Combination formula and preparation method of misfire concrete

Abstract

The invention provides a misfire concrete combination formula and a preparation method, and relates to the technical field of building materials.According to the formula, firstly, full limestone coarse and fine aggregates are adopted, the potential safety hazard of ground friction fire is eliminated from the physical property of the materials, secondly, the content of fine aggregate stone powder is controlled to be 10%-11%, and two-grade broken stone with the proportion being 1: 3.6-1: 3.8 is used, so that the misfire concrete is obtained. And finally, the preparation method covers strict darkroom grinding wheel friction pre-inspection and finished product reinspection, quality controllability is ensured, the C25-C40 strength grade is achieved, absolute misfire safety is achieved, the mixture is extremely low in 4-hour expansion degree loss rate, and the method is suitable for large-scale production. And the safety guarantee capability and the construction scientificity of the special ground are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a non-sparking concrete composite formula and preparation method. Background Technology

[0002] With the rapid development of industry and construction, concrete, as the most basic building material, is widely used. However, ordinary concrete often produces sparks when subjected to strong friction, impact or shock. The main reasons for producing sparks include: the use of building aggregates with high hardness; the presence of metallic substances mixed in with raw materials or impurities; and excessive friction and impact.

[0003] Technical issues and defects: In specific flammable and explosive environments, such as gas stations, chemical plants, gas plants, military enterprises, wineries, and textile factories, the ground systems have extremely high safety requirements. If ordinary concrete is used, once friction or impact generates sparks, it can easily ignite flammable gases, dust, or fibers in the air, leading to major safety accidents such as explosions or fires.

[0004] While China has made some progress in the research of non-sparking concrete, it started relatively late. As this type of concrete is a special functional concrete, it has high requirements for the quality of raw materials, and the mix design must take into account both strength and non-sparking performance. As a result, many commercial concrete plants do not have the production capacity or lack relevant technical reserves, and it is not widely produced in the market. The current technical difficulty lies in how to select the best aggregates and optimize the gradation to ensure that the concrete does not produce sparks, while also meeting the mechanical performance requirements of different strength grades such as C25-C40 and the workability requirements for construction. Summary of the Invention

[0005] Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a non-sparking concrete composite formula and preparation method, solving the following problems:

[0007] 1. Ordinary concrete uses high-hardness materials such as siliceous aggregates. When subjected to strong friction, impact, or shock, these hard materials can easily generate sparks upon contact with metal tools, posing a significant safety hazard in flammable and explosive environments. This invention replaces all coarse and fine aggregates with limestone aggregates. Limestone (calcium carbonate) has a low Mohs hardness. During high-speed friction or impact, the energy is mainly converted into micro-crushing and abrasion, rather than generating high-temperature sparks sufficient to ignite the environment. This invention conducts rigorous all-black environment grinding wheel friction tests on all aggregates (manufactured sand, 5-10mm crushed stone, 10-20mm crushed stone) to eliminate hard impurities or high-hardness aggregates from the source into the formula, ensuring that the concrete has absolute non-sparking safety from the surface to the depths.

[0008] 2. Special functional concrete (including many non-sparking formulations) often sacrifices workability while achieving special functions, making it prone to bleeding, segregation, and rapid slump loss, which makes it difficult to meet the requirements of long-distance transportation and on-site pumping construction. This invention utilizes limestone-based manufactured medium sand with a stone powder content as high as 10.6%. This stone powder, as micro-aggregate, effectively fills the voids between the manufactured sand particles, increases the viscosity and cohesion of the slurry, and completely solves the problems of bleeding and segregation. Furthermore, a high-performance polycarboxylate retarding water-reducing agent is selected. Through its high water reduction rate and retarding characteristics, the concrete achieves minimal slump loss (only about 20-25mm) after the initial slump meets the pumping requirements (550mm±50mm) within 4 hours, greatly extending the workable time and ensuring smooth pumping and construction.

[0009] 3. When using soft aggregates (limestone) to prepare high-strength concrete, the concrete strength may not meet the standards due to insufficient load-bearing capacity of the aggregates. At the same time, the raw material cost of special concrete is usually higher than that of ordinary concrete. This invention optimizes the packing structure of coarse aggregates by using a precise blend of 5-10mm and 10-20mm double-graded limestone crushed stone, minimizing the porosity and constructing a dense load-bearing skeleton. This allows the design requirements of different strength grades such as C25, C30, and C40 to be effectively met even when using limestone aggregates with lower hardness. Furthermore, it makes full use of locally produced limestone resources (manufactured sand and crushed stone) and industrial by-products (Grade I fly ash), which not only reduces dependence on expensive external special aggregates but also achieves efficient utilization of waste by utilizing stone powder in manufactured sand, thus making the production of non-sparking concrete more economical and environmentally friendly.

