Foreword

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This document was prepared by Technical Committee ISO/TC 71, Concrete, reinforced concrete and pre-stressed concrete, Subcommittee SC 3, Concrete production and execution of concrete structures.

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Introduction

With the development of the construction industry, the wastes from the construction phase and the demolition phase (often called the construction and demolition wastes) are increasing. The landfill of the construction and demolition wastes will cause the shortage of available land area and environmental pollution. After being crushed and sorted, the construction and demolition wastes can be upcycled in the form of recycled aggregates. Recycled aggregate concrete can be produced by substituting all or part of natural aggregates with recycled aggregates. Recycled aggregate concrete can reduce the amount of the construction and demolition wastes as well as alleviate the consumption of natural aggregates through the use of recycled aggregates. In addition, it can reduce landfill area and environmental impact. As a result, recycled aggregate concrete has become the subject of growing interest. Its primary objective is to promote the use of recycled aggregates, which are produced from construction and demolition wastes, in structural and non-structural concrete.

The properties of recycled aggregates are different from those of natural aggregates, resulting in the variation of mix proportion, consistence, strength, deformation, durability between recycled aggregate concrete and natural aggregate concrete. This technical specification is primarily concerned with promoting the application of recycled aggregate concrete and provides additional provisions for ISO 22965 to address the differences between recycled aggregate concrete and natural aggregate concrete.

The relationship of this document (TS 21056) with other International Standards is shown in Fig 1.

1 Scope

This document provides principles and a framework for the specification, performance, production and execution of recycled aggregate concrete (RAC).

This document applies to concrete for structures cast in situ, pre-cast structures and non-structural concrete. The concrete can be mixed on site, ready-mixed concrete or produced in a plant for pre-cast concrete products.

2 Normative references

3 Terms and definitions

4 Symbols and abbreviated terms

5 Constituent materials

5.1 Requirements

5.2 Quality inspection of recycled aggregate

5.3 Storage and transportation of recycled aggregate

6 Performance of recycled aggregate concrete

6.1 Consistence

6.2 Mechanical property

6.3 Drying shrinkage and creep

6.4 Carbonation resistance

6.5 Permeability

6.6 Chloride resistance

6.7 Thermal parameters

6.8 Alkali-silica reactivity

7 Mix proportion of recycled aggregate concrete

7.1 General

7.2 Determination of target compressive strength

7.3 Determination of water content for recycled aggregate concrete

7.4 Determination of cementitious material content

7.5 Determination of coarse and fine aggregate content

8 Production of recycled aggregate concrete

8.1 Preparation

8.2 Mixing recycled aggregate concrete

9 Delivery and transportation of recycled aggregate concrete

9.1 Delivery of ready-mixed fresh concrete

9.2 Transportation of ready-mixed fresh concrete

10 Execution of recycled aggregate concrete

10.1 Pumping

10.2 Casting and curing

Bibliography