PCI 1&2 Review Questions
1.3 There are several categories of shop drawings. Define at least two types of shop drawings.
- Erection drawings: Show an overall layout of products for a particular area. May be a wall layout (or elevation) for architectural concrete cladding panels or a plan layout for double-tee floor members in a garage. - Individual piece drawing (shop ticket): Piece drawings are prepared to show the plant all information needed to produce an individual piece. This includes overall dimensions of the product, sizes and locations of all projections, recesses, and block-outs, all finishes and their locations, concrete strength, stripping instructions, and detail the internal reinforcement to be cast in a particular unit. Also shown are embedded items, connection assemblies, material lists, concrete strengths, dunnage placement, weight, and concrete volume. - Assembly drawings: These drawings show special embedments that are manufactured by the plant or a supplier for use within a product.
4.26 Define the temperature limits as they apply to accelerated concrete curing as outlined in PCI MNL-116.
1. Maximum temperature rise of 36 °F (20 °C) per hour 2. Maximum curing temperature of 158 °F (70 °C)
4.25 When not employing accelerated curing methods, concrete curing involves controlling what two factors for the concrete?
1. Moisture 2. Heat retention
3.20 When evaluating a new source for coarse aggregate or if your supplier is changing his particular source, what testing should be performed, if any, on the aggregate material?
A new source of coarse aggregate should have the aggregate checked for soundness, abrasion, reactivity, organic impurities, deleterious substances, specific gravity and absorption.
4.17 Scales should be calibrated at intervals not greater than: a) 6 months b) 1 month c) 1 year d) 3 months
A. 6 months
4.16 Water-measuring equipment should be calibrated at intervals not exceeding: a) 6 months for scales, 3 months for meters b) 1 month c) 1 year d) 3 months for scales, 6 months for meters
A. 6 months for scales, 3 months for meters
1.19 Which lines are used to represent what is happening on the side opposite from that which is being viewed? a. Hidden b. Solid c. Center d. Opposite
A. Hidden
3.7 Which of the following is not a benefit of using retarders as admixtures? a) Reduction of 28-day strength b) Offset of the adverse effects of hot weather (an ambient temperature of 27 °C (80 °F) or higher, and an evaporation rate that exceeds 1 kg/m2/h.) by delaying the setting of concrete and maintaining the workability for a longer period of time c) Slow the rate of temperature rise in mass concrete and lower the peak temperature, thereby reducing thermal cracking d) Delay initial set for special finishes such as exposed aggregate
A. Reduction of 28-day strength. Early strength reduction is expected but strength at later stages is not affected when using retarders.
3.1 You will need early strength from a concrete mixture design in order to strip the product as soon as possible. What type of cement should you consider and what characteristic of this cement make it a good choice?
ASTM C150 Type III cement is used when early strength is desired. Type III is ground finer than other cements allowing more cement to react with water faster to provide high early strengths.
4.24 ASTM C403 is the standard for determining what concrete characteristics?
ASTM C403 is the standard test method for determining set time for a concrete mixture design. The test determines the elapsed time, after initial contract of water and cement, required for the mortar sieved from the concrete to reach penetration resistance of 500 psi (3.5 MPa).
2.3 Architectural concrete finishing areas should include what characteristics? Name three.
An architectural concrete finishing area should have the following properties: - Uniform lighting that matches daylight as closely as possible - Adequate size for panels being produced - Adequate handling equipment and product dunnage - Proper ventilation and safety equipment - Approved sample rack for comparison of the panel finish with sample
3.23 Name five advantages of using pozzolans.
Any five of the following: - Can reduce the amount of cement in the mixture - Improve workability - Plasticity - Reactivity - Permeability - Reduce heat of hydration
2.12 Quality control should routinely inspect the beds for several things. Name four.
Any four of the following: - Abutment movement and deformation - Self-stressing from damage - Cracked welds - Bent plates - Offset form joints - Loose clamps - Other cracks or damage
2.10 Architectural concrete panels have finishes on their face. There are a number of factors that can affect the color of the finish. Name at least five of these factors.
