CN112979248A - Sandstone crushed stone C60 low-creep concrete for bridge engineering - Google Patents
Sandstone crushed stone C60 low-creep concrete for bridge engineering Download PDFInfo
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- CN112979248A CN112979248A CN202110341461.5A CN202110341461A CN112979248A CN 112979248 A CN112979248 A CN 112979248A CN 202110341461 A CN202110341461 A CN 202110341461A CN 112979248 A CN112979248 A CN 112979248A
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
- C04B2201/52—High compression strength concretes, i.e. with a compression strength higher than about 55 N/mm2, e.g. reactive powder concrete [RPC]
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Abstract
The invention belongs to the technical field of engineering materials, and particularly relates to sandstone crushed stone C60 low-creep concrete for bridge engineering. The technical points are as follows: the composite material comprises the following components in percentage by mass: 11.37-13.83% of Portland cement, 2.96-3.79% of fired ultrafine fly ash, 2.96-3.79% of ground granulated blast furnace slag powder, 28.31-28.69% of sand, 46.19-46.81% of sandstone macadam, 5.5-5.73% of water, 0.002-0.013% of internal curing agent and 0.016-0.034% of shrinkage-reducing polycarboxylic acid high-performance water reducer. The invention achieves the purpose of reducing the creep of the sandstone crushed stone C60 concrete by utilizing the super superposition effect among components of the fired fine fly ash, the ground granulated blast furnace slag powder and the like and the shrinkage and performance complementary action of the internal curing agent and the shrinkage-reducing polycarboxylic acid high-performance water reducing agent, and realizes the application of the sandstone crushed stone in the low-creep concrete of bridge engineering.
Description
Technical Field
The invention belongs to the technical field of engineering materials, and particularly relates to sandstone crushed stone C60 low-creep concrete for bridge engineering.
Background
The continuous rigid frame bridge is a structural system commonly used in the construction of large-span bridges, has the advantages of simple and convenient construction operation, reasonable stress, economic manufacturing cost and the like, but the continuous rigid frame bridge, particularly the large-span continuous rigid frame bridge, has two common problems of long-term main-span downwarping and beam body cracking in the long-term bridge operation process at home and abroad. The main reasons for causing mid-span downwarping and cracking of the large-span continuous rigid frame bridge are many, and the self creep of concrete is the primary factor for causing the downwarping and cracking of the concrete bridge due to long-term prestress loss.
Research shows that the lithology of the coarse aggregate has obvious influence on the concrete creep, and the higher the elastic modulus of the aggregate is, the lower the porosity is, and the lower the prepared concrete creep is. Compared with the crushed stones with other lithologies, the sandstone crushed stones have low elastic modulus and high porosity, and the prepared concrete creep value can reach more than 2 times of that of the similar limestone crushed stone concrete with the same parent rock strength grade, so that the sandstone crushed stones are difficult to be used in the low-creep concrete of bridges. However, part of bridge works have a problem that the lithological selectivity of the concrete macadam is limited in a short distance due to the restrictions of traffic conditions and the conditions of aggregates for regional concrete. For example, the selectable concrete macadam near part of bridge engineering (within 500 km around) is only sandstone, if limestone or other lithologic macadam is forcibly adopted, high transportation cost needs to be increased, and construction period extension caused by problems of unsmooth transportation and the like in the transportation process further increases engineering construction cost. The preparation of low-creep concrete by adopting sandstone crushed stones is the most direct and economic technical means for solving the problems, but how to reduce the creep of the sandstone crushed stone concrete is a technical problem which is urgently needed to be solved in the field.
In view of the defects of the existing sandstone crushed stone concrete, the inventor develops the sandstone crushed stone C60 low-creep concrete for bridge engineering based on years of abundant experience and professional knowledge of the materials, and cooperates with theoretical analysis to conduct research and innovation, so that the sandstone crushed stone C60 concrete creep is greatly reduced, the 90d creep value of the prepared sandstone crushed stone C60 concrete can approach to that of the limestone crushed stone concrete with the same parent rock strength grade, and is even lower, the feasibility of applying the sandstone crushed stone in the low-creep concrete for bridge engineering is realized, and the sandstone crushed stone concrete has good economic benefit and practical value.
Disclosure of Invention
The invention aims to provide sandstone crushed stone C60 low-creep concrete for bridge engineering, which responds to reduce the creep of sandstone crushed stone C60 concrete by utilizing the super-superposition effect among components such as calcined fine fly ash, ground granulated blast furnace slag powder and the like, and realizes the application of the sandstone crushed stone in the low-creep concrete for bridge engineering.
