ABSTRACT:In a series of studies, the authors have developed a powdery silica-based solidification material composed of heat-treated inorganic solid wastes with a high content of silica products (such as waste glass and waste fly ash) mixed with alkali aids. This material is most suitable for use with iron or steel slag, such as that which comes from a blast furnace or a steel-making process. The powdery silica-based solidification material mixed with iron and steel slag can be expected to exhibit higher mechanical strength and more predominant characteristics than a powdery cement-based solidification material. In this study, the solidification mechanism for the mixture of the silica-based solidification material, blast furnace slag and water is clarified from the viewpoints of chemistry and mineralogy by conducting X-ray diffraction analysis, X-ray fluorescence spectrometry and inductively coupled plasma spectroscopy.
Chemical grouting techniques are used as ground improvement methods to obtain stable ground. In this method, soft sandy soils are solidified by injecting liquid solidification agents into the soils to prevent liquefaction as well as to increase strength. In this study, liquid glass grouting agents containing liquid glass with a higher polymerization degree (No. 5 liquid glass grouting agents) are being developed and discussed while focusing on the liquid agents to be used for chemical grouting techniques. Specifically, the solidification properties of No. 5 liquid glass grouting agents and the influence of the molar ratio of liquid glass to the strength and shrinkage characteristics of sand-gel and homo-gel are experimentally studied. As a result, the sand-gel made of No. 5 liquid glass grouting agents is superior in strength and has smaller shrinkage ratios after gelation, and therefore, is superior in soil improvement.
Water-swelling friction reducing materials (WSFRMs) are commonly used as a "pulling-out assisting material" for temporary works such as steel sheet-piles and H-steels that are required to be removed and collected after use. Generally, WSFRMs are coated to steel sheet-piles and H-steels before these are driven into the ground or placed in mortar fluid. The WSFRMs absorb moisture in the ground or mortar to swell and form a swelling membrane over the piles. Then, the membrane works also as a lubricating membrane and as a result it can reduce friction. The authors pay attention to these characteristics of WSFRMs and try to develop a special material that can swell only when soaked in an alkaline moisture environment without swelling in acid or a neutral water environment, in addition to the conventional material that swells in any type of moisture environment. In this paper, considering that both types (alkaline and conventional) of WSFRMs are used as "pulling-out assisting material" for temporary steel sheet-piles and Hsteels, we perform through experiments on the swelling ratios of the materials as well as on the pulling-out characteristics of the steel flat-bar to which the WSFRMs are coated in advance.
Although waste recycling has been promoted in response to increasing environmental awareness in Japan, its marketability is being questioned due to the recycling cost. The ultimate goal of waste recycling is to reduce the environmental load. In this paper, we examined the evaluation method for social environmental efficiency to socially evaluate waste recycling, by incorporating environmental load as an environmental cost in addition to the direct cost. The social environmental efficiency evaluation including consideration of uncertainties is conducted, because waste recycling involves various uncertain elements. As the results, the social environmental significance of construction sludge recycling can be evaluated quantitatively while focusing on the particular construction sludge with a lower recycling rate.
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