Architectural concrete panels can be affected by any of the following factors: - Cement type and color - Aggregate color, size, and physical and chemical properties - Form material - Mixture design - Mixing - Water-Cement Ratio - Consolidation - Dunnage marks - Curing - Finishing techniques - Weather Conditions
3.14 What is the maximum fineness modulus variation allowed from the established base value for the fine aggregate? a) +/- 0.1 b) +/- 0.2 c) +/- 0.3 d) +/- 2.0
B. +/- 0.2
4.10 Typically, what is the maximum allowable, sustained curing temperature for *accelerated* concrete curing? a) 185 °F (85 °C) b) 158 °F (70 °C) c) 176 °F (80 °C) d) 104 °F (40 °C)
B. 158 °F (70 °C)
4.5 A sand sample is taken for a morning reading. The wet weight of the sample is 800 g. After drying completely, the dry weight is 762 g. We know from the supplier that the absorption for the sand is 1.2% What is the saturated surface dry weight of this sample? a) 830 g b) 771 g c) 760 g d) 809.6 g
B. 771 g is the most correct answer. Based on the data given: Absorption is 1.2% Dry weight = 762 g Amount of water the dry sample can absorb = 762 * .012 = 9.14 g SSD = 9.14 + 762 = 771
4.12 The maximum concrete temperature at placement should be: a) 90 °F (32 °C) b) 95 °F (35 °C) c) 100 °F (100 °C) d) 1 04 °F (104 °C)
B. 95 °F
6.2 Post-pour inspections are conducted: a) following (post) plants audits b) after a product has been cast c) following concrete batching setup d) whenever personnel can get to it
B. After a product has been cast
4.4 An aggregate that is saturated surface dry is: a) An aggregate in its natural state b) An aggregate with no free moisture c) An aggregate with pent-up water demand d) An aggregate with free moisture to contribute
B. An aggregate with no free moisture
3.6 Chlorides are detrimental to precast concrete because: a) chlorides limit the amount of entertained air that can be produced in a concrete mixture b) chlorides promote corrosion of embedments, reinforcing, and prestressing strand c) chlorides limit the ability of concrete slump to reach desired levels
B. Chlorides promote corrosion of embedments, reinforcing, and prestressed strand.
1.20 The flag shown on the weld symbol indicates: a. shop-fabricated weld b. field weld c. critical weld d. ground finish required
B. Field weld
4.15 In the evaluation of aggregate moisture, what type of moisture is considered as contributing water to the mixture? a) Free moisture and absorbed moisture b) Free moisture c) Absorbed moisture d) Saturated surface dry moisture
B. Free moisture
5.7 What purpose does initial tension play in tensioning operations? a) To set the tensioning jack b) To establish a fixed point for measurement of elongation c) To tighten the strand for final tension d) Take the curl out of the strand
B. To establish a fixed point for measurement of elongation
2.8 Prior to stripping a prestressed product line, what should be reviewed and done?
Before stripping a prestressed product line, the following should be done: - Test compression cylinders to determine whether the required stripping strength has been reached. - Hold-down devices should be removed to avoid restraining the product. - Side form should be loosened and/or removed to avoid constraining the products. - Any bolts or other devices used to hold embedments to the form or soffit should be removed to avoid binding the products.
2.5 What must be determined before welding of ASTM A615, ASTM A616, ASTM A617 reinforcement?
Before welding of A615, A616, or A617 reinforcement, the carbon equivalent of the reinforcement must be determined. For A615 reinforcement, the following formula is used to determine its carbon equivalent: % C + (% Mn)/6 A706 may also require 50 °F (10 °C) preheat.