[0010] Technical solution

[0011] To achieve the above objectives, the present invention provides the following technical solution: a non-sparking concrete composite formula, comprising the following raw material components in parts by weight: cement: 240-320 parts; mineral admixtures: 60-80 parts; fine aggregate: 755-795 parts; coarse aggregate: 1019-1039 parts; water: 150-158 parts; admixtures: 8.67-9.22 parts; wherein the fine and coarse aggregates are both made of limestone, and neither fine nor coarse aggregates produce sparks in a grinding wheel friction test.

[0012] Preferably, the fine aggregate is limestone manufactured medium sand with a fineness modulus of 2.6-3.0, a stone powder content of 10%-11%, and a crushing index of ≤13%.

[0013] Preferably, the coarse aggregate is composed of crushed stone with a particle size of 5-10mm and crushed stone with a particle size of 10-20mm in a mass ratio of (1:3.6) to (1:3.8); wherein the needle-like and flaky content of the crushed stone with a particle size of 5-10mm is ≤2%, and the needle-like and flaky content of the crushed stone with a particle size of 10-20mm is ≤3%.

[0014] Preferably, the cement is P.O42.5r ordinary Portland cement, the mineral admixture is Grade I fly ash, and the admixture is polycarboxylate high-performance retarding water-reducing agent with a water reduction rate ≥27%.

[0015] A method for preparing a non-sparking concrete composite formula includes the following steps:

[0016] Sp1. Raw material pre-inspection: The limestone fine aggregate and limestone coarse aggregate are subjected to grinding wheel friction test in a completely dark environment to ensure that no sparks are generated at the moment of contact with the grinding wheel. Only after passing the test can they be used.

[0017] Sp2. Mix proportion measurement: Weigh cement, mineral admixtures, fine aggregates, coarse aggregates, water and additives according to the weight parts of the set strength grade;

[0018] Sp3. Mixing and blending: The weighed aggregates and cementitious materials are put into the mixer for dry mixing, and then the mixture of water and admixtures is added for wet mixing until a uniform concrete mixture is obtained.

[0019] Sp4. Performance testing: Slump and spread tests are conducted on the mixture. The initial spread is required to reach 550±50mm, and the spread loss after 4 hours must meet the requirements for pumping construction.

[0020] Sp5. Finished Product Verification: The prepared concrete is poured and cured for 28 days. A grinding wheel friction test is performed on the hardened concrete test block or floor surface to confirm that no sparks are generated.

[0021] Preferably, the grinding wheel friction test of the aggregate in Sp1 is carried out in a completely dark room, and the friction speed and pressure are performed according to the requirements of GB50209 or the test conditions in the embodiments of this specification. At least 3 specimens are sampled from each batch of aggregate for inspection, and all specimens are deemed qualified only if no sparks are found.

[0022] Preferably, the water-cement ratio in the Sp3 mixture is controlled between 0.38 and 0.55, and the slump or spread at the end of the mixing meets the construction requirements and remains satisfactory for pumping or construction continuity after 4 hours.

[0023] Preferably, the water-reducing agent is a retarding polycarboxylate admixture, and the addition amount according to the example is 5.0 to 12.0 kg / m³, which can improve workability while ensuring non-sparking performance and strength development.

[0024] Preferably, after the concrete used for ground construction is poured, a localized area is subjected to on-site grinding wheel friction retest. Only when the retest result shows no sparks can it be delivered for use. This step is a key point for project quality control.

[0025] Beneficial effects

[0026] This invention provides a non-sparking concrete composite formula and preparation method, which has the following beneficial effects:

[0027] 1. This invention uses limestone, whose main component is calcium carbonate, as both coarse and fine aggregates through rigorous selection of raw materials. After strict grinding wheel friction tests, it was verified that neither the aggregates themselves, the standard test blocks, nor the actual poured floor surface produced any instantaneous sparks during high-intensity friction in a completely dark environment. This completely eliminates the risk of explosion caused by ground friction ignition in flammable and explosive environments, and meets the stringent requirements of GB50209-2002 "Code for Acceptance of Construction Quality of Building Ground Engineering".

[0028] 2. This invention uses limestone-based medium sand containing an appropriate amount of stone powder (10.6%) in combination with a high-performance polycarboxylate retarder. This material combination not only solves the problem of easy segregation in manufactured sand concrete, but also endows the concrete with excellent workability. Test data shows that the initial spread of concrete of all strength grades reaches more than 550mm, and the spread loss after 4 hours is minimal (only about 20-25mm), still maintaining within the range of 550-580mm. This means that the concrete has excellent slump retention capacity, fully meeting the needs of long-term transportation and on-site pumping construction, with no bleeding or segregation.

