FREQUENT

NON CONFORMANCES

OBSERVED BY

ACO

REF # 10-NC May 2010 To: All CPCI Certified Plants Fr: Quality Assurance Council One of the objectives of the CPCI Precast Concrete Certification Program for Architectural and Structural Precast Concrete Products and Systems as identified by the Quality Assurance Council is continuous improvement. To that end the Quality Assurance Council has asked our ACO, Kassian Dyck and Associates to provide a list of the most recent non-conformances that they have observed throughout their audits, that we could forward to all of our participating plants . It is our intent to provide an update to this list on an annual basis. Your comments are appreciated. Some Frequent Non-conformances Observed by Kassian Dyck’s Auditors: A. Reinforcement shall be accurately located as indicated on the approved shop drawings. Bars are sometimes added, changed or relocated from the locations designated on the drawings without documentation of these deviations from the precast design engineer. All revisions should be approved and recorded on the drawings. B. Dissimilar metals should not be placed in direct contact unless experience has shown that no detrimental (galvanic) reactions will occur. Documentation of experience and acceptance of dissimilar metal contact is deficient. Galvanized reinforcement shall not be in contact with uncoated reinforcement and should be isolated with polyethylene or similar tape and tied with plastic tie wire. C. When tying rebar cages with tie wire, bend tie wires inward away from concrete edges or surfaces to provide maximum concrete cover. D. Coated reinforcing bars shall be stored on timbers or protective contact areas, and handled with protective pads or nylon slings. Do not handle coated bars with metal chains, steel lifting straps, or other steel devices or tools. Bundles of coated bars should be lifted at multiple pick points to minimize sag. E. For curing of concrete without additional heat, the surface of the concrete is to be kept covered or moist until the stripping/transfer strength is obtained. It is not apparent how a building itself without using tarps, enclosures, or other moisture retention measures can ensure free water is present on all concrete surfaces at all times. F. All wet concrete QC tests (such as air content and slump tests) for a new batch of concrete should be conducted prior to the concrete pour, to confirm acceptability prior to casting.

G. Aggregate sieve analysis gradation results sometimes have gradation readings slightly outside of the specified limits. There is generally no record or documented resolution on the acceptability of the aggregate, if retests were performed, or action taken. H. If the concrete compression test cylinder does not fracture in a cone (hourglass) shape, then the type of cylinder failure is to be recorded (CSA A23.2-9c). I. Our auditors have found that the sequence of batching materials into mixers varies with different types of batching systems, and often it is not in conformance with sequencing prescribed in PCI MNL 116. We are currently collecting information from members on the sequencing of materials into mixers. In upcoming audits we will be requesting precasters provide a written description of their batching sequence, so we can review and assess what the industry is doing in comparison to PCI MNL-116 requirements. For further information contact: Kassian Dyck & Associates, Consulting Engineers A Division of 594798 Alberta Ltd. Wayne Kassian, P. Eng Ph. (403)255-6040

REF # 11-NC August 2011 To: All CPCI Certified Plants Fr: Quality Assurance Council One of the objectives of the CPCI Precast Concrete Certification Program for Structural, Architectural and Specialty Precast Concrete Products and Systems, as identified by the Quality Assurance Council, is continuous improvement. To that end the Quality Assurance Council has asked our ACO, Kassian Dyck and Associates, to provide an annual list of the most recent non-conformances that they have observed throughout their audits and forward these to all of our participating plants. Some Frequent Non-conformances Observed by Kassian Dyck’s Auditors:

A. In accordance with Table 2 of CSA A23.4-09, when concrete temperatures are measured

during accelerated curing, the temperatures should be recorded until the end of the curing cycle to ensure cooling continues until the concrete temperature is not more than 20 0C above the ambient temperature. In order to achieve this, the ambient temperature must be recorded and often mobile thermocouple data loggers are required to continuously record concrete temperatures in the curing chamber or storage location.

B. When stockpiling aggregates, the divider walls between compartments should be of sufficient

height to store material without cross contamination. Sometimes aggregates are stockpiled slightly higher than the divider walls, allowing some material to flow into an adjacent stockpile. Also, equipment should not operate directly on the stockpiles, and accordingly wheels should not contact stored aggregate that can cause contamination.

C. Hardware shall be held firmly in place prior to concrete placement, so concrete can be properly

consolidated around the hardware. Attachments or jigging may be required. Some embedded items such as dowels or inserts may be installed while the concrete is in a plastic state, but only when approved by the precast engineer and provided the item is not required to be hooked or tied to reinforcement within the element. Wet set items shall be properly anchored and maintained in the correct position as the concrete hardens.