2.13 Minimum concrete temperature during initial curing should be: a. 32 °F (0 °C) b. 75 °F (24 °C) c. 50 °F (10 °C) d. 60 °F (16 °C)
C. 50 °F (10 °C)
4.18 When using internal vibrators, the vibrator should be: a) Inserted slowly under its own weight, then withdrawn as quickly as possible b) Inserted slowly, then be withdrawn at a rate of 3 seconds per foot (3 seconds per 300mm) c) Sink quickly, then be withdrawn slowly d) Sink quickly, then be withdrawn quickly
C. Allow to sink quickly then withdraw slowly
3.13 Which one of the following is NOT a result of using water reducers? a) Increases workability b) Increases compressive strength c) Decreases slump
C. Decrease the slump
4.9 Accelerated curing of concrete by adding heat generally results in what potential results? a) Increased air in the final product b) Increased early strength and slightly increased 28-day strengths c) Increase early strength and slightly decreased 28-day strengths d) Decreased strengths at early age
C. Increased early strength and slightly decreased 28-day strength
4.6 A week later, after long, hot, dry days, another sample is taken from the same material noted in question 5. The wet weight is 800 g, but the dry weight is 795 g. How much free moisture will be available from the sand when batched today? a) 5 g b) 0.6% c) None d) 11 lb (5 kg) per 1000 lb (450 kg) of sand
C. None The new sample has a wet weight of 800 g and a dry weight of 795 g. The total moisture is (800 - 795)/795 * 100 = 0.6% This means that the absorption of the sand has not been met.
6.1 Mill certificates represent the following: a) Mill thickness for material coatings b) Fine-tuned grinding compliance for embedments c) Testing results for material compliance at the production mill d) Testing for measurement conformance
C. Testing results for material compliance at the production mill
4.3 If the sand moisture increases from 4% to 8% and the same batch quantities are used with the change in moisture, what will be the result for the mixture? a) The amount of sand will be the same and the water will increase. b) The amount of sand will increase and the water will decrease. c) The amount of sand will decrease and the water will increase. d) The amount of sand will decrease and the water will decrease.
C. The amount of sand will decrease and the water will increase.
4.1 What ratio is used as the primary control for concrete design? a) The wet-dry aggregate ratio b) The ratio of admixtures to cement c) The water-cementitious materials ratio d) The slump-water ratio
C. The water-cementitious materials ratio
3.8 Pozzolans are beneficial in concrete because: a) they provide for water disposal b) they make the mixture less sticky for finishing c) they react with calcium hydroxide to provide cementitious benefits d) they increase early strength development of the concrete mixture
C. They react with calcium hydroxide to provide cementitious benefits.
3.15 You have received some reinforcing steel that conforms to ASTM A615. What must you do, if anything, prior to using this material in a welded assembly?
Check the carbon equivalence to determine if preheating is required.
3.11 Low-alkali cement has an equivalent Na[2]0 content of less than: a) 3.0% b) 1.2% c) 0.1% d) 0.6%
D. 0.6%
4.14 Accelerated curing must be monitored at what locations on a long line bed? a) At each piece b) At 50-foot (15-meter) intervals c) One per product line d) At 200-ft (60-meter) intervals
D. 200 ft (61 m) intervals
3.10 The general specification for prestressed strand is: a) ASTM A767 b) ASTM A775 c) ASTM A185 d) ASTM A417
D. ASTM A416
3.9 Concrete placing temperature should be maintained at an appropriate level because: a) lowering cement temperature may delay hydration of the cement b) lowering temperature will require more energy to set c) early strength development may be delayed d) All of the above
D. All of the above
4.2 An increase in the amount of water used in a mixture could mean: a) An increase in the slump of the concrete b) A decrease in the strength produced by the concrete c) Maintaining slump as the temperature rises d) All of the above
D. All of the above
3.22 Mixing water from a source other than a municipal water supply should be tested: a) once b) every 6 months c) every 5 years d) annually
D. Annually
1.16 A plant producing architectural concrete products must have: a. at least one Level III technician b. at least one Level I and Level II technician c. at least one Level II technician d. at least one Level I technician
D. At least a Level 1 technician
2.18 To judge the appearance of architectural concrete products, panels should be viewed: a. from approximately 10 ft (3 m) in the shade b. at any distance in good daylight c. from approximately 5 ft (1.5 m) in good daylight d. from approximately 20 ft (6 m) in good daylight
D. From approximately 20 feet (6 m) in good daylight
3.12 Which of the following answers is NOT a good reason for using air-entraining admixtures? a) Improves durability b) Resists surface scaling c) Reduces permeability d) Increases segregation
