Laboratory Workflow
Part One: Instruments and Personnel Arrival, Laboratory Establishment Phase
l Laboratory Functions
Determine the function of the test operation area, power modification, pedestal installation, office area construction, purchase of instruments, installation and debugging of instruments, etc. According to functional areas, it is mainly divided into cement room, aggregate room, mechanics room, cement concrete room, sample room, office, etc. Each functional area/room must have a dedicated person responsible for safety and health.
l Instruments
1. Instrument serial number and filing - the file content should include instrument calibration certificate, instrument instruction manual, instrument and equipment management records, etc.; the special custodian for instrument setting , establish an identification card, and whoever is responsible for this part of the main test will be responsible for maintaining and maintaining the instrument.
2. Instrument calibration and self-inspection and self-calibration - major instruments are calibrated by qualified measurement departments. Small instruments or if there are no mandatory requirements in the specifications, they can be self-calibrated by the laboratory. The following is a breakdown of which instruments require self-calibration:
A. Cement room: including cement mortar test molds, thunder clamps, containers for specific surface area meters, etc.
B. Geotechnical chamber: including sand filling cylinder (standard sand density, cone sand quality in the sand filling cylinder, etc.), geotechnical box, square plate, compaction cylinder, CBR cylinder, etc.
C. Mechanics room: including continuous steel bar dotting machine, crushing value meter, etc.
D. Concrete room: concrete mixer, slump meter, concrete and mortar test mold, shotcrete test mold, concrete drilling core machine.
E. On-site inspection: dynamic preliminary detector, concrete drilling core machine.
F. Measuring tools: beaker, measuring cylinder, pycnometer.
l Personnel
1. Testers should hold certificates to work. Generally, the construction site laboratory should be equipped with 2 divisions and 6 people. If conditions permit, additional test workers should be added. And the inspection qualification of the inspection engineer should cover all categories of the project. For example, if the project has tunnels, bridges, roadbeds and other engineering categories, the inspection engineer's qualification certificate should cover all projects. Missing items will result in inspection points being deducted.
2. Personnel should be assigned positions and personnel to be responsible for specialized tests, which mainly involve signature issues and test time issues. Special attention will be paid during the inspection. Personal energy is limited and it is impossible to involve all test categories. The test will be fake. Serious consequences such as revocation of qualifications may result.
3. Personnel should establish files, including job qualifications (mainly tester or testing engineer certificates), identity certificates, professional title certificates, graduation certificates, personal resumes, and some should also have job contract documents and other materials .
l Laboratory Qualifications
The construction site laboratory is an agency dispatched by the parent testing agency. It is supervised and managed by the parent company and should have independent testing capabilities. The setting process is as follows:
1. The parent testing organization shall, in the form of a letter of authorization, grant the test items and categories to the construction site laboratory, authorize the main personnel of the relevant laboratory, and dispatch permanent personnel to the parent body, etc.
2. After obtaining authorization, the construction site laboratory must organize relevant information, prepare a qualification application, and submit capability certification materials to the owner of the project location, including parent information, construction site laboratory personnel information, and instrument information , the test items and categories that can be carried out, etc., prove that it has the test capability, and then the quality supervision station will verify the ability. If the verification is passed, the test test can be carried out.
Part 2: Laboratory work development period
l Standard test article
1. Concrete mix ratio:
A. First It is a material source investigation, that is, the screening of raw materials must be done, and factors such as material transportation distance, quality, and supply capacity must be comprehensively considered. Materials are divided into supply materials (generally steel bars and cement) and floor materials (mainly gravel and sand), as well as admixtures, etc. The investigation of material sources is mainly to select the raw materials, and several tests must be done to determine their quality. Stable and qualified in testing indicators.
B. The proportion should be made first with a low grade of ≤C30, because the bridge superstructure started relatively late, and high-grade concrete is required relatively late. The proportion of ≤C30 can already meet the needs of small structures in the early stage. Construction requirements for structures and bridge substructure; see the “Mixture Design Instructions” on the information disk for details on the proportions.
2. Geotechnical standard test: It is mainly the original ground and geotechnical standard compaction test, which provides control standards for the on-site compaction degree test, mainly the optimal moisture content and maximum dry density.
Pay attention to the study standards for the above standard tests.
Part Three: Inspection of Incoming Raw Materials
l Concept
Incoming Raw Materials: Refers to the material department purchasing various raw materials after the mixing station is put into use. , that is, the arrival of materials, is closely related to the laboratory, because once the materials enter the site, they must be tested in a timely manner. In principle, they must be tested before they can be used.
l Practical Operation
1. After the raw materials arrive, the materials department will notify the laboratory, with an inspection form as evidence to prove the material quantity, specifications, and material recipients, etc. , attach the appearance certificate, quality certificate and other information (may be provided by the work area and mixing station), the laboratory will send a dedicated person to take samples, and notify the supervisor to witness (normal procedure), fill in the sampling form; after the sample is retrieved, a dedicated person will receive it Samples (part of the test, part of the retained sample - cement); fill in the sample retention ledger and sample management ledger.
