Cement stabilized macadam base admixture and cement stabilized macadam base prepared based on admixture

Abstract

The invention discloses a cement stabilized macadam base admixture and a cement stabilized macadam base prepared based on the admixture. The admixture comprises inorganic sodium salt, potassium persulfate, styrene, a silane coupling agent, triethanolamine, a water reducing agent, polyethylene glycol, water glass, calcium chloride and the balance of water. When the cement stabilized macadam base is prepared, inorganic sodium salt, water glass, calcium chloride, styrene, triethanolamine and polyethylene glycol are mixed with part of water, and a solution A is obtained; potassium persulfate, a silane coupling agent and a water reducing agent are mixed with the remaining water, and a solution B is obtained; and finally, mixing the macadam, the cement, the solution A and the solution B, supplementing water according to the water content of the cement stabilized macadam base mixture, stirring, and transporting to paving. After the cement stabilized macadam base admixture is doped into a cement stabilized macadam base material, the early strength of a base can be improved, the maintenance time is shortened, vibration is reduced, meanwhile, the interface bonding capacity of macadam and cement can be effectively improved, and reflection cracks are avoided.

Description

Technical Field

[0001] This invention belongs to the technical field of cement-stabilized crushed stone base course, and particularly relates to an admixture for cement-stabilized crushed stone base course and a cement-stabilized crushed stone base course prepared based on the admixture. Background Technology

[0002] Highway pavement structures generally consist of a surface layer, a base layer, and a subbase layer. Compared with other base layer structures, cement-stabilized crushed stone has advantages such as high strength, strong integrity, and good durability. After completion, it does not become muddy when it rains and has a solid surface, making it a relatively ideal semi-rigid base layer material and one of the most commonly used base layer materials for highway pavements, especially high-grade pavements.

[0003] However, in cement-stabilized crushed stone base materials used in the subgrade, the crushed stone is highly susceptible to drying shrinkage and thermal shrinkage cracks due to the cement hydration reaction. Furthermore, the strip-shaped structure of roads exacerbates this, making transverse cracks in the base layer even more likely. Under vehicle loads, these cracks propagate to the overlying asphalt concrete structural layer, leading to severe "reflective cracking" in the road surface, causing pavement damage and necessitating structural repair measures. To ensure sufficient load-bearing capacity, the early strength development of cement-stabilized crushed stone base is slow, requiring at least 7 days of curing before surface layer construction. However, with increasing traffic volume, excessively long curing times can easily cause traffic congestion. Rapidly improving the early strength of cement-stabilized crushed stone to enable rapid traffic reopening is one effective means to address these challenges.

[0004] In addition, vibratory rollers are commonly used for compaction during the paving of cement-stabilized crushed stone. As the tonnage of vibratory rollers increases, their excitation force also increases. The mechanical waves generated by the excitation force are very harmful to nearby buildings. The energy of the mechanical waves causes nearby buildings to vibrate along with them, and can even cause cracks in the buildings.

[0005] Based on this, we are now studying a new type of cement-stabilized crushed stone base course that does not require or requires low-tonnage vibration compaction, can significantly shorten the curing time, and avoids the generation of "reflective cracks". Summary of the Invention

[0006] Purpose of the invention: The technical problem to be solved by the present invention is to provide a cement-stabilized crushed stone base course admixture, which, when added to the cement-stabilized crushed stone base course, can not only improve the early strength of the base course, reduce curing time and vibration, but also effectively improve the interfacial bonding ability between crushed stone and cement, and avoid the generation of "reflective cracks".

[0007] Technical solution: The cement-stabilized crushed stone base admixture of the present invention comprises the following raw materials by mass fraction: 9-12% inorganic sodium salt, 0.2-0.6% potassium persulfate, 1.0-2.0% styrene, 0.1-0.3% silane coupling agent, 3-4.5% triethanolamine, 15-20% water-reducing agent, 2-4% polyethylene glycol, 10-13% water glass, 10-15% calcium chloride, and the balance being water.

[0008] Furthermore, the inorganic sodium salt used in this additive can be sodium thiosulfate and sodium nitrite in a mass ratio of (0.9-1.3):1.

[0009] Furthermore, the water-reducing agent used in this admixture can be a polycarboxylate water-reducing agent with a water reduction rate of ≥20% and a solid content of 35-40%.

[0010] Furthermore, the polyethylene glycol used in this additive has an average molecular weight of 4000-6000 and a water glass modulus of 2.8-3.0.