D. Increase segregation
2.9 Dunnage points can create a problem on the contact face. What is that problem and why does it happen?
Dunnage resting against a product can create a dark spot if the dunnage is in full contact with the product. This contact holds moisture on the contact surface and creates a dark spot. Ventilation is required to allow the moisture to evaporate.
2.7 Embedments made with headed studs should be reviewed and checked when placed for four different items or continuous. Name them.
Embedments made with headed studs should be reviewed both before and as placed in the form for the following items against the shop drawings: - Welded-stud ferrules are removed and a 360 degree weld puddle (flash) is formed - Bolt or stuff diameter - Plate size and orientation - Anchorage bars in correct position - Embedment is secured to the form - The applicable coating had been applied - Proper length consummation in welding for automatic welded studs
1.18 Production personnel may be involved in quality control activities in practices where they were directly involved--true or false?
False. Production personnel may not be involved in quality control activities of production practices in which they were directly involved.
2.11 Quality control personnel do not need to concern themselves with plant safety policies because their first priority is to inspect products--true or false?
False. Quality control personnel must be aware of the plant's safety program through employee training and ongoing safety meetings.
2.4 Stainless steel can only be welded to other stainless steel--True or false?
False. Stainless steel can be welded to other low-carbon steels if done in accordance with AWS B2.1, AWS A5.4, and AWSD1.1. Special procedures are required to deal with sensitization of the heat-affected zone.
5.4 Because tack welds are small, the concern over preheat does not apply--true or false?
False. Steel chemistry requires preheat for some steels. Weld size is not a parameter in determining if steel preheat is necessary. All welds to that steel would require preheat.
2.15 The dimensional tolerance for the forms should be the same as those specified for the finished product--true or false?
False. The dimensional tolerance for the form should be less than those specified for the finished products.
3.4 Nondrinkable water should not be used to make concrete--true or false? Explain.
False. Water suitable for making concrete does not need to be fit for drinking. However, non-potable water must meet the chemical limits given in Table C3.1.6 of PCI manuals MNL-116 and MNL-117.
5.3 Galvanized no. 6 bars are bent to fabricate them for a beam. Some cracking and flaking occurs at the bend. The bars are rejected--true or false?
False. When bent, galvanized bars often have cracking and flaking of the galvanized coating. This should be repaired by painting with a zinc-rich paint.
3.3 How are fine and coarse aggregates defined by the standard and how does a plant check these criteria?
Fine and coarse aggregates are generally defined by ASTM C33 in relation to their gradation or particle size, distribution and fineness for sand. A plant reviews material by testing for and computing the gradation.
2.1 Forms and abutments for casting of precast concrete products should be monitored by quality control for what potential problem?
Forms and abutments should be reviewed between casting for the following potential degradation: - Cracked welds - Bent plates - Offset form joints - Other cracks or damage - Size and shape
3.21 Name the types of admixtures identified as high-range water-reducing admixtures. What is the general specification number of which those types are a sub-group?
High-range water-reducing admixtures are Type F or G in the general specification ASTM C494.
4.19 List three desirable characteristics for concrete.
Impermeability, durability, high strength
5.1 What role does conventional reinforcement or prestressing play in a concrete beam?
In a concrete beam, conventional reinforcement or prestressing carries the tension stresses that develop in the beam.
3.5 As a general statement, what are admixtures?
In a general sense, any item added to concrete other than cement, aggregates, and water is an admixture.
1.9 Inspection and recordkeeping should cover many areas in production. List four of the areas mentioned in this chapter.
