scholarly journals Evaluation of the Volume Stability and Resource Benefit of Basic Oxygen Furnace Slag and Its Asphalt Mixture Based on Field Application

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yuechao Zhao ◽  
Jiangkai Song ◽  
Jun Xie ◽  
Fusong Wang ◽  
Meizhu Chen ◽  
...  

Applying basic oxygen furnace (BOF) slag as aggregate in asphalt mixture is continuously investigated due to the increasing shortage of natural aggregate in recent years. However, the negative effect of BOF’s expansion in water greatly limits its further application in pavement construction. To address this problem, this paper studied the volume stability of BOF, and its asphalt mixture relied on actual engineering. The asphalt mixtures contained BOF aggregate was designed by the Marshall method with three different gradation types (AC-16, AC-20, and ATB-25). Besides, both laboratory samples and the core samples from field drilling were investigated in volume expansion rate after curing in a water bath. The economic and resource benefits of BOF replacement of natural aggregates were also analyzed. The results showed that the free calcium oxide content of BOF slag is positively related to the particle sizes. Nevertheless, the expansion rates of both the BOF aggregate and its asphalt mixture were less than 1%, which meant the BOF aggregate applied to the asphalt mixture meets the practical engineering requirements. The maximum allowable free calcium oxide content for large-grain size of steel slag is the smallest; it is also recommended that the expansibility of large-grain steel slag should be the first concern in the application. The resource assessment indicated that the use of steel slag for the construction of a trial section of one kilometer of single lane can save 967 tons of natural aggregates. The economic evaluation showed that the use of steel slag instead of natural aggregates for surface course construction could reduce the investment by 16.87%. The experimental methods and conclusions mentioned in this article provide stable references to enhance the development of sustainable pavement by recycling metallurgical slag in highway construction.

Author(s):  
Santanu Pathak ◽  
Rajan Choudhary ◽  
Abhinay Kumar

Open graded asphalt friction courses (OGAFCs) are specialty asphalt mixtures used to improve skid resistance and surface drainage. OGAFCs have additional benefits of reduced splash and spray, and lower tire–pavement interaction noise. Prolonged exposure to rainwater and load transfer through stone-on-stone contact in OGAFCs demands aggregates that are strong and hydrophobic. Rainwater acidity is expected to affect the aggregate–asphalt bond and thus moisture damage performance of OGAFC. This paper investigates the effect of rainwater acidity on moisture sensitivity of OGAFC mixtures with different aggregate types (natural aggregate, basic oxygen furnace (BOF) steel slag, and combinations of both) and modified binder types. For the first time, the present research reports the moisture damage potential of BOF OGAFC mixtures under different moisture conditioning environments created by varying the pH of contact water. With different combinations of BOF slag and natural aggregates (100:0, 25:75, 50:50, 75:25, and 0:100), and binders (polymer and crumb rubber modified), OGAFC mixtures were characterized for moisture damage through tensile strength ratio, wet Cantabro abrasion loss, and modified boiling water tests. Functional aspects of OGAFC mixtures subjected to moisture conditioning under different pH environments were also evaluated through permeability testing. Results showed that an acidic environment exacerbated the moisture damage, however, OGAFC mixtures containing BOF slag showed better performance than the control mixture (with natural aggregates only). Inclusion of BOF slag in OGAFC mixtures enhanced resistance to moisture damage under both pH environments. OGAFC mixes with 100% BOF slag content performed the best considering all moisture damage tests under both conditioning environments.


Author(s):  
Long-Sheng Huang

The basic oxygen furnace slag (BOF) was wide used in road construction, but there was a lack of characteristics in different asphalt mixtures. This study investigates the properties of hot-mixed asphalt (HMA) containing stone mastic asphalt (SMA), porous asphalt (PA) and dense-graded BOF as a partial substitution for natural aggregates. The purpose of this study is to evaluate various BOF slag contents in the asphalt mixtures would affect the cooling behavior after compaction. Asphalt mixture specimens contained 0%, 20%, 40% and 60% BOF slag, respectively, as coarse aggregate. Test results showed that BOF slag has a lipophilic property, so it can be adsorbed by asphalt cement, thereby reducing the cost of asphalt. The stability value of all asphalt mixtures increases with the proportion of BOF slag replacement. In addition, the voids in the mineral aggregate (VMA) value variable exhibited significant differences among asphalt mixtures, and could determine the deviation of the cooling trend of asphalt mixtures. Furthermore; it was found that the cooling procedure of the BOF slag used in dense-graded asphalt mixture takes about 100 min, and that the temperature tends to be moderate; however, it took about 120 min of cooling the SMA and PA mixture with BOF slag. In addition, the voids distribution of dense asphalt mixture was not uniform. It would result in various locations of thermal energy temperature on asphalt mixtures that were inconsistent.


Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 203 ◽  
Author(s):  
Lei Rao ◽  
Yuanchi Dong ◽  
Mancheng Gui ◽  
Yaohui Zhang ◽  
Xingmei Shen ◽  
...  

Basic oxygen furnace (BOF) slag was modified by adding 3.5% SiO2 and holding at 1673 K for 0, 5, 40, 90, 240, or 360 min. Kilo-scale modification was also carried out. The growth, stratification, and liberation of P-rich C2S in the modified slag were investigated. The optimum holding time was 240 min, and 90% of C2S grains were above 30 μm in size. The phosphorus content increased with holding time, and after modification, the phosphorus content in C2S was nearly three times higher than that in the original slag (2.23%). Obvious stratification of C2S was observed in the kilo-scale modification. Upper C2S particles with a relatively larger size of 20–110 μm was independent of RO (FeO-MgO-MnO solid solution) and spinel, which is favorable for liberation. Lower C2S was less than 3 μm and was embedded in spinel, which is not conducive to liberation. The content of phosphorus in upper C2S (6.60%) was about twice that of the lower (3.80%). After grinding, most of the upper C2S existed as free particles and as locked particles in the lower. The liberation degree of C2S in the upper increased with grinding time, from 86.02% to 95.92% in the range of 30–300 s, and the optimum grinding time was 180 s. For the lower slag grinding for 300 s, the liberation degree of C2S was 40.07%.


Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2169
Author(s):  
Song Li ◽  
Rui Xiong ◽  
Jiahui Zhai ◽  
Kaiyin Zhang ◽  
Wenyu Jiang ◽  
...  

In order to ensure the safety of traffic, asphalt pavement is commonly required to utilize aggregates with excellent anti-abrasion property. This results in the lack of high-quality aggregates. The incorporation of solid waste in the aggregates is regarded as a high potential alternative for solving this problem. Since its material properties, such as rough surface, high Polished Stone Value (PSV) and the excellent adhesion property of asphalt, Basic Oxygen Furnace (BOF) slag can effectively improve the skid resistance of asphalt mixtures. First, the material properties of BOF slag are reviewed in this study. Then, the skid resistance of asphalt mixtures and aggregates are commendably evaluated by the Polished Stone Value test, Wehner/Schulze Tester, Aachen Polishing Machine, British Pendulum Test and Sand Patch test. The physical and mechanical properties of BOF slag play a key role in asphalt mixtures. This review found that the skid resistance mechanism of the BOF slag asphalt mixture is governed by factors such as BOF slag properties, incorporation methods and gradation types. Finally, the economic and environmental benefits of BOF slag asphalt mixtures were discussed. In addition, the function of gas catalysis and the melting of ice and snow can be added to the BOF slag asphalt mixture for a cleaner development in engineering. Furthermore, the existing problems, research directions and corresponding measures in this field are directed towards more durable and functional asphalt pavement construction.


2014 ◽  
Vol 936 ◽  
pp. 1399-1403 ◽  
Author(s):  
Peng Guan Li ◽  
Feng Qing Zhao ◽  
Zhao Ma

Steel slag is a solid waste produced in the process of steelmaking, and applying it to the field of building materials is the main utilization approach at present. However, steel slag contains free calcium oxide and magnesium oxide, existing serious stability problem. The purpose of this work is to discuss the approaches to solve volume stability problem of steel slag through mechanical modification, chemical modification and other methods. Two successful cases we completed recently were presented to illustrate the combined use of several modifying methods for volume stability treatment of steel slag.


Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2322 ◽  
Author(s):  
Yong Ye ◽  
Shaopeng Wu ◽  
Chao Li ◽  
Dezhi Kong ◽  
Benan Shu

Due to the difference of cooling and treatment processes (rolling method, hot braised method, layer pouring method), basic oxygen furnace (BOF) steel slag can be mainly classified as roller steel slag (RSS), hot braised steel slag (HBSS) and layer pouring steel slag (LPSS). Treatment difference directly results in the performance variations of different BOF steel slag and corresponding asphalt mixtures. The primary purpose of this research was to examine the effects of different cooling and treatment processes on the morphological discrepancy of different BOF steel slag. Also, the road performances of corresponding asphalt mixtures, and mechanism between steel slag performance and road performance were studied. The results show that LPSS owns the largest variability of angular index and texture index, and RSS has the most balanced morphological parameters. The structure of RSS asphalt mixture is advantageous for improving the ability of the asphalt mixture to resist the deformation and enhancing the stability of structure. Higher content of CaO and lower content of SiO2 make the acid-base reaction of RSS asphalt mixture most intense, which contribute to the best road performance of it.


2013 ◽  
Vol 689 ◽  
pp. 304-308
Author(s):  
Zong Wu Chen ◽  
Shao Peng Wu ◽  
Jun Xie ◽  
Ju Yong Chen

Steel slag, a kind of industrial waste, has been considered applying in road construction as aggregate based on abundant indoor tests. The permanent deformation performance of asphalt mixture with Basic Oxygen Furnace (BOF) slag is evaluated by test with UTM-25 and simulation with equations at different temperatures and various stress levels in this study. Results show that the permanent deformation behavior of BOF base asphalt mixture is relatively sensitive to temperature and it can be perfectly modeled with proper equations, otherwise, strain per load cycle of specimen is responsible for mixture failure instead of accumulated permanent strain.


2011 ◽  
Vol 356-360 ◽  
pp. 1919-1927 ◽  
Author(s):  
Qing Lin Zhao ◽  
Jochen Stark ◽  
Ernst Freyburg ◽  
Ming Kai Zhou

Together with the chemical analysis as well as XRD and DTA, effects of steam and autoclave treatments on structure characteristics of basic oxygen furnace slag (BOFS) and electric arc furnace slag (EAFS) are investigated. The results show that steam and autoclave treatments on slag contribute to the conversion of f-CaO and f-MgO to Ca(OH)2 and Mg(OH)2 ,which improve the volume stability of slag by reducing the contents of free lime and periclase, and the autoclave treatment is more effective. Meanwhile, for the utilization of steel slag, the effects on the volume stability by CaO and MgO that were wrapped in eutectic in the crystallite form should be a key factor, besides the contents of f-CaO and coarse periclase crystalline. The thermal reactivity of slag treated by steam and autoclave increased, especially the reactivity of elemental iron and wuestite. The reactivity of EAFS increased more significantly at high temperature due to its higher content of iron.


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