PubMed · 15773680
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Linda F Johnson. 2005. Master jugglers.. https://pubmed.ncbi.nlm.nih.gov/15773680/
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This research was undertaken to address environmental concerns associated with industrial solid waste and to reduce cement consumption in geotechnical engineering. It specifically investigates the feasibility of using steel slag (SS) and silica fume (SF) as partial substitutes for ordinary Portland cement (OPC) in soil stabilization. The effects of SS, SF, OPC, and initial moisture content on the unconfined compressive strength (UCS) of stabilized soil were investigated through single-factor experiments and response surface methodology (RSM). The results show that SS and SF can synergistically enhance the strength of stabilized soil, although their interaction effect was not statistically significant within the investigated ranges. Compared with soil stabilized solely with OPC, the addition of 18 % SS and 10 % SF reduced OPC consumption by 3 % without compromising strength. Microstructural and compositional analyses further revealed that SS mainly supplied calcium- and silica-bearing components, while SF provided highly reactive silica and micro-filling effects, jointly promoting hydration reactions and improving the compactness of the stabilized soil matrix. As a result, more hydration products were formed in the OPC/SS/SF-stabilized soil than in the OPC-stabilized soil, which contributed to pore filling and strength enhancement. This study provides useful guidance for the sustainable utilization of industrial solid waste and the low-carbon development of soil stabilization materials.
This paper reports on the influence of calcining temperature (800 and 1000 degrees C) on the pozzolanic activation of sugar cane straw (SCS). The reaction kinetics of SCS ash-lime mixtures were inferred from physicochemical characteristics (X-ray diffraction patterns and thermogravimetry analysis. The fitting of a kinetic-diffusive model to the experimental data (fixed lime versus time) allowed the computing of the kinetic parameters (reaction rate constant) of the pozzolanic reaction. Results obtained confirm that the sugar cane straw ash (SCSA) calcined at 800 and 1000 degrees C have properties indicative of very high pozzolanic activity. No influence of calcining temperature on the pozzolanic activity was observed. Also, no crystalline compounds during the pozzolanic reaction were identified up to 90 days of reaction. Environmental durability and strength of the consequential mortars remain to be assessed.
The preferred management option for municipal solid waste incinerator (MSWI) bottom ash in Denmark is utilisation rather than landfilling, but the current environmental quality criteria for bottom ash to be utilised in bulk quantities are rather strict. To evaluate the impact and risk assessments, upon which those criteria are based, a large-scale test site has been established. Three different MSWI bottom ashes have been used as sub-base in six test units ranging from 100 to 200 m2 with top covers of asphalt, flagstones and pebbles, respectively. All units, except one, are equipped with bottom liners and leachate collection equipment. The test site provides information on the leachate quality and quantity as a function of time under different conditions and on the flow pattern in asphalt and flagstone covered roads and squares with MSWI bottom ash sub-base. In addition, the leaching behaviour of the bottom ashes has been studied in the laboratory. The test site was established in October 2002 and the project is still ongoing. Water balance results indicate that the water flow distribution is strongly influenced by lateral flow on or in the upper part of the bottom ash layer and possibly by preferential flow. Comparisons between eluates from laboratory leaching tests on the bottom ashes and observations of the leachate from the site as a function of L/S show fairly good agreement for salts but less agreement for some trace elements. Most likely, this is partly due to the fact that the pH observed in the leachate from the field sites is lower than that observed in the eluates from the laboratory leaching tests.