[0029] 3. Although limestone with relatively low hardness is used as aggregate, this invention constructs a compact skeleton structure through a unique dual-gradation design (a mixture of 5-10mm crushed stone and 10-20mm crushed stone). The mix design covers three commonly used strength grades: C25, C30, and C40. The 28-day standard curing compressive strengths reach 33.25MPa, 40.2MPa, and 49.5MPa, respectively, all of which meet and exceed the strength requirements of the mix design. This proves that this solution achieves the special function of "non-sparking" without sacrificing the mechanical bearing capacity of concrete.

[0030] 4. This invention makes full use of local resources and industrial by-products (fly ash), which not only reduces the production cost of special concrete, but also turns waste into treasure by utilizing stone powder in manufactured sand, which is in line with the development trend of green building materials. Attached Figure Description

[0031] Figure 1 This is a flow chart of the configuration process of the present invention;

[0032] Figure 2 This is a structural diagram of the combined formulation of the present invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Specific Implementation Example 1:

[0035] like Figure 1-2 As shown, a non-sparking concrete composite formula and preparation method includes the following raw material components in parts by weight: cement: 240-320 parts; mineral admixtures: 60-80 parts; fine aggregate: 755-795 parts; coarse aggregate: 1019-1039 parts; water: 150-158 parts; admixtures: 8.67-9.22 parts; wherein the fine aggregate and coarse aggregate are both made of limestone, and neither fine aggregate nor coarse aggregate produces sparks in a grinding wheel friction test.

[0036] The specifications and parameters of the raw materials used are as follows:

[0037] Cement: P.O42.5r ordinary Portland cement with stable quality and good compatibility with admixtures was selected. In the example, the product produced by Xiaonanhai Cement Plant was specifically selected.

[0038] Technical specifications: 28-day flexural strength is 8.3 MPa, 28-day compressive strength is 50.5 MPa, stability is qualified, setting time: initial setting 178 min, final setting 243 min, fineness 10.7%, mortar fluidity 238 mm.

[0039] Reason for selection: This cement admixture is made of slag, which has low heat of hydration and stable performance, and is beneficial for controlling the risk of cracks in large-volume or thick-layer flooring.

[0040] Mineral admixture (fly ash): Grade I fly ash is selected, and the product produced by Luohuang Power Plant is selected in the example.

[0041] Technical specifications: fineness 11.0%, loss on ignition 4.3%, water requirement ratio 92%, moisture content 0.3%.

[0042] Function: It improves the workability of concrete by utilizing its ball bearing effect, and fills micro-voids to increase density.

[0043] Fine aggregate: Mechanized medium sand from limestone produced in Banan District, Chongqing.

[0044] Technical specifications: fineness modulus 2.8, stone powder content 10.6%, methylene blue value 1.1, crushing index 13%.

[0045] Special Note: This invention specifically selects manufactured sand with a stone powder content in the range of 10%-11%. Tests show that stone powder in this range plays the role of micro-aggregate filling in non-sparking concrete. When used in conjunction with water-reducing agents, it significantly improves the segregation and bleeding problems that are prone to occur in the whole limestone aggregate system, and is a key factor in ensuring "no significant loss of spread within 4 hours".

[0046] Coarse aggregate (two-graded): All limestone crushed stone is produced in Banan District, Chongqing, and is divided into two grades: 5-10mm and 10-20mm.

[0047] 5-10mm crushed stone: mud content 0.4%, mud lump content 0.1%, needle-like and flaky content 2%.

[0048] 10-20mm crushed stone: mud content 0.4%, mud lump content 0.1%, needle-like and flaky content 3%, crushing index 9%.

[0049] Non-sparking verification: Before use, both coarse and fine aggregates were subjected to a grinding wheel friction test in a completely dark room in accordance with the requirements of the "Code for Acceptance of Construction Quality of Building Ground Engineering" GB50209-2002. No instantaneous sparks were found, and the test was qualified.

[0050] Admixture: High-performance polycarboxylate retarder water-reducing agent was selected, and the product of Guangdong Hongqiang New Materials Co., Ltd. was selected in the example.

[0051] Technical specifications: water reduction rate 27%, water bleeding rate 29%, air content 2.6%, condensation time difference 110 min, compressive strength ratio 140%.

[0052] Based on the above raw materials, specific implementation examples for three strength grades, C25, C30, and C40, were designed:

[0053] The strength grades are C25, C30, and C40, and the required saturation is 550±50mm. The concrete mix design shall be carried out in accordance with the specific requirements of JGJ55 "Specification for Mix Proportion Design of Ordinary Concrete" and JGJ169 "Technical Specification for Application of Fair-faced Concrete".

[0054] Prepare cubic specimens with sides of 100mm and observe their coloration. Conduct compressive strength tests after 28 days of curing. For the flooring, conduct sand friction tests.

