Organic Polymers for Stabilization/Solidification - Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes - page 79

5 Organic Polymers

for Stabilization/
Solidification

Paul D. Kalb

CONTENTS

5.1 Introduction .................................................................................................... 79
5.2 Thermosets ..................................................................................................... 81
5.2.1 Urea-Formaldehyde............................................................................ 81
5.2.2 Polybutadiene ..................................................................................... 82
5.2.3 Polyester Resins ................................................................................. 83
5.2.4 Summary for Thermosets................................................................... 84
5.3 Thermoplastics ............................................................................................... 86
5.3.1 Bitumen .............................................................................................. 86
5.3.2 Polyethylene ....................................................................................... 90
References................................................................................................................ 95

5.1 INTRODUCTION

Chapter 4 discussed conventional hydraulic cements used for S/S purposes. Con-
ventional hydraulic cement-based (i.e., grout) S/S processes rely on the chemistry
of cement hydration to convert the waste, usually in liquid form, to a solid monolithic
product. For some types of waste, e.g., toxic metals, the hydration reaction and
associated alkaline pH convert ionic metal contaminants to less-soluble hydroxide
forms and thus chemically stabilize the waste. In addition, conversion of the waste
into a solid monolithic form, with reduced permeability and surface area in contact
with potential groundwater leachant, helps to immobilize both radioactive and haz-
ardous constituents from the environment.
In some cases, the effectiveness of hydraulic cement-based waste forms is limited
due to interactions between waste constituents and the binder materials that impede
the chemistry of hydration. 1 These interactions, discussed in more detail in Chapter
7, can lead to:

• Accelerated or retarded set times or failure to set