Environmental Engineering Reference
In-Depth Information
7
Interactions between
Wastes and Binders
Julia A. Stegemann
CONTENTS
7.1 Introduction .................................................................................................. 151
7.2 Interferences with Binder Hydration ........................................................... 152
7.2.1 Introduction ...................................................................................... 152
7.2.2 Effects of Inorganic Compounds on Cement Hydration................. 154
7.2.3 Effects of Organic Compounds on Cement Hydration ................... 161
7.2.4 Other Effects .................................................................................... 162
7.2.5 Effects of Wastes.............................................................................. 163
7.3 Contaminant Immobilization ....................................................................... 163
7.3.1 Introduction ...................................................................................... 163
7.3.2 Physical Encapsulation .................................................................... 164
7.3.3 Precipitation ..................................................................................... 165
7.3.4 Uptake by Cement Hydration Products........................................... 167
7.4 Summary ...................................................................................................... 169
Acknowledgments.................................................................................................. 170
References.............................................................................................................. 170
7.1
INTRODUCTION
Wastes treated by stabilization/solidification (S/S) may originate from a great variety
of industrial processes (Chapter 3). Inorganic wastes tend to be more compatible
with cementitious binders; most wastes treated by S/S with cement contain metal
contaminants in an inorganic matrix composed mainly of calcium, aluminum, and
silicon, such as dusts from air pollution control systems, sludges, and soil. USEPA
has acknowledged that organic compounds interfere with cement-based S/S, partic-
ularly when the organic concentration exceeds 1% total organic carbon by mass.
1
However, there are numerous instances in which organic wastes have been solidified
with cement,
2
and many primarily inorganic wastes contain some organic contami-
nation. In fact, although some wastes can be successfully blended or treated with
cement in higher proportions than others, there are virtually no limits on their
physical and chemical characteristics, other than that they must be liquids or finely
divided solids at ambient temperature. Wastes may contain some of the chemicals,
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