The technical purpose of the invention is realized by the following technical scheme:
the invention provides sandstone crushed stone C60 low-creep concrete for bridge engineering, which comprises the following components in percentage by mass: 11.37 to 13.83 percent of Portland cement, 2.96 to 3.79 percent of fired ultrafine fly ash, 2.96 to 3.79 percent of ground granulated blast furnace slag powder, 28.31 to 28.69 percent of sand, 46.19 to 46.81 percent of sandstone macadam, 5.5 to 5.73 percent of water, 0.002 to 0.013 percent of internal curing agent and 0.016 to 0.034 percent of shrinkage-reducing polycarboxylic acid high-performance water reducer. The Portland cement is a cementing material of a concrete system, plays a role of a cementing agent and is a key for generating the strength in the concrete, but the Portland cement has certain chemical shrinkage, the higher the doping amount is, the larger the shrinkage is generated, when the Portland cement accounts for 11.37-13.83%, the strength required by the concrete can be provided, meanwhile, the generated chemical shrinkage is smaller, and the compressive strength and the elastic modulus of the concrete in the doping amount range meet the requirements; the calcined ultrafine fly ash contains abundant glass beads, can improve the fluidity of concrete, has a certain promotion effect on the strength and the fluidity of the concrete due to the filling effect of the 'microaggregate', can improve the microscopic morphology of a slurry and an aggregate interface and reduce the creep of the concrete due to the 'volcanic ash' effect of the calcined ultrafine fly ash, but can increase the setting time of the concrete and reduce the early strength when the doping amount of the calcined ultrafine fly ash is too high, has a certain promotion effect on the fluidity and the strength of the concrete when the doping amount of the calcined ultrafine fly ash is 2.96-3.79 percent, reduces the creep degree of the concrete, does not remarkably prolong the setting time, and does not remarkably reduce the early strength. The 'micro aggregate' filling effect of the ground granulated blast furnace slag powder improves the concrete strength, the 'volcanic ash' effect of the ground granulated blast furnace slag powder can improve the microscopic appearance of a slurry and an aggregate interface and reduce the concrete creep, and the 'volcanic ash' effect and the lamination effect of fired ultrafine fly ash generate a synergistic effect and can play a role of 1+1 & gt 2; but when the mixing amount of the ground granulated blast furnace slag powder is too high, the setting time of the concrete is increased, the bleeding rate is increased, and the fluidity is reduced, when the mixing amount of the ground granulated blast furnace slag powder is 2.96-3.79%, the concrete strength is improved to a certain extent, the creep degree of the concrete is reduced, the setting time is not obviously prolonged, the bleeding rate is not obviously increased, and the fluidity is not obviously reduced. The sand is used as the fine aggregate of the concrete system, plays a role in filling gaps among coarse aggregates (broken stones), supporting and constructing the coarse aggregates and hardening the cementing material slurry, can improve the fluidity and the wrapping property of concrete mixtures, can cause the fluidity of grouting materials to be poor and reduce the strength due to excessive sand, has a certain improving effect on the fluidity and the wrapping property of the concrete within the range of 28.31-28.69 percent, and can not reduce the strength of the concrete; the broken stones play a structural role in the concrete, compared with cement slurry, the broken stones are relatively low in compressive creep, after the concrete is hardened, the broken stones and the hardened cement slurry are bonded into a whole, the broken stones which are relatively small in compressive deformation under the action of external force have a good inhibiting effect on the deformation of the cement slurry, and further the creep of the concrete is reduced, however, the mixing amount of the broken stones needs to be within a reasonable range, when the mixing amount of the broken stones is too large, the cement slurry in the concrete can not fully wrap the surfaces of the broken stones, so that the strength is reduced, the creep is increased, when the mixing amount of the broken stones is too large, the problem of homogeneity of the concrete can be caused, further, the strength of the concrete is reduced, the homogeneity of the concrete is good, and the strength is not reduced. The water is a necessary component required by hydration reaction of a cementing material in the concrete and is a necessary component generated by good fluidity of the concrete, a proper amount of water can ensure that the cementing material component in the concrete is fully hydrated and can ensure the fluidity required by concrete construction, the strength of the concrete is reduced and the workability problems of bleeding, segregation and the like can occur if the mixing amount of the water is too large, the fluidity and the strength of the concrete meet the requirements within the range of 5.5-5.73 percent of the water in the concrete, the workability of a concrete mixture is good, and the workability problems of bleeding, segregation and the like do not occur.
Further, the composition comprises the following components in percentage by mass: 11.37 to 13.83 percent of Portland cement, 3 to 3.79 percent of fired ultrafine fly ash, 3 to 3.79 percent of ground granulated blast furnace slag powder, 28.31 to 28.69 percent of sand, 46.19 to 46.81 percent of sandstone, 5.5 to 5.73 percent of water, 0.006 to 0.013 percent of internal oxygen protectant and 0.02 to 0.034 percent of shrinkage-reducing high-performance polycarboxylic acid water reducer.