D. CSA A23.2-09 test method 9C requires diameter of cylinders be measured for determination of

average diameter assumed for cylinder strength results. Measure 1 in every 10 specimens or 3 specimens per day, whichever is greater, if all cylinders are made from a single lot of reusable molds. Measure diameter by averaging two diameters measured at right angles to each other at mid-height of the specimen.

E. When batch plant scales are load tested and calibrated, ensure the calibration company tests

the scales to include the full range of materials weighed at the mixer. Sometimes scales are only calibrated at their low range and not to the mass of material commonly batched.

F. CSA A23.4-09 Clause 16.3.1 requires that when two different concrete mixes are used

monolithically within one element, ensure the two mixes are within 10% of each other with respect to cementing materials and water/cementing materials ratio. This requirement should be reviewed when face mixes are used in veneered construction to ensure the two mixes are compatible with expansion/contraction and shrinkage.

G. Concrete batching records are to include mix proportions by weight, as well as mixing water

corrections. At some plants where computerized printouts of batched ingredients are not automatically recorded, information from the mix design is manually recorded rather than the actual batched ingredients. All concrete shall be accurately batched and recorded.

H. The specified concrete cover must be provided to all reinforcing bars or welded wire mesh,

including cover at the ends of bars or wires, not just the side cover. Also, the specified cover on architectural or ribbed surfaces is the cover measured from the deepest (or recessed) point of the surface, including reveals or other depressions.

I. Often the vertical ruler scales on the batch plant admixture calibration holding tubes are not in

exact alignment with the liquid in the tube, such that the zero reading on the tube’s scale does not match the meniscus of the liquid in the tube before filling with the admixture. Although some residual admixture liquid can slowly drip down the tube after dispensing, the “zero” reading on the tube’s scale should be set to match the liquid level before filling the tube. This is required so batch plant personnel can visually verify proper amounts of admixture are batched.

J. In the past year, the Quality Assurance Council has been asked in one instance by an owner to investigate the possibility that records of temperature logs at a manufacturing plant may have been tampered with. Allegations of tampering with Quality Control Records is a serious concern as it not only suggests a violation of the requirements of certification under the “CPCI Precast Concrete Certification Program for Structural, Architectural and Specialty Precast Concrete Products and Systems”, but potentially undermines the integrity of the program in the eyes of the end user. While no conclusive evidence was found through the ACO’s subsequent investigation in this instance, allegations of falsification will be treated with the utmost seriousness and will be investigated by the auditors under the special audit provisions within the program. Any violators will be dismissed from the program.

For further information contact: Kassian Dyck & Associates, Consulting Engineers A Division of 594798 Alberta Ltd. Wayne Kassian, P. Eng Ph. (403)255-6040

REF # 13-NC November 2013 To: All CPCI Certified Plants Fr: Quality Assurance Council One of the objectives of the CPCI Precast Concrete Certification Program for Structural, Architectural and Specialty Precast Concrete Products and Processes, as identified by the Quality Assurance Council, is continuous improvement. To that end the Quality Assurance Council has asked our ACO, Kassian Dyck and Associates, to provide an annual list of the most recent non-conformances that they have observed throughout their audits and forward these to all of our participating plants. Some Frequent Non-conformances Observed by Kassian Dyck’s Auditors:

A. As a plant’s operations, organizational structure or plant procedures change due to ongoing development,

the Quality System Manual needs to be updated so the manual’s quality assurance documentation matches current practice and procedures.

B. QC personnel undertaking CSA A23.2 concrete tests such as air content, slump and making and testing

concrete cylinders need to fully comply with all apparatus and procedures of the various test methods, including specified modifications for SCC concrete.

C. In accordance with CSA A23.1-09, air content shall be determined with every strength test, for all classes

of concrete.

D. At batch plants not utilizing equipment having automatically generated batch records, batch records need to include actual mix proportions by weight, mixing time, as well as mixing water corrections.

E. When reinforcing bars are welded to structural steel members, the provisions of CSA W186 require rebar

not be welded within two bar diameters or 50 mm minimum, from the beginning point of tangency of a cold bend.

F. When fabricating insulated wall panels, unless an air space was specified in the panel design, the

insulation is to be placed tight to the face mix concrete without and gaps or air space. Insulation boards that are too tight within the form mould can bind on form edges and not fit tightly against the concrete, creating an undesired gap or air space between the concrete and the insulation at edges of insulated wall panels.

