The properties of prepared foamed lightweight soils (FLSs) using prefabricated foam requires high foam stability. This paper investigates the geometrical characteristics of different foam densities, different types of foaming agents in the air, and the presence of slurry. Then, it studies their effects on the pore structure and mechanical properties of FLS. Results show that with the increase in foam density the bleeding rate of foam in the air for 1 h increases and the foam with a foam density of 50 kg/m³ is the most stable in the air. The stability of foam in slurry is not directly related to the property of foam in the air. The FLS prepared with the same foaming agent had the best performance with the FLS designed with a foam density of 50 kg/m³, which had the smallest average pore size and the most minor pore size distribution, and had the highest compressive strength. Among the three different foaming agents, Type-S was the best, and the slurry had the lowest rate of increase in wet density after the defoaming test, indicating that the foam had the best stability in the cement slurry. The FLS prepared with the density of 50 kg/m³ using the Type-S foaming agent and mixed with the slurry of cement, fly ash:slag:water = 105:105:140:227.5, was hardened to a mean pore size of 299 μm, and the 7 days, 28 days, and 56 days compressive strengths were 0.92 MPa, 2.04 MPa, and 2.48 MPa, respectively, which had the smallest average pore size and the highest compressive strength among the FLSs prepared using the three foaming agents.

Electrical properties are one of the essential parameters of cement-based materials used in suspension porcelain insulators. This paper studied the electrical properties of aluminate cement adhesives (ACA) containing silica fume (SF), as well as their compressive strength and porosity. The results indicated that the addition of silica fume improved the resistivity of ACA under a saturated state (relative humidity is 50%). This was mainly attributed to the decrease of the ACA’s pore connectivity due to the SF’s filling effect. However, the early compressive strength of ACA was slightly reduced by the addition of SF. Under an unsaturated state, the ACA’s resistivity without the SF gradually exceeded that with the SF at the extension of drying time. The nuclear magnetic resonance (NMR) results indicated that the addition of SF content increased the ACA’s porosity; for the tiny pores especially, (the size less than 25 nm), this increased by 3.4%. Meanwhile, the addition of SF increased the tortuosity of the ACA’s conductive channels, which could improve its resistivity. Therefore, SF is recommended to be used in cement-based adhesives on insulators to lower the cost and improve the resistivity.

Foamed lightweight soil (FLS) is a lightweight cementitious material containing a large number of tiny closed pores and has been widely used as a filler in places such as railways, roads and airports. However, there has been little research into the resistance of FLS to sulphate attack in practical engineering applications. The performance of FLS against different sulphate erosion concentrations was studied to elucidate the engineering characteristics of using large volumes of FLS as fill material for the road base in the construction of intelligent networked vehicle test sites. The results showed that the compressive strength of FLS prepared using 30% Portland cement (C), 30% granulated blast furnace slag (GBFS), 40% fly ash (FA) and a small amount of a concrete antiseptic agent (CA) as cementitious materials reached 0.8 and 1.9 MPa at 7 and 28 d, respectively, when the wet density was about 600 kg/m³, which met the design requirements. The FLS prepared via the above-mentioned cementitious system had a low carbon emission, with a CO₂ emission reduction rate of up to 70%. It also had excellent sulphate attack resistance: the corrosion resistance coefficient of the cementitious material system reached 0.97, which was considerably better than that of C (0.83). For an erosion medium environment with SO₄²⁻ concentrations of less than 1000 mg/L (moderate), 40% GBFS or FA can be used to prepare FLS. When the concentration of SO₄²⁻ is less than 4000 mg/L (severe), 30% C, 30% GBFS and 40% FA can be used as cementitious materials, preferably in combination with an appropriate amount of CA, to prepare FLS.

The foamed lightweight soil (FLS) with superior performance was prepared to be used as a subgrade filling material in an intelligent networked vehicle test site. The production process of practical engineering FLS is simulated in the laboratory. The performance of the prepared FLS is the same as that of practical engineering. The test results show that the FLS prepared with 30% cement, 30% granulated blast furnace slag, and 40% fly ash as cementing material has a flow factor of 175 mm. It has good fluidity and is easy to pump. Wet density reaches 593 kg/m³ within the range of the control index of 600 ± 30 kg/m³. The compressive strength of 7 d and 28 d reaches 0.82 MPa and 1.90 MPa, respectively, which is higher than the design strength of 0.5 MPa and 1.0 MPa. Compared with FLS made of pure cement as a cementing material, the FLS has a low heat of hydration, good volume stability, no cracks on the surface, excellent sulfate resistance, good economy, and low carbon characteristics. In the meantime, it can reduce 70% CO₂ emissions in cement production. The advanced vehicle-mounted mobile intelligent control system is flexible and convenient in actual engineering construction. It can display the wet density of FLS online, which is easy to adjust and control to ensure the quality stability of FLS.

This study simulated the production process of low-carbon foamed lightweight soil (LCFLS) prepared using prefabricated foam technology in real engineering conditions. The preparation and properties of LCFLS with a wet density of 600 kg/m³ were systematically investigated. The effects of different mix designs of large dosing granulated blast furnace slag and fly ash on the properties of LCFLS were investigated. The workability, rheological properties, and mechanical properties of LCFLS were studied. XRD, TG–DTG, and SEM were used to analyze the hydration mechanism of LCFLS. The results showed that fly ash could improve the flowability of LCFLS, while excessive fly ash could lead to foam and slurry delamination. Granulated blast furnace slag improved the mechanical properties of LCFLS, while excess granulated blast furnace slag caused the foam to break and merge, affecting the soil’s homogeneity. The higher the dynamic yield stress of the freshly mixed slurry, the better the homogeneity, and the smaller and more evenly distributed pore sizes formed after hardening. The main hydration products of LCFLS were C-S-H gel and CH, with small amounts of the carbonation products CaCO₃, Hc, and Mc. The LCFLS prepared with 30% cement, 30% fly ash, and 40% granulated blast furnace slag had a flowability of 170–180 mm, with slight differences between wet and quasi-dry densities. The rheological properties of the slurry following the Bingham model showed a dynamic yield stress of 9.41 Pa, an average pore size after hardening of around 300 μm, and compressive strengths at 7 d and 28 d reaching 0.92 MPa and 2.04 MPa, respectively.