| S.No. | Checkpoint | IS Requirement | Status |
|---|---|---|---|
| A. MORTAR PREPARATION AND SPECIMEN CASTING | |||
| A1 | Mortar mix proportions per IS 4031: Cement:Sand = 1:3 by mass Acceptance: Cement mass: 500g; Sand mass: 1500g (ISO standard sand); water: normal consistency % | Cl. 5.1 — Mix design | OK NC NA HOLD |
| A2 | Sand quality verified: ISO standard sand used (0.1-2 mm graded sand) Acceptance: ISO standard graded sand; specific gravity 2.6-2.8; moisture content <0.1% | Cl. 5.1.1 — Sand specification | OK NC NA HOLD |
| A3 | Water addition: normal consistency percentage determined and used Acceptance: Water % as per normal consistency test (typically 10-12% by weight of cement); documented | Cl. 5.1.2 — Water content | OK NC NA HOLD |
| A4 | Mortar mixing: mechanical mixer used; mixing time 3-5 minutes at specified speed Acceptance: Mixer speed 140±10 rpm; mixing duration 4-5 min; homogeneous mix achieved | Cl. 5.2 — Mixing procedure | OK NC NA HOLD |
| A5 | Cube mould dimensions: 70.6 mm (±0.5 mm) per side; non-porous and rigid Acceptance: Mould dimension accuracy within tolerance; internal surfaces smooth; no corrosion | Cl. 5.3 — Mould specification | OK NC NA HOLD |
| A6 | Mortar filled in mould in 2 layers with compaction by vibration or tamping Acceptance: Layer compaction: 32 blows per layer using standard tamper; no air voids; uniform density | Cl. 5.4 — Casting procedure | OK NC NA HOLD |
| A7 | Specimens struck off flush with mould top and marked with identification Acceptance: Excess mortar removed; surface level with mould; clear marking: batch, date, test age | Cl. 5.5 — Specimen finishing | OK NC NA HOLD |
| B. SPECIMEN CURING CONDITIONS | |||
| B1 | Initial curing: specimens kept in mould for 24 hours at room temperature (20-27°C) Acceptance: Temperature maintained 20-27°C; humidity >90%; no vibration or disturbance | Cl. 5.6 — Demoulding time | OK NC NA HOLD |
| B2 | Demoulding: specimens removed from mould after 24 hours without damage Acceptance: Gentle removal; no cracking or spalling; surfaces intact | Cl. 5.6.1 — Demoulding procedure | OK NC NA HOLD |
| B3 | Water curing: specimens submerged in potable water at 23±2°C until testing Acceptance: Continuous submersion in water; temperature 23±2°C; no exposure to air between curing and testing | Cl. 5.6.2 — Curing method | OK NC NA HOLD |
| B4 | Curing water replaced periodically; pH >7; no stagnation or contamination Acceptance: Water changed every 7 days or as needed; clean, potable water; no algae growth | Cl. 5.6.2 — Curing water quality | OK NC NA HOLD |
| C. 7-DAY COMPRESSIVE STRENGTH TESTING | |||
| C1 | Specimens tested at exactly 7 days after casting (±30 minutes tolerance) Acceptance: Age precisely 7 days; testing time documented; maximum deviation ±30 min from exact age | Cl. 5.7 — Testing age | OK NC NA HOLD |
| C2 | Specimens surface-dried before testing; no water droplets or excess moisture Acceptance: Specimens wiped dry; allowed to reach room temperature (20-27°C) before testing | Cl. 5.7.1 — Pre-test preparation | OK NC NA HOLD |
| C3 | Compression testing machine calibrated per ASTM/ISO standards with ±1% accuracy Acceptance: Machine certified; load application rate 0.6-1.2 MPa/s; alignment verified | Cl. 5.7.2 — Equipment calibration | OK NC NA HOLD |
| C4 | Load applied uniformly and continuously until specimen fails; no shock loading Acceptance: Constant rate of loading; specimen centered on platen; failure mode observed and recorded | Cl. 5.7.3 — Loading procedure | OK NC NA HOLD |
| C5 | Ultimate load at failure recorded for each specimen tested Acceptance: Load in kN recorded accurately; minimum 3 specimens tested; failure pattern documented | Cl. 5.7.4 — Data recording | OK NC NA HOLD |
| C6 | 7-day compressive strength calculated: Strength = Load / Area (in MPa) Acceptance: Strength = (Load in N) / (Area 50 mm × 50 mm); reported in MPa to 1 decimal place | Cl. 5.8 — Strength calculation | OK NC NA HOLD |
| C7 | 7-day strength compared with IS code minimum requirement Acceptance: 33 Grade: min 17 MPa; 43 Grade: min 23 MPa; 53 Grade: min 27 MPa; average of 3 specimens | Cl. 6 — Acceptance criteria 7-day | OK NC NA HOLD |