Preferred temperature for placing concrete (IS practice) For quality control in Indian site conditions, concreting is preferably carried out when the concrete temperature during placing is closest to which value?

Introduction / Context:
Temperature significantly affects concrete workability, setting time, and early strength. Excessive heat accelerates setting and increases water demand; very low temperatures risk delayed set and early-age damage. In Indian practice, quality checks and many fresh-concrete tests reference a preferred temperature band around ambient tropical conditions.

Given Data / Assumptions:

• General site concreting (not extreme hot- or cold-weather concreting with special measures).
• Objective is to place concrete near the reference conditions used for test correlations.
• Indian context referencing typical QA/QC practices.

Concept / Approach:
Workability tests (e.g., slump, compaction factor) and standard mixing/curing controls in India often cite 27 ± 2°C as the preferred reference temperature. Placing concrete close to this band helps ensure the behaviour observed in tests corresponds to the behaviour on site. Significant deviations call for hot- or cold-weather concreting provisions (e.g., chilled water, ice, insulation, or heating).

Step-by-Step Solution:
Identify the reference band commonly used: 27 ± 2°C.Relate this band to practical site placement for consistent properties.Select 27 ± 2°C as the preferred placing temperature under normal Indian conditions.

Verification / Alternative check:
Field specifications frequently state that measured fresh concrete temperature should be near 27°C; otherwise adopt hot/cold-weather measures to maintain consistency with laboratory expectations.

Why Other Options Are Wrong:
0–10°C are cold-weather conditions requiring special measures; 20–23°C are acceptable in many climates, but the canonical Indian reference is 27 ± 2°C for tests and control.

Common Pitfalls:
Ignoring temperature corrections; mix water temperature control and shaded batching areas help maintain target temperature and slump retention.

Final Answer:
27 ± 2°C