap unless a non-contact lap is specifically detailed.

Question 15Core units of competency

Why is it important to stagger lap splices in adjacent bars rather than ending them all at the same section?

  1. To make the bars easier to deliver
  2. To avoid a weak plane where many bars are lapped at once Correct answer.
  3. To allow the concrete to set faster
  4. To save binding wire

Explanation

If every bar in a member is lapped at the same cross-section, that section has less effective steel and becomes a weak plane where cracking and failure can concentrate. Staggering the laps spreads the discontinuity along the member so the design strength is maintained at every section.

Question 16Core units of competency

Which practice best protects workers when a crane is lifting a bundle of reinforcement over the site?

  1. Signalling the crane driver by shouting
  2. Standing under the load to guide it by hand
  3. Keeping the exclusion zone clear and using taglines from outside the drop zone Correct answer.
  4. Walking beside the suspended bundle to steady it

Explanation

Suspended loads can fall or swing, so no one should stand or walk beneath them; the lifting area is kept clear and controlled by the dogger. Taglines let a worker guide the load from a safe distance outside the drop zone, and communication is by agreed signals or radio.

Question 17Core units of competency

A fixer must work at height on a steel frame to tie column bars. Which control should be in place first?

  1. A harness worn but not attached
  2. A documented safe work method with a suitable platform or fall-arrest system Correct answer.
  3. Reliance on the worker's experience to avoid falls
  4. A warning sign at ground level only

Explanation

Work at height requires a documented risk assessment and a safe system of work, with the hierarchy of controls applied: eliminate the need to work at height, then use a platform or edge protection, then fall-arrest as a last resort. Any harness must be anchored to a rated point and used by a trained worker.

Question 18Core units of competency

What is the correct way to handle a long, flexible bar by hand with a workmate?

  1. Carry it on the shoulder across a walkway
  2. Both workers lift together with coordinated grip and clear communication Correct answer.
  3. One person carries it alone to save time
  4. Drag the bar along the ground behind the worker

Explanation

Long bars are awkward and can whip or swing, so two or more workers should lift together with a planned grip and clear signals, keeping the bar level and the path clear. Carrying bars across walkways or near overhead lines creates additional struck-by and contact hazards that must be controlled.

Question 19Core units of competency

A worker is asked to cut reinforcement with an angle grinder. Which combination of controls applies?

  1. Use the grinder without a guard to fit the bar
  2. Fit the guard, use the correct disc, and wear eye and hearing protection Correct answer.
  3. Remove the handle for better reach
  4. Cut dry in a closed area with no ventilation

Explanation

An angle grinder must be used with its guard in place and the correct disc for metal, by a trained operator, with eye and hearing protection and fire precautions for sparks. Removing guards or handles defeats the machine's designed safety features and is not permitted.

Question 20Core units of competency

Why must reinforcement be clean and free of form oil, mud and ice immediately before concrete is placed?

  1. To ensure the concrete bonds to the steel Correct answer.
  2. To make the bars easier to lift
  3. To stop the bars rusting after the pour
  4. To reduce the amount of concrete needed

Explanation

Bond between concrete and steel depends on direct contact, and coatings such as oil, mud, paint or ice break that contact and reduce the anchorage and lap capacity. The steel should be cleaned and the inspection recorded before the pour proceeds.

Question 21Core units of competency

What does a shape code on a bar schedule define?

  1. The surface finish of the bar
  2. The standard bent shape and its dimensioning points Correct answer.
  3. The grade of steel to be used
  4. The number of bars in a bundle

Explanation

Shape codes are standard references for common bent bar geometries, and each code specifies which dimensions must be given to fully describe the bend. Using the correct shape code ensures the bar is bent to the designed geometry and that the bending dimensions are interpreted consistently.

Question 22Core units of competency

During a pour, a fixer sees a top mat of slab reinforcement being pushed down under the concrete. What is the most appropriate response?