Further, the composition comprises the following components in percentage by mass: 11.37 to 12.83 percent of Portland cement, 3 to 3.79 percent of fired ultrafine fly ash, 3 to 3.79 percent of ground granulated blast furnace slag powder, 28.31 to 28.59 percent of sand, 46.31 to 46.81 percent of sandstone, 5.5 to 5.73 percent of water, 0.010 to 0.013 percent of internal oxygen protectant and 0.025 to 0.034 percent of shrinkage-reducing high-performance polycarboxylic acid water reducer.
The internal curing agent has good water storage and sustainable water replenishing functions, can provide necessary water for long-term hydration of concrete, inhibits creep increase caused by insufficient late hydration, has good inhibition effect on drying shrinkage of the concrete due to continuous self-water replenishing, but reduces fluidity and strength of the concrete due to excessive internal curing agent, and compared with the concrete without the internal oxygen protective agent, the concrete with 0.002-0.013% of the internal curing agent is reduced in drying shrinkage and creep, and the fluidity and strength are not obviously reduced; the shrinkage-reducing high-performance polycarboxylate superplasticizer has the effects of reducing and reducing creep, can improve the fluidity of concrete and reduce the creep of the concrete, and can prolong the setting time of the concrete and cause the concrete to have the workability problems of bleeding, layering and the like at the same time due to the excessive water reducer; the shrinkage-reducing high-performance water reducing agent is in the range of 0.016-0.034%, can improve the fluidity of concrete and reduce the creep of the concrete, and simultaneously can not cause the problems of greatly prolonging the setting time of the concrete and bleeding and layering.
Furthermore, the portland cement is early-strength type 52.5-grade portland cement. The early-strength type 52.5-grade portland cement is selected to be more beneficial to the generation of the early strength of the concrete, ensure the strength requirement of the early prestress tension of the concrete and simultaneously solve the problem of lower early strength caused by the mixing of the calcined ultrafine fly ash and the ground slag powder.
Furthermore, the burned ultrafine fly ash is collected from flue gas generated after burning coal in a thermal power plant, and the average particle size is less than 5 mu m. The ultrafine fly ash sintered in the particle size range can fill gaps among cement particles to be the most compact, so that the concrete can reach the optimal strength value, the lowest creep and the optimal flow property under the lower content of the ultrafine fly ash sintered.
Further, finely grinding the slag powderIs S105 level fine grinding and granulating blast furnace slag powder, and the specific surface area is more than 600m2The activity index of the catalyst per kg and 28d is more than 110 percent. The selected grade of the grain size ground granulated blast furnace slag powder has the best activity, and the selected grain size ground granulated blast furnace slag powder in the specific surface area range can form good micro-filling effect with powder particles such as cement, fired ultrafine fly ash and the like under a lower mixing amount, so that the concrete can reach the optimal strength value and the lowest creep, and further the crushed rock sand concrete can be applied to a rigid frame bridge.
Furthermore, river sand is selected as the sand, the fineness modulus is 2.6-3.0, the mud content is less than 1.0%, preferably the mud content is less than or equal to 0.5%, the river sand within the fineness modulus is moderate in fineness and reasonable in gradation, and compared with the sand with other fineness moduli, the requirement on concrete fluidity can be met under the condition of lower sand rate and lower consumption of cementing materials, and layering is not suitable, so that the creep control of concrete is facilitated.
