STABILIZATION OF HEAVY METALS IN PORTLAND CEMENT, SILICA FUME/PORTLAND CEMENT AND MASONRY CEMENT MATRICES

TL;DRAbstract

The effects of heavy metals on the physical and chemical properties of portland-cement based pastes were studied using different types of cement, four metal oxides, and four soluble metal salts. Type I (high calcium aluminate content) and Type V (low calcium aluminate content) portland cements were used to study the effects of their chemical differences on paste properties and metal stabilization. Fresh pastes were tested for workability, initial setting times, and heats of hydration. Hardened pastes were tested for strength and leachability by both TCLP (Toxic Characteristic Leaching Procedure) and column leaching with acetic acid. The cement matrix was an excellent stabilization matrix, better than could be projected from pH considerations alone. The investigation also involved examining Type I portland cement paste treated with three metals together - chromium, cadmium and lead, added at very high (1% by mass of cement) and intermediate (1000 ppm by mass of cement) levels. The leach

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