  1. Note it on the drawing and take no further action
  2. Continue the pour and report it at the end of the shift
  3. Stop the pour in that area, restore the steel to its correct level and inform the supervisor Correct answer.
  4. Add extra concrete to hide the depression

Explanation

Displaced top steel reduces the effective depth and the slab's capacity, so the pour should be paused locally while the mat is lifted back to its chairs and the supervisor is informed. The event and the corrective action should be recorded, and the area may need review by the engineer.

Question 23Core units of competency

A lap length on the drawing is given as 40 times the bar diameter. For 16 mm bars, what is the required lap length?

  1. 160 mm
  2. 560 mm
  3. 400 mm
  4. 640 mm Correct answer.

Explanation

The lap length is the multiplier times the bar diameter, so 40 multiplied by 16 mm gives 640 mm. The overlap must be measured between the ends of the two bars and held over the full length, with the bars tied in contact as detailed.

Question 24Core units of competency

Two bar bundles are delivered with identical diameters but different grade designations. Why must they be kept separate and matched to the drawings?

  1. Because the colour of the bar changes with grade
  2. Because higher grade bars are always heavier
  3. Because lower grade bars cannot be bent
  4. Because the specified grade controls the strength and lap lengths required in the design Correct answer.

Explanation

Grade designation indicates the yield strength of the steel, and the design lap lengths, anchorage and member capacity are based on the grade specified. Substituting a different grade without approval can make laps and anchorages inadequate even though the bar diameter looks correct.

Question 25Core units of competency

A fixer finds that a column starter bar is set 40 mm outside its correct position relative to the formwork. What is the correct technical response?

  1. Cut the bar off and rely on the concrete alone
  2. Report it so the engineer can approve a controlled correction such as a crank over the permitted slope Correct answer.
  3. Move the formwork to suit without telling anyone
  4. Bend the bar over sharply at the base to bring it into line

Explanation

A misplaced bar reduces cover on one face and may affect the column's capacity, so the deviation must be assessed rather than corrected by eye. The engineer can approve a controlled crank within permitted limits, or another remedy, and the correction is documented; sharp local bends are not acceptable.

Question 26Core units of competency

What is the main purpose of tying reinforcement bars together with tie wire before concrete is placed?

  1. To hold the bars in their designed positions during handling and pouring Correct answer.
  2. To replace the need for bar chairs under the top mat
  3. To prevent the bars from rusting while stored on site
  4. To increase the tensile strength of the individual bars

Explanation

Tie wire is a temporary fixing that keeps bars in the position shown on the placing drawing so that they do not move when workers walk on the mat or when concrete is placed and vibrated. The wire does not add structural strength to the bar itself and does not protect against corrosion. Correct spacing and cover depend on the bars staying where they were set out.

Question 27Core units of competency

Which tool is normally used to cut reinforcing bar to length on a construction site?

  1. A wood saw with a carbide blade
  2. A hammer and bolster chisel
  3. A bar-cutting guillotine or shears Correct answer.
  4. A bolt cutter with hardened jaws

Explanation

Reinforcing bar is cut with a purpose-made bar cutter, such as a mechanical guillotine or hydraulic shears, which produces a clean square cut without heat damage. Abrasive saws are also used but generate sparks and dust, so they need specific controls. Hand tools such as bolt cutters are only suitable for small diameters and light wire.

Question 28Core units of competency

What does the cover of reinforcement refer to?

  1. The number of ties used to hold a cage together
  2. The thickness of concrete between the outside of a bar and the nearest concrete surface Correct answer.
  3. The protective paint applied to bars before placing
  4. The overlap length where two bars are lapped together

Explanation

Cover is the depth of concrete protecting the steel, measured from the bar surface to the face of the finished concrete. It is essential for durability because it shields the steel from moisture and oxygen, and it also provides fire resistance. Cover is controlled with spacers and chairs and checked before the pour.

Question 29Core units of competency

Which personal protective equipment is essential when tying reinforcement by hand?

  1. Gloves and safety glasses Correct answer.
  2. Steel-capped boots only
  3. Ear muffs and a dust mask
  4. A high-visibility vest only

Explanation

Hand tying exposes workers to cut and puncture injuries from bar ends and tie wire, and to eye injury from flying wire ends, so gloves and safety glasses are essential. Other items may also be required depending on the task, but these two address the main hand-tying hazards. Boots and vests are standard site wear but do not protect the hands or eyes.