Inspection and record keeping should cover the following areas: - Identification, examination, acceptance, and plant testing of materials and subassemblies - Inspecting and recording of tensioning - Inspection of beds and forms prior to concreting - Checking if dimension members, numbers, size and positions of tendons, reinforcing steel, other incorporating materials, openings, blockouts, and the like - Regular inspection of batching mixing, conveying, placing, compacting, finishing, and curing concrete - Preparation of concrete specimens for strength testing and performance of concrete tests (slump, air content, cylinder strength) - Inspecting operations of detensioning, product removal from beds, handling and storing - Final inspection of finished product prior to shipment. Monitoring dimensions, camber, blockouts, embedments, and finishes. - General observation of plant equipment, working conditions, weather, and other items that have the potential for affecting the products. - Products purchased from suppliers shall comply with requirements for in-plant production as outlined in PCI's quality control manuals MNL-116 and MNL-117. - To establish evidence of proper manufacturing and monitoring as outlined, a system of records shall be utilized in each plant for the procedures outlined.
5.5 What are three losses that calculated force or elongation should be adjusted for?
Live-end chuck seating Dead-end chuck seating Abutment rotation Bed shortening Thermal changes
4.13 What are the average densities for normalweight concrete, semi-lightweight concrete, and all lightweight concrete?
Normalweight: 145 lb/ft^3 (2325 kg/m^3) Semi-lightweight: 125 lb/ft^3 (2017 kg/m^3) All lightweight: 110 lb/ft^3 (1775 kg/m^3)
2.17 Name four undesirable surface conditions that may occur when overworking the surface.
Overworking the surface will tend to draw fines and water to the surface, which can create a number of undesirable surface conditions such as: - checking (random hairline surface cracks) - crazing (hairline surface cracks originating from a common point) - dusting (light, sandy film on the surface) - discoloring
1.11 Post-pour inspection covers many areas that need to be checked. Name three from this chapter.
Post-pour inspections should include: - Product identification - Visual inspection of product - Product dimensional verification - Strand slippage - Camber - Product storage - Product finish
2.6 What is the purpose of preheating in the welding of ASTM A615 reinforcing bars to other steel sections? What criteria are used to determine preheating?
Preheating it steel reinforcement and shapes that are to be welded is done to avoid rapid cooling of the materials after welding. Preheating is determined by the carbon equivalent of the reinforcing bar or requirements of the other shape. Preheating is also performed to remove hydrogen from the base metal and minimize the effects of contamination.
1.10 The prepour inspection should address which three areas of operation in particular?
Prepour inspection should address: - All dimensions of the form or mold - Reinforcing in the form or mold both for conformance of size and type as well as spacing - Security of embeds to remain in place during casting - Embedments, size, locations and number.
1.8 A number of principle factors in quality control are mentioned in this chapter. Name four of these.
Principal factors in quality control include: - Management commitment to quality and quality control program - Qualified personnel for all stages of design and production - Testing and inspection of the various materials selected for use as well as product storage and handling - Clear and complete shop drawings. Good production drawings translate contract documents into usable information for manufacture, handling, and erection of precast and prestressed concrete units - Accurate testing procedures - Control of dimensions and tolerances - Proper position of all embedded items - Correct size and positioning of reinforcing steel - Proper handling, placing, and consolidation of concrete - Proper proportioning and adequate mixing of concrete - Inspection and documentation of approved corrective action - Appropriate and controlled curing - Proper procedure for detensioning and stripping Proper handling, storing, transporting, and erection of members - Complete and accurate production documentation
1.7 Project samples should be used for what project conditions?
Project samples should be used when required by the project specifications and when special finishes are involved.
4.21 Define saturated-surface dry conditions.
Saturated surfe surface dry conditions for aggregates are as follows: - Coarse aggregate: Saturated surface dry is the condition when no water is apparent on the aggregate surfaces and the aggregate has absorbed all the moisture it possibly can. - Fine aggregate: Saturated surface dry is the condition when the aggregate has just reached the free-flowing condition and are no longer clumping together.
