1、Guide for Concrete Plant Inspection and Testing of Ready-Mixed Concrete This guide is intended for use in establishing basic duties and reports required of inspection personnel. It can be used for all types and sizes of projects but should be supplemented with additional inspection requirements when
2、 the complexity of the project so dictates. Refer to AC1 31 1.4R for guid- ance on additional requirements and to SP-2 for more detailed information on concrete production practices and inspection and testing of concrete. This guide recommends minimum requirements for inspection at the concrete plan
3、t when such inspections are required by speci3cations or the ownex It also recommends minimum requirements for field and laboratory testing of concrete. It is intended for use by specifiers, architects, engi- neers, owners, contractors, or other groups needing to monitor the ready- mixed concrete pr
4、oducers activities at the concrete plant and concreting activities at the project site through the use of an independent inspection agency or in-house inspection organization. This guide also recommends minimum testing laboratory qualifications, minimum inspector qual$cations, duties, and reports. A
5、C1 Committee Reports, Guides, Standard Practices, and Commentaries are intended for guidance in planning, designing, executing, and inspecting construction. This document is intended for the use of individuals who are competent to evaluate the significance and limitations of its content and recommen
6、dations and who will accept responsibility for the application of the material it contains. The American Concrete Institute disclaims any and all responsibility for the stated principles. The Institute shall not be liable for any loss or damage arising therefrom. Reference to this document shall not
7、 be made in contract documents. If items found in this document are desired by the ArchitectEngineer to be a part of the contract documents, they shall be restated in mandatory language for incorporation by the ArchitectEngineer. It is the responsibility of the user of this document to establish hea
8、lth and safety practices appropriate to the specific circumstances involved with its use. AC1 does not make any representations with regard to health and safety issues and the use of this document. The user must determine the applicability of all regulatory limitations before applying the document a
9、nd must comply with all applicable laws and regulations, including but not limited to, United States Occupational Safety and Health Administration (OSHA) health and safety standards. Keywords: batch plants; contract documents; curing; high-shength concrete; quality control; ready-mixed concrete; tes
10、t. Q nc; r 2. The minimum duties of an inspector; and 3. The type of reports that should be made. The scope and responsibility involved in plant inspection should be established in the contract documents, which should also define the relationships between the owner, concrete contractor, concrete sup
11、plier, and the inspector. 1.2-Inspector qualifications The plant inspector should be qualified by education, training, and experience to perform the minimum duties set forth in this guide. The inspector should have a technical understanding of the materials used to produce concrete along with the pr
12、inciples involved in concrete batching and should know the basic operating sequence of the concrete plant. The inspector should provide evidence of his or her training and experience. AC1 inspector or technician certifi- cations, Reinforced Concrete Special Inspector Certification (co-sponsored by A
13、C1 and various building code organiza- tions) or appropriate state agency certifications are accept- able evidence that the person has completed minimum training and examination requirements for specific areas of inspection and testing covered in this document. The inspector should also have and bec
14、ome familiar with the published standards referenced in this guide and with project specification requirements. The authority of the plant inspectors and to whom they report should be established before the start of the project. 1.3-Inspector duties 1.3.1 To determine required inspections, the inspe
15、ctor should review and fully understand the project specifica- tions, plans, and other project documents. The inspector should observe that the facilities, scales, and truck mixers meet the specified project requirements. The provisions of the following documents should normally be incorporated in t
16、he project specification: AC1 301; ASTM C 94/C 94M; Plant qualification in accordance with the National Ready Mixed Concrete Association (NRMCA) check- list for certification of ready-mixed concrete production facilities; and Local, state, or federal agency specifications. 1.3.2 Inspectors should co
17、nduct activities in accordance with all safety policies, health standards, and safe work prac- tices in effect at the job site. 1.3.3 The inspector should verify proper storage of all materials on a daily basis. All storage areas should be clean and free of contamination. Cementitious materials shou