Question 30Core units of competency

What is the usual purpose of a spacer block placed against formwork in a wall or column?

  1. To tie the vertical bars to the horizontal bars
  2. To act as a chair supporting the bottom mat of a slab
  3. To keep the formwork panels from bowing under concrete pressure
  4. To hold the reinforcement cage at the correct cover from the form face Correct answer.

Explanation

Spacers are fixed to the outside of the cage so that when the cage is set in the formwork the bars sit at the cover distance specified on the drawing. They are made in a grade and shape that will not create a path for water into the concrete. Chairs perform a similar role under slabs but are not used against vertical form faces.

Question 31Core units of competency

What does the grade designation on a delivery docket, such as 500N, tell the fixer?

  1. The mass of the bundle in kilograms
  2. The number of bars in the bundle
  3. The specified yield strength of the bar in megapascals Correct answer.
  4. The length of the bar in millimetres

Explanation

The grade number indicates the specified yield strength of the steel in megapascals, so grade 500 bar has a yield strength of 500 MPa. The fixer must ensure that bar of the correct grade is used in each location, because bars of different grades can look identical. Diameter, length and bundle count are shown separately on the docket.

Question 32Core units of competency

Why should reinforcement be lifted off the ground when it is stored on site?

  1. To make it easier to count the bars in each bundle
  2. To allow the delivery truck to reverse closer
  3. To reduce corrosion and keep the bars clean before fixing Correct answer.
  4. To stop the bars from being stolen

Explanation

Bars stored directly on the ground stay damp and collect mud and water, which promotes corrosion and contamination that must be removed before concrete is placed. Supporting the bundles on bearers allows water to drain and air to circulate. Clean steel bonds properly with concrete, so storage practice directly affects the quality of the finished work.

Question 33Core units of competency

Which document shows the bar marks, sizes, shapes and quantities needed to fix a concrete element?

  1. The formwork inspection checklist
  2. The concrete delivery docket
  3. The site safety plan
  4. The bar schedule and placing drawings Correct answer.

Explanation

The bar schedule lists each bar mark with its size, shape, length and quantity, and the placing drawings show where each mark is located in the element. Together they tell the fixer exactly what to cut, bend and place. The other documents deal with safety, concrete supply and formwork, not with the reinforcement detail.

Question 34Core units of competency

A beam drawing shows 6N16 longitudinal bars. How many 16 mm bars must the fixer place in that beam?

  1. One bar
  2. Three bars
  3. Sixteen bars
  4. Six bars Correct answer.

Explanation

In the notation 6N16, the leading number gives the quantity and the number after the letter gives the bar diameter in millimetres. The letter N indicates the bar type or grade convention used on the drawing. Therefore the beam requires six bars of 16 mm diameter.

Question 35Core units of competency

A fixer needs a lap of 35 bar diameters on a 20 mm bar. What lap length should be provided?

  1. 200 mm
  2. 350 mm
  3. 700 mm Correct answer.
  4. 35 mm

Explanation

Lap length is calculated by multiplying the number of diameters by the bar diameter, so 35 times 20 mm equals 700 mm. The fixer must measure from the end of one bar to the end of the other along the lap, not from the ends of the bars. Getting this wrong can leave a splice that is too short to transfer the force.

Question 36Core units of competency

Why must tie wire ends be bent away from the concrete surface after tying?

  1. To make the cage easier to lift with a crane
  2. To stop the wire ends from rusting in storage
  3. To prevent the wire ends from sitting in the cover zone and creating a corrosion path Correct answer.
  4. To keep the tie wire from loosening during transport

Explanation

Tie wire ends left pointing toward the formwork can sit within the cover concrete and allow moisture to reach the steel, causing staining and corrosion. Bending the ends into the body of the cage keeps them well inside the concrete. This is a simple habit that protects the durability of the finished element.