Furthermore, the porosity of the sandstone crushed stone is less than or equal to 42 percent, the total content of the needle-shaped flaky particles is less than or equal to 5 percent, and the mud content is less than or equal to 0.5 percent. The lower the porosity of the sandstone crushed stone and the lower the total content of the needle-shaped particles, the lower the amount of slurry required for the concrete mixture to reach a specified fluidity, and the lower the amount of the cementing material used for the concrete, so that the shrinkage and creep of the concrete are smaller, the lower the mud content of the sandstone crushed stone is, and the lower the risk of the shrinkage and creep increase of the concrete caused by the reduction of the interfacial binding power between the cementing material slurry and the aggregate due to the soil doping in the concrete, the increase of the porosity of the hardened slurry of the cementing material, and the like. The void ratio is less than or equal to 42 percent, the total content of the needle flake particles is less than or equal to 5 percent, and the mud content is less than or equal to 0.5 percent. The specific sandstone macadam process adjustment and quality control measures mainly comprise the following steps: 1) the distance between the spacers and the size of the screen holes of the spacer screen of the vibration feeder are increased from 5cm to 8cm, the vibration frequency of the vibration feeder is increased from 1200 times/min to 2600 times/min, and the mud content of the crushed stones is greatly reduced; 2) the secondary crushing and the tertiary crushing of the sandstone crushed stones are adjusted into impact crushing with better crushed stone shaping effect by jaw crushing and cone crushing, the gap between an impact frame and a rotor of the impact crushing is reduced from 20mm to 15mm, the speed of the rotor is increased from 400n/min to 1000n/min, the particle shape of the sandstone in the crushing process is optimized, and the void ratio and the total content of needle-shaped particles of the sandstone are reduced; 3) on the basis of ensuring the capacity requirement, the inclination angle of the screen of the vibrating screen is reduced from 25 degrees to 15 degrees, the number of screen layers is increased from 2 layers to 3 layers, the distribution of all-level crushed stone particles is optimized, and the void ratio and the total content of needle-shaped particles are further reduced. Further, the internal curing agent is sodium polyacrylate, and the water absorption capacity of the internal curing agent is more than or equal to 500 g/g. According to the invention, the super-high water-absorption sodium polyacrylate is selected as the internal curing agent, the water absorption capacity is not less than 500g/g, when the water absorption capacity of the internal curing agent is not less than 500g/g, the optimal internal curing effect can be achieved at a lower mixing amount, if the water absorption capacity of the curing agent is less than 500g/g, the internal curing agent can achieve the corresponding internal curing effect at a higher mixing amount, but the problem of concrete strength reduction is aggravated due to the large mixing amount of the internal curing agent.
Furthermore, the 28d shrinkage ratio of the shrinkage-reducing polycarboxylate superplasticizer is less than or equal to 90 percent. In the invention, the smaller the 28d shrinkage ratio of the shrinkage-reducing polycarboxylic acid high-performance water reducing agent is, the stronger the inhibition effect on the concrete shrinkage and creep when being mixed into the concrete is, and the 28d shrinkage ratio of the shrinkage-reducing polycarboxylic acid high-performance water reducing agent is less than or equal to 90%, the obvious inhibition effect on the concrete shrinkage and creep can be generated under the lower mixing amount, if the 28d shrinkage ratio of the shrinkage-reducing polycarboxylic acid high-performance water reducing agent is more than 90%, the required mixing amount of the shrinkage-reducing polycarboxylic acid high-performance water reducing agent is increased when the corresponding reduction effect is achieved, and the problems of concrete bleeding, segregation and prolonged setting time caused by the increase of the mixing amount are more obvious.
Further, the preparation method of the sandstone crushed stone C60 low-creep concrete for bridge engineering provided by the invention comprises the following steps:
s1, putting sandstone crushed stones, sand and portland cement, fired ultrafine fly ash and ground granulated blast furnace slag powder into a forced mixer in sequence, and then stirring for 30 seconds;
and S2, respectively putting the water and the admixture into a forced mixer to continue mixing for 120 seconds, so that the raw materials are uniformly mixed and stirred to obtain the concrete.
In conclusion, the invention has the following beneficial effects:
1. according to the invention, the fired ultrafine fly ash and the ground slag powder are ultrafine powder particles with different particle sizes, and can be well filled with cement particles in a micro-grading manner, so that the fluidity and the compactness of concrete are improved, the strength of the concrete is improved, the volcanic ash effect can be more fully exerted under the superposition effect of the two types of particles, the microscopic performance of the slurry interface of the aggregate and the cementing material is further optimized, the binding force between the aggregate and the cementing material is improved, and the shrinkage and creep inhibition effect on the concrete is enhanced; the volcanic ash effect superposed by the fired ultrafine fly ash and the ground slag powder can be continued for a long time (more than 14 days) along with the hydration reaction of a cementing material system, the external curing time is generally not more than 7 days in the actual engineering construction, the curing requirements of 14 days and more than 14 days are difficult to achieve, the requirement of the hydration reaction of the concrete in a long age (more than 14 days) can be ensured by doping the internal curing agent, and simultaneously the absorption water continuously released from the internal curing agent timely and effectively inhibits the dehydration and drying shrinkage of the concrete under the supply action of the hardened concrete in the long age, thereby having good inhibition effect on drying shrinkage and creep. The shrinkage-reducing polycarboxylic acid high-performance water reducing agent has dual effects of water reduction and shrinkage reduction, can reduce the surface tension of a pore structure in concrete on the basis of providing good fluidity required by concrete construction pouring, and further has a good inhibiting effect on concrete shrinkage and creep.
2. The sandstone crushed stone C60 low-creep concrete for bridge engineering provided by the invention has the advantages of good fluidity, good workability, strength meeting requirements and low shrinkage and creep, solves the problem of large shrinkage and creep deformation of the conventional sandstone concrete on the premise of meeting basic engineering requirements, has 90d creep degree close to or even lower than that of limestone concrete with the same strength grade, and can be used for low-creep bridge engineering.