G. When tying rebar cages with tie wire, bend tie wires inward away from concrete edges or surfaces to

provide maximum concrete cover.

H. The specified concrete cover must be provided to all reinforcing bars or welded wire mesh, including cover at the ends of bars or wires, not just the side cover.

I. Often the vertical ruler scales on the batch plant admixture calibration holding tubes are not in exact

alignment with the liquid in the tube, such that the zero reading on the tube’s scale does not match the meniscus of the liquid in the tube before filling with the admixture. This is required so batch plant personnel can visually verify proper amounts of admixture are batched.

J. Intake pipes for cement silos should be capped to prevent contamination of cement. For further information contact: Kassian Dyck & Associates, Consulting Engineers A Division of 594798 Alberta Ltd. Wayne Kassian, P. Eng Ph. (403)255-6040

QUALITY ASSURANCE

COUNCIL

ADVISORIES

REF# 11-01

November 29, 2011

To: All CPCI Certified Plants

Fr: CPCI Certification Quality Assurance Council

The Quality Assurance Council wishes to remind all CPCI Certified Plants of the requirements under clause 5.4.2 of the program. It has come to our attention that there are instances of certified manufacturers re-selling products from manufacturers who are not certified to the CPCI Precast Concrete Certification Program for Structural, Architectural and Specialty Precast Concrete Products and Systems. The intent of Clause 5.4.2 is to ensure the transparency and integrity of the program to clients. Re-selling products from non-certified plants may mislead owners into thinking that the products are coming from a certified plant. Fail ure to abide by the terms of the CPCI certification program will result in the loss of the manufacturer’s certification. Clause 5.4.2 is excerpted below, and the current listing of CPCI Certified Plants follows: 5.4.2

Further, the Manufacturer shall:

- Establish and maintain the highest standard of integrity, skill and practice in the design and fabrication of its

products.

- Undertake the performance of only those services and the production of only those products for which they

are qualified.

- Not knowingly associate with, or permit the use of their name or the ACO’s name in any business venture by

any person or firm that they know, or have reason to believe is engaged in questionable or unprofessional

practices,

- Be in compliance with current governing codes and regulations, and

- Sell products only from a Manufacturer that is certified under the CPCI Precast Concrete Certification

Program.

Current CPCI Certified Plants are listed below:

APS Architectural Precast Structures (Langley, BC) armtec (50th Ave Calgary, AB) armtec (89th Ave Calgary, AB) armtec (Acheson, AB) armtec (Richmond, BC)

armtec (Winnipeg, MB) armtec (St-Jean-sur-Richelieu, QC) armtec (Brampton, ON) armtec (Woodstock, ON) BDPL (Trans-Canada, St-Eugene) BPDL (Bombardier, Alma, QC) BPDL (Papeterie, Alma, QC) BPDL (Prefab de Beauce, Saint Marie) Camcon Precast (Dartmouth, NS) Co-Pipe Products Inc. (Taylor, MI USA) Con Cast Pipe / Sky Cast (Guelph, ON)

Coreslab (Dundas, ON) Expocrete Concrete Products (Saskatoon, SK) Granite Prestressed Concrete (Sudbury, ON)

Hanson Pipe & Precast (Whitby, ON) Hanson Pipe & Precast (Uxbridge, ON) International Precast Solutions (River Rouge, MI) Lafarge (Calgary, AB) Lafarge (Edmonton, AB)

Lafarge (Winnipeg, MB) Lockwood Bros. Concrete Products (Armstrong, BC) MSE Precast Ltd (Nanaimo, BC) Munro Ltd (Utopia, ON) Newton Parking Structures Ltd. (Guelph, ON) P. Kruger Concrete Products (Edmonton, AB) Prestressed Systems Inc. (Windsor, ON) RES Precast Inc. (Innisfil, ON) Schokbeton Quebec Inc. (St-Eustache, QC) Strescon (Bedford, NS) Strescon (Saint John, NB)

Surespan Structures (Duncan, BC) Tri-Krete (Weston, ON) Wells Concrete (Grand Forks, ND USA)

Please check the CPCI certification website at www.precastcertification.ca for updates to the certified plant

listings on a regular basis.

