Construction Technology, Materials and Quality Control
The sequence and its controls
Work proceeds through earthworks, foundations, structure, envelope and finishes, with a quality gate at each stage. Control has three layers: incoming inspection of materials (certificates, batch data, visual and dimensional checks), operational control during work (formwork geometry, reinforcement placement, concrete placing and compaction), and acceptance control (tests and as-built records). Hidden works are closed only after a signed hidden-works act (թաքնված աշխատանքների փակման ակտ), which is a favourite examination topic.
Concrete as the model case
Concrete quality depends on water/cement ratio, aggregate grading, mixing, transport time, compaction and curing. Slump or flow tests check workability at delivery; cube or cylinder specimens check strength. Standard acceptance strength is the 28-day value; results at 7 days are only an early indicator and must not be used for acceptance. Specimens are taken at a defined frequency per volume and per day of placing, cured on site and tested in an accredited laboratory. Curing must continue long enough to develop the specified strength and limit cracking.
Other materials
Reinforcement must be stored clear of the ground, free of scale and oil, and fixed at the specified cover using spacers; substitution of bar class requires designer approval. Masonry depends on unit strength, mortar grade, proper bonding and filling of vertical joints. Cement has a limited storage life and loses strength in damp conditions. Waterproofing, thermal insulation and backfill each have their own acceptance rules.
Traps
- Accepting concrete on 7-day results.
- Confusing cube strength with in-situ strength; cores or rebound tests are used for existing structures.
- Skipping hidden-works acts and trying to reconstruct them later.
- Storing cement and rebar in the open, then using them without retesting.
Rule of thumb
No document, no acceptance. Every stage is signed before the next covers it, because after backfill or plastering the evidence is gone.