[0011] The cement-stabilized crushed stone base course of the present invention comprises a base course material composed of crushed stone and cement, and the aforementioned admixture incorporated into the base course material, and is prepared by the following steps:

[0012] (1) Inorganic sodium salt, water glass, calcium chloride, styrene, triethanolamine and polyethylene glycol are mixed with water accounting for (1 / 2-3 / 4) of the mass to obtain solution A;

[0013] (2) Mix potassium persulfate, silane coupling agent and water-reducing agent with the remaining water to obtain solution B;

[0014] (3) Mix crushed stone, cement, solution A and solution B, add water according to the moisture content of cement stabilized crushed stone base mixture, mix and transport to paving.

[0015] Furthermore, in step (3) of the preparation of the cement-stabilized crushed stone base course of the present invention, the total amount of solution A and solution B added is 0.5-1.5% of the cement mass.

[0016] Furthermore, in step (3) of the preparation of the cement-stabilized crushed stone base course of the present invention, the amount of cement added is 3.5%-5% of the mass of the cement-stabilized crushed stone.

[0017] Beneficial Effects: Compared with the prior art, the significant advantages of this invention are as follows: This admixture is based on inorganic sodium salts, potassium persulfate, water glass, and calcium chloride, which enhance early strength performance. It incorporates water-reducing agents, triethanolamine, and polyethylene glycol, as well as potassium persulfate, styrene, and silane coupling agents to form a compound system. Furthermore, it utilizes aqueous solutions of inorganic sodium salts, water glass, calcium chloride, styrene, triethanolamine, and polyethylene glycol, and aqueous solutions of potassium persulfate, silane coupling agents, and water-reducing agents, respectively. When these are incorporated into cement-stabilized crushed stone base materials, it not only improves the early strength of the base layer and shortens the curing time, but also reduces the adsorption loss of the water-reducing agent by soil or stone powder in the cement-stabilized crushed stone, fully utilizing the role of the water-reducing agent. This improves the fluidity of the mixed cement-stabilized crushed stone base material, enabling excellent compaction even under conditions where vibration compaction is not required or is done at low tonnage. Simultaneously, it enhances the interfacial bonding between cement and crushed stone and the flexibility of the base layer, preventing the formation of "reflective cracks." Attached Figure Description

[0018] Figure 1 This is a product image of the core sample prepared in Example 1 of the present invention;

[0019] Figure 2 This is a product image of the core sample prepared in Comparative Example 1 of the present invention;

[0020] Figure 3 A product image of the core sample prepared in Comparative Example 2 of this invention;

[0021] Figure 4 This is a product image of the core sample prepared in Example 2 of the present invention;

[0022] Figure 5 This is a product image of the core sample prepared in Comparative Example 3 of the present invention;

[0023] Figure 6 This is a product image of the core sample prepared in Comparative Example 4 of the present invention. Detailed Implementation

[0024] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0025] It should be noted that all raw materials used in this invention are commercially available. In the following examples and comparative examples, the inorganic sodium salt used is sodium thiosulfate and sodium nitrite in a 1:1 mass ratio. The silane coupling agent used is KH560. The polycarboxylate superplasticizer has a water reduction rate of ≥20% and a solid content of 35-40%. The polyethylene glycol has an average molecular weight of 4000 and a water glass modulus of 2.8-3.0.

[0026] In the following embodiments of the present invention, the gradation of the crushed stone in the cement-stabilized crushed stone base course is (0-2.36mm):(2.36-4.75mm):(4.75-9.5mm):(9.5-31.5mm) = 13:1:16:20. However, the gradation of the cement-stabilized crushed stone suitable for the admixture of the present invention is not limited to the above one, and any gradation known in the art can be used.

[0027] Example 1

[0028] The raw material composition of the cement-stabilized crushed stone base course admixture in Example 1 is shown in Table 1 below.

[0029] Table 1. Raw material composition of cement-stabilized crushed stone base course admixture in Example 1

[0030]

[0031] The cement-stabilized crushed base course prepared based on the admixture of Example 1 includes the following steps:

[0032] (1) Inorganic sodium salt, water glass, calcium chloride, styrene, triethanolamine and polyethylene glycol are first mixed with water (19.95%) to obtain solution A;

[0033] (2) Mix potassium persulfate, silane coupling agent and water-reducing agent with the remaining water to obtain solution B;

[0034] (3) Mix crushed stone, cement, solution A and solution B, add water according to the moisture content of cement stabilized crushed stone base course mixture of 5%, mix and transport to the paving site.

