The recycling and reuse of SWM are meaningful to alleviate resource shortages and promote the sustainable economic development. Including municipal solid waste (MSW) and industrial solid waste (ISW), MSW is commonly produced during human activities (Aneeta, 2020; Mohammad et al., 2020; Razzaq et al., 2021; Soroudi et al.,2018). ISW, containing residue, dust, sludge and etc., is always generated during the industrial production (Soliman and Moustafa, 2020; Tsai et al., 2021; Vsevolod et al.,2017). Generally, traditional incineration and landfilling are considered as the unsustainable way to reuse the non-degradable MSW, such as domestic refuse and plastics. For instance, Huang et al. (2018) compared recycling, incineration, and landfill treatment methods. And recycling was found to be the most environmentally friendly way to reduce greenhouse effect.
Additionally, there is not enough land for waste disposal in landfills owing to the rising land-use with housing, business and planting purpose. Wesley et al. (2015) and Chad et al., (2020) claimed that 80–90% are municipal solid waste incineration bottom ash (MSWI-BA) through the waste incineration process, which is an appropriate method to deal with the harmful elements within the SWM and MSW. Aneeta (2020) presented the SWM was found to be the granular and dense material with similar performance to natural aggregate. Therefore, it is used as a subgrade filling material and a modified material for subgrade filling. However, few studies have been conducted to mix MSWI-BA and silt to fill roads and subgrades, except to deal with the high-water content riverway silt deposits (Abdulnaser et al., 2020; Razzaq et al., 2021; Tseng et al., 2021). Waste incineration is involved to be unsustainable and harmful for environment. Prior studies stated that the improper recycling of waste was caused by the lacking of waste classification management, commercial reuse method and low recycling benefits. Thus, the economical and environment-friendly reuse methods for MSW, such as the production of bio-butanol, the production of clean hydrogen, power generation and the production of microbial fuel cells were explored (Khodier et al., 2021; Sara et al., 2020; Tsai et al., 2021). In addition, Japan, USA, Germany and China have successively issued national laws on the classification of household waste to promote the reuse of MSW.
Instead, the ISW contains construction solid waste (CSW), industrial slag waste, stones and tailings from the mining industry, cement dust, and ceramic waste (Tang et al., 2020; Wu et al., 2021). Therefore, civil construction is the major industry to reuse the ISW. For instance, Cristina et al. (2017) employed bottom ash, crushed slag and silica fume as the auxiliary materials for the production of cement, which is a traditional method to reuse ISW with finer particle size. Yao et al. (2019) stated that the directly waste conversion at the waste disposal site, reducing the transportation and storage costs, is an environment friendly and economical reuse method. The coarse aggregates in ISW, including tailings, waste rock, damaged asphalt pavements and construction waste aggregates, are mainly used to build civil structures or roads after mixed with concrete (Abdulnaser et al., 2020; Zhang et al., 2019).
Recently, reuse of riverway silt and sediment as the building material has attracted increasing attention in various countries. Riverway silt was previously used to replace clay as building materials. For example, instead of clay, incinerated sewage sludge ash (ISSA) was mixed with silt to produce ceramic floor tiles, and the silt was mixed with zeolite and clay to produce ceramsite (Xu et al.,2017; Wang et al.,2020). In addition, riverway silt and sediment were utilized to produce new blended cement and mix cement concrete (Abdulgazi, 2020; Chu and Yao., 2020; Du and pang, 2018). Although a few studies have investigated the reuse of riverway silt, the environmental hazards of heavy metal sludge have been neglected due to the lack of the chemical composition analysis of riverway silt.
Moreover, aforementioned approach is insufficient for the rapid and large-amount recycle of silt, while the engineering filler shows great potential in reuse of riverway silt. The rapid development of infrastructure construction and restrictions on excavation of mountains or cultivated land has caused the imbalance of supply-demand of engineering filler. Thus, the riverway silt waste has become a possible substitute for clay filler. Several existing literatures presented the use of riverway silt and sediment to the foundation layer of roads, land reclamation, embankment filling material, green grass planting soil on river and lake embankments (Ahmed et al., 2020). This reuse method can effectively deal with final disposal of riverway silt and sediment, specifically for the land damage.
Although riverway silt and sediments have high plasticity, the cohesiveness, compressibility and bearing capacity are low, which presents the poor properties as fillers. In most engineering scenarios, they need to be modified by adding lime, cement, and a curing agent to obtain good mechanical properties and ensure the successful utilization. However, the silt sediments are not allowed to be directly used as subgrade fillers and the technical application still need to be further explored. It is meaningful to evaluate the type and composition of improved materials, especially for the ability of construction waste and garbage slag to improve the mechanical properties of sludge sediment. Moreover, from the perspective of harmless reuse, there is few chemical composition and content analysis of riverway silt and sediment, as well as the analysis of the environmental impact of road subgrade filling.