Engineering properties of controlled low strength desulfurization slags (CLSDS)

Recently, governments worldwide are paying attention to the reuse of industrial wastes and the recycling of resources for reducing energy consumption. This study is aimed at the application of the desulfurization of slags (DDS) in the production of controlled low strength materials (CLSM) to effectively address the problems of the increase of waste products and the shortage of construction materials as well as to improve the quality of backfill materials. In the experimental study, we select 6 different portions of desulfurization slags (0%, 10%, 20%, 30%, 40%, and 50%) in the replacement of natural fine aggregates in CLSDS to conduct laboratory tests, such as fresh physical properties (including slump, slump flow, tube flow, and unit weight), engineering properties (including hardness, compressive strength, ball drop, and ultrasonic pulse velocity) and some surface properties (including surface electric resistance, sulfate attack, elongation and thermal expansion). Laboratory tests depict the following results: (1) the slump, slump flow and tube flow of CLSDS increase with the portion of desulfurization slag replacement; (2) the unit weight of CLSM decreases with the addition of desulfurization slag replacement because of its light weight compared with natural fine aggregates; (3) the 28-day compressive strength decreases to 36.1-62.5% per addition of 10% desulfurization slag replacement but still satisfies the strength requirement of 84 kgf/cm(2) (9 MPa) used in Taiwan; (4) the maximal drop values increase 25% when 50% replacement is employed but remains within 7.6 cm, which is adequate for continuous construction and loading support; (5) the ultrasonic pulse velocity and surface electric resistance decrease with the portion of replacement; and (6) the erosion and swelling increase with the portion of replacement, although the specimen starts to fail for replacement levels above 50%. We conclude that using an appropriate portion of desulfurization slags in the replacement of natural fine aggregates can reduce the construction time, improve the efficiency and shorten the pending time for a testing run. (c) 2016 Elsevier Ltd. All rights reserved.