306R-88
Cold Weather Concreting (Reapproved 2002)
1988, 23 pp.
$49.50

The general requirements for producing satisfactory concrete during cold weather are discussed, and methods for satisfying these requirements are described. One of the objectives of cold weather concreting practice is to provide protection of the concrete at early ages to prevent damage from freezing. For many structural concretes, protection considerably in excess of that required to prevent damage by early freezing is needed to assure development of adequate strength. The following items are discussed in the report: recommended temperature of concrete, temperature records, temperature of materials, preparations prior to placement, duration of protection period, methods for determining in-place strength, form removal, protective insulating covers, heated enclosures, curing methods, and accelerating admixtures. References are included that provide supplementary data on the effects of curing temperature on concrete strength.

Contents:

Chapter 1--Introduction

1.1--Definition of cold weather
1.2--Standard specification
1.3--Objectives
1.4--Principles
1.5--Economy

Chapter 2--General requirements

2.1--Planning
2.2--Protection during fall and spring
2.3--Concrete temperature
2.4--Temperature records
2.5--Heated enclosures
2.6--Exposure to freezing and thawing
2.7--Concrete slump

Chapter 3--Temperature of concrete as mixed and placed and heating of materials

3.1--Placement temperature
3.2--Mixing temperature
3.3--Heating mixing water
3.4--Heating aggregates
3.5--Steam heating of aggregates
3.6--Overheating of aggregates
3.7--Calculation of mixture temperature
3.8--Temperature loss during delivery

Chapter 4--Preparation before concreting

4.1--Temperature of surfaces in contact with fresh concrete
4.2--Metallic embedments
4.3--Removal of snow and ice
4.4--Condition of subgrade

Chapter 5--Protection against freezing and protection for concrete not requiring construction supports

5.1--Protection to prevent early-age freezing
5.2--Need for additional protection
5.3--Length of protection period
5.4--Stripping of forms
5.5--Temperature drop after removal of protection
5.6--Allowable temperature differential

Chapter 6--Protection for structural concrete requiring construction supports

6.1--Introduction
6.2--Tests of field-cured specimens
6.3--In-place testing
6.4--Maturity method
6.5--Attainment of design strength
6.6--Increasing early strength
6.7--Cooling of concrete
6.8--Estimating strength development
6.9--Removal of forms and supports
6.10--Requirements

Chapter 7--Materials and methods of protection

7.1--Introduction
7.2--Insulating materials
7.3--Selection of insulation
7.4--Enclosures
7.5--Internal electric heating
7.6--Covering after placement
7.7--Temporary removal of protection
7.8--Insulated forms

Chapter 8--Curing requirements and methods

8.1--Introduction
8.2--Curing during the protection period
8.3--Curing following the protection period

Chapter 9--Acceleration of setting and strength development

9.1--Introduction
9.2--Calcium chloride as an accelerating admixture
9.3--Other accelerating admixtures

Chapter 10--References

10.1--Recommended references
10.2--Cited references
10.3--Selected references