Thirteen: Characteristics of Bubble Mixed Lightweight Soil for Highway Applications

1. Lightweight and high-strength

Bubble-mixed lightweight soil contains a high number of bubbles, making it lighter than conventional construction materials. Its bulk density can be adjusted between 5 to 13 KN/m³.

The core application of lightweight materials lies in reducing load, minimizing post-construction settlement, and uneven settlement. Traditional filling materials often include soil cover and concrete, which are heavy in weight. Bubble-mixed lightweight soil materials are light in weight, have a small load, and cause minimal disturbance to other structural elements. The use of bubble-mixed lightweight soil achieves the goal of reducing structural load.

Insulation, heat resistance, and corrosion prevention

Bubble-mixed lightweight soil contains a large number of sealed air pores, which boasts superior thermal inertia compared to other materials, significantly reducing the thermal conductivity of bubble-mixed lightweight soil. Therefore, in the field of building energy conservation, bubble-mixed lightweight soil is often used as insulation and heat-insulating materials. Bubble-mixed lightweight soil is a silicate cement product with excellent durability and corrosion resistance. It provides thermal insulation, frost protection, and corrosion resistance, effectively extending the service life of structures.

3. High liquidity with minimal filling pressure

Due to the absence of coarse aggregates found in cement concrete, the bubble-mixed lightweight soil boasts significantly higher fluidity compared to cement concrete (with a water-cement ratio of 0.5, the flow value is around 180mm), exhibiting self-leveling properties during construction. It can be pumped through hoses during actual work, with a maximum horizontal pumping distance of up to 900 meters.

4. Fill-in Self-Compacting

Due to the separation of the production point and the construction pouring point for bubble-mixed lightweight soil, and the small construction space occupied by the pouring point, it is possible to work in confined spaces. Combined with the self-leveling property of bubble-mixed lightweight soil, it fills self-compactly without the need for vibration or compaction, making the construction process convenient. It is an excellent material for filling narrow spaces and underground voids.

5. Adjustable Density and Strength

By adjusting the bubble content rate in the aerated lightweight soil, the dry density can be controlled between 300 and 1200 kg/m³, with strength adjustable within the range of 0.3 to 5 Mpa (the main application range for strength in engineering is 0.3 to 1.5 Mpa).

6. Solidified Independence

The Bubble Mixed Lightweight Soil utilizes cement as a solidifying agent, thus forming an overconsolidated state after the initial setting of cement. Once cured, it possesses independent characteristics and exerts no lateral pressure on other structural elements.

7. Compressible, low-resilience, shock-absorbent

After the completion of underground construction, creep deformation may still occur, which is prone to cause damage to structural objects due to excessive deformation pressure. Due to the high compressibility and good ductility of bubble-mixed lightweight soil, it can withstand significant deformation without overall failure, making it suitable as filling material for tunnels. This material can absorb deformation pressure and improve the distribution of forces on the structural components.

When an earthquake occurs, the low density of the aerated lightweight soil, due to the presence of air bubbles, results in a smaller horizontal inertial force. Additionally, the low elastic modulus of the aerated lightweight soil enhances its shock energy absorption capabilities. This provides the structural element with excellent cushioning properties, ensuring that it remains undamaged during seismic activity.

8. Durability

Bubble Mixed Lightweight Soil is a type of cement material with an lifespan equivalent to that of cement concrete, offering excellent durability.

9. Superior Environmental Features

Bubble-augmented lightweight soil has no polluting effects on the natural environment, including soil, water, and air. Moreover, when used in filling and excavation construction, bubble-augmented lightweight soil can prevent environmental damage caused by excessive filling and excavation, which is of great significance for protecting ecological and natural environments and offers clear environmental benefits.

10. Construction Convenience

Construction sites for roads, bridges, and tunnels, located near residential areas and streets, face challenges due to limited space, heavy traffic, and difficult transportation of materials. Expansion is only possible within the existing site conditions without increasing land area; efforts are made to minimize the impact of ground deformation on existing roads and nearby buildings during expansion. In light of these circumstances, air-entrained lightweight soil is utilized, which, due to its lightness and self-supporting properties, effectively addresses the road widening issues encountered. Moreover, the construction process is simplified, resulting in cost savings.

Section 14: New Applications for Bubble-Mixed Lightweight Soil

(1) National Defense (Modern warfare utilizes information and advanced maneuvering equipment as its tools of attack.)

