Liquefied Road Soil Stabilizer Rammed Earth Wall Solidification Agent

Chinese liquid soil stabilizer, rock forming agent, road solidification

Rammed earth wall solidification agent rammed earth technology rammed earth wall solidification agent rammed earth wall

 

Adding cement Type A soil stabilizer

JUSTSOLID ^® technology manual

 

 

I . Product introduction

1.1 Definition of soil stabilizer

 

  Soil stabilizer is a new type of environmental protection curing material, which acts directly on the soil to solidify the soil into a dense, uniform, high strength and durable composite stabilized soil layer.

 

  Composite stabilized soil is a semi-rigid material formed by new engineering material soil stabilizer and soil stabilization. Compared with the commonly used inorganic combined stabilized materials, the composite stabilized soil can achieve local materials, and has the characteristics of convenient construction, short construction period, low cost and excellent technical indicators for road use. In a certain range, it can replace the commonly used gravel, crushed stone, reduce the amount of lime and other inorganic binding materials, thus reducing the project cost, saving resources, saving energy, and conducive to ecological environmental protection. This technology is used in the construction and repair of composite stabilized soil subbase and base of new and reconstructed highway engineering, as well as pavement construction, wall construction and repair of different purposes. It has broad application prospects in municipal, transportation, water conservancy, foundation treatment and other projects.

 

1.2 Classification of soil stabilizer

 

  In CJJ/T286-2018 Technical Standard for the Application of Soil Solidifying Agent, the soil solidification agent is divided into Class A soil solidification agent and Class B soil solidification agent.

 

  Class A soil stabilizer: a powder or liquid additive that can improve the engineering performance of the foundation soil by physical or chemical reaction with cement (or lime and other cementitious materials), soil, water and air after being added into the soil.

 

  Class B soil stabilizer: after being added into the soil, it is a soil stabilizer that can be used alone through the physical or chemical reaction with soil, water and air, not mixed with cement (or lime and other cementitious materials), and a powder additive that can improve the engineering performance of the foundation soil.

 

II. Physical and chemical properties

                                         

           Form: liquid or granular powder                                   Solubility: soluble in water  

     Type: ionic polymer type biological enzyme type        Safety: ecological and environmental protection

 

III.　Action mechanism

 

  The working principle of composite stabilized soil is to make the surface current of soil micelle reduce energy and fix a large amount of free water in the soil in the form of crystal water. The engineering properties of the soil are changed by a series of physical and chemical reactions after the soil stabilizer is mixed with the soil. The particles tend to agglomerate, the electrolyte concentration increases, and the volume expands to further fill the soil pores; Under the action of compaction, the whole structure is formed to make the solidified soil easy to be compacted and stable, reach the compactness that cannot be achieved by conventional methods, and improve its strength, compactness, modulus of resilience, deflection value, CBR, shear strength and other properties, so as to meet the requirements of road technical indicators.

IV.Adaptability and scope of use

  Soil stabilizer can be applied to a variety of soil properties, such as clay, silt and sand; Mineral powder, slag, construction waste, etc. According to different soil properties, different curing schemes are formulated by adjusting the material ratio.

1.  Subgrade construction

    The subbase of the expressway is hardened, and the base and subbase of the first class road and below are hardened. Hardening of base course and surface course of simple road or temporary road. Cement soil, soft soil and soft foundation solidification.

2.  Site hardening

  Hardening treatment of parking lot, road, stockyard, storage yard, drilling well pad, production and processing yard, etc.

3.  Rammed earth wall

  Vegetable, flower and breeding greenhouse; Construction or repair of ancient building walls; Earth wall of folk houses, etc.

4. Making unburned bricks

  After fully mixing the clay with the soil curing agent, it is supplemented with other hydraulic materials and directly pressed by the brick press.

V. Construction plan

5.1  Basic Requirements

① Cementitious material: cement. It shall comply with the current national standard General Portland Cement (GB175). Cement of the same grade, brand, variety and delivery shall not be mixed. Cement grade 425 and above. The initial setting period is required to be more than 3 hours, and the final setting period is about 6 hours, not more than 10 hours.

②Water quality requirements: the water shall be non-polluting water (potable water for livestock). It conforms to the current industrial standard Standard for Concrete Water JGJ 63.

③ Construction thickness: the compaction thickness of each layer should be 15-20 cm (cm), and the total compaction thickness should be determined according to the construction requirements.

④ Addition of cementitious materials: the amount of cementitious materials generally accounts for 3% - 6% of the total soil amount. The details shall be determined according to the construction requirements and process.

