[The demolition and recycling of concrete structures]

By

ACKNOWLEDGEMENT

I would take this opportunity to thank my research supervisor, family and friends for their support and guidance without which this research would not have been possible

DECLARATION

I, [type your full first names and surname here], declare that the contents of this dissertation represent my own unaided work, and that the dissertation has not previously been submitted for academic examination towards any qualification. Furthermore, it represents my own opinions and not necessarily those of the University

Signed __________________ Date _________________

Table of Content

INTRODUCTION6

Reuse of construction elements8

Coarse demolition9

Partial demolition10

AIMS AND OBJECTIVES OF PROJECT13

DEMOLITION14

Technical requirements17

Aggregates18

Environmental requirements18

Requirement of the wastes18

UK specification for aggregates in concrete20

RECYCLING21

The production of the wastes21

The recycling activity22

Applications of Recycled Concrete24

Concrete Recycling Equipment29

Recycling of Concrete in United States29

NANO-PARTICLES30

ENVIRONMENTAL IMPACTS33

Problems for optimal recycling36

Policy and legislation: the ideal situation37

Policy and legislation: the present situation38

HEALTH IMPLICATIONS40

Initial Approach41

Health Hazards42

Safety hazards44

REFERENCES48

Introduction

A rehabilitation of buildings has been made mostly when buildings, building components, or materials were physically deteriorated with age. However, there is a trend to rehabilitate rather new buildings. For example, the recent development of the earthquake engineering requires that the seismic safety of existing buildings must be re-evaluated and increased, if necessary. To increase the seismic safety, the structural rehabilitation; strengthening, is necessary. Another example is the rehabilitation due to the change of the use of the building. The reform of the educational system, which is a recent trend in Japan, is requiring the remodel of existing school buildings associated with structural renovation. These non-physical reasons could be called “deterioration of software”, while the physical reasons “deterioration of hardware”. (Olarewaju, 2008, 45)

A large number of reinforced concrete buildings have been designed and constructed in Japan since 1920's according to the seismic codes requiring rather high level of seismic capacity. However, the recent experience of earthquake damage and the current knowledge in earthquake engineering suggest that some of the existing buildings do not have sufficient seismic capacity.

Recycling of structural material in Germany is still far from getting a real closed-loop recycling-system. Though building rubble is increasingly recycled more than discarded as sanitary landfill, valuable demolition rubble is still reused for secondary purposes as sub base for roads and noise protection walls. If a closed-loop system is to be achieved, this material has to serve its original purpose. The commonly used procedure can be compared with a declining spiral. That is why the recycled material is decreasing in usefulness and value. (Chen, Yen, Chen, 2003, 130)

Probably a real closed-loop cannot be achieved. Just in a few exceptional cases the quality of the recycling products will be similar or even higher than the quality of the original material. Nevertheless reuse on the highest level should be aimed at to delay the descending motion of that spiral. (Hansen, Narud, 1983, 79)

As opposed to structural and stiffening elements, 'used material' has been recently allowed for use in pavement concrete. To support technical progress, the latest edition of ZTV Beton-StB (1991) remarks that recycled material can be used if tender conditions permit ...