PubMed · 8328609
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B Gerwel, D Valiante, J Pescatore, M Stanbury. 1993. Lead exposure in bridge construction workers.. https://doi.org/10.2105/ajph.83.7.1054-a
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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.
In this paper the adoption of technological innovations to improve the work of bricklayers and bricklayers' assistants is evaluated. Two studies were performed among 323 subjects to determine the adoption of the working methods, the perceived workload, experiences with the working methods, and the reasons for adopting the working methods. Furthermore, a comparison of the results of the studies was made with those of two similar studies in the literature. The results show that more than half of the sector adopted the innovations. The perceived workload was reduced. The employees and employers are satisfied with the working methods and important reasons for adoption were cost/benefit advantages, improvement of work and health, and increase in productivity. Problems preventing the adoption were the use of the working methods at specific sites, for instance in renovation work. The adoption of the new working methods could perhaps have been higher or faster if more attention had been paid to the active participation of bricklayers and bricklayers' assistants during the development of the new working methods and to the use of modern media techniques, such as the Internet and CD/DVD.
A metal-plating waste filter cake treated by stabilisation/solidification (S/S) using ordinary Portland cement (OPC) and pulverised fuel ash (PFA) has been characterised after exposure to the environment in SE England for approximately 10 years. The surface region ( approximately 5cm) was severely degraded, extensively carbonated and had reduced acid neutralisation capacity (ANC) compared to bulk samples. Large 'plate-like' deposits of predominantly calcium hydroxide with a calcium carbonate upper layer were found close to, but below the surface of the exposed S/S waste. Calcium zinc hydroxide (Ca(Zn(OH)(3))(2).2H(2)O) was the major crystalline phase found in the S/S waste in the region below the calcium hydroxide plates (10-15cm). Samples taken from the bulk of the environmentally exposed S/S waste, at a depth of approximately 0.5m, were more amorphous, contained no readily identifiable crystalline phases and had negligible strength but retained high acid neutralisation capacity. Metal analysis of homogenised samples taken from different depths into the S/S waste indicated a reduction in the concentration of heavy metals, such as Zn, Fe and Cr, in the top 5cm of the S/S waste and an increase in concentration of these metals in bulk samples. The majority of crystalline mineral phases detected in the 28-day samples were not identified in the 10-year-old samples.