⑤ Amount of soil stabilizer: about 0.5 kg per cubic meter of compacted earth; It is about 0.03% (three thousandths) of the mixture by weight. Curing agent for sealing layer: after curing, spray on the surface of solidified soil, dilute with water about 20 times, and spray the sealing layer.

⑥ Moisture determination method:

      

 

                        Figure1  Soil moisture meter        Figure2  Traditional simple method      

       

    Use a soil moisture meter or traditional simple method: grab a handful of soil, put it in your hand and hold it tightly, and the soil mass will be formed without scattering; One meter from the ground, let the soil mass fall freely, and the soil mass spread evenly (fall to the ground and blossom), indicating that the moisture content is about 15%.

⑦ Material consumption:

    For example, the area of the soil to be solidified is calculated as 5 square meters, the thickness is 20 cm, and the total volume is 1 cubic meter after compaction. The density after compaction is calculated as 2 tons/cubic meter, and the total volume is 2 tons.

 

*Earthwork=area * thickness=5 square meters * 0.2 meters=1 cubic meter * Total soil volume=earthwork * compaction density=1 * 2=2 tons;

 

*Amount of cementitious material (cement)=total soil quantity * 10%=2 * 10%=0.2 tons；

 

*Amount of soil stabilizer=total earthwork * amount of soil stabilizer=1 m3 * 0.5 kg/m3=0.5 kg;

 

*Water consumption of diluting and curing agent=(optimum moisture content * total solid content) - (initial soil moisture content * total soil content)

=18% * (soil volume+cement+diluted water) - 12% * total soil volume

 

Note: In the formula, the initial water content of soil is calculated as 12%, and the optimum water content is calculated as 18%; The specific construction shall be subject to the actual water content.

5.2  Construction tools

   The construction machinery can only use traditional road construction machinery, and the quantity and selection shall be determined according to the actual situation:

        Table 1 Allocation of construction machinery and equipment

Order number	Equipment name	Specification and model	Unit	Quantity	Remarks
1	Stabilized aggregate mixing equipment	Continuous	Tower	1	Field mixing method
2	(Cold regeneration) Road mixer	——	Tower	1	Road mixing method
3	Spade	——	Grasp	5	The details are determined according to the project needs
4	Excavating Machinery	CAT320C	Tower	2
5	Loader	ZL-50	Tower	2
6	Grader	180H	Tower	4
7	Small roller	VV170	Tower	1
8	Tyre roller	9-16T 9-16 Tons	Tower	1
9	Vibratory roller	CA25	Tower	1
10	Double-drum static roller	Special for base construction	Tower	1
11	3-wheel smooth static roller	18-26T 18-26Tons	Tower	1
12	Watering car	5-10T 5-10 Tons	Tower	Undetermined
13	Curing agent	SV series	Ton	Undetermined
14	Geotextile	——	Square	Undetermined	The specific consumption is calculated according to the project requirements
15	Cement	425 grade ordinary silicate	Ton	Undetermine

                                       

                                           Table 2 Staffing Table

Order number	Type of work	Number of people	Remarks
1	Management	2-3	The specific number of personnel shall be determined according to the construction situation.
2	Operator	3-6
3	Surveying technician	1-2

5.3 Construction process

5.3.1 Introduction to construction technology

① Pretreatment

   Determine the length, width and loose paving thickness of the test section. If vegetation has been planted in the construction section, please remove the topsoil of about 20-30 cm in the upper layer; If the moisture content of the soil is too high or the soil is sticky, it needs to be sunned or pretreated to improve it to about 10% - 12% of the natural moisture content.

② Subgrade compaction

   Use a bulldozer to push the soil in the section to be constructed to both sides of the road, compact the roadbed for 3-5 times, manually level the soil while compacting, backfill the first layer of soil to be solidified, break the soil and level it.

②  Dilution and spraying of soil stabilizer, stuffy material

   Determine the water content, determine the amount of soil stabilizer and the dilution ratio of the stabilizer, and dilute the soil stabilizer; Then spray the diluted soil stabilizer for 1-2 times, and mix it evenly mechanically; Then carry out blanking (whether or not and the time of blanking shall be determined according to the construction soil quality and construction progress).

③ Spread cement or lime

  Calculate the amount of cement or lime, evenly spread the cement or lime, fully mix it evenly, and measure the water content (determine whether water replenishment is required).

④  Compaction and curing

   First use crawler to compact and level, and then use 18-22t roller to compact for 3-5 times; Then use single drum vibratory roller for compaction and leveling. Finally, double drum vibratory roller is used for compaction. When rolling, the principle of "light before heavy, slow before fast, both sides before middle, static pressure before vibration" shall be followed. After compaction, cover the geotextile and sprinkle water regularly to keep the pavement wet and free of water, and maintain it for at least 7 days.