Detailed Description
To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the concrete embodiments, characteristics and effects of the sandstone crushed stone C60 low creep concrete for bridge engineering according to the present invention are described in detail below.
The materials used in the examples of the present invention are commercially available as follows:
52.5 grade early strength portland cement: purchased from Guangdong Tai mud (End) Cement, Inc.;
firing ultrafine fly ash and I-grade fly ash: purchased from Guangdong Yangxi power plant;
s105-grade fine-grinding blast furnace slag powder and S95-grade blast furnace slag powder: purchased from Guangdong England;
river sand: purchased from Guangdong mountain;
sandstone crushed stones and limestone crushed stones are purchased from Guangdong Huizhou;
internal oxygen protectant: purchased from basf shares company;
polycarboxylic acid high-performance water reducing agent and shrinkage-reducing polycarboxylic acid high-performance water reducing agent: purchased from Guangdong red wall New materials, Inc.
Example 1
The C60 low-creep concrete suitable for bridge engineering provided by the embodiment is 2480kg, and specifically comprises the following components: 392kg of 52.5 grade early strength portland cement, 49kg of S105 grade ground blast furnace slag powder, 49kg of fired ultrafine fly ash, 702.043kg of river sand, 1145.425kg of sandstone macadam, 0.049kg of internal curing agent, 0.392g of shrinkage-reducing polycarboxylic acid high-performance water reducing agent and 142kg of water.
Wherein, the 52.5-grade early strength portland cement is compounded with the standard requirements of 'general portland cement'; river sand meets the standard requirements of 'sand for construction', the fineness modulus is 2.5-3.0, and the mud content is less than 1.0%; the specific surface area of the ground granulated blast furnace slag powder is more than 600m2/kg, 28d activity index greater than 110%; the sandstone macadam meets the requirements of the existing standard construction pebbles and macadams (GB/T14685) on the type I macadam, the void ratio is less than or equal to 42 percent, the total content of needle-shaped particles is less than or equal to 5 percent, and the mud content is less than or equal to 0.5 percent; the 28d shrinkage ratio of the shrinkage-reducing polycarboxylic acid high-performance water reducing agent is less than or equal to 90 percent, and the average grain diameter of the fired ultrafine fly ash is less than 5 mu m.
The preparation method comprises the following steps:
s1, sequentially putting the sandstone crushed stone, the sand and the portland cement with the mass, the fired ultrafine fly ash and the ground granulated blast furnace slag powder into a forced mixer, and then stirring for 30 seconds;
s2, respectively putting the water, the internal curing agent and the shrinkage-reducing polycarboxylic acid high-performance water reducing agent into a forced mixer, and continuously stirring for 120 seconds to uniformly mix and stir the raw materials to obtain the concrete C2。
Example 2
The C60 low-creep concrete suitable for bridge engineering provided by the embodiment is 2480kg, and specifically comprises the following components: 343kg of 52.5-grade early strength portland cement, 73.5kg of S105-grade fine blast furnace slag powder, 73.5kg of fired ultrafine fly ash, 702.043kg of river sand, 1145.425kg of sandstone macadam, 0.049kg of internal curing agent, 0.392g of shrinkage-reducing polycarboxylic acid high-performance water reducing agent and 142kg of water.
Wherein, the 52.5-grade early strength portland cement is compounded with the standard requirements of 'general portland cement'; river sand meets the standard requirements of 'sand for construction', the fineness modulus is 2.5-3.0, and the mud content is less than 1.0%; the specific surface area of the ground granulated blast furnace slag powder is more than 600m2/kg, 28d activity index greater than 110%; the sandstone macadam meets the requirements of the existing standard construction pebbles and macadams (GB/T14685) on the type I macadam, the void ratio is less than or equal to 42 percent, the total content of needle-shaped particles is less than or equal to 5 percent, and the mud content is less than or equal to 0.5 percent; the 28d shrinkage ratio of the shrinkage-reducing polycarboxylic acid high-performance water reducing agent is less than or equal to 90 percent, and the average grain diameter of the fired ultrafine fly ash is less than 5 mu m; the internal curing agent is sodium polyacrylate with ultrahigh water absorption capacity of more than or equal to 500 g/g.
The preparation method comprises the following steps:
s1, sequentially putting the sandstone crushed stone, the sand and the portland cement with the mass, the fired ultrafine fly ash and the ground granulated blast furnace slag powder into a forced mixer, and then stirring for 30 seconds;
s2, respectively putting the water, the internal curing agent and the shrinkage-reducing polycarboxylic acid high-performance water reducing agent into a forced mixer, and continuously stirring for 120 seconds to uniformly mix and stir the raw materials to obtain the concrete C3。
Example 3
The C60 low-creep concrete suitable for bridge engineering provided by the embodiment is 2480kg, and specifically comprises the following components: 343kg of 52.5-grade early strength portland cement, 73.5kg of S105-grade fine blast furnace slag powder, 73.5kg of fired ultrafine fly ash, 701.885kg of river sand, 1145.182kg of sandstone macadam, 0.245kg of internal curing agent, 0.588g of shrinkage-reducing polycarboxylic acid high-performance water reducing agent and 142kg of water.
