## 1 Introduction
Compared with soils treated using lime, cement-stabilized soils present a relatively higher strength [22]. This is mainly associated with the formation of additional calcium aluminate hydrates (CAH) that could create a strongly bonded fabric within the soil [23]. The cement paste formed by cement hydration usually sets and hardens into a hard solid within a few hours [23]. However, the use of only cement as the stabilizer may not be suitable for the treatment of large-scale waste soils, as the cement-stabilized soils, after hardening, cannot achieve high compactness during the subgrade filling. Combined stabilizers (i.e., lime and cement) are also very popular for improving waste soils [10; 11; 18; 24] because the lime- and cement-stabilized soils obtain the improvement advantages of both cement and lime. There are few studies on the effect of soils with combined and single stabilizers at different contents on-road performance. Moreover, a tailored improvement plan was required through experimentation rather than by replicating experiences from other areas. So far, the long-term stability performance of modified soil subgrades is also a key issue. Due to rainfall or elevated water tables, the disintegration breakage of improved residual soils often leads to severe settlement and a decrease in the stability of the subgrade [25; 26]. The water resistance of the treated subgrade filler is essential to the long-term service performance of the subgrade. A disintegration test is used to test the water resistance of the soil and to evaluate the disintegration characteristics [27; 28; 29]. Many researchers have conducted water stability experiments on untreated soil and its impact factors, including initial water content [30], temperature [31], sample shape [32], particle size [33], salinity [34], mineral composition [35; 33] and micro-structure [36; 37], etc., but compactness is rarely considered an important quality control index for subgrade. With respect to the stabilized soils, investigations into water stability have primarily emphasized two aspects: analyzing the concentration changes of cations (e.g., calcium ions, sodium ions, etc.) in the solution of stabilized soils after leaching [8; 24; 38] and assessing the weakening of strength propertiesresulting from water immersion [9; 26; 39]. Little literature has been found on disintegration characteristics for stabilized soils; moreover, there is a lack of relevant disintegration models to describe the evolution of disintegration characteristics of stabilized soils, which can be useful for the design of subgrade engineering. To address the mentioned concerns, this work delves into laboratory test results and examines the evolution of disintegration breakage in stabilized waste soils. The physical and mechanical parameters of untreated soils, which were the typical waste soils from urban construction in Shaoxing, China, were first determined. Two types of stabilizers, namely lime or lime + cement, were selected considering their suitability for large-scale applications in subgrade construction. Subsequently, the engineering properties of the two stabilized soils with different stabilizer contents were evaluated to identify an appropriate range of stabilizers. The effect of different compactness and stabilizer contents on the disintegration characteristics for untreated and treated waste soils was also revealed. Finally, the evolution model of the disintegration ratio for stabilized soils was derived using the Weibull distribution, and the new formulas to calculate the disintegration rate were derived.