Question 37Core units of competency

What is the correct way to check that a slab's bottom mat is at the specified level before the pour?

  1. Check the number of chairs against the delivery docket
  2. Count the number of bars per metre against the drawing
  3. Confirm the bars are the correct grade from the bundle tag
  4. Measure the depth from the top of the formwork or a level line to the bars Correct answer.

Explanation

The position of the mat is verified by measuring from a known reference, such as the top of the formwork or a set level line, down to the bars. This confirms both the depth and, by checking several points, that the mat is level and not sagging. Counting bars or chairs does not confirm the height of the steel.

Question 38Core units of competency

A fixer is asked to bend a bar on site that is shown as a straight bar on the schedule. What is the appropriate action?

  1. Cut it shorter so that it fits the formwork
  2. Bend it by hand to suit the site conditions
  3. Bend it with a bar bender to the nearest convenient angle
  4. Do not bend it without approval from the designer or engineer Correct answer.

Explanation

Bar shapes and lengths are designed for a reason, and bending or cutting a bar changes its anchorage and the way forces are carried. Site changes must be approved by the person responsible for the design before work proceeds. Bending by hand or to a convenient angle can crack the bar or leave it unable to perform its function.

Question 39Core units of competency

A column cage is being lifted into position by crane. What should be checked before the lift begins?

  1. That the bar schedule has been signed
  2. That the concrete truck has arrived on site
  3. That the cage is tied securely and lifting points are suitable for the load Correct answer.
  4. That the formwork has been oiled

Explanation

A cage can distort or shed bars if it is not tied firmly and lifted from suitable points, so the tie condition and lifting arrangement must be checked first. The lift plan should identify the weight, the rigging and the exclusion zone. Concrete supply and formwork oiling are separate activities that do not affect the safety of the lift.

Question 40Core units of competency

Two bars of different diameters are to be lapped. Which diameter should be used when calculating the lap length?

  1. The larger diameter Correct answer.
  2. The smaller diameter
  3. The average of the two diameters
  4. Either diameter, since the result is the same

Explanation

Where bars of different sizes are lapped, the lap length is based on the larger diameter because the smaller bar must be able to develop its force into the larger one. Using the smaller diameter would produce a lap that is too short. The fixer should check the drawing, which normally states the lap requirement.

Question 41Core units of competency

Why is it important to check bar spacing at several points along an element rather than at one place only?

  1. Because the bar grade changes along the element
  2. Because the concrete cover is the same everywhere
  3. Because spacing can vary where bars are pulled out of line during fixing Correct answer.
  4. Because the drawing only shows one spacing value

Explanation

Bars can be pulled out of position during handling and tying, so a single check may miss local areas where the spacing is too wide or too tight. Checking at several points confirms the whole element complies with the drawing. Uniform spacing matters because it affects crack control and the distribution of forces.

Question 42Core units of competency

What should a fixer do if a delivery of reinforcement arrives without identification tags?

  1. Use the bars in any location where bar of that size is required
  2. Set the bars aside and report the problem so the material can be identified Correct answer.
  3. Cut a sample and estimate the grade from its colour
  4. Install the bars and record the issue in the site diary later

Explanation

Untagged bar cannot be confirmed as the correct grade or specification, so it must be segregated and the issue reported for identification against the delivery documents. Using unidentified steel risks placing the wrong grade in a structural element. Colour is not a reliable indicator of grade.

Question 43Core units of competency

A wall has two layers of vertical bars. Why are ligatures or cross-ties used between the layers?

  1. To replace the horizontal bars in the wall
  2. To increase the cover to the outer face
  3. To hold the two layers at the correct separation and tie the cage together Correct answer.
  4. To act as spacers against the formwork

Explanation

Cross-ties or ligatures connect the two layers of reinforcement and maintain the designed distance between them, which is essential for the wall to act as intended. They also help to keep the cage rigid during handling and pouring. Cover and spacing to the form face are controlled by separate spacers.

Question 44Core units of competency

During a pour, a fixer notices a spacer being dislodged under the top mat of a slab. What is the best response?