⑤ Construction of the second layer or other layers

   If the construction is carried out in two or more layers, after the construction of the first layer is completed, the geotextile shall be covered with water (recommended) or the film shall be covered for curing (special cases), and then other soil layers shall be constructed according to the construction method of the first layer.

⑥  Seal curing

After the completion of pavement construction and maintenance, spray the diluted seal curing agent for seal curing to further improve the compaction and anti-seepage effect.

⑦ Matters needing attention

 The construction progress shall be determined according to the final setting time of cement, and the construction shall be completed before the final setting.

5.3.2 The specific construction process is as follows (the picture is the construction picture of other sections, only for reference)

(1)Determination of construction section survey

  Use the total station or corresponding measuring instrument to measure according to the coordinate method, and set out the subgrade side line according to the design width of the subgrade. In order to ensure the effective compaction of the subgrade and the stability of the slope, it is appropriate to set out the subgrade side line so that the width of the side lines on both sides is 20 cm - 40 cm. Then, the survey technician shall accurately set out the leveling line, determine the elevation of the vertical and horizontal sections, and mark the side drill according to the design elevation. The loose paving coefficient shall be taken into account in the leveling elevation control.

(2)Soil preparation and leveling

   The soil shall be loosened according to the amount of earthwork required in the construction stage, and roughly leveled according to the measured height and width. The leveling method is generally manual with bulldozer. The soil with large particles shall be screened in advance for standby.

Soil preparation and leveling

 

(3)Soil pre-treatment (this step depends on the soil quality, which generally does not require pre-treatment)

  Spreading improved curing agent Mix evenly

 

  For high cohesive soil, the soil is easy to agglomerate after water, and the soil is pretreated by adding a certain proportion of improved curing agent. The improved curing agent shall be evenly distributed in the divided squares according to the mix proportion, and there shall be no blank position on the surface. The plane shall be as flat as possible. During the paving process, oversize particles and other sundries shall be picked up. Dry mixing is generally carried out once by rotary tiller (or by road mixer); Small areas can be mixed manually.

(4)Cement spreading and mixing

   The cement shall be evenly distributed in the divided squares according to the mix proportion, and there shall be no blank position on the surface. The plane shall be as flat as possible. During the paving process, oversize particles and other sundries shall be picked up. Dry mixing is generally carried out once by rotary tiller (or by road mixer); Small areas can be mixed manually.

 

Manual  spreading cement 

 

or  cement spreader spreading cement evenly mixed

 

(5) Spraying curing agent and wet mixing

 

  Dilute soil stabilizer in sprinkler Spreading diluted curing agent

 

  Take a representative point to test the water content and accurately calculate the total amount of make-up water required for the operation section. Dilute the curing agent according to the proportion calculated in advance. The soil curing agent shall be sprayed in 2-3 times, and the mechanical mixing shall not be less than twice until the mixing color is consistent.

 

(6)Initial compaction, leveling and rolling of solidified soil

   After the mixture is mixed evenly, the bulldozer shall be used for preliminary pressure discharge immediately, and then the grader shall be used for leveling. During leveling, for local low-lying areas, the newly mixed mixture shall be used for leveling. Thin layer leveling shall not be carried out on a smooth plane during leveling.

 

   After determining the loose paving thickness and shaping, compact at the optimum moisture content, and formulate the corresponding rolling scheme according to the different road width and roller track width. It is required to carry out rolling operation according to the principle of "low - high, slow - fast, static pressure - vibration, weak vibration - strong vibration". The front and rear rollers are required to cooperate with each other in construction. Overlapping operation shall be carried out in close sections, and the traveling speed of roller shall be controlled between 2-4km per hour. If large rolling machinery can not be compacted locally, small machinery or manual method can be selected for supplementary compaction. In order to avoid water evaporation, which will seriously affect the compaction effect, the paving and rolling shall be carried out on the same day.

Initial compaction, leveling and rolling of solidified soil

 

(7)Construction of the second floor

       After the curing of the first layer is completed, cover the soil or film for curing, and carry out the second layer construction according to the construction requirements.

 

(8)Joint treatment

    At the end of each day, manually cut the rolling end into a straight joint. At the beginning of the next day, transverse rolling shall be carried out for the transverse joint. During the transverse rolling, the roller shall be placed on the forming layer completely, and each time the roller shall extend 20-30cm to the new layer, until the width of the roller is placed on the new layer, and then the longitudinal rolling shall be carried out.