Wherein, the 52.5-grade early strength portland cement is compounded with the standard requirements of 'general portland cement'; river sand meets the standard requirements of 'sand for construction', the fineness modulus is 2.5-3.0, and the mud content is less than 1.0%; the specific surface area of the ground granulated blast furnace slag powder is more than 600m2/kg, 28d activity index greater than 110%; the sandstone macadam meets the requirements of the existing standard construction pebbles and macadams (GB/T14685) on the type I macadam, the void ratio is less than or equal to 42 percent, the total content of needle-shaped particles is less than or equal to 5 percent, and the mud content is less than or equal to 0.5 percent; the 28d shrinkage ratio of the shrinkage-reducing polycarboxylic acid high-performance water reducing agent is less than or equal to 90 percent, and the average grain diameter of the fired ultrafine fly ash is less than 5 mu m; the internal curing agent is sodium polyacrylate with ultrahigh water absorption capacity of more than or equal to 500 g/g.
The preparation method comprises the following steps:
s1, sequentially putting the sandstone crushed stone, the sand and the portland cement with the mass, the fired ultrafine fly ash and the ground granulated blast furnace slag powder into a forced mixer, and then stirring for 30 seconds;
s2, respectively putting the water, the internal curing agent and the shrinkage-reducing polycarboxylic acid high-performance water reducing agent into a forced mixer, and continuously stirring for 120 seconds to uniformly mix and stir the raw materials to obtain the concrete C4。
Example 4
The C60 low-creep concrete suitable for bridge engineering provided by the embodiment is 2480kg, and specifically comprises the following components: 282kg of 52.5-grade early strength portland cement, 94kg of S105-grade ground fine blast furnace slag powder, 94kg of fired ultrafine fly ash, 711.649kg of river sand, 1161.111kg of sandstone macadam, 0.235kg of internal curing agent, 0.705g of shrinkage-reducing polycarboxylic acid high-performance water reducing agent and 136kg of water.
Wherein, the 52.5-grade early strength portland cement is compounded with the standard requirements of 'general portland cement'; river sand meets the standard requirements of 'sand for construction', and the fineness modulus2.5-3.0, and the mud content is less than 1.0%; the specific surface area of the ground granulated blast furnace slag powder is more than 600m2/kg, 28d activity index greater than 110%; the sandstone macadam meets the requirements of the existing standard construction pebbles and macadams (GB/T14685) on the type I macadam, the void ratio is less than or equal to 42 percent, the total content of needle-shaped particles is less than or equal to 5 percent, and the mud content is less than or equal to 0.5 percent; the 28d shrinkage ratio of the shrinkage-reducing polycarboxylic acid high-performance water reducing agent is less than or equal to 90 percent, and the average grain diameter of the fired ultrafine fly ash is less than 5 mu m; the internal curing agent is sodium polyacrylate with ultrahigh water absorption capacity of more than or equal to 500 g/g.
The preparation method comprises the following steps:
s1, sequentially putting the sandstone crushed stone, the sand and the portland cement with the mass, the fired ultrafine fly ash and the ground granulated blast furnace slag powder into a forced mixer, and then stirring for 30 seconds;
s2, respectively putting the water, the internal curing agent and the shrinkage-reducing polycarboxylic acid high-performance water reducing agent into a forced mixer, and continuously stirring for 120 seconds to uniformly mix and stir the raw materials to obtain the concrete C5。
Example 5
The C60 low-creep concrete suitable for bridge engineering provided by the embodiment is 2480kg, and specifically comprises the following components: 282kg of 52.5-grade early strength portland cement, 94kg of S105-grade ground fine blast furnace slag powder, 94kg of fired ultrafine fly ash, 711.5kg of river sand, 1160.966kg of sandstone macadam, 0.235kg of internal curing agent, 0.705g of shrinkage-reducing polycarboxylic acid high-performance water reducing agent and 136kg of water.