2. The sampled materials generally need to be processed before testing. For details, please refer to various specifications (note that cement must be allowed to stand for 24 hours in the same testing environment before testing)
3. The test steps are as follows:
A. Sample preparation
B. Fill in the original test record and instrument usage record along with the test process.
C. After the test is completed, the test report shall be issued from the original records, signed, sealed and filed. Based on the test results, fill in the test ledger (whether it is qualified or not) and complete the relevant ledger information.
D. Non-conforming products must be filled in the non-conforming product ledger (generally, the rectification notice issued to the work area and mixing station will be contacted)
E. After the material test passes, fill in the Prepare raw material inspection forms and submit them for inspection in a timely manner; raw materials such as sand, gravel and steel bars, and welding, are generally submitted for inspection on the same day as the test, and cement must be submitted for inspection after 28 days of passing the strength test.
Part 4: On-site Test
l Concept
According to the progress of the construction process, when the on-site construction reaches a certain stage, the laboratory must conduct tests and tests. On-site inspection can reflect the construction level and construction information for the next process.
l Testing
1. Bridge work area
A. On-site concrete pouring: The laboratory will issue a mix ratio notice and go to the site to check the raw materials. Quality, monitor concrete quality and slump loss, and urge the work area to make concrete specimens.
B. Structural rebound: Structures that are 28 days old, generally exposed parts of bridges, must undergo strength rebound; in particular, the quality of beams and plates must be strictly controlled, and rebound must be timely and effective. .
C. Bearing capacity test of the bridge abutment or expanded foundation: A bearing capacity test must be conducted before concrete pouring to ensure that the design requirements are met.
D. Bridge abutment rebound compaction test: After the bridge abutment body is completed and reaches a certain age, the bridge abutment must be backfilled and compacted in layers. The laboratory must be on-site for testing and issue a compaction certificate. Reality data.
2. Tunnel work area
A. Concrete pouring process control such as bridge work area
B. Anchor pulling: part of the tunnel anchoring project, different The surrounding rock grade and supporting anchors are different, and the design pull-out force is also different. Please refer to the tunnel specifications and drawings for details.
3. Subgrade work area
A. Subgrade compaction: original ground compaction detection, and soil and rock mixed filling compaction detection.
B. Foundation bearing capacity test: soft soil foundation treatment, dredging and filling, etc.
4. Small construction area
Mainly used for round pipe culverts and channel backfilling, and compaction control.
Part Five: Outsourced Testing and Pile Foundation Testing
l Outsourced Testing
Items for which the construction site laboratory does not have qualifications outside the parent company’s authorized testing scope, It must be sent for external inspection, that is, it is entrusted to an external qualified unit for inspection, which is called outsourced inspection. The general materials include steel strands, anchor clamps, admixtures, fly ash, I-beams, waterproof membranes, waterstops, and geotechnical materials. Grilles etc. When sampling, it is also necessary to have a supervisor witness and fill out the outsourced test order form. The supervisor must keep a copy on file.
l Pile Foundation Testing
After the pile foundation is poured for 7 days, the quality of the pile foundation can be tested. Only after it is qualified and qualified can the next construction process be carried out, which is usually organized and arranged by the laboratory. For pile foundation testing, notify a third-party testing unit to conduct it. Generally, construction site laboratories do not have the qualifications. After the self-inspection is completed, it needs to be reported to the resident office laboratory for random inspection and the general director office central laboratory inspection.
Part 6: Concrete Strength
l The testing of sand, gravel, cement, admixtures, fly ash or other external admixtures all serve concrete, and Concrete strength testing is a comprehensive reflection of all raw materials plus on-site construction level. It is also the main reference when measuring. The quality of various raw materials must be strictly controlled to ensure that the concrete strength is qualified.
l During the strength test, concrete specimens with different grades have different loading speeds. Please refer to the cement and concrete specifications.
l Preliminary maintenance is very critical to increase the strength of concrete. After the specimen is produced, it must be cured under standard conditions. The temperature and humidity must be controlled in place to achieve actual strength.
Part 7: Laboratory work and outside work
l Basically divided by work location, this section mainly introduces the inside work, that is, the operation and maintenance of the entire laboratory.
1. Office
A. Ledger sorting and registration: feedback registration of various information on the construction site, including statistics on daily concrete pouring parts, statistics on the bridge progress image table, and progress On-site raw material statistics, pile inspection information statistics, etc.
B. Archiving of various materials: archiving of instruments and personnel; archiving of test data, filling in and summarizing catalogs of various information files, etc.
C. Current work focus: maintenance records of instruments and equipment starting from the entry into the site; periodic calibration of major instruments (usually one year); self-inspection and self-calibration of small instruments (refer to self-calibration records and previous records); calibration of mixing facilities at each mixing station; calibration of jacks in beam yards.
D. Reporting of various types of correspondence, registration of receipts, etc.
2. Test operation room
A. Temperature and humidity monitoring and recording of concrete standard curing room and cement room curing box, safety and health maintenance, timely strength test of specimens upon expiration, etc. .
B. Check the sample ledger in the sample retention room, remove expired cement, and register various sample information in a timely manner.