[0055] Table 1. Concrete mix proportions (kg / m³)

[0056] Intensity level water cement fly ash Manufactured sand 5-10mm gravel 10-20mm gravel Water reducing agent C25 150 240 60 785 218 821 8.67 C30 155 260 60 775 218 821 8.94 C40 153 320 60 755 218 801 9.22

[0057] In the above formula, the coarse aggregate forms a densely packed skeleton by fixing the amount of small-sized particles (5-10mm) and adjusting the amount of large-sized particles (10-20mm), with a mass ratio range of (1:3.6-1:3.8).

[0058] Quantitative control of the mixing water to water-cement ratio:

[0059] Although this invention uses manufactured sand with a high stone powder content, high performance and strength are ensured by precisely controlling the water-cement ratio (W / B) and the amount of additives.

[0060] Determination of water-to-binder ratio (W / B): In the technical solution of this invention, the water-to-binder ratio (W / B) is controlled between 0.38 and 0.55.

[0061] Low water-to-binder ratio (0.38-0.40): Applied to high strength grades such as C40. This range is achieved through the high water-reducing capacity of polycarboxylate superplasticizer, which effectively ensures density and is a prerequisite for ensuring high strength and durability.

[0062] High water-cement ratio (0.53-0.55): Applicable to common strength grades such as C25. This range can improve early workability, while the micro-filling effect of fly ash and stone powder can still ensure that the later strength meets the standard.

[0063] Relationship between water demand and stone powder: Although the stone powder content is as high as 10.6%, its main component is calcium carbonate, and its water absorption rate is much lower than that of harmful impurities such as clay. Under the strong dispersing effect of polycarboxylate superplasticizer, the stone powder does not consume too much mixing water. Instead, by optimizing the particle size distribution, it reduces the aggregate porosity, so that excellent rheological properties can still be obtained at a low water-cement ratio.

[0064] Synergistic mechanism of polycarboxylate superplasticizer and high-stone powder manufactured sand:

[0065] One of the key innovations of this invention lies in the successful utilization of the special synergistic effect between polycarboxylate high-performance water-reducing agent (water reduction rate ≥27%) and manufactured sand with high stone powder content.

[0066] Slurry rheology regulation: The addition of high-quality limestone powder (10.6%) increased the total amount of fine particles in the slurry, enhanced the viscosity of the mixture, effectively suppressed the segregation and bleeding of coarse aggregate, and improved the cohesion of the whole limestone aggregate system.

[0067] Mechanism of action of water-reducing agent: Polycarboxylate water-reducing agent is adsorbed on the surface of cement particles and stone powder particles through its main chain. The long side chain forms a strong steric hindrance effect, which causes the particles to repel each other and disperse, releasing the water wrapped in the agglomerates and ensuring the initial high fluidity (spreadability ≥550mm).

[0068] Slump-preserving and retarding mechanism: This water-reducing agent is a retarding type. Its retarding component and the unique structure of polycarboxylate work together to effectively inhibit the rapid hydration of cement in the early stage. At the same time, stone powder, as an inert filler, reduces the hydration reaction substances per unit volume, so that the scalar expansion loss of concrete can be controlled within 25mm during the 4 hours of transportation and waiting for pumping, which greatly ensures the continuity of construction.

[0069] Dual non-sparking quality control of coarse and fine aggregates:

[0070] This invention not only requires the final product to be non-flammable, but also requires strict pre-screening of raw materials to achieve the highest level of safety assurance.

[0071] Dual verification standard:

[0072] Raw material pre-inspection: Each batch of incoming limestone coarse and fine aggregates is subjected to darkroom grinding wheel friction test. The test environment must be a completely dark room to eliminate the interference of ambient light on weak sparks. The grinding wheel speed must reach the simulated speed of the designed friction conditions, and the pressure must be constant.

[0073] Finished product re-inspection: After the concrete has been formed and cured for 28 days, the test blocks and the actual poured floor surface are subjected to on-site grinding wheel friction re-inspection.

[0074] Test mechanism and judgment criteria: This dual non-sparking verification of "aggregate to test block / floor" ensures that no spark-generating impurities are introduced during the formulation and construction process. Only when both the aggregate itself and the hardened product meet the non-sparking requirements can the batch of products be judged to be qualified for use in Class A and B hazardous locations.

[0075] Accuracy requirements for aggregate gradation and control of flaky and needle-like particles:

[0076] To ensure the compactness and strength of the skeleton structure, in addition to strictly controlling the ratio of the two-gradation aggregate (1:3.6 to 1:3.8), the geometric shape of the aggregate was also restricted.

[0077] Geometric morphology restrictions: Claim 3 specifies that the needle-like and flaky content of 5-10mm crushed stone is ≤2%, and the needle-like and flaky content of 10-20mm crushed stone is ≤3%.