Yours Sincerely,

Robert Burak, P. Eng Administrator Quality Assurance Council

Canadian Precast / Prestressed Concrete Institute Institut canadien du béton préfabriqué et précontraint

100 - 196 Bronson Avenue, Ottawa, ON, K1R 6H4 Tel: (613) 232-2619 Fax: (613) 232-5139 Toll free: (877) 937 2724

Email: info@cpci.ca Web: www.cpci.ca

April 3, 2012 REF# 12-1A To: Whom it may concern Re: Advisory on Certification Requirements for Precast Concrete Products according to the National Building Code of Canada It has come to our attention that some building projects have been tendered to precast manufacturers who are not certified in accordance with the requirements of the National Building Code of Canada. The National Building Code of Canada requires conformance to CSA A23.3 Design of Concrete Structures and CSA A23.4 Precast Concrete - Materials and Construction as follows: National Building Code of Canada – Division B: Clause 4.3.3.1.(1) – “Buildings and their structural members made of plain, reinforced and prestressed concrete shall conform to CSA A23.3, Design of Concrete Structures.” Clause A-4.3.3.1.(1) - Precast Concrete- “CSA A23.3, Design of Concrete Structures, requires precast concrete members to conform to CAN/CSA-A23.4, Precast Concrete – Materials and Construction” CSA A23.3 – Design of concrete structures: CSA-A23.3 - Clause 16.2.1 – All precast concrete elements covered by this standard shall be manufactured and erected in accordance with CSA A23.4. CSA A23.4 – Precast concrete – Materials and construction: CSA-A23.4 - Clause 4.2.1 – Precast concrete elements produced and erected in accordance with this standard shall be produced by certified manufacturers, with certification demonstrating the capability of a manufacturer to fabricate precast concrete elements to the requirements of this Standard. CSA-A23.4 - Clause 4.2.2 – Conformity assessment of precast concrete products or elements to this Standard shall be performed by an organization accredited to do so.

Canadian Precast / Prestressed Concrete Institute Institut canadien du béton préfabriqué et précontraint

100 - 196 Bronson Avenue, Ottawa, ON, K1R 6H4 Tel: (613) 232-2619 Fax: (613) 232-5139 Toll free: (877) 937 2724

Email: info@cpci.ca Web: www.cpci.ca

Note: In Canada, the accrediting body is the Standards Council of Canada. Purchasers of precast concrete products may accept certification from other organizations that are equivalent. The CPCI Certification Program for Structural, Architectural and Specialty Precast Concrete Products and Systems is designed to qualify manufacturers who fabricate architectural and structural precast concrete. The purpose of this audit based program is to provide owners and designers with the confidence that certified precast concrete manufacturers are qualified to manufacture the products they supply to the marketplace, are competent to provide quality precast and have adequate personnel and facilities. Only those precast manufacturers who demonstrate strict conformance to current standards, and are committed to continually improving the quality of their products and systems are certified under this program. The program is governed by an independent multidisciplinary body and each plant, in addition to having a mandated number of audits annually, also requires a comprehensive Quality System Manual. CPCI Certification ensures conformance to both Canadian and U.S. standards. Through this certification, manufacturers are certified in accordance to the requirements of CSA Standard A23.4, including Appendices A and B, and with PCI Manuals for Quality Control, MNL-116 and 117. If you should have any questions please feel free to call me. Sincerely,

Rob Burak, P.Eng President

REF # 12-01

July 2, 2012 Quality Assurance Council Advisory

CSA A23.1-09 and A23.4-09 do not specifically identify maximum concrete temperature limits during hydration of concrete for normal non-accelerated cured concrete. The maximum curing temperature should be limited, particularly for products that will be subjected to a moist environment during service. CSA A23.1 Clause 8.5.5 indicates the maximum temperature reached during hydration shall not exceed 70⁰C, but this clause applies to high strength concrete only (greater than 70 MPa).

CSA A23.4-09 Clause 23.2.2.3 and Table 2 limits of 60⁰C and 70⁰C for damp and dry moisture

categories apply specifically to accelerated curing. For concrete not accelerated cured, the Quality Assurance Council has determined that the requirements in Table 2 of CSA A23.4-09 shall apply as part of the CPCI Certification Program. The Technical Committee on Precast Concrete CSA A23.4 has been contacted to address this issue in the next edition.

REF # 12-02

July 2, 2012 Quality Assurance Council Advisory

Tensioning of strands is critical for both member performance and structural safety, and stressing and elongation must be undertaken within required tolerances. Tensioning calculations require the careful evaluation of many variables. Strand elongation and calculations must account for all operational losses and compensations, including but not limited to the following: 1. Dead end seating 2. Live end seating 3. Splice chuck seating 4. Friction 5. Form shortening (self-stressing forms) 6. Abutment rotation or movement 7. Thermal effects 8. Other corrections, such as compensation for deflected strands Force corrections and calculations must account for the following 1. Live end chuck seating 2. Friction 3. Form shortening (self-stressing forms) 4. Abutment rotation or movement 5. Thermal effects 6. Other corrections, such as compensation for deflected strands 7. Gauge correction based on calibration data For elongation calculations, the modulus of elasticity of the strand shall be determined from mill certificates provided by the strand manufacturer. Calculation forms shall clearly indicate all assumptions, losses, corrections, and compensations.

