Search

Various problems are often encountered during the backfilling process of deep foundation pits. The development of low-cost and efficient solidified materials for the preparation of fluidized solidified soil is currently an ideal solution. This article used industrial solid waste (granulated blast furnace slag, fly ash, carbide slag, etc.) as the main raw material to study the hydration hardening properties of solidified materials and the construction feasibility of fluidized solidified soil prepared from solid waste materials. The results are as follows: Compared with cement-based materials, solid waste-based solidified materials had lower early activity. The cumulative heat release within 72 h was less than 200 J/g. Different solid wastes, such as fly ash and carbide slag, had different effects on the properties of solidified materials. Overall, they had the potential to prepare fluidized solidified soil. The prepared fluidized solidified soil had a fluidity greater than 350 mm, a 28d compressive strength greater than 3 MPa, and exhibited good workability and excellent mechanical properties. Hydration products such as C-S-H and AFt were filled in the soil structure. The 28d compressive strength well above the design requirements of general engineering projects. Meanwhile, the prepared fluidized solidified soil had good adaptability to conventional water reducers (fluidity could be increased by more than 40%) and early strength agents (1d compressive strength could be increased by more than 60%). • Use fluidized solidified soil to solve the problem of backfilling deep foundation pits. • Utilize the synergy between industrial solid waste to improve the solidification effect. • Establish the connection between solidified materials and fluidized solidified soil. • The adaptability of fluidized solidified soil to admixtures was studied. [ABSTRACT FROM AUTHOR]

As a part of by-product generated during the incineration, the municipal solid waste incineration fly ash (MFA) is a secondary pollutant. The ordinary Portland cement (OPC)-based stabilization/solidification (S/S) is a prevalent and robust technique for the treatment of MFA, which can not only effectively dispose the MFA, but also decrease the demand of OPC and reduce the greenhouse gas emissions. However, when MFA was directly utilized to partly replace the cement with a replacement ratio of 15%, the MFA-OPC based composites exhibited inferior mechanical properties. The nano silica (NS) was considered to be introduced to compensate for the strength loss caused by the MFA. In this research, the NS with varying dosages and particle sizes were integrated into the MFA-OPC composites and in total seven groups of the composites were prepared. The mechanical properties of the composites were examined and the results indicated that the composites containing 2 wt% 100 nm NS presented relatively superior mechanical properties. The incorporation of NS could increase the compressive strength of MFA-OPC composites by 37.5% at later age. Then, thermodynamic modelling and the micro-structural analysis including hydration heat, XRD, TG, MIP and SEM were coupling applied to probe into the NS modification mechanism. Experimental results indicated that the addition of NS enhanced the strength of OPC containing MFA at both early and later ages via pozzolanic reaction, hydration acceleration and micro filling effects. Overall considering the macro performance improvement and microstructure modification effect, the 2 wt% NS with particle size of 100 nm was recommended to be utilized. Therefore, this study expands the emerging application of NS and demonstrates that NS-augmented binders can ensure low-carbon and high-performance S/S of hazardous materials. • The nanoSiO 2 with varying particle sizes and dosages were utilized to compensate for the performance loss caused by the MFA. • The experimental analysis and thermodynamic modeling were coupling used to investigate the effect of nanoSiO 2 on the composites. • The optimal nanoSiO 2 particle size (100 nm) and dosage (2%) was recommended. [ABSTRACT FROM AUTHOR]