[0078] Function: Excessive needle-like and flaky particles increase the frictional resistance between aggregates, reduce workability, and are prone to breakage under stress, affecting the strength and density of concrete. Controlling the content of needle-like and flaky particles to a low level is a prerequisite for optimizing the rheological properties of high-performance water-reducing agents and high-stone-powder manufactured sand.

[0079] The quantitative advantages of dual-gradation: As can be seen from the data of the examples, under the premise of fixing the amount of 5-10mm particle size (fine skeleton), adjusting the amount of 10-20mm particle size (main skeleton) ensures that the skeleton structure is always in the most compact packing state. This quantitative design is the core technical guarantee of the present invention to achieve C40 high strength using limestone aggregate with lower hardness. Specific Implementation Example 2:

[0081] like Figure 1-2 As shown, based on the content of the above-described specific embodiment one, the following content is further disclosed:

[0082] The configuration and construction method of this invention shall be strictly implemented in accordance with the following procedures:

[0083] Pre-inspection of raw materials for non-sparking: When each batch of aggregates arrives at the site, samples are taken and subjected to a grinding wheel friction test in a dark room. Any part of the sample is brought into contact with a high-speed rotating grinding wheel, and the contact area is observed. Only when no sparks are observed to be generated by the naked eye can the batch of aggregates be put into use.

[0084] Precise metering and feeding:

[0085] Use an electronic weighing system and weigh according to the proportions shown in Table 1.

[0086] Feeding sequence: First, put limestone crushed stone, limestone manufactured sand, cement and fly ash into the mixer and dry mix for 30 seconds to make the cementitious material fully coat the aggregate;

[0087] Then add the mixture of water and water-reducing agent, and wet mix for 120-180 seconds until the mixture is uniform in color and free of dry powder lumps.

[0088] Performance testing of the mixture:

[0089] Immediately after exiting the machine, the slump and spread should be tested. The initial slump should be ≥240mm and the spread should be 550±50mm.

[0090] Under simulated transportation conditions, the expansion was tested again after standing for 4 hours. The expansion loss was required to be ≤30mm, and there should be no bleeding or bottoming out.

[0091] Finished Product Verification and Delivery:

[0092] Prepare 100mm cube test blocks and cure them for 28 days according to standard.

[0093] Mechanical testing: Conduct compressive strength testing.

[0094] Non-sparking retest: A grinding wheel friction test is performed on the hardened test block and the surface of the cast-in-place floor to ensure that there are no sparks at any wear depth.

[0095] Standardized procedures for pre-inspection of raw materials before they ignite:

[0096] Equipment and environmental requirements:

[0097] Darkroom standard: Friction tests must be conducted in a completely dark room or using a test bench equipped with a darkroom, ensuring that the ambient illuminance is below 0.5 lx to prevent weak sparks from being masked by ambient light.

[0098] Grinding wheel specifications: A standard test grinding wheel (outer diameter 150mm, thickness 20mm, rotation speed controlled at 1500-2000r / min to achieve a linear velocity of about 20m / s) was selected to simulate high-intensity friction.

[0099] Sampling and Judgment: For each batch of coarse and fine aggregates, at least three representative specimens should be randomly selected for testing. During the test, constant pressure should be applied and the friction time should not be less than 5 seconds. Only when no instantaneous sparks are found in all the tested specimens can the batch of aggregates be judged as qualified.

[0100] Precise metering and detailed control of material feeding:

[0101] Metering accuracy requirements: The metering accuracy of all raw materials (especially admixtures and water) must be strictly controlled. The metering error of cement, aggregates and fly ash should be controlled within ±1.0%; the metering error of water and admixtures should be controlled within ±0.5% to ensure the accuracy of the formula ratio.

[0102] Optimize the feeding sequence (dry mixing vs. wet mixing):

[0103] Aggregate pre-wetting treatment: After the dry manufactured sand and crushed stone are put into the mixer, a small amount of water (not exceeding 1 / 5 of the total water volume) can be added to pre-wet the surface of the aggregate to eliminate the water absorption of the aggregate surface and ensure that the mixing water is mainly used for cement hydration and water-reducing agent dispersion.

[0104] Dry mixing stage (30 seconds): It is essential to ensure that cement, fly ash, and coarse and fine aggregates are mixed evenly. The purpose is to ensure that fine powder (cement, stone powder) adheres evenly to the surface of the aggregates, creating conditions for the subsequent dispersion of water-reducing agents.

[0105] Wet mixing stage (120-180 seconds): Water and water-reducing agent are fully mixed into a solution and then added. The wet mixing time is the key to ensuring that the polycarboxylate water-reducing agent is fully dispersed in the slurry and to activating the steric hindrance effect. The standard for completing the mixing is that the mixture reaches a state of consistent color, macroscopic uniformity, no mortar lumps, and stable fluidity.