REF # 12-03

July 2, 2012 Quality Assurance Council Advisory

With SCC concrete, strand located near the top surface of concrete members, such as in thin slabs or horizontally cast wall panels or spandrels, can have significantly longer transfer lengths and potentially longer development lengths as compared to bond with conventional concrete. This affect should be evaluated in products where strand bond and transfer length is critical. Further research is required on this topic, but strand bond appears to be affected by all of the concrete’s constituent materials, including admixtures and viscosity-modifying admixtures (VMA). The bond can vary for each mix and any changes in the concrete mix ingredients, including admixtures, cement and aggregates can affect the results. Refer to PCI’s Technical Bulletin 07-001 dated 04-20-07 and PCI’s “Strand Bond Bulletin”: http://www.pci.org/pdf/publications/journal/Peterman.pdf It is recommended that the acceptability of strand bond of any SCC mixes be tested by direct structural tests of prestressed products or by flexural development length tests. A standard test method for strand bond has been proposed by Peterman “A Simple Quality Assurance Test for Strand Bond” PCI Journal 54:pages 143 – 161, (revised May 2009): http://www.pci.org/view_file.cfm?file=JL-09-SPRING-14.pdf For the strand bond tests, small prestressed beams are fabricated and a concrete dead weight is suspended below the beam for more than 24 hours to ensure the member can sustain the full applied load. It is also been observed that bond for both strand and reinforcing bars can be significantly affected by excessive bleeding and lack of stability in poorly designed SCC mixes. Manufacturer’s are advised to evaluate strand bond in SCC, particularly when a member’s design is bond critical. Peterman (2009) has suggested “bond critical” members be defined as members that become structurally deficient when the assumed transfer length or development length is increased by 60%.

REF # 12-04

July 2, 2012 Quality Assurance Council Advisory

To: All Provincial Ministries of Transportation From: CPCI Quality Assurance Council The CPCI Quality Assurance Council wishes to advise all Provincial transportation authorities that the CPCI Certification Program for Structural, Architectural and Specialty Precast Concrete Products and Systems continues to be committed to our mission to: Conduct and administer a certification program for the Canadian precast concrete industry based on independent inspections of production facilities, equipment and personnel that will assure specifiers and owners of uniform, high quality and ever-improving precast concrete products and systems. To that end, the CPCI Quality Assurance Council recently approved Version 1.5 of the CPCI Certification Program Requirements. This is the fifth edition of the program requirements since its inception in 2007. When comparing the CPCI certification program to others, the CPCI program is recognized for the thoroughness and frequency of audits, the stringency in attaining first certification, the strict requirements for the maintenance of certification as well as for adding new product groups, and many other program principles such as compliance with the more stringent requirements of either CSA A23.4 or PCI MNL 116 and 117. The CPCI program continues to set itself apart from all other precast certification programs in Canada. Please contact us for your copy of the most recent version at info@cpci.ca. Sincerely, Peter Quail, P.Eng. Chairman

REF # 13-01

February 26, 2013 Quality Assurance Council Advisory

To: All CPCI Certified Plants From: CPCI Quality Assurance Council Advisory on Ledge Punching Shear Capacity on L-Beams The CPCI Quality Assurance Council advises CPCI Precasters to monitor the PCI Journal with respect to updates regarding the PCI Design Manual equations used to predict ledge punching shear capacity on L-beams. Recent PCI sponsored load bearing spandrel torsion research had some ledge failures occur at load levels much less than predicted by the PCI Design Handbook equations. It is advised that CPCI members that are designing beams with ledges that the PCI design manual approach may be un-conservative and is under review.

PCI has funded and awarded a research grant to study this issue in depth, to develop the design methodology to more accurately predict the punching shear capacity, and to devise appropriate reinforcing and detailing, as necessary, to accommodate more heavily loaded cases. Results of this research are expected to be available in early 2014.

