---
title: "Hot weather concreting precautions"
subject: "Concrete Technology and Masonry Structure"
chapter: 3
key: "semester_5/concrete_technology_and_masonry_structure:hot-weather-precautions"
source: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/hot-weather-precautions
site: BCT Engineering
---

# Hot weather concreting precautions

Concrete Technology and Masonry Structure · Chapter 3: Mix design of concrete and property of green concrete

- Asked in: 2082 Bhadra, 2 marks; 2082 Baisakh, 2 marks (asked 2 times)
- Video: [Hot Weather Concreting Precautions & Effects | Concrete Works | Concrete in Hot Weather? ~CivilWork](https://www.youtube.com/watch?v=N5SFT9K0Oh8) — Civil Work
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/hot-weather-precautions
- Whole chapter: https://www.bctengineer.com/md/semester_5/concrete_technology_and_masonry_structure/chapter-3

## Question

What are the precautions to be exercised during hot weather concreting?

## Short answer

Cool materials (shade aggregates, use chilled water/ice), use retarders, keep mix time short, place at cooler times, wet forms and subgrade, start curing immediately with continuous moist curing for at least 10 days, and protect from wind to prevent plastic shrinkage cracks.

## Answer

Hot weather (ambient temperature above 40 °C, or high temperature with low humidity and wind; IS 7861 Part 1, referred to by IS 456 cl. 14.1, and ACI 305) speeds up setting, reduces slump, increases water demand and causes plastic shrinkage cracking. The concrete temperature at placing should preferably be kept below about 35 °C, and IS 7861 does not allow it above 40 °C.

#### Precautions
1. **Materials**: keep aggregates in the shade and sprinkle them with water; use chilled water or crushed ice as part of the mixing water; shade water tanks and pipes and paint them white; do not use cement that is still hot from the silo.
2. **Mix**: use a low-heat cement or PPC, a lower cement content, and a **retarder or water-reducing retarder** admixture; keep the w/c fixed and do not add water to regain slump.
3. **Transport and placing**: shorten the time between mixing and placing; cover mixers, ready-mix trucks and pump lines; place at night or early in the morning; avoid delays and cold joints.
4. **Forms and subgrade**: wet the formwork, reinforcement and subgrade before placing (with no standing water); shade the work with sunshades.
5. **Protection and curing**: start curing immediately; use fog sprays, evaporation retarders, wet hessian, plastic sheeting or a curing compound; cure continuously for at least 10 days (IS 456 cl. 13.5.1 for hot, dry weather); protect from wind to prevent plastic shrinkage cracks.
6. Provide additional **joints** and thermal control in thick sections.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which admixture is used in hot weather?
   A. Accelerator
   B. Retarder or water-reducing retarder
   C. Antifreeze
   D. Shrinkage agent
   Answer: B. It delays set and holds slump. (Key point: Mix admixture)

2. To cool materials you may...
   A. Use chilled water or ice and shade aggregates
   B. Heat water
   C. Use warm cement
   D. Dry aggregate in sun
   Answer: A. Lower the temperature of concrete at placing. (Key point: Materials)

3. To regain slump in hot weather you should...
   A. Add water on site
   B. Not add water; keep w/c fixed
   C. Add cement
   D. Leave it
   Answer: B. Adding water raises w/c and lowers strength. (Key point: Slump regain)

4. Curing should be...
   A. Started immediately and continuous for at least 7 days
   B. Delayed 3 days
   C. Skipped
   D. Only once
   Answer: A. Prevents plastic shrinkage cracks. (Key point: Curing)

## Related in Concrete Technology and Masonry Structure

- [Hot weather concreting: effects, precautions](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Ahot-weather-effects-precautions) — Concrete Technology and Masonry Structure, chapter 3
- [Cold weather concreting](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Acold-weather-concreting) — Concrete Technology and Masonry Structure, chapter 3
- [Hot climate concreting and curing](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Ahot-weather-methods-curing) — Concrete Technology and Masonry Structure, chapter 3