High-strength and crack-resistant marine mass concrete

Abstract

The application belongs to the field of building materials, and particularly relates to high-strength and anti-cracking marine mass concrete, which comprises 420-480 kg / m 3 of cement, 50-70 kg / m 3 of fly ash floating bead, 25-35 kg / m 3 of micro powder, 700-800 kg / m 3 of sand, 1050-1200 kg / m 3 of stone, 0.5-06 kg / m 3 of retarder, 10-18 kg / m 3 of anti-cracking shrinkage reducing agent, 13-15 kg / m 3 of water reducing agent, 100-115 kg / m 3 of water, wherein the cement comprises low-heat slag Portland cement and sulphoaluminate cement. The concrete of the application not only avoids the generation of concrete temperature stress, but also meets the early and late strength development of the concrete. Under the condition of low water-binder ratio, a dense structure is formed, so that the concrete has high mechanical properties in the later period and the impermeability of the concrete is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building materials, in particular to a high-strength and anti-cracking marine mass concrete. BACKGROUND

[0002] With the continuous development of China's economy and technology, the development of marine resources has become a current trend, and the development and utilization of marine resources must rely on large marine structures. Unlike land engineering buildings, marine environments are constantly subjected to chloride salt, sulfate salt erosion and wave splash tide action, resulting in extremely high requirements for material durability. However, due to the difference in use environment, conventional concrete cannot be directly used as marine concrete, so how to improve the service life of marine concrete in harsh environments has become a research focus.

[0003] As another branch of the field of concrete, mass concrete has great differences in mix design and construction technology from ordinary concrete. Generally, mass concrete uses a lower dosage of cementitious materials and low-activity mineral admixtures to reduce the internal hydration temperature rise. However, the mechanical properties and durability of concrete with the above mix design ideas are generally low, and the application of marine concrete cannot meet the 50-year or even 100-year service life. As we all know, the strength and durability of concrete are positively correlated with the dosage and activity of cementitious materials, and a high dosage of cementitious materials usually leads to easy shrinkage and cracking of concrete. Therefore, applying ordinary high-strength concrete design ideas to marine mass concrete undoubtedly brings problems of cracking and poor durability. Therefore, how to use new technologies and new materials to prepare high-strength and high-anti-cracking marine mass concrete has become a prominent problem in the development of marine concrete. SUMMARY

[0004] The purpose of the present application is to solve the above problems, and provide a high-strength and anti-cracking marine mass concrete.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is:

[0006] A high-strength and anti-cracking marine mass concrete, comprising 420-480 kg / m 3 of cement, 50-70 kg / m 3 of fly ash floating beads, 25-35 kg / m 3 of micro powder, 700-800 kg / m 3 of sand, 1050-1200 kg / m 3 of stone, 0.5-06 kg / m 3 of retarder, 10-18 kg / m 3 of anti-cracking and shrinkage reducing agent, 13-15 kg / m 3 of water reducing agent, 100-115 kg / m 3The cement includes low-heat slag Portland cement and sulphoaluminate cement, and the mass ratio of the low-heat slag Portland cement and the sulphoaluminate cement is (6-8):3.

[0007] Further, the cement is a mixture of 42.5-grade low-heat slag Portland cement and 42.5-grade sulphoaluminate cement in a mass ratio of 7:3.

[0008] Further, the fly ash floating bead has an activity index of greater than or equal to 95% and a loss on ignition of less than or equal to 3%.

[0009] Further, the active silicon dioxide in the micro-powder has a mass fraction of greater than or equal to 94%, an activity index of greater than or equal to 104%, and a specific surface area of greater than or equal to 16000 m 2 / kg.

[0010] Further, the sand is quartz sand with a fineness modulus of 1.9-2.2.

[0011] Further, the stone is basalt or diabase stone with a particle size of 5-20 mm in continuous gradation.

[0012] Further, the retarder is one of boric acid or sodium gluconate.

[0013] Further, the anti-cracking shrinkage reducing agent is prepared by the following method:

[0014] Step 1, dolomite and bauxite are fully ground and mixed in a mass ratio of 1:(0.6-08), and then are placed into a high-temperature furnace and calcined to 1000-1100 DEG C, and then are naturally cooled to room temperature for 6-7 hours, and then are ground by a ball mill for 30 min and passed through a 200-mesh square hole sieve to obtain a mixture A;

[0015] Step 2, phosphogypsum is passed through a 200-mesh sieve, and is fully mixed with the mixture A in a mass ratio of 1:(1-1.2) to obtain the anti-cracking shrinkage reducing agent.

[0016] The present application has the following beneficial effects:

[0017] 1, sulphoaluminate cement and low-heat cement are used in combination, the sulphoaluminate cement has high early strength and micro-expansion characteristics, and a certain amount of retarder is added to delay the hydration time of the sulphoaluminate cement, prevent the internal temperature of the concrete from rising too fast, and generate temperature stress. The low-heat cement has low early strength, and the sulphoaluminate cement provides early strength, and the low-heat cement has a slow heat release rate and continuously increases in late strength, so that the combination of the two not only avoids the generation of temperature stress of the concrete, but also meets the development of early and late strength of the concrete.

[0018] 2. In the concrete mix design, the amount of cementitious material in the concrete is properly increased due to the use of low-heat cement, the high-activity fly ash and microsphere are selected as mineral admixtures according to the principle of closest packing design, the quartz sand and 5-16mm continuous gradation high-strength gravel are selected as aggregate, and the dense structure is formed under the condition of low water-binder ratio, so that the concrete has high mechanical properties in later period and the impermeability of the concrete is improved.