4.27 Concrete strength gain during the curing period falls into three stages. Define those stages as to the strength gains that can be expected and the amount of time that each stage entails.
Stage 1 -- A dormant period of three to five hours when little strength gain is made. Stage 2 -- The most active period lasting seven to eight hours with strength gains of 500 psi (3.5 MPa) to 100 psi (4.8 MPa) per hour. Stage 3 -- A slow period of strength gain lasting eight to twelve hours with strength gains of 50 psi (0.345 MPa) to 100 psi (0.69 MPa) per hour
2.2 In a review of a weld shop, a roof leak is noted. Some stick electrodes were splattered by the water from the leak hitting the shop table. What should be done with these electrodes?
Stick electrodes that become wet must be discarded. Electrodes that have been out of their containers may be redried once, but electrodes that are wet cannot be redried.
3.19 You need to order some headed steel studs for use on an upcoming project. What is the applicable ASTM standard for the material from which these studs will be manufactured?
The ASTM specification for welded-stud materials is A108. This material produces studs that can be welded by stud-gun welders such as those manufactured by KSM and Nelson and will perform in accordance with published test data from these manufacturers.
5.2 If bottom reinforcement is placed too high in a concrete beam, what is the consequence?
The ability of a reinforced concrete beam to resist applied load relates directly to the position of the reinforcement. If the bottom reinforcement is placed too high, the beam's capacity is reduced. Also, cracking along the beam becomes more severe.
1.6 A basic weld symbol is shown. Describe the information that would be shown in the circled area.
The circled area of the weld symbol would describe the size, length and type of weld to be placed at the side of joint opposite to where the arrow point is located.
1.1 A commitment to quality starts where in the organization?
The commitment to quality begins with a company's top management.
2.19 If an insert shown on a shop drawing is located on the far side, where is it located?
The far side indicates the side opposite to the one in view. A top view of a panel with a note calling for an insert at a given location but on the far side would indicate a location on the bottom of the piece.
2.14 Name three means of accelerated curing.
The following are means of accelerating curing: - Radiant heat from steam, hot-water or oil pipes - Space heaters - Live steam - Electric heat
4.11 Name five procedures that may be used to prevent plastic shrinkage.
The following procedures help prevent shrinkage cracking: - Shaded storage for aggregates - Sprinkling, fog spraying, or chilling aggregates with liquid nitrogen - Burying, insulating, and/or shading water-supply facilities - Use of cold water in batching - Use of shaved or crushed ice for a portion of the mixing water. Only as much ice should be used as will be entirely melted at the completion of the mixing period. - Maintaining concrete surfaces in a cool and moist condition by use of wet coverings such as burlap, sprinkling, or ponding as soon as the water sheen disappears. - Shading of the product surface during and after casting to avoid heat buildup in direct sunlight Use of cement with temperatures under 170 F, unless special measures to control concrete temperature as outlined in ACI 305, Recommended Practice for Hot Weather Concrete, are used and verified to produce concrete of acceptable performance. - White-pigmented membranes maybe used, but they are not recommended in hot-weather conditions until after the first 24 hours, as such membranes do not cool the concrete as well as wet-curing methods - Set-retarding admixtures, which can delay the concrete setting time and provide a longer period for placing and finishing
3.16 You have some reinforcing bar in your storage area that is marked with a W. What does this mean?
The mark W on reinforcing bars signifies the material is ASTM A-706, which is weldable reinforcing steel.
1.17 With what frequency should the quality assurance program be reviewed?
The quality assurance program must be reviewed at regular intervals, not to exceed one year.
4.7 The following quantities are the batch weights per cubic yard (0.76 m^3) for a mixture. The batch quantities for aggregates are dry weights. The conditions for today's batch are: Sand: 1.3% absorption 6.2% total moisture Stone: 0.85% absorption 1.6% total moisture Batch weights: Cement 705 lb (320 kg) Sand 1250 lb (569 kg) (dry) Stone 1700 lb (770 kg) (dry) Water 250 lb (110 kg) What will be the saturated surface dry weights for aggregate today?