The following link is from the spring 2012 Issue of the PCI Journal

http://pci.org/view_file.cfm?file=JL-12-SPRING-16.pdf

Sincerely, Peter Quail, P.Eng. Chairman

REF # 13-02 March 1, 2013

Advisory on Specifying Certification for Precast Concrete

The Canadian Precast/Prestressed Concrete Institute (CPCI) recommends that owners and specifiers require precast manufacturers to be certified "at time of bid", in their project and general specifications. While it has always been implied and expected that the precast concrete manufacturer be certified at the time of bid, it has not been explicitly stated. This has created somewhat of a grey area, when it comes to a non-certified precast plant bidding on projects requiring certification. This includes, and is not limited to:

Non-certified plants that bid on a project with the intent of applying for certification if awarded the project, and who also intend to be certified by the time they begin manufacture of the precast components.

Plants that have applied and are in the process of certification but at the time of bid are "certification pending".

There is a defined process from initial application to the first successful audit for any plant with a time line that will vary between plants, depending on their preparedness. Including and enforcing "time of bid" in project specifications ensures unequivocally that the plant is certified at the time of manufacture and that all participants in the project do not encounter pressure to award the precast component to a non-certified plant that may not attain certification by the time manufacture of the precast components begin. The following revised wording is recommended: Manufacturer: Certified to Canadian Precast/Prestressed Concrete Institute (CPCI) Certification Program at the time of bid. CPCI recommends specifiers and owners request a valid certificate from the certified plant at the time of bid confirming the specific categories for which the plant is certified. CPCI also maintains an updated listing of certified plants along with their category at www.precastcertification.ca. Specifiers can also download guide specifications that include the above wording, at http://www.cpci.ca/?sc=specs.

Robert Burak, P.Eng. CPCI Quality Assurance Council Administrator

REF # 13-03 June 17, 2013

Advisory on Plant Engineer Requirements In addition to the responsibilities as outlined in CSA A23.4-09, the CPCI Quality Assurance Council has implemented the following minimum requirements for the designated plant engineer (manufacturer’s engineer):

1. Shall have a minimum four years experience in the design and manufacture of precast concrete. 2. Shall visit the plant at least monthly. The duration of the visit is dependent on the professional

engineer’s judgment. 3. Review non-conforming product reports and customer complaints. 4. Review stressing calculations and stressing records, as well as periodic review of stressing

procedures. 5. Review concrete test results including strength and air content. 6. Review CPCI audit reports. 7. Visit the plant when unique or special production is undertaken. 8. A documented monthly sign-off by the plant engineer is required, indicating these items have been

reviewed, as applicable.

The above requirements are effective June 2013, and will be included in the CPCI Certification Program Requirements.

Robert Burak, P.Eng. CPCI Quality Assurance Council Administrator (On behalf of the CPCI Quality Assurance Council)

REF # 13-04

June 17, 2013

Advisory on Elongation Calculations

This advisory is related to Advisory # 12-02 from July 2012 which advised, among other requirements, that for elongation calculations, the modulus of elasticity of the strand shall be determined from mill certificates provided by the strand manufacturer. The ACO has observed that at least one strand producer is typically providing average modulus values that do not appear to vary from one strand pack to another. CSA A23.4-09 Clause 28.2.5.3.1 requires "elongation calculations be based on actual modulus of elasticity determined from the stress-strain curve furnished by the tendon manufacturer". Stressing and elongation calculations are directly affected by the strand modulus of elasticity, and should therefore be provided for each individual strand pack . Precast manufacturers are advised to contact their strand suppliers to verify mill certificate values are based on the actual stress strain curve and are not average values.

Robert Burak, P.Eng. CPCI Quality Assurance Council Administrator (On behalf of the CPCI Quality Assurance Council)

REF # 13-05

June 17, 2013

Advisory on Dead-end Force Measurement for Draped Strand PCI MNL 116 Clause 5.3.14 requires when stressing draped (harped) strand from one end, the force in at least two strands must be measured at the other end.

In lieu of load cells or other more complex methods the ACO will accept elongation measurements at the far end to verify “force”. This can be accomplished by placing two pieces of tape or marks on the draped strand after initial pull, spacing the marks on the strand far apart at the opposite end being stressed (6m apart is typical) and checking that the measured elongation between the two marks after final pull corresponds to a calculated value.

Robert Burak, P.Eng. CPCI Quality Assurance Council Administrator (On behalf of the CPCI Quality Assurance Council)

REF # 13-06

June 17, 2013

Advisory to US-based Plants of the CPCI Certification Program The CPCI Quality Assurance Council wishes to advise that all United States based plants are required to provide mill certificates (or the equivalent) for all materials, to confirm compliance with Canadian standards. This includes, but is not limited to, aggregates, cement and reinforcing.