  1. Note the location and arrange to drill in extra bars afterwards
  2. Replace or reposition the support immediately, before more concrete is placed Correct answer.
  3. Ignore it, because the concrete will hold the bars in place
  4. Wait until the pour is finished and report it to the supervisor

Explanation

The fixer should act at once to restore the support so the top mat stays at the correct depth while concrete is still workable. Once concrete has set around displaced steel, correcting the cover becomes difficult and costly. Reporting after the pour does not prevent the defect from forming.

Question 45Core units of competency

What is the main reason for keeping different bar marks in separate bundles on site?

  1. To allow the bundles to be stacked higher
  2. To avoid paying for extra storage space
  3. To reduce the total weight of each crane lift
  4. To make it easy to find and issue the correct bars for each location Correct answer.

Explanation

Bars of different marks have different lengths, shapes or sizes and must be placed in specific locations, so mixing them leads to errors and rework. Keeping marks separate allows the correct bars to be issued quickly to each work front. This is a simple housekeeping control that protects quality.

Question 46Core units of competency

A fixer is setting out column starter bars and finds the drawing dimension conflicts with the grid line on site. What is the correct action?

  1. Set the bars to the grid line and continue
  2. Set the bars to the drawing dimension and continue
  3. Split the difference between the two dimensions
  4. Stop and refer the discrepancy to the supervisor or engineer for a decision Correct answer.

Explanation

A conflict between the drawing and the site grid must be resolved by the person responsible for the design before work continues, because the wrong choice can misplace the whole column. Raising a query protects both the structure and the fixer. Guessing or averaging dimensions is never acceptable.

Question 47Core units of competency

Why does the position of a lap splice along a bar affect the performance of a reinforced concrete member?

  1. Because laps change the grade of the bar
  2. Because laps are always placed where bending moments are highest
  3. Because laps transfer force over a length, and placing them in low-stress zones reduces the risk of weakness Correct answer.
  4. Because laps increase the cover at that point

Explanation

A lap works by transferring force from one bar to the next through bond over the lap length, so the splice is a locally critical region. Designers position laps away from zones of maximum stress, such as mid-span of a beam, to reduce the risk of failure. The fixer must therefore place laps where the drawing shows them.

Question 48Core units of competency

A bundle of bars has developed a light, tight surface rust after storage. What is the appropriate assessment before use?

  1. Accept it only if the bars are painted before placing
  2. Accept it if the rust is surface only and does not reduce the bar section or form loose scale Correct answer.
  3. Reject the whole bundle because any rust is unacceptable
  4. Accept it only if the bars are used in non-structural locations

Explanation

Light surface rust on reinforcement is generally acceptable because it does not reduce the cross-section and actually improves bond with concrete. The concern is loose, flaking scale or pitting that reduces the bar area, which requires assessment and possible rejection. The fixer should judge the condition and refer doubtful cases for a decision.

Question 49Core units of competency

Why must a fixer avoid welding or applying intense heat to reinforcement on site without approval?

  1. Because heat makes the bar too heavy to handle
  2. Because heat changes the steel properties and can reduce the strength of the bar Correct answer.
  3. Because welding always removes the bar mark
  4. Because welding is only permitted on stainless steel

Explanation

High heat from welding or flame cutting alters the metallurgical structure of the steel and can reduce its strength and ductility at that point. Welded connections to reinforcement therefore require specific approval and procedure. The fixer must not improvise welded joints or use heat to bend bars.

Question 50Core units of competency

A fixer is asked to place a top mat in a cantilever slab. Why is the height of this mat especially critical?

  1. Because the top mat is only needed to support the workers
  2. Because the top mat only controls cracking and carries no force
  3. Because the top mat carries the main tension in a cantilever and lowering it reduces the slab's capacity Correct answer.
  4. Because the top mat determines the concrete cover to the bottom face

Explanation

In a cantilever the tension from bending occurs at the top of the slab, so the top mat is the main structural steel. If it is pushed down during the pour, the effective depth is reduced and the capacity of the cantilever falls sharply. This is why chairs and careful pour attendance are essential in cantilever slabs.