Investigating the interaction mechanism and effect of different calcium sulfate whiskers on performance of asphalt binder

Dong

et al. 2022

Sci Rep

Phosphogypsum (PG) is a massive industrial solid waste. In this paper, PG was purified by flotation method, and α-hemihydrate gypsum (α-HH) was prepared by the autoclaving method. The morphology of α-HH was adjusted by adding different doses of Maleic acid and Aluminium sulfate. The results showed that after flotation purification, the impurity content in PG was significantly reduced, the soluble phosphorus content decreased from 0.48 to 0.07%, the PG purity increased from 73.12 to 94.37%, and the PG whiteness risen from 19.4 to 40.5. Then the performance of α-HH prepared from PG before and after purification was compared. Fixing the amount of aluminium sulfate at 0.2 wt%, the reaction temperature at 140 °C, and the reaction time at 120 min, the average length/diameter ratio of α-HH crystals decreased from 7.2 to 0.6 as the amount of Maleic acid increased from 0 to 0.17 wt%. When the amount of Maleic acid was 0.13 wt%, the α-hemihydrate gypsum reached the best mechanical properties. The mechanical strength of high strength gypsum prepared from PG concentrate was significantly better than that of raw PG, indicating that flotation purification can effectively improve the performance of PG. In this study, a new method of PG purification and resource utilization was proposed.

Section: Resultsmentioning

confidence: 99%

The study on the effect of flotation purification on the performance of α-hemihydrate gypsum prepared from phosphogypsum

Dong

et al. 2022

Sci Rep

“…Calcium sulfate whisker (CSW) is an inorganic fibrous single-crystal material and produced from gypsum, calcium saltphosphogypsum, and flue gas desulfurization gypsum as raw materials [18]. CSW has the advantages of good compatibility, high strength, and high temperature resistance.…”

Section: Calcium Sulfate Whisker and Polyester Fibermentioning

confidence: 99%

Road Performance of Calcium Sulfate Whisker and Polyester Fiber Composite‐Modified Asphalt Mixture

Dong

Advances in Materials Science and Engineering

2020

Self Cite

In order to better improve the practical engineering problems such as rutting, cracking, pit, and groove in highway engineering, the stability and strength characteristics of calcium sulfate whisker and polyester fiber in asphalt mixture are evaluated based on the road performance test. In this experiment, three different methods of the calcium sulfate whisker content and three different polyester fiber content were used to determine the best asphalt aggregate ratio to prepare different modified asphalt mixture samples. Its high temperature stability, water stability, and low-temperature performance were tested. The results show that the composite modifier of calcium sulfate whisker and polyester fiber can significantly improve the strength stability of asphalt mixture and make its high temperature stability reach 2900.3∼4230.7 Times/mm without reducing its low-temperature bending strength. The optimum content of calcium sulfate whisker is in the range of 2‰∼2.5‰ and polyester fiber is in the range of 2‰∼3‰. The rutting strength and Marshall stability reach the maximum.

“…Additionally, CSHW has a strong market competitiveness as its price is only 1/200–1/300 of SiC, and it is easy for surface treatment. Therefore, CSHW have been widely used in papermaking, plastic, resin, rubber, friction materials, lightweight building materials and other fields [ 5 , 6 ]. The most important parameters of CSHW are the diameter and the aspect ratio, which have significant influence on the comprehensive performance of CSHW.…”

Section: Introductionmentioning

confidence: 99%

Preparation of CSHW with Flue Gas Desulfurization Gypsum

Gao

et al. 2022

Materials

Calcium sulfate hemihydrate whiskers (CSHW), a multi-functional and high value-added building material, were prepared with flue gas desulfurization (FGD) gypsum by hydrothermal method, which could be a reasonable disposal of FGD gypsum. In order to obtain CSHW of a high aspect ratio, a series of manufacturing parameters such as reaction temperature, stirring speed, material–water ratio, and reaction time were investigated. The effect of stabilizing treatment and glycerol concentration on CSHW morphology were also studied by environmental scanning electron microscopy (ESEM) and statistical analysis. The results showed that the optimum preparing conditions of reaction temperature, stirring speed, water–material ratio, and reaction time were 160 °C, 200~300 rpm, 11:1 and 1 h, respectively. Furthermore, stabilizing treatment with octodecyl betaine was necessary for the preparation of CSHW. The final prepared whiskers had smooth surface, uniform morphology, a diameter of 260 nm, and a corresponding aspect ratio of 208.2. Moreover, the addition of glycerol reduced the activity of water, contributing to a lower reaction temperature and much smaller diameter.