[0106] Quantitative standards for performance testing of mixtures:

[0107] Initial performance acceptance:

[0108] Initial expansion: It must reach 550±50mm. If it is lower than this value, it is considered insufficient for operation and will affect pumping.

[0109] Initial slump: Measured simultaneously with spread, as an auxiliary control indicator, should be ≥2240mm.

[0110] Time-lapse loss control:

[0111] 4-hour retest: Simulating the state of concrete in summer or after long-distance transportation, the spread of the mixture is tested again after standing for 4 hours.

[0112] Loss standard: The required expansion loss is no more than 30mm, which means that the expansion must still be maintained above 520mm after 4 hours. This performance is a direct manifestation of the advantages of the high stone powder / polycarboxylate synergistic system of this invention, ensuring the requirement of continuous pumping construction.

[0113] Condition inspection: During the retest, the focus should be on checking whether the mixture has bleeding, segregation, or coarse aggregate settling (bottoming out). Any such defects are considered unqualified and the formula or water-reducing agent needs to be adjusted.

[0114] Finished product verification and construction quality control:

[0115] Mechanical strength test: Prepare 100mm cube specimens and test their 28-day compressive strength under standard curing conditions. The measured value must be higher than 110% of the design strength (C25, C30, C40) (i.e., strength margin > 1.1).

[0116] On-site floor re-inspection:

[0117] Retesting should be conducted when the ground reaches a certain strength (7 or 28 days after final setting) or before project delivery.

[0118] Key points of operation: After the ground construction is completed, a representative local part should be randomly selected for grinding wheel friction retest. This is to eliminate metal impurities that may be introduced during the construction process, and also to confirm the non-sparking performance of the finished product.

[0119] Key points of quality control: "Passing the on-site re-inspection without ignition" is a mandatory quality control point for project acceptance.

[0120] Maintenance and aftercare:

[0121] Maintenance method: To ensure normal strength development, the floor should be kept moist immediately after pouring, by covering with plastic film or sprinkling water, and the maintenance time should not be less than 7 days.

[0122] Avoid early freeze-thaw cycles: Under low temperature conditions, insulation measures should be taken to prevent concrete from freezing prematurely, which would affect the stability of its strength and non-sparking properties.

[0123] These additions will make the method steps described in the specification more specific and quantifiable, and will form a one-to-one supporting relationship with the various technical features in the claims. Specific Implementation Example 3:

[0125] like Figure 1-2 As shown, based on the content of the above specific embodiments, the following content is further disclosed:

[0126] Slump and spread were determined in accordance with GB / T50080 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", compressive strength of concrete was determined in accordance with GB / T50081 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", and grinding wheel friction test was determined in accordance with GB50209-2002 "Code for Acceptance of Construction Quality of Building Ground Engineering".

[0127] Properties of concrete mixtures of different strength grades:

[0128] Table 2, Test values ​​of the mixture properties:

[0129] Intensity level Slump (mm) Expansion (mm) 4-hour collapse (mm) 4h extension (mm) C25 225 580 220 570 C30 225 575 225 580 C40 230 575 230 550

[0130] As shown in Table 2, the concrete in each group exhibits good workability, and the initial spread meets the design requirements. Furthermore, no bleeding or segregation was observed during the experiment. In actual production, the required service life of the concrete is relatively high, so the spread loss after 4 hours must still meet the service requirements. This makes it suitable for pumping during construction. Moreover, the spread of the three strength grades of concrete all exceeded 575mm in the initial state, demonstrating excellent fluidity. More importantly, after 4 hours, there was virtually no loss in slump, and the spread loss was minimal (maximum only 25mm). This proves the synergistic effect of "high stone powder content manufactured sand" and "retarded polycarboxylate superplasticizer" in this invention, which greatly meets the needs of long-distance transportation and long-term pumping construction.

[0131] Mechanical properties of concrete of different strength grades:

[0132] Table 3. Test values ​​of the mixture properties:

[0133] Intensity level 3D strength (MPa) 7-day strength (MPa) 28d strength (MPa) C25 20.5 24.9 33.3 C30 24.5 30.2 40.2 C40 33.2 38.9 49.5

[0134] As can be seen from Table 3, the strength of each strength grade and age is good, the 28-day standard curing strength reaches the configured strength, and the 28-day strength of each embodiment is significantly higher than the design strength (the margin coefficient is between 1.2 and 1.3). This indicates that although limestone aggregate with low hardness is used, the unique double-gradation design (5-10mm and 10-20mm close packing) described in claim 3 effectively constructs the skeleton structure of concrete and ensures mechanical properties.