For prestressing strand, epoxy bar and welded wire mesh, the CSA standards reference ASTM as a default, so it is not anticipated that there will be problems acquiring letters or certificates of conformance. Similarly, US based cementitious material suppliers can supply mill test reports showing conformance to CSA A3001. Reinforcing bars will require mill certificates indicating conformance to CSA G30.18. Aggregates will require conformance to CSA A23.1, including the requirements outlined for alkali aggregate reactivity. Robert Burak, P.Eng. CPCI Quality Assurance Council Administrator (On behalf of the CPCI Quality Assurance Council)

REF: 14-01 April 9, 2014

Advisory on Permissible Use of Form Release Oils in Mixers The CPCI QAC advises not to use form release oil inside mixers or in transportation buckets. Using oil in mixers and buckets can affect the air content of the first batch and also contaminate the first batch of concrete. The Accredited Certification Organization has observed some plants heavily oiling a mixer at the end of the day or in the morning before concrete mixing, to facilitate cleaning at the end of daily batching. Sometimes the oil is simply left to drain. If oil must be used it has to be thoroughly cleaned. It is recommended to use a batch of sand and pressurized water to clean the equipment, or even discard a first cleansing batch of waste concrete. One precaster has reported good success with a water based form release agent that dries white and allows personnel to see it has been washed away when cleaned in the morning. Reportedly the use of this agent in a mixer, overnight, has had no noticeable effect on air content of first batch of concrete, or other plastic properties. Since this product is water based it can have lower environmental impact. Further information on this particular product is available from the ACO, and manufacturers are encouraged to seek out similar products, but in either case it is incumbent on the manufacturer to ensure that compatibility with their next day's first batch of concrete. Robert Burak, P.Eng CPCI Quality Assurance Council Administrator (On behalf of the CPCI Quality Assurance Council)

REF: 14-02 April 9, 2014

Advisory on Recording of "Representative Ambient Temperature" The Accredited Certification Organization has observed that some precasters are recording ambient temperature within the curing enclosure at a location that is close to the concrete member. When this is done, the "ambient" temperature tends to mirror and follow the concrete temperature. The intent of recording ambient temperature is to ensure that the member is not exposed to thermal shock when it is removed from the curing enclosure. "Representative ambient temperature" is defined as the temperature of the member to which it will be exposed following removal from the curing enclosure. The differential between the concrete temperature and representative ambient temperature shall be used to determine the appropriate time for transfer of a member from the curing enclosure to the air. Note: This advisory is not intended to preclude "under the tarp" monitoring that may be required in project specific specifications. Robert Burak, P.Eng CPCI Quality Assurance Council Administrator (On behalf of the CPCI Quality Assurance Council)

REF: 14-03 April 9, 2014

Advisory on Frequency of Measurements for Chuck Seating Anchor Losses

Accurate stressing calculations for elongation and gauge readings must include appropriate allowances for chuck seating, tendon slippage at splice chucks, and any other stressing compensations that are considered variable. The QAC has advised that chuck seating anchor losses used in stressing calculations are to be verified at a frequency not to exceed 6 months, or more often if elongation inaccuracies are encountered during stressing. Stressing calculations are to be updated accordingly.

Robert Burak, P.Eng CPCI Quality Assurance Council Administrator (On behalf of the CPCI Quality Assurance Council)

REF: 14-04 April 9, 2014

Advisory on Definition of Point of Discharge for Precast Plant Sampling

CSA A23.1-09 Clause 4.4.2 indicates "Samples of concrete for testing purposes shall be secured in accordance with CSA A23.2-1C. When the owner elects to assess the quality of concrete at a location other than the point of discharge from the delivery equipment, the owner shall state the point from which the samples shall be taken." In a precast plant using concrete delivery buckets, the concrete used for testing purposes should be taken at the discharge gate of the concrete bucket. Similarly, for plants using mixing or transportation trucks, the concrete used for testing should be obtained from the end of the chute representing concrete as it is to be cast into the forms. If concrete needs to be pre-qualified for air content and slump prior to discharging from the mixer, tests could also be undertaken at the batch plant. However, concrete used for actual test results and documentation is to be sampled after the concrete has travelled though all equipment, gates, chutes or devices as these can affect the concrete properties and air content. This does not have to be at the casting bed. The Quality Assurance Council has also determined that the sample shall be taken from the first concrete discharged, not between the 10% and 90% points of discharge. Similarly this would be the case for concrete supplied from a concrete mixer providing the truck has not been used for primary mixing and is only being used to agitate and transport centrally mixed concrete to a precast form. The 10% and 90% still apply when the truck is the primary source of mixing. Robert Burak, P.Eng CPCI Quality Assurance Council Administrator (On behalf of the CPCI Quality Assurance Council)

