Optimization of Steelmaking Energy Efficiency Scheduling Based on an Equipment Set Shutdown Strategy.

The steel industry accounts for a large proportion of power consumption in industries. To greatly reduce the power consumption of production, it is urgent to adjust and optimize the steelmaking production mode. The paper combines production scheduling with equipment energy efficiency indicators, establishing an optimization model for steelmaking energy efficiency scheduling and determining the shutdown strategy of steelmaking equipment sets. Taking two equipment sets of a company processing the same batch of steel as an example, this paper calculates that the unit energy consumption under the optimal scheduling scheme is 79.492 and 22.056 kWh, respectively. The energy consumption of the former to complete the production task is greater than that of the latter. Therefore, by choosing to shut down this equipment set, a total of 65 038.2 kWh of electricity can be saved. Industrial examples were executed to validate the effectiveness of the model, and the results showed that the proposed method can obtain optimal solutions in a short period of time and significantly reduce energy consumption in the workshop. This study first combines scheduling issues with equipment energy efficiency indicators to provide a basis for energy consumption decisions.

Preparation of Artificial Pavement Coarse Aggregate Using 3D Printing Technology.

Coarse aggregate is the main component of asphalt mixtures, and differences in its morphology directly impact road performance. The utilization of standard aggregates can benefit the standard design and performance improvement. In this study, 3D printing technology was adopted to prepare artificial aggregates with specific shapes for the purpose of making the properties of artificial aggregates to be similar to the properties of natural aggregates. Through a series of material experiments, the optimal cement-based material ratio for the preparation of high-strength artificial aggregates and corresponding manufacturing procedures have been determined. The performance of the artificial aggregates has been verified by comparing the physical and mechanical properties with those of natural aggregates. Results indicate that using 3D printing technology to generate the standard coarse aggregate is feasible, but its high cost in implementation cannot be ignored. The 3D shape of the artificial aggregate prepared by the grouting molding process has a good consistency with the natural aggregate, and the relative deviation of the overall macro-scale volume index of the artificial aggregate is within 4%. The average Los Angeles abrasion loss of artificial cement-based aggregate is 15.2%, which is higher than that of diabase aggregate, but significantly lower than that of granite aggregate and limestone aggregate. In a nutshell, 3D printed aggregates prepared using the optimized cement-based material ratio and corresponding manufacturing procedures have superior physical and mechanical performance, which provides technical support for the test standardization and engineering application of asphalt pavements.

Effect of Lignin Modifier on Engineering Performance of Bituminous Binder and Mixture.

Lignin accounts for approximately 30% of the weight of herbaceous biomass. Utilizing lignin in asphalt pavement industry could enhance the performance of pavement while balancing the construction cost. This study aims to evaluate the feasibility of utilizing lignin as a bitumen performance improver. For this purpose, lignin derived from aspen wood chips (labeled as KL) and corn stalk residues (labeled as CL) were selected to prepare the lignin modified bituminous binder. The properties of the lignin modified binder were investigated through rheological, mechanical and chemical tests. The multiple stress creep recovery (MSCR) test results indicated that adding lignin decreased the Jnr of based binder by a range of 8% to 23% depending on the stress and lignin type. Lignin showed a positive effect on the low temperature performance of asphalt binder, because at -18 °C, KL and CL were able to reduce the stiffness of base binder from 441 MPa to 369 MPa and 378 MPa, respectively. However, lignin was found to deteriorate the fatigue life and workability of base binder up to 30% and 126%. With bituminous mixture, application of lignin modifiers improved the Marshall Stability and moisture resistance of base mixture up to 21% and 13%, respectively. Although, adding lignin modifiers decreased the molecular weight of asphalt binder according to the gel permeation chromatography (GPC) test results. The Fourier-transform infrared spectroscopy (FTIR) test results did not report detectable changes in functional group of based binder.

Laboratory Investigation of Lignocellulosic Biomass as Performance Improver for Bituminous Materials.

Lignocellulosic biomass has gained increasing attention as a performance modifier for bituminous material due to the vast amount available, its low cost and its potential to improve the durability of pavement. However, a comprehensive study concerning both the binder and mixture performance of modified bituminous material with lignocellulose is still limited. This research aims to evaluate the feasibility of applying lignocellulose as bitumen modifier by rheological, chemical and mechanical tests. To this end, two lignocellulosic biomass modified bituminous binders and corresponding mixtures were prepared and tested. The chemical characterization revealed the interaction between lignocellulosic biomass and bitumen fractions. Rheological test results have shown that lignocellulosic modifiers improve the overall performance of bituminous binder at high, intermediate and low temperatures. The findings obtained by mixture mechanical tests were identical to the binder test results, proving the positive effect of lignocellulosic biomass on overall paving performance of bituminous materials. Although lignocellulosic modifier slightly deteriorates the bitumen workability, the modified bitumen still meets the viscosity requirements mentioned in Superpave specification. This paper suggests that lignocellulosic biomass is a promising modifier for bituminous materials with both engineering and economic merits. Future study will focus on field validation and life cycle assessment of bituminous pavement with lignocellulosic biomass.

Modification of Asphalt Rubber with Nanoclay towards Enhanced Storage Stability.

Asphalt rubber (AR), which is prepared by blending crumb rubber and bitumen, provides various advantages, including superior rutting resistance, lower road-tire noise and longer service life. However, contractors have expressed concerns regarding its poor storage stability, which in turn limits its wider application. This study aims to address the storage stability concern by incorporating nano-montmorillonite (nanoclay). Three types of nanoclay were dispersed into hot AR binder by high shear blending. The rheological properties of nanoclay-crumb rubber modifier (CRM)-modified bitumen were evaluated through Superpave performance grade (PG) tests and the storage stability was characterized by measuring the difference in softening points or complex moduli at the top and bottom portions of binders after lab-simulated storage. X-ray diffraction (XRD) evaluation was conducted to observe the variation of nanoclay layer gap distance for mechanism investigation. It was found that all selected nanoclays had insignificant effects on workability, rutting and fatigue properties. The layered nanoclay transformed to intercalated or exfoliated structures after interaction with bitumen fractions, providing superior storage stability. Among the three selected nanoclays, pure montmorillonite with Na⁺ inorganic group, which has an intermediate hydrophilic property and middle layer gap, showed the most obvious effect on enhancing the storage stability of AR.