[0019] 3. The prepared anti-cracking and shrinkage reducing agent can react with calcium hydroxide generated by cement hydration to form expansive ettringite, which can avoid the generation of early cracks of the concrete and fill the internal voids of the concrete to improve the impermeability of the concrete; on the other hand, the calcined magnesium oxide can be used as a delayed expansion component to reduce the shrinkage generated by the hydration of the concrete in later period. The prepared high-strength anti-cracking marine mass concrete has the properties of high strength, low hydration heat, no temperature cracks and good durability, has significant application value, and is suitable for marine mass concrete engineering. DETAILED DESCRIPTION

[0020] The principles and characteristics of the present application are described below, and the examples are only used to explain the present application and are not used to limit the scope of the present application.

[0021] The high-strength anti-cracking marine mass concrete of each embodiment of the present application is prepared according to the following method:

[0022] Each raw material is weighed according to Table 1, the weighed cement, fly ash, microsphere, sand, gravel, retarder and anti-cracking and shrinkage reducing agent are poured into a concrete mixer for pre-mixing for 3min, the weighed water reducing agent and water are pre-loaded into a measuring cylinder and fully stirred, and then poured into the mixer for stirring for 10min, so that the high-strength anti-cracking marine mass concrete is obtained. The cement is a mixture of 42.5 low-heat slag portland cement and 42.5 sulphoaluminate cement in a mass ratio of 7:3; the fly ash has an activity index of 96% and a loss on ignition of 2%; the microsphere has an active silicon dioxide content of 95%, an activity index of 107% and a specific surface area of ≥17000m 2 / kg; the sand is quartz sand with a fineness modulus of 2.0; the gravel is basalt with a particle size of 5-20mm continuous gradation; the retarder is boric acid; the water reducing agent is a polycarboxylic acid water reducing agent with a solid content of 30% and a water reducing rate of ≥32%; and the water is tap water.

[0023] The anti-cracking and shrinkage reducing agent of each embodiment of the present application is prepared by the following method:

[0024] Dolomite, bauxite are mixed according to the mass ratio of 1:0.8, and then put into a high-temperature furnace and calcined to 1000-1100 DEG C, and then naturally cooled to room temperature after keeping warm for 6 hours, and then ground by a ball mill for 30 min and passed through a 200-mesh square hole screen to obtain a mixture A; 2) phosphogypsum is passed through a 200-mesh screen, and then mixed with the mixture A according to the mass ratio of 1:1.1 to obtain the anti-cracking shrinkage reducing agent.

[0025] Table 1: The mixing proportion of high-strength and anti-cracking marine mass concrete of examples 1-5 kg / m 3

[0026]

[0027]

[0028] The test results of each performance of the high-strength and anti-cracking marine mass concrete of examples 1-5 are shown in Table 2:

[0029] Table 2: The performance indexes of high-strength and anti-cracking marine mass concrete of examples 1-5

[0030]

[0031] It can be seen from Table 1 and Table 2 that the high-strength and anti-cracking marine mass concrete prepared by the above examples 1-5 not only has good mechanical performance characteristics, but also has small adiabatic temperature rise, meets the construction technical requirements of mass concrete, and the impermeability grade reaches P25 or more, and the 5d dry shrinkage is less than 300*10 -6 It is illustrated that the high-strength and anti-cracking marine mass concrete prepared by the present application has the advantages of high strength, anti-cracking, good durability and the like, and has significant application value.

[0032] The above description is only the preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A high-strength anti-cracking marine mass concrete, characterized by, The cement includes 420-480 kg / m 3 of cement, 50-70 kg / m 3 of fly ash floating beads, 25-35 kg / m 3 of micro powder, 700-800 kg / m 3 of sand, 1050-1200 kg / m 3 of stone, 0.5-06 kg / m 3 of retarder, 10-18 kg / m 3 of anti-cracking shrinkage reducing agent, 13-15 kg / m 3 of water reducing agent, 100-115 kg / m 3 of water, the cement includes low-heat slag Portland cement and sulphate aluminate cement, the mass ratio of the low-heat slag Portland cement and sulphate aluminate cement is (6-8) : 3; the anti-cracking shrinkage reducing agent is prepared by the following method: Step 1, after the dolomite and bauxite are fully ground and mixed at a mass ratio of 1 :(0.6-08), they are put into a high-temperature furnace and calcined to 1000-1100 ℃, and then naturally cooled to room temperature after keeping warm for 6-7 hours, the ball mill is used to grind for 30 min and pass through a 200-mesh square hole sieve to obtain a mixture A; Step 2, the phosphogypsum is passed through a 200-mesh sieve, and is fully mixed with the mixture A at a mass ratio of 1 :(1-1.2) to obtain the anti-cracking shrinkage reducing agent.

2. The high-strength anti-cracking marine mass concrete according to claim 1, characterized by, The cement is a mixture of 42.5-grade low-heat slag Portland cement and 42.5-grade sulphate aluminate cement at a mass ratio of 7:

3.

3. The high-strength, crack-resistant marine mass concrete according to claim 1, characterized in that, The fly ash floating beads have an activity index of ≥95% and a loss on ignition of ≤3%.

4. The high-strength, crack-resistant marine mass concrete according to claim 1, characterized by The active silicon dioxide in the micro powder has a mass fraction of ≥94%, an activity index of ≥104% and a specific surface area of ≥16000 m 2 / kg.

5. The high-strength, crack-resistant mass concrete for marine structures according to claim 1, characterized by The sand is quartz sand with a fineness modulus of 1.9-2.

2.

6. The high-strength, crack-resistant marine mass concrete according to claim 1, characterized by The stone is basalt or diabase stone with a particle size of 5-20 mm continuous gradation.

7. The high-strength, crack-resistant marine mass concrete according to claim 1, characterized by The retarder is one of boric acid or sodium gluconate.

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