18、ld be stored in weatherproof silos or similar structures. Aggregate storage areas should provide for separation and free draining of stockpiled materials. Storage areas should be equipped with water spray systems for maintaining aggregates in a saturated condition. Means for protecting and preventin
19、g freezing of aggregates during winter production should also be provided. Admixture storage areas should be suitably insulated or heated to prevent freezing. 1.3.4 All tests and inspections should be conducted at the frequencies required by the project specifications in a manner that does not inter
20、fere unnecessarily with the manu- facture and delivery of the concrete. During the first batch being shipped to the project under the inspectors jurisdic- tion, the inspector should be present at the batching console to verify that the specified type and amount of materials, conforming to the approv
21、ed design mixture proportions, are batched and delivered to the mixer. If the operation is automated and recorded, the inspector should make observations as often as possible, preferably on a continuous basis, but at least once per hour. If the batching operation is manual, the inspector should be p
22、resent at the batching console during all batching. The inspector should verify that quantities of materials for each batch fall within the tolerances set forth by the project spec- ifications. 1.3.5 The inspector should verify that coarse- and fine- aggregate gradation tests are being performed in
23、accordance with ASTM C 136 and that the results meet the project requirements. If deviation occurs, batch plant personnel and the client should be notified immediately, or previously authorized action should be taken. 1.3.6 The inspector should verify that aggregate moisture contents are properly de
24、termined in accordance with ASTM C 566, and that the batch quantities of materials are adjusted to compensate for free moisture in the aggregates. If aggre- gate moisture contents are being measured by rapid methods, daily correlation tests following ASTM C 566 should be conducted. 1.3.7 The inspect
25、or should determine that the trucks are in good operating condition and not loaded beyond their rated capacities for mixing and agitation. Trucks should also be inspected (safety regulations regarding confined spaces should be followed, if applicable) for blade wear, build-up of concrete on the blad
26、es, and for proper mixing speed as described in Section 3 of the NRMCA Quality Control Manual. Truck mixers should be equipped with counters or similar means to enable verification of the number of revo- lutions applied to the drum. 1.3.8 The inspector should verify that the scales and other measure
27、ment systems have been properly calibrated within the time period specified by the project specifications or referenced documents 1.3.9 The capability of the production facility to produce concrete within the temperature limits of the project specifi- cation should also be evaluated and verified. In
28、 cold weather this generally requires a water and aggregate heatin capacity of 15 boiler horsepower per 100 yd3 (76 m ) production. In hot weather, this generally requires a system for spraying and cooling aggregates and a system for effi- ciently weighing and deliverin crushed ice to the mixer in t
29、he range of 40 to 100 lb per yd (18 to 45 kg per m3). 1.3.10 For each batch of concrete the inspector should verify that the concrete plant is furnishing to the purchaser a delivery ticket conforming to ASTM C 94/C 94M. A place should be provided on the ticket to reflect the following information: D
30、ate; Truck number; Name of the purchaser; ? 3 Name of the concrete plant; Serial number of the ticket; Project designation (name and location); Class or designation of concrete; GUIDE FOR CONCRETE PLANT INSPECTION AND TESTING OF READY-MIXED CONCRETE 31 1.5-3 Amount of concrete batched; Time batched;
31、 The amount of water added by receiver of concrete and receivers initials; The amount of water withheld during batching, if any, and the admixtures that may be added at the jobsite; and Any additional information required by the purchaser or the project specification. 1.4-Reports 1.4.1 The inspector
32、 should sign the delivery ticket, issue an inspection report, or supply other evidence that the concrete batching has been inspected. 1.4.2 The inspector should issue a daily inspection report showing all test results and documenting observations made during the day. Deficiencies and to whom they we
33、re reported should be clearly identified. The ACZ Manual of Concrete Inspection (SP-2) contains guidance on reporting and samples of reports. CHAPTER 2-TESTING OF READY-MIXED CONCRETE 2.1-Introduction and scope This chapter recommends minimum requirements for the testing of ready-mixed concrete at t