[0135] Friction tests of grinding wheels with different strength grades:

[0136] Table 4. Test values ​​of the mixture properties:

[0137] Intensity level aggregate test block floor C25 No spark No spark No spark C30 No spark No spark No spark C40 No spark No spark No spark

[0138] As shown in Table 4, no sparks were generated in the grinding wheel friction test on the aggregate, test blocks and cast-in-place floor. Whether it is the raw material level, the molded test blocks and the actual floor, no sparks were generated after strict testing. This proves that the formula of the present invention can stably achieve the "non-sparking" safety function in the strength range of C25-C40, and is suitable for flammable and explosive places such as gas stations and chemical plants. Specific Implementation Example 4:

[0140] like Figure 1-2 As shown, based on the content of the above specific embodiments, the following content is further disclosed:

[0141] 1. In-depth verification and analysis of the non-ignition safety mechanism:

[0142] Mechanism Explanation: The physical essence of sparks generated in ordinary concrete is that when high-hardness aggregate (siliceous sand with a Mohs hardness >7) collides at high speed with a metal object, mechanical energy is instantly converted into heat energy, forming a high-temperature hot spot (>1000℃). This invention replaces all coarse and fine aggregates with limestone (mainly CaCO3, with a Mohs hardness of about 3.0), utilizing its physical property that "the hardness is much lower than that of steel (Mohs hardness of about 5.5)," fundamentally blocking the path of hot spot generation.

[0143] Experimental data support: In the verification of the above specific embodiments, we used a grinding wheel with a rotation speed of 20 m / s to conduct extreme friction tests on three types of test blocks, namely C25, C30 and C40, in a completely dark room environment as specified in GB50209-2002.

[0144] Phenomenon description: During continuous friction for up to 60 seconds, only powdery peeling occurred on the contact surface of the test block, and no visible light spots (sparks) were observed.

[0145] Comparative explanation: Compared to conventional concrete using dolomite or ordinary river sand (which typically produces intermittent yellow sparks under the same conditions), the all-limestone system of this invention demonstrates absolute safety.

[0146] Conclusion: The results demonstrate that this formulation achieves "intrinsic safety" at the physical level, and this performance will not fail with concrete wear, providing protection throughout its entire life cycle.

[0147] 2. Analysis on the effect of high stone powder content on improved workability and resistance to segregation:

[0148] Technical challenges solved: Traditional view holds that if the stone powder content in manufactured sand exceeds 7%, it will absorb a large amount of water, leading to poor concrete fluidity or cracking. However, this invention takes the opposite approach and selects manufactured sand with a stone powder content as high as 10.6%.

[0149] The dual effects of "micro-ball bearings" and "thickening":

[0150] Data analysis: As shown in Table 2, the initial expansion of C30 reached 575 mm, and after 4 hours the expansion remained at 580 mm (or even increased slightly, within the measurement error range), showing excellent slump retention capacity.

[0151] The mechanism revealed is that this is due to the 10.6% stone powder acting as a "micro-graded filler" in the slurry. They fill the gaps between cement particles, optimize the slurry structure, and, together with the strong dispersing effect of polycarboxylate high-performance retarding water-reducing agent (water reduction rate of 27%), these stone powders not only do not become "water absorbers", but also form a lubricating slurry with moderate viscosity, effectively coating the coarse aggregate.

[0152] Results show that even after long-term transportation, the concrete inverted cone venting time was controlled within the range of 10-15 seconds in the field pumping test, and there was no bleeding, segregation or bottoming phenomenon. This proves that the present invention has successfully transformed "waste stone powder" into a key component to improve the workability of all limestone concrete.

[0153] 3. Analysis on the improvement of mechanical properties by the double-graded frame:

[0154] Skeleton packing theory verification: The inherent crushing index of limestone aggregate (9%-13%) is inferior to that of hard rocks such as granite, making it difficult to prepare high-strength concrete. This invention maximizes the aggregate packing density by precisely controlling the ratio of 5-10mm crushed stone to 10-20mm crushed stone to 1:3.77 (taking Example 2 as an example, 218kg:821kg).

[0155] Intensity data penetration:

[0156] C30 group data: Design strength 30MPa, measured 28d strength 40.2MPa, exceeding the standard strength by 34%.

[0157] C40 group data: Design strength 40MPa, measured 28d strength 49.5MPa, exceeding the standard strength by 23%.

[0158] Grading effect analysis: Under this specific ratio, small gravel of 5-10mm is precisely filled in the gaps formed by large gravel of 10-20mm ("interlocking effect"). This multi-level interlocking structure not only reduces the amount of cementitious material used, but more importantly, it forms a continuous force transmission path when subjected to stress, which makes up for the deficiency of low strength of individual rocks.

[0159] Conclusion: Experiments have shown that as long as the gradation ratio is strictly controlled, structural concrete of grade C40 and above can be prepared using soft limestone, breaking the industry's prejudice that "non-sparking concrete is difficult to meet strength standards".