REF: 14-05 April 9, 2014 Advisory on Permissible Calibration Procedures of Water and Admixture Metering Systems by Plant

Personnel

Water and admixtures are to be calibrated every 90 days or whenever there is a reason to question accuracy. Small quantities of admixtures can create large changes in the properties of the concrete, so measurement and calibration of water and admixtures needs to be undertaken accurately. The Quality Assurance Council has determined that these calibrations can be done by the plant, and do not need to be done by a third party, providing the following steps and documentation procedures are followed for eventual review by the auditors: 1. When calibrating these systems at the batch plant, ensure that at least three readings are measured covering the full quantity range of material typically dispensed. 2. Verify the accuracy of water and each admixture by discharging a required amount covering the full spectrum of batch sizes, from minimum to maximum size of batch. 3. Verify the accuracy of the system is within the required tolerances. 4. Calibration records should include the date, name of personnel undertaking the test, and all relevant test data, and be provided to the auditors at the time of the audit. 5. Plants using Ready Mix Concrete Suppliers are to ensure the Ready Mix batch plant also complies with the above requirements. Robert Burak, P.Eng CPCI Quality Assurance Council Administrator (On behalf of the CPCI Quality Assurance Council)

REF: 14-06 April 9, 2014

Advisory on Minimum Permissible Temperatures of Formwork

CSA A23.1-09 Table 14 provides permissible concrete temperatures at time of placement. 10°C is the minimum for section thicknesses less than 1 m. In addition, Clause 7.2.4.9 states that "Concrete shall not be placed on or against any surface that will lower the temperature of the concrete in place below the minimum value shown in Table 14". To satisfy these requirements, the Quality Assurance Council also requires the temperature of the formwork, steel reinforcement, or the material on which the concrete is to be placed shall be at a minimum temperature of 5 °C prior to placing concrete. Similarly, in hot weather, the temperature of formwork, steel reinforcement, or the material on which the concrete is to be placed is of critical importance. The Council advises to keep all equipment that touches the concrete cool (i.e. chutes, conveyors, reinforcement and buggies). Protecting equipment from the direct sun will assist. If it can’t be kept continuously cool, spray-cool it as necessary with water. Protecting forms with shade or tarps and sprinkle or mist cool water onto forms and reinforcing just prior to placing, is also acceptable, but the precaster should ensure water evaporates and that there is no standing water before concreting. In either condition, hot or cold, the Council advises that the precaster develop a plant specific procedure to assess the temperature uniformity of the formwork. Robert Burak, P.Eng CPCI Quality Assurance Council Administrator (On behalf of the CPCI Quality Assurance Council)

REF: 14-07 April 9, 2014

Advisory on Marking of Mass on Products

CSA A23.4-09 Clause 29.5 requires individual precast concrete elements be clearly marked with identification as shown on the shop drawings, including date of casting. In addition, note 2 to the clause states that "The approximate mass of the elements should be marked on them, particularly in cases where shipping or installation crews cannot easily identify the masses of the precast elements." The Quality Assurance Council believes indicating the mass of precast elements is important for yarding, trucking and erection. As a result, Note No. 2 to this clause is considered mandatory, with the addition that "actual mass" replaces "approximate mass". Robert Burak, P.Eng CPCI Quality Assurance Council Administrator (On behalf of the CPCI Quality Assurance Council)

REF # 14-08

November 6, 2014

Advisory on Minimum Slump Flow for Self Consolidating Concrete CSA A23.1/2 defines Self-consolidating concrete (SCC) as "a highly flowable, yet stable, concrete that can spread readily into place, fill the formwork, and encapsulate the reinforcement, if present, without any mechanical consolidation and without undergoing any significant separation of material constituents". Generally concrete with a minimum slump flow of 500 mm is considered to be SCC. The Quality Assurance Council advises that SCC at 500mm may not be flowable enough to guarantee no voids in highly congested areas of reinforcement, particularly those elements with thinner sections. Plants are advised to confirm their own SCC mixtures to determine the appropriate minimum slump flow to ensure complete encapsulation while maintaining the normal characteristics required for SCC according to CSA A23.1/2. This may require a series of tests using similar size forms, and deconstruction to confirm full consolidation.

Robert Burak, P.Eng CPCI Quality Assurance Council Administrator (On behalf of the CPCI Quality Assurance Council)