Wherein, the 52.5-grade early strength portland cement is compounded with the standard requirements of 'general portland cement'; river sand meets the standard requirements of 'sand for construction', the fineness modulus is 2.5-3.0, and the mud content is less than 1.0%; the specific surface area of the ground granulated blast furnace slag powder is more than 600m2/kg, 28d activity index greater than 110%; the sandstone macadam meets the requirements of the existing standard construction pebbles and macadams (GB/T14685) on the type I macadam, the void ratio is less than or equal to 42 percent, the total content of needle-shaped particles is less than or equal to 5 percent, and the mud content is less than or equal to 0.5 percent; the 28d shrinkage ratio of the shrinkage-reducing polycarboxylic acid high-performance water reducing agent is less than or equal to 90 percent, and the average grain diameter of the fired ultrafine fly ash is less than 5 mu m; the internal curing agent is sodium polyacrylate with ultrahigh water absorbabilityThe water absorption capacity is more than or equal to 500 g/g.
The preparation method comprises the following steps:
s1, sequentially putting the sandstone crushed stone, the sand and the portland cement with the mass, the fired ultrafine fly ash and the ground granulated blast furnace slag powder into a forced mixer, and then stirring for 30 seconds;
s2, respectively putting the water, the internal curing agent and the shrinkage-reducing polycarboxylic acid high-performance water reducing agent into a forced mixer, and continuously stirring for 120 seconds to uniformly mix and stir the raw materials to obtain the concrete C6。
Comparative example 1
The low-creep concrete suitable for bridge engineering C60 provided by the comparative example is 2480kg, and specifically comprises the following components: 392kg of 52.5 grade early strength portland cement, 49kg of S95 grade ground blast furnace slag powder, 49kg of I grade fly ash, 702.053kg of river sand, 1145.455kg of limestone macadam, 0.392g of polycarboxylic acid high-performance water reducing agent and 142kg of water.
Wherein, the 52.5-grade early strength portland cement is compounded with the standard requirements of 'general portland cement'; the river sand meets the standard requirements of 'sand for construction', the fineness modulus is 2.5-3.0, and the mud content is less than 1.0%.
The preparation method comprises the following steps:
s1, sequentially putting the sandstone crushed stone, the sand and the portland cement with the mass, the fired ultrafine fly ash and the ground granulated blast furnace slag powder into a forced mixer, and then stirring for 30 seconds;
s2, respectively putting the water and the polycarboxylic acid high-performance water reducing agent into a forced mixer to continue mixing for 120 seconds to uniformly mix and stir the raw materials to obtain concrete C0。
Comparative example 2
The C60 low-creep concrete suitable for bridge engineering provided by the embodiment is 2480kg, and specifically comprises the following components: 392kg of 52.5 grade early strength portland cement, 49kg of S95 grade ground blast furnace slag powder, 49kg of fired ultrafine fly ash, 7102.053g of river sand, 1145.45kg of sandstone macadam, 0.392g of polycarboxylic acid high-performance water reducing agent and 142kg of water.
Wherein, the 52.5-grade early strength portland cement is compounded with the standard requirements of 'general portland cement'; the river sand meets the standard requirements of 'sand for construction', the fineness modulus is 2.5-3.0, and the mud content is less than 1.0%.
The preparation method comprises the following steps:
s1, sequentially putting the sandstone crushed stone, the sand and the portland cement with the mass, the fired ultrafine fly ash and the ground granulated blast furnace slag powder into a forced mixer, and then stirring for 30 seconds;
s2, respectively putting the water and the polycarboxylic acid high-performance water reducing agent into a forced mixer to continue mixing for 120 seconds to uniformly mix and stir the raw materials to obtain concrete C1。
And (3) performance testing:
testing the finished concrete C after molding0～C6The test method of slump, the expansion degree and the bleeding rate is carried out according to the existing standard of 'standard of testing the performance of common concrete mixtures' (GB/T50080), the test method of compressive strength is carried out according to the existing standard of testing the physical and mechanical properties of concrete '(GB/T50081), the test method of shrinkage and the bleeding rate is carried out according to the existing standard of testing the long-term performance and the durability of common concrete' (GB/T50082), and the detailed test results are shown in Table 1:
TABLE 1 finished concrete C0-C6Performance test data of
According to the requirement of DB 32/T2170 technical specification of the low-shrinkage low-creep bridge high-performance concrete, the dry shrinkage of the low-shrinkage low-creep concrete 28d for the bridge is not more than 250 multiplied by 10-6Creep should not be greater than 30X 10 for 90 days-6MPa-1Comparison with this standard, C with limestone macadam0Meets the requirements, adopts C of sandstone crushed stone1Does not meet the requirements. Invention (C)2-C6) For use in connection with engineering sitesLimestone crushed stone concrete (C)0) Compared with the prior art, the concrete has the advantages of higher slump and expansion, higher 28d compressive strength, lower 28d shrinkage and 90d creep and the like. The invention can obviously improve the preparation of concrete (C) by directly adopting sandstone macadam1) The problems of low slump and expansion, high bleeding rate, low 28d compressive strength, and high 28d shrinkage and 90d creep degree which do not meet the requirements exist.