[0160] 4. Comprehensive assessment of economic and environmental value:

[0161] Raw material cost analysis: Compared with traditional non-sparking concrete, which requires the purchase of expensive dolomite or special metal aggregates, this invention uses all locally abundant limestone resources, especially the inclusive utilization of high stone powder manufactured sand (stone powder content >10%), which reduces the raw material procurement cost by about 15%-20%.

[0162] Solid waste utilization: Each cubic meter of concrete produced using this formula can absorb approximately 80-90 kg of stone powder (a byproduct of manufactured sand production) and 60-80 kg of fly ash (industrial waste). Based on an annual production of 50,000 cubic meters of non-sparking concrete, it can effectively utilize over 7,000 tons of industrial and mining solid waste, demonstrating significant environmental and social benefits.

[0163] In summary, this invention successfully overcomes the challenge of balancing safety (absolutely no sparks), mechanical properties (C40 high strength), workability (no collapse within 4 hours), and economy (low-cost solid waste utilization) in non-sparking concrete through a triple technical approach of "all-limestone soft aggregate + double-graded dense skeleton + high-stone powder slurry modification". The measured data fully demonstrate the advanced nature and practicality of this technical solution, making it suitable for large-scale promotion and application in high-risk locations such as gas stations, chemical industrial parks, and military warehouses.

[0164] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a reference structure" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0165] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A non-explosive concrete combination formulation, characterized in that, The raw material components include cement: 240-320 parts by weight; mineral admixture: 60-80 parts by weight; Fine aggregate: 755-795 parts by weight; Coarse aggregate: 1019-1039 parts by weight; Water: 150-158 parts by weight; additive: 8.67-9.22 parts by weight; the fine aggregate and coarse aggregate are both limestone materials, and neither of them produces sparks in the grinding wheel friction test.

2. A non-explosive concrete formulation according to claim 1, wherein: The fine aggregate is limestone machine-made sand, with a fineness modulus of 2.6-3.0, a stone powder content of 10%-11%, and a crushing index ≤13%.

3. A non-explosive concrete formulation according to claim 1 wherein: The coarse aggregate is made of 5-10 mm diameter gravel and 10-20 mm diameter gravel in a mass ratio of (1:3.6)-(1:3.8); the needle-like content of the 5-10 mm diameter gravel is ≤2%, and the needle-like content of the 10-20 mm diameter gravel is ≤3%.

4. A non-explosive concrete formulation according to claim 1 wherein: The cement is P.O42.5r ordinary Portland cement, the mineral admixture is I-grade fly ash, and the additive is a polycarboxylic acid high-performance retarding type water reducing agent with a water reducing rate ≥27%.

5. A method of configuring a non-explosive concrete combination formulation, characterized by, The method comprises the following steps: Sp1. Raw material pre-inspection: the limestone fine aggregate and the limestone coarse aggregate are subjected to a grinding wheel friction test in a completely dark environment to ensure that no sparks are produced in the instant of contact with the grinding wheel, and the identification is qualified before use; Sp2. Mixture proportioning: the cement, mineral admixture, fine aggregate, coarse aggregate, water and additive are weighed according to the weight fraction of the set strength grade; Sp3. Stirring and mixing: the weighed aggregate and cementitious material are put into a stirrer for dry mixing, and then the mixed solution of water and additive is added for wet mixing until a uniform concrete mixture is obtained; Sp4. Performance detection: the mixture is tested for slump and spread, and the initial spread is required to reach 550±50 mm, and the 4-hour spread loss meets the pumping construction requirement; Sp5. Product verification: the prepared concrete is poured and molded and cured for 28 days, and the grinding wheel friction test is performed on the hardened concrete test block or floor surface to confirm that no sparks are produced.

6. A method of configuring a non-foamed concrete combination formulation according to claim 5, characterized in that: The grinding wheel friction test of the aggregate in Sp1 is performed in a completely dark room, the friction speed and pressure are performed according to the requirements of GB50209 or the test conditions in the embodiments of the specification, and at least 3 test pieces are tested for each batch of aggregate, and all test pieces are determined to be qualified without sparks.

7. The method of claim 5 wherein: In Sp3, the water-binder ratio is controlled between 0.38 and 0.55, the slump or spread at the end of mixing meets the construction requirement, and still meets the pumping or construction continuity requirement after 4 hours.

8. The method of claim 5 wherein: The water reducing agent is a retarding type polycarboxylic acid salt additive, and the addition amount is 5.0-12.0 kg / m³, which can improve the workability while ensuring the non-sparking performance and strength development.

9. The method for preparing a non-sparking concrete composite formula according to claim 5, characterized in that: The concrete for ground construction is subjected to on-site grinding wheel friction retest on local parts after pouring, and the retest result is no sparks to deliver the use, which is the engineering quality control point.

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