This expanded polystyrene concrete can be used for immediate repairs to military engineering such as airports and major transportation roads damaged by enemy bombings. Our equipment and technology can swiftly restore the enemy's destroyed engineering. Experimental results show that the repairs can be used for aircraft take-offs and landings, as well as tank passage within just 10 minutes.

(II) Retaining Wall

The rock walls are primarily used for harbors. Using bubble-mixed lightweight soil as a lightweight backfill material behind seawalls can reduce vertical loads and also diminish lateral loads on the seawalls. This is because bubble-mixed lightweight soil is a rigid body with good cohesive properties, which does not exert lateral pressure on the seawalls around the edges. With reduced settlement, maintenance costs are accordingly decreased, thereby saving a significant amount of expenses.

(III) Construction of Sports Fields and Track and Field Tracks

Utilizing permeable bubble mixed lightweight soil as the base material with a density of 800-900 kg/m3, covered with gravel or artificial turf, these sports fields are suitable for activities like hockey, soccer, and tennis. Alternatively, by adding a 0.05m thick porous asphalt layer and a plastic layer on top of the bubble mixed lightweight soil, the surface can be used as an athletic track.

(4) Core Component

During the prefabrication of reinforced concrete components, bubble mixed lightweight soil can be used as the core, endowing it with excellent performance of light weight, high strength, and thermal insulation. Bubble mixed lightweight soil with a density of 400-600 kg/m³ is typically employed.

(V) Used as composite wall panels

Utilizing bubble-mixed lightweight soil to produce various lightweight panels, these are used as thermal insulation fillings in frame structures or combined with thin steel plates to form composite wall panels. The density of bubble-mixed lightweight soil is typically around 600 kg/m³.

Section 6: Pipeline Backfill

Abandoned underground oil tanks, pipelines (filled with crude oil and chemicals), wastewater pipes, and other voids are prone to fires or collapses. The use of foamed lightweight soil backfilling can address these hazards at a reduced cost. The density of the foamed lightweight soil depends on the pipeline diameter and groundwater level, typically ranging from 600 to 1100 kg/m³.

(7) Lean concrete filling layer

Flexible hoses make it highly workable and adaptable to mix air with lightweight soil, thus they are frequently used in lean concrete fill layers. For applications where insulation is not a high priority, lean concrete fill layers with a density of around 1200 kg/m3 are used, with an average thickness of 0.05m. For high insulation requirements, lean concrete fill layers with a density of 500 kg/m3 are employed, averaging 0.1-0.2m in thickness.

(S) Roof Slope

Bubble-mixed lightweight soil for roof slopes offers advantages such as low weight, fast construction speed, and low cost. The slope is typically 10mm/m, with a thickness of 0.03-0.2m, using bubble-mixed lightweight soil with a density of 800-1200kg/m3.

(9) Support for the bottom of the storage tank

Bubble-mixed lightweight soil is poured at the bottom of the steel storage tank (filled with crude oil, chemicals) at the base, and can also form a convex foundation if necessary. This ensures the entire base of the tank is in a good stress state during welding, allowing for the use of thin-plate tank bottoms. Additionally, the convex foundation is easy to clean. The density of the bubble-mixed lightweight soil used is 800-1000 kg/m³.

(10) Environmental Coverage

Primarily used for waste sterilization and harmless coverage, bio-seeded concrete foam ground surfaces, and sand area water retention covers.

(Landscape Applications)

Bubble lightweight concrete artificial rock, cast-in-place bubble mixed lightweight soil rockery, miniature simulated chicken bone stone for bonsai; foamed colored decorative garden ceramic beads, foamed wood-like materials, soilless cultivation lightweight substrate.

(12) Industrial Applications

12.1 Chemical Application - Perforated bubble mixed lightweight soil is an excellent filter material. Additionally, foam concrete is used for casting at the bottom of chemical storage tanks.

12.2 Refractory Applications

Suitable for in-situ insulation layers for furnace kilns, spray insulation layers, foam concrete refractory insulation bricks, etc.

12.3 Industrial Pipe Insulation

Primarily used for producing pipe insulation shells or pipe insulation coatings.

12.4 Ceramic Industry

Used for manufacturing ceramic products of bubble mixed lightweight soil.

(13) Miscellaneous

Bubble-mixed lightweight soil can also be used for insulation filling in firewalls, soundproofing floor filling, tunnel lining backfill; as well as for isolation of power and water supply lines.