 

Joint  treatment

 

(9)Health care and traffic control

  

Sprinkler watering for curing Laying geotextile for curing in flood

 

  After the compaction of each section of the solidified soil layer is completed, the traffic shall be interrupted immediately after the compaction degree is checked to be qualified, and the pavement shall be covered with geotextile and watered for maintenance. The pavement shall be kept wet for 7-14 days.

 

(10)Spraying sealing curing agent

 

Spreading sealing curing agent

 

     After the maintenance of the (pavement) works is completed, spray the seal curing agent for the seal curing, which can further improve the impermeability, compactness and strength of the surface layer. Whether to arrange this construction of subgrade depends on the soil quality, season, climate and other conditions of construction.

 Ⅵ. Product advantages

6.1  Improve road performance

  Improve compressive strength: soil stabilizer can improve the compactness and flexibility of soil. After compaction and maintenance, not only can the soil be treated into a solid roadbed on the spot, but also other inorganic waste materials can be added to improve the synergy effect, which can not only improve the compressive strength, but also enhance the economic transformation of other inorganic wastes.

 

   Improve water stability: after adding soil stabilizer to solidify, the soil density will increase, and the capillary will be gradually closed and blocked. The hydrophilicity of the soil is greatly reduced and the hydrophobicity is greatly improved. The soil particles were bridged and connected by crystal growth, which solidified the soil surface, changed the physical and chemical properties, and greatly improved the corresponding water stability. The practice of completed subgrade in the equatorial region that has experienced dry and rainy seasons shows that the subgrade still maintains high strength after repeated cycles of long-term immersion and drought, which fully demonstrates its excellent water resistance.

 

   Improve the frost stability: the fundamental to improve the frost resistance is to improve its water stability and water absorption. Because the water absorption of this solidified soil is very low and its water stability is very good, the impact of its water freezing in it is very small. Therefore, the freeze-thaw resistance is excellent. At low temperature (below 0 ℃), the absolute value of temperature shrinkage coefficient of solidified soil is also much smaller than that of conventional lime soil and lime soil.

 

  Improve the comprehensive quality of the road: Through a lot of indoor experiments and long-term construction experience verification, the strength, compactness, modulus of resilience, deflection value, CBR (load ratio), shear strength, etc. of the solidified soil have reached and exceeded the acceptance standard of the subgrade material, thus greatly improving the comprehensive quality of the road and extending its service life.

 

6.2 Reduce the cost of road construction

   Using local materials and comprehensive utilization, all different soil or construction waste, waste residue, etc. on the construction site can be reused, greatly reducing the cost of road construction. Compared with the traditional pavement base, the cost can be reduced by 10% - 40% year-on-year.

VII.Benefit analysis

7.1  Economic benefit analysis

  Taking local materials: directly take local soil for construction on the subgrade without using transport vehicles to transport sand, stone, water and other materials from a long distance, replacing the traditional road construction materials, saving material costs, a large amount of transportation costs and labor costs, and reducing costs by about 20-40% compared with traditional road construction materials and processes. The utilization rate of equipment and vehicles has been greatly reduced, which saves a lot of investment only in terms of equipment investment, and it is not necessary to add new equipment to use the original road construction tools. It is especially suitable for areas with high transportation costs and high vehicle costs. If the costs of land acquisition, soil excavation and transportation are considered, the overall cost will be greatly reduced.

  Very low dosage: the amount of soil stabilizer used is several parts per 10000. Such a low dosage can achieve very good road compression resistance, water resistance and frost resistance, and the benefits are very obvious. The types of cementitious materials shall be determined according to the grade requirements and the road soil conditions. The strength of the cementitious materials can be greatly increased after being used with appropriate cementitious materials.

 

  Good water stability: it solves the problem of water permeability, reduces the height of the subgrade as a whole, and saves a lot of labor, construction period, earthwork, sand, cement, lime and other materials. After adding curing agent, the road has good waterproof property, which is not easy to cause road damage due to the rainy season, prolonging the service time of the road and reducing the maintenance time.

7.2 Environmental benefit

  After use, the soil stabilizer will react with soil and cementitious materials in organic and inorganic physical and chemical reactions, and will not cause pollution and toxicity to the soil; After the road is abandoned, it can be returned to farmland and cultivated again, which can effectively solve the environmental pollution caused by the mining of traditional road construction materials and the waste treatment problems after the road is abandoned.

7.3 Overall benefit analysis

  From the above overall situation, the use of soil curing agent to transform the existing road can receive very good social and economic benefits, and its associated benefits are also very huge.

 

 

 

 

 

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