The quantities for aggregates are given in their dry condition. To change them to saturated surface dry (SSD), you need to add absorption. Dry Sand 1250 lb (568 kg) x 1.013 Stone 1700 lb (772 kg) x 1.0085 SSD 1266.25 (574.88 kg) use 1266 lb (575 kg) 1714.45 (778.36 kg) use 1714 lb (778 kg)
1.2 Each plant should have a written quality assurance program. What is this written program called and what are the minimum items to be addressed by it?
The written quality assurance program for a plant is called its quality system manual (QSM). The minimum items to be addressed by the QSM are: - management commitment to quality - definition of organization structure - management review of the quality assurance program - plant facilities layout and definition - records on corrective repairs - purchasing procedures for quality control compliance including project specifications - uniform methods for reporting, reviewing, and managing records - identification of training needs for production and specific training in quality assurance requirements - control, calibration and maintenance of necessary inspection, measuring, and test equipment - standards for shop drawings to ensure accuracy and uniform interpretation of instructions for manufacturing and handling - procedures for review and dissemination of project-specific requirements to production and quality control personnel.
4.20 Name the two parts that make up total aggregate moisture.
Total aggregate moisture is made up of absorbed moisture and free moisture.
4.28 Accelerated curing impairs the 28-day strength of a particular mixture--true or false?
True. Accelerated curing will reduce the 28-day strength of a particular mixture design by up to 10%.
2.16 Determining the concrete maturity is not an acceptable substitute for cylinder strength testing--true or false?
True. It is only used as a general guide to determine when cylinders are likely to be up for strength.
3.2 Fine and coarse aggregates should generally conform to which standard?
Unless specifically stated otherwise, both coarse and fine aggregates should conform to ASTM C33.
4.23 Based on the *batch* quantities in question 22, compute the water-cement ratio.
Water/Cement = 195 lb (127 kg)/611 lb (277 kg) = 0.32
3.17 You have received some wire mesh that you ordered as a 6 in. x 6 in. (150 mm x 150 mm) grid. The grid spacing on one stack of sheets ranges from 5.75 in. (146 mm) to 6.25 in. (159 mm), while the spacing on a second stack ranges from 5.25 in. (133 mm) to 6.5 in. (165 mm). Which stack, if either, is acceptable according to specification ASTM A185?
Wire spacing must be within 0.25 in. (6 mm) of the design spacing for welded-wire mesh. Mesh with spacing of 5.75 in. (133 mm) to 6.25 in. (159 mm) would be within these tolerances, while mesh with spacing from 5.25 in (133 mm) to 6.5 in. (165 mm) would not.
3.18 You have received a stack of welded-wire fabric sheets 8 ft x 12 ft (2.4 m x 3.7 m). The grid in both directions is a 6 in. (150 mm) grid. As you examine the stacks of mesh sheets, you notice there are broken welds. The number of these breaks ranges from three to seven per sheet. Is there a level of acceptable breakage in accordance with the applicable ASTM standard, and if so, which of these sheets should have an acceptable level of breakage?
Wire-mesh sheets of 8 ft x 12 ft (2.4 m x 3.7 m) size with wires spaced at 6 in. (150 mm) centers each way would have 425 weld points. The acceptable tolerance for broken welds is 1% of the welds for sheet mesh or 425 x 0.01 = 4.25, or four welds per 8 x 12 (2.4 m x 3.7 m) sheets, but not over one-half the broken welds on any one wire. Therefore, any sheet with four or less broken welds and not over two broken per wire will be acceptable.
5.6 Your tensioning jack has just been calibrated. At a jack reading of 32,500 lb (145,000 kN), the actual load recorded by the load cell during calibration was 32,000 lb (142,000 kN). Can you use the jack system as is for tensioning control?
Yes, variance between jack reading and load record is permitted when under 2%. The readings of 32,000 lb (142,000 kN) and 32,500 lb (145,000 kN) are within 1.5%
