Quality Assurance in Construction

Quality Assurance and Control

• Quality assurance provides confidence regarding the adequacy of a product or service.
• A Quality Assurance program is essential for the implementation of construction QA.
• Making and revising QA specifications should involve engineers, inspectors, and technicians from both the agency and industry.

QA Program Elements

• Design bid build and Design build construction QA programs share the same six elements.
• Quality control (QC) activities include sampling, testing, and visual inspection.
• QC plans should be project-specific and address individual processes for various work categories.

Responsibilities and Acceptance

• Acceptance of work is the responsibility of the transportation agency.
• Engineering limits define absolute threshold values for individual test results.
• QA specifications utilize quality measures for evaluation.

Internal Audits and Comparisons

• Internal Audit (IA) aims to identify discrepancies in testing procedures or equipment.
• IA comparison is conducted using split samples.
• If contractor QC test results are excluded from acceptance, a dispute resolution system is unnecessary.

Accreditation and Certification

• All agency central labs must be accredited through the AASHTO accreditation program (AAP).
• Personnel must be recertified every 2-5 years for qualifications.

Compliance and Standards

• Each agency construction QA program must comply with 23 CFR 637B, requiring FHWA approval.

Sampling Techniques

• The D-3665 Random number table contains 10,000 numbers ranging from 0.0000 to 1.
• Random numbers help ensure unbiased sample collection.
• A "lot" is defined as an isolated quantity of materials from a single source, assumed to be produced and placed uniformly.

Sub-lots and Sample Collection

• Sublots are established to ensure sample collection from various locations within a lot.
• To find the row of a random number, multiply the number by 500 and round to the nearest whole number.
• Statistical samples consist of samples made up of individual increments.

Sampling Procedures

• D 3665 recommends stratified random sampling as the most effective approach to represent the full range of construction processes.
• Random numbers, once drawn, cannot be altered.
• The sampling methods can be applied beyond QC sampling situations, emphasizing their broader relevance.

Importance of Sampling

• Proper sampling is as crucial as testing and should be executed with care.
• Maximum size is defined as the smallest sieve size through which all material must pass.
• AASHTO sampling procedures generally require samples to consist of multiple increments.

Sampling Equipment and Techniques

• Devices used for sampling from flowing aggregate must interrupt all material passing through them.
• Power equipment is preferred for sampling purposes.
• Sampling stockpiles may involve remixing, re-entering, rolling out the sampling pile, back-dragging, and quadrant sampling.

Manual Sampling Practices

• When sampling from a stockpile without power equipment, subdivide the pile into quarters, collecting samples from each.
• Only the inner layer of material should be taken when shoveling from a stockpile.

This quiz covers key concepts of quality assurance and control specifically in construction projects. It discusses the essential elements of QA programs, responsibilities of transportation agencies, and quality control activities. Test your knowledge on QA specifications and internal auditing in construction.