[0035] The total amount of solution A and solution B added is 1% of the cement mass. The amount of cement added is 4% of the cement-stabilized crushed stone mass.

[0036] Comparative Example 1

[0037] The composition of the admixture in Comparative Example 1 is the same as that in Example 1, except that the admixture components are directly incorporated into the crushed stone and cement as a whole. The specific steps are as follows:

[0038] (1) Mix inorganic sodium salt, potassium persulfate, styrene, silane coupling agent, triethanolamine, water reducing agent, polyethylene glycol, water glass, calcium chloride and the balance being water to obtain a composite solution;

[0039] (2) Mix crushed stone, cement and composite solution, add water according to the moisture content of cement stabilized crushed stone base mixture of 5%, mix and transport to paving.

[0040] The total amount of the composite solution added is 1% of the cement mass. The amount of cement added is 4% of the cement-stabilized crushed stone mass.

[0041] Comparative Example 2

[0042] The application steps and parameters of the additive in Comparative Example 2 are the same as those in Example 1. The difference lies in the raw materials of the additive, namely, potassium persulfate is not added, as shown in Table 2 below.

[0043] Table 2. Raw material composition of potassium persulfate in Comparative Example 2

[0044]

[0045] The cement-stabilized crushed stone base course prepared based on the admixture in Comparative Example 2 includes the following steps:

[0046] (1) Inorganic sodium salt, water glass, calcium chloride, styrene, triethanolamine and polyethylene glycol are first mixed with water (19.95%) to obtain solution A;

[0047] (2) Mix the silane coupling agent and water-reducing agent with the remaining water to obtain solution B;

[0048] (3) Mix crushed stone, cement, solution A and solution B, add water according to the moisture content of cement stabilized crushed stone base course mixture of 5%, mix and transport to the paving site.

[0049] The total amount of solution A and solution B added is 1% of the cement mass. The amount of cement added is 4% of the cement-stabilized crushed stone mass.

[0050] Example 2

[0051] The raw material composition of the cement-stabilized crushed stone base course admixture in Example 2 is shown in Table 3 below.

[0052] Table 3. Raw material composition of cement-stabilized crushed stone base course admixture in Example 2

[0053]

[0054] The cement-stabilized crushed stone base course prepared based on the admixture of Example 2 includes the following steps:

[0055] (1) Inorganic sodium salt, water glass, calcium chloride, styrene, triethanolamine and polyethylene glycol are first mixed with water (19.5%) to obtain solution A;

[0056] (2) Mix potassium persulfate, silane coupling agent and water-reducing agent with the remaining water to obtain solution B;

[0057] (3) Mix crushed stone, cement, solution A and solution B, add water according to the moisture content of cement stabilized crushed stone base course mixture of 5%, mix and transport to the paving site.

[0058] The total amount of solution A and solution B added is 1% of the cement mass. The amount of cement added is 4% of the cement-stabilized crushed stone mass.

[0059] Comparative Example 3

[0060] The composition of the admixture in Comparative Example 3 is the same as that in Example 2, except that the admixture components are directly incorporated into the crushed stone and cement as a whole. The specific steps are as follows:

[0061] (1) Mix inorganic sodium salt, potassium persulfate, styrene, silane coupling agent, triethanolamine, water reducing agent, polyethylene glycol, water glass, calcium chloride and the balance being water to obtain a composite solution;

[0062] (2) Mix crushed stone, cement and composite solution, add water according to the moisture content of cement stabilized crushed stone base mixture of 5%, mix and transport to paving.

[0063] The total amount of the composite solution added is 1% of the cement mass. The amount of cement added is 4% of the cement-stabilized crushed stone mass.

[0064] Comparative Example 4

[0065] The application steps and parameters of the additive in Comparative Example 4 are the same as those in Example 2. The difference lies in the raw materials of the additive; potassium persulfate is not added, as shown in Table 4 below.

[0066] Table 4. Raw material composition of cement-stabilized crushed stone base course admixture in Comparative Example 4

[0067]

[0068] The cement-stabilized crushed stone base course prepared based on the admixture in Comparative Example 4 includes the following steps:

[0069] (1) Inorganic sodium salt, water glass, calcium chloride, styrene, triethanolamine and polyethylene glycol are first mixed with water (19.5%) to obtain solution A;

[0070] (2) Mix potassium persulfate, silane coupling agent and water-reducing agent with the remaining water to obtain solution B;

[0071] (3) Mix crushed stone, cement, solution A and solution B, add water according to the moisture content of cement stabilized crushed stone base course mixture of 5%, mix and transport to the paving site.

