# Influence of Some Additives on the Properties of OPC Solidified Sandy Silt
## 1 Introduction  
With rapid urbanization, massive housing demolitions and foundation pit excavations have produced infinite construction waste soil. The inappropriate accumulation and landfill of this construction waste soil will cause serious land depletion casualties, such as the severe landslide accident in Shenzhen in 2016 [1, 2]. Therefore, how to use this construction waste soil reasonably is still an enormous challenge for geotechnical engineers. Hangzhou, a large city located in the southeast of China, generated more than 8.5 million tons of construction waste soil in 2015. Currently, a large number of methods has been used to handle the mechanical property disadvantages, such as the soil replacement cushion, the vibroflotation process, dynamic compaction, the bored pile method, etc. [3, 4, 5]. However, additives have been proved to improve the properties of waste soil effectively, including ductility as well as compressive and shear behaviors [6, 7]. Ordinary Portland cement (OPC) is the topmost volume cementitious material, and it has been considered as the primary binding agent for both stabilizers and concrete because of its acceptable available and mechanical properties as well as its high-temperature resistance [8, 9]. Recently, various types of additives have been employed to improve the performance of the OPC-based stabilizer in practice. To achieve an appropriate proportion of bentonite with OPC and lime, [PERSON] et al. [10] studied the mechanical properties of solidified soil, and relevant test results showed that 20% bentonite plus 1% lime or OPC can mainly enhance the strength of red soil: the early strength of the OPC-stabilized soils increased rapidly; for lime-cured soil, the later strength increased faster. According to the optimal moisture content and compaction degree, [PERSON] et al. [11] compared the compressive strength performance of cured soil specimens in different contents of curing montmorillonite soil with OPC only, OPC plus lime, and lime only. The results illustrated that 7%, 8%, and 9% were the best contents of these three stabilizers, respectively. [PERSON] et al. [12] studied the compaction characteristics, stress-axial strain, and unconfined compressive strengthof solidified soil with different contents and ages by using the ratio of hard boracite slag and OPC that had to solidified clay. [PERSON] et al. (2018) conducted tests on solidified soil, and the results showed that the increase of the soil-OPC ratio improved solidified soil. [PERSON] et al. (2018) established a nonlinear functional strength model of OPC-cured soil taking the unknown factors of strength development into consideration. [PERSON] et al. (2018) studied the influence of OPC content, water-cement ratio, and age on the compressive strength of solidified soil and analyzed the test results through bonding parameters. [PERSON] et al. (2018) obtained the relationship between the porosity, OPC content, and strength of solidified soil through an experimental study on OPC-stabilized soil with different moisture content, porosity, OPC content, and curing time and proposed that the cost of solidifying soil could be reduced by controlling the porosity and OPC content. In general, previous research has mainly focused on solidified clay, and the mechanism for how to solidify it. Furthermore, the cost analysis of OPC with different additives has not been systematically analyzed. It is easy for sandy silt to cause various geological disasters due to its loose structure, poor cohesive strength, and liquefaction that can be easily caused by vibrations. For pouring sandy silt into a foundation pit with groundwater can form quicksand during excavation (2017); aa sandy silt slope of a highway can be damaged by rainfall infiltration (2018); a sandy silt bank the slope on a river course can be damaged by erosion, which can cause bank collapse under the action of water flow (2019); sandy silt can be liquefied due to earthquakes, thus causing foundation invalidation, ground subsidence, and other destruction (2020).