34、he project site when required by specifications. It includes requirements for curing of specimens, testing of specimens for strength, and qualification requirements for testing technicians and labora- tories. It is intended for use by specifiers, architects, engi- neers, owners, contractors, or othe
35、r groups interested in monitoring the concreting activities at the project site through the use of an independent inspection agency or in-house inspection organization. 2.2-Qualif ications Technicians conducting field tests of concrete are required by ASTM C 94/C 94M to be certified as an AC1 Concre
36、te Field Testing Technician-Grade I, or equivalent. For labora- tory testing, AC1 certification as a Laboratory Testing Techni- cian or Concrete Strength Testing Technician, or equivalent, is required. Technicians should also be furnished with and become familiar with published standards as referenc
37、ed in this guide and with project specification requirements. Before the start of the project, the owner should establish the technicians scope of authority and the requirements for submittal of reports and notification of deficiencies. 2.3-Testing laboratory All required laboratory acceptance tests
38、 (that is, laboratory curing and testing of concrete strength specimens) should be performed by an independent testing laboratory or by the owners in-house testing personnel. The laboratory conducting acceptance testing shall meet the requirements of ASTM C 1077. To comply with ASTM C 1077 the labor
39、a- tory must be inspected by an independent agency such as the Cement and Concrete Reference Laboratory (CCRL) or the AASHTO Material Reference Laboratory (AMRL) within the last 3 years and should show that any deficiencies mentioned in the report of that inspection have been corrected. The laborato
40、ry should be accredited by the AASHTO Accreditation Program (AAP), the National Voluntary Laboratory Accreditation Program (NVLAP), the American Association for Laboratory Accreditation (A2LA), or similar programs as approved by the owner. 2.4-D ut es 2.4.1 The field technician should check each del
41、ivery ticket to verify that the mixture with the correct designation is being delivered and, if possible, determine whether adjust- ments to proportions, such as admixtures, have been made. Immediate action should be taken, as authorized, in the case of a discrepancy. Immediate verbal notification s
42、hould be given to the placing contractor and the concrete supplier. Truck mixers are not loaded in excess of mixer plate capacity; Concrete appears to be uniform and adequately mixed before discharge at the project site; Field additions of water, admixtures, or fiber reinforce- ment are properly con
43、ducted and documented; Concrete delivery and placement falls within the time constraints of the project specifications; and All data required by ASTM C 94/C 94M, the purchaser, or the job specification are included on the delivery ticket. Immediately report any discrepancies to the placing contracto
44、r and the concrete supplier. 2.4.3 The technician should cast at least one set of strength test specimens in accordance with ASTM C 31/C 31M for each 100 yd3 (76 m3), or fraction thereof, of each class of concrete placed in any one day. Tests of concrete that should be conducted whenever strength sp
45、ecimens are cast include the following: slump, air content, temperature, and density (whenever yield is to be calculated or as required by project specifications). When sampling concrete, a composite sample repre- senting concrete conditions as delivered to the forms should be obtained in accordance
46、 with ASTM C 172, and the date, time, placement location, truck number, and ticket number should be reported. 2.4.4 The first truckload of concrete should be tested for slump, concrete temperature, air content, and, if specified, density, so that any necessary adjustments can be made at the plant to
47、 bring concrete within specifications immediately. 2.4.5 The technician should measure slump in accordance with ASTM C 143/C 143M for composite samples used to cast strength test specimens and whenever the consistency of the concrete appears to vary. 2.4.6 The technician should determine the air con
48、tent of composite concrete samples for each strength test in accor- dance with ASTM C 173, ASTM C 231, or ASTM C 138, and density (when required) in accordance with ASTM C 138. 2.4.7 Specimens for determining equilibrium density of low-density concrete should be cast and tested in accordance with AS
49、TM C 567. 2.4.8 The technician should determine the ambient air temperature and the composite concrete sample temperature at the time of sampling for each strength test in accordance with ASTM C 1064. 2.4.9 For each test age specified for acceptance, the tech- nician should cast a minimum of two strength specimens according to ASTM C 31/C 31M from each composite concrete sample. Casting of additional specimens for infor- mational testing at other ages may also be required. 2.4.2 The field technician should determine that: 31 1.5-4 AC1 STANDARD 2.4.10 The contractor should provide a sui
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