[0072] The total amount of solution A and solution B added is 1% of the cement mass. The amount of cement added is 4% of the cement-stabilized crushed stone mass.

[0073] Example 3

[0074] The raw material composition of the cement-stabilized crushed stone base course admixture in Example 3 is shown in Table 5 below.

[0075] Table 5. Raw material composition of cement-stabilized crushed stone base course admixture in Example 3

[0076]

[0077] The cement-stabilized crushed stone base course prepared based on the admixture of Example 3 includes the following steps:

[0078] (1) Inorganic sodium salt, water glass, calcium chloride, styrene, triethanolamine and polyethylene glycol are first mixed with water (24.85%) to obtain solution A;

[0079] (2) Mix potassium persulfate, silane coupling agent and water-reducing agent with the remaining water to obtain solution B;

[0080] (3) Mix crushed stone, cement, solution A and solution B, add water according to the moisture content of cement stabilized crushed stone base course mixture of 5%, mix and transport to the paving site.

[0081] The total amount of solution A and solution B added is 1% of the cement mass. The amount of cement added is 4% of the cement-stabilized crushed stone mass.

[0082] Comparative Example 5

[0083] The composition of the admixture in Comparative Example 5 is the same as that in Example 3, except that the admixture components are directly incorporated into the crushed stone and cement as a whole. The specific steps are as follows:

[0084] (1) Mix inorganic sodium salt, potassium persulfate, styrene, silane coupling agent, triethanolamine, water reducing agent, polyethylene glycol, water glass, calcium chloride and the balance being water to obtain a composite solution;

[0085] (2) Mix crushed stone, cement and composite solution, add water according to the moisture content of cement stabilized crushed stone base mixture of 5%, mix and transport to paving.

[0086] The total amount of the composite solution added is 1% of the cement mass. The amount of cement added is 4% of the cement-stabilized crushed stone mass.

[0087] Comparative Example 6

[0088] The application steps and parameters of the additive in Comparative Example 6 are the same as those in Example 3. The difference lies in the raw materials of the additive; potassium persulfate is not added, as shown in Table 6 below.

[0089] Table 6. Raw material composition of cement-stabilized crushed stone base course admixture in Comparative Example 6

[0090]

[0091] The cement-stabilized crushed stone base course prepared based on the admixture in Comparative Example 6 includes the following steps:

[0092] (1) Inorganic sodium salt, water glass, calcium chloride, styrene, triethanolamine and polyethylene glycol are first mixed with water (24.85%) to obtain solution A;

[0093] (2) Mix potassium persulfate, silane coupling agent and water-reducing agent with the remaining water to obtain solution B;

[0094] (3) Mix crushed stone, cement, solution A and solution B, add water according to the moisture content of cement stabilized crushed stone base course mixture of 5%, mix and transport to the paving site.

[0095] The total amount of solution A and solution B added is 1% of the cement mass. The amount of cement added is 4% of the cement-stabilized crushed stone mass.

[0096] Example 4

[0097] The raw material composition of the cement-stabilized crushed stone base course admixture in Example 4 is shown in Table 7 below.

[0098] Table 7. Raw material composition of cement-stabilized crushed stone base course admixture in Example 4

[0099]

[0100] The cement-stabilized crushed stone base course prepared based on the admixture of Example 4 includes the following steps:

[0101] (1) Inorganic sodium salt, water glass, calcium chloride, styrene, triethanolamine and polyethylene glycol are first mixed with water (14.3%) to obtain solution A;

[0102] (2) Mix potassium persulfate, silane coupling agent and water-reducing agent with the remaining water to obtain solution B;

[0103] (3) Mix crushed stone, cement, solution A and solution B, add water according to the moisture content of cement stabilized crushed stone base course mixture of 5%, mix and transport to the paving site.

[0104] The total amount of solution A and solution B added is 1% of the cement mass. The amount of cement added is 4% of the cement-stabilized crushed stone mass.

[0105] Performance testing

[0106] The cement-stabilized crushed stone base materials of Examples 1-4 and Comparative Examples 1-6 were made into samples, and their compaction degree and mechanical strength were tested (wherein, vibration compaction was carried out without the aid of external force equipment during the laying process). The results are shown in Table 8 below.

