# Preparation of a Low-Cement-Content Silty Soil Stabilizer Using Industrial Solid Wastes
## 1 Introduction  
Silty soil is widely distributed in the alluvial plain of the Yellow River in Shandong Province, China. It is difficult for silty soil to meet the requirements for roadbed filling due to the loose structure of silt [1, 2]. Generally, silty soil must be replaced [3, 4]. This treatment is costly, and the materials used for backfilling are not always available in some regions. Chemical soil stabilization has been considered an effective means of enhancing the engineering properties of soils [5]. It has obvious advantages, such as the ability to improve strength and stability, a wide source of raw materials, and more convenient on-site construction and maintenance [6]. Stabilizers can be classified into four different groups, namely, inorganic, organic, ionic, and bioenzymatic. Among them, inorganic stabilizers have an especially wide range of applications since they can stabilize various soils, such as clay, silt, and sand [7, 8]. The most commonly used inorganic stabilizers are cement and lime [9]. However, the production of these two materials leads to a large amount of CO\({}_{2}\) emissions; this is especially true of cement, which contributes 6-8% of total global anthropogenic CO\({}_{2}\)[10] and consumes approximately 12-15% of total industrial energy [11, 12]. Additionally, [PERSON] et al. [6] revealed that a pure cement stabilizer leads to large shrinkage, while a pure lime stabilizer causes poor early age mechanical properties. Thus, there is a demand for stabilizers that meet the performance requirements for soil stabilization while minimizingenvironmental pollution. Using industrial solid waste as a stabilizing material is thought to be a promising means for achieving this [13]. Industrial by-products such as fly ash (FA), flue gas desulfurized (FGD) gypsum, and granulated blast furnace slag (GBFS) are produced in a great amount every year. The global annual output of FA is approximately 900-1000 Mt [14; 15], and it is approximately 140-330 Mt for GBFS [14; 16]. China is the world's largest FGD gypsum producer [17], with an annual production of over 71.5 Mt [18]. The current treatment method for solid waste is mostly stacking and storage, which causes serious environmental pollution and a low utilization rate of solid waste. This study selected multiple types of solid waste to prepare stabilizers, which can help improve the utilization rate of solid waste and alleviate environmental pollution. According to the literature, the performance of stabilizers can be modified by using the aforementioned solid wastes as admixtures. [PERSON] et al. [19] used OPC, fly ash, and silica fume along with phosphogypsum to stabilize oily sludge. The results showed that when the content of the stabilizer reached 20% (OPC/fly ash/silica fume = 1:0.7:0.8), the soil samples' 28-day compressive strength increased compared to the samples with the same content of OPC due to the refined pore structure. [PERSON] et al. [20] suggest that tropical soils can be stabilized using blends of electric arc furnace slag and fly ash. [PERSON] et al. [21] found that 7.62% of reactive MgO, 11.31% of FGD gypsum, and 5.80% of steel slag can make the dredged sediment's microstructure more stable, thus improving its mechanical properties. [PERSON] et al. [22] applied cement kiln dust to stabilize expansive soil. The results showed that the swell-collapse potential of the stabilized soil sample was fully diminished, and the compressive strength increased considerably compared to the unstabilized soil sample. [PERSON] et al. [23] used ground GBFS, FGD gypsum, and calcium carbide slag (CCS) to treat marine soft soil. The experimental results showed that the best proportion of ground GBFS, FGD gypsum, and CCS was 61:8:31; the 28-day compressive strength of the stabilized soil exceeded 8.7 MPa, which was 1.23 times higher than that of OPC-stabilized soil.