According to the invention, by optimizing key mix proportion parameters and preferably selecting special functional materials, additives and the like, the sandstone crushed rock concrete has the advantages of good flowing property, high compressive strength, low shrinkage and small creep, and when the sandstone crushed rock concrete is used for bridge concrete engineering, the construction performance and strength of the concrete can be ensured, the shrinkage and creep of the concrete are lower than those of the conventional limestone crushed rock concrete, and the engineering quality is ensured.
Specifically, the consumption of the concrete cementing material is low, and the chemical shrinkage caused by hydration of the cementing material can be reduced; the superfine fly ash, the superfine slag powder, the superfine limestone powder and other superfine powder materials are obtained by complex blending and sintering, and the 'micro-grading' effect of the superfine powder materials can be exerted to increase the compactness of a concrete structure, reduce the porosity and reduce the shrinkage and creep; the composite use of the fired ultrafine fly ash and the ultrafine slag powder can play the superimposed volcanic ash effect, improve the micro-morphology of the concrete slurry and the aggregate interface, increase the binding force of the slurry and the aggregate interface and further reduce the concrete creep; the selected internal oxygen protective agent can play a role in continuously supplying hydration water, so that the hydration reaction degree of the concrete in a long-term period is ensured, and the drying shrinkage is reduced; the selected shrinkage-reducing polycarboxylic acid water reducing agent can reduce the surface tension of the early-stage pore structure of the concrete, can effectively inhibit the shrinkage and creep deformation of the concrete compared with other high-performance water reducing agents or high-efficiency water reducing agents, and can reduce the shrinkage and creep of the C60 sandstone concrete to the maximum extent by the aid of the measures.
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. The sandstone crushed stone C60 low-creep concrete for bridge engineering is characterized by comprising the following components in percentage by mass: 11.37-13.83% of Portland cement, 2.96-3.79% of fired ultrafine fly ash, 2.96-3.79% of ground granulated blast furnace slag powder, 28.31-28.69% of sand, 46.19-46.81% of sandstone macadam, 5.5-5.73% of water, 0.002-0.013% of internal curing agent and 0.016-0.034% of shrinkage-reducing polycarboxylic acid high-performance water reducer.
2. The sandstone crushed stone C60 low-creep concrete for bridge engineering according to claim 1, wherein the portland cement is early-strength type 52.5-grade portland cement.
3. The sandstone crushed stone C60 low-creep concrete for bridge engineering according to claim 1, wherein the fired ultrafine fly ash is collected from flue gas generated after combustion of coal fired in a thermal power plant, and has an average particle size of less than 5 μm.
4. The sandstone crushed stone C60 low-creep concrete for bridge engineering according to claim 1, wherein the ground slag powder is S105-grade ground granulated blast furnace slag powder, and the specific surface area of the ground slag powder is more than 600m2The activity index of the catalyst per kg and 28d is more than 110 percent.
5. The sandstone crushed stone C60 low-creep concrete for bridge engineering according to claim 1, wherein the sand is river sand, the fineness modulus is 2.6-3.0, and the mud content is less than or equal to 0.5%.
6. The sandstone crushed stone C60 low-creep concrete for bridge engineering according to claim 1, wherein the sandstone crushed stone has a porosity of less than or equal to 42%, a total content of needle-shaped particles of less than or equal to 5%, and a mud content of less than 1.0%.
7. The sandstone crushed stone C60 low-creep concrete for bridge engineering according to claim 2, wherein the internal curing agent is sodium polyacrylate, and the water absorption capacity of the internal curing agent is not less than 500 g/g.
8. The sandstone crushed stone C60 low-creep concrete for bridge engineering according to any one of claim 1, wherein the 28d shrinkage ratio of the shrinkage-reducing polycarboxylic acid water reducer is less than or equal to 90%.
9. The sandstone crushed stone C60 low-creep concrete for bridge engineering according to claim 1, wherein the preparation method of the concrete is as follows:
s1, putting the sandstone crushed stone, the sand and the silicate cement, the fired ultrafine fly ash and the ground granulated blast furnace slag powder into a forced mixer in sequence, and then stirring for 30 seconds;
and S2, respectively putting the water and the admixture into a forced mixer, and continuously stirring for 120 seconds to uniformly mix and stir the raw materials to obtain the concrete.
10. The sandstone crushed stone C60 low-creep concrete for bridge engineering according to any one of claims 1 to 9, wherein the sandstone crushed stone is treated before use by the following treatment method: setting the vibration frequency of the vibration feeder to 2600 times/min; adopting counterattack for the secondary and third-level crushing of the sandstone crushed stone, wherein the gap between a counterattack frame and a rotor of the counterattack is 15mm, and the speed of the rotor is 1000 n/min; the inclination angle of the vibrating screen is 15 degrees.
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