[0107] Table 8 Mechanical properties of Examples 1-4 and Comparative Example-6

[0108]

[0109] As can be seen from Examples 1 to 4 in Table 8, the admixture system of the present invention, when incorporated into cement-stabilized crushed stone base material, not only improves the early strength of the base layer and shortens the curing time, but also ensures the integrity of the sample. Figure 1 , Figure 4 As shown, it improves the fluidity of the mixed cement-stabilized crushed stone base material, enabling it to achieve excellent compaction without the need for vibration compaction; at the same time, it enhances the interfacial bonding ability and flexibility between cement and crushed stone, and has a low 28-day drying shrinkage rate, effectively preventing the generation of "reflective cracks".

[0110] Further analysis of the performance data from Examples 1-3 and Comparative Examples 1, 3, and 5 reveals that the present invention, by independently preparing aqueous solutions of inorganic sodium salts, water glass, calcium chloride, styrene, triethanolamine, and polyethylene glycol, and aqueous solutions of potassium persulfate, silane coupling agents, and water-reducing agents, compared to preparing a monolithic composite solution and mixing it with cement-stabilized crushed stone base material, although the core samples prepared in Comparative Examples 1, 3, and 5 are intact, such as... Figure 2 and Figure 5 As shown, its compaction degree, strength and dry shrinkage rate are significantly weaker than those of the example.

[0111] Furthermore, based on Examples 1-3, and Comparative Examples 2, 4, and 6, it can be seen that although sodium salts with the same early strength function were used to replace potassium persulfate, which has an early strength agent, the early strength still differed significantly from that of the examples, and the prepared core samples were incomplete, such as... Figure 3 and Figure 6 As shown, both compaction degree and dry shrinkage rate decreased significantly.

[0112] In addition to the embodiments described above, the technical effects claimed above can be achieved using the raw materials and processes defined in this invention, and therefore, further testing is not required. For example, in preparing a cement-stabilized crushed stone base course, inorganic sodium salt, water glass, calcium chloride, styrene, triethanolamine, and polyethylene glycol are mixed with a portion of water. The amount of water added can be 1 / 2 to 3 / 4 of the water volume in the admixture. The total amount of solution A and solution B added can be 0.5% to 1.5% of the cement mass. The amount of cement added can be 3.5% to 5% of the cement-stabilized crushed stone mass.

Claims

1. A cement-stabilized crushed stone base course admixture, characterized in that, The raw materials are comprised by mass fraction as follows: 9-12% inorganic sodium salt, 0.2-0.6% potassium persulfate, 1.0-2.0% styrene, 0.1-0.3% silane coupling agent, 3-4.5% triethanolamine, 15-20% water-reducing agent, 2-4% polyethylene glycol, 10-13% water glass, 10-15% calcium chloride, and the balance being water.

2. The cement-stabilized crushed stone base course admixture according to claim 1, characterized in that, The inorganic sodium salt is sodium thiosulfate and sodium nitrite in a mass ratio of (0.9-1.3):

1.

3. The cement-stabilized crushed stone base course admixture according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of ≥20% and a solid content of 35-40%.

4. The cement-stabilized crushed stone base course admixture according to claim 1, characterized in that, The polyethylene glycol has an average molecular weight of 4000-6000 and a water glass modulus of 2.8-3.

0.

5. A cement-stabilized crushed stone base course, characterized in that, The base material comprises crushed stone and cement, and the admixture as described in claim 1, which is incorporated into the base material, and is prepared by the following steps: (1) Inorganic sodium salt, water glass, calcium chloride, styrene, triethanolamine and polyethylene glycol are mixed with water accounting for (1 / 2-3 / 4) of the mass to obtain solution A; (2) Mix potassium persulfate, silane coupling agent and water-reducing agent with the remaining water to obtain solution B; (3) Mix crushed stone, cement, solution A and solution B, add water according to the moisture content of cement stabilized crushed stone base mixture, mix and transport to paving.

6. The cement-stabilized crushed stone base course according to claim 5, characterized in that, In step (3), the total amount of solution A and solution B added is 0.5-1.5% of the cement mass.

7. The cement-stabilized crushed stone base course according to claim 5, characterized in that, In step (3), the amount of cement added is 3.5%-5% of the mass of cement-stabilized crushed stone.

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