118 results about "Sorptivity" patented technology

The invention discloses a preparation process of a fireproof lightweight thermal-insulation cement-based mortar material, which comprises the following steps: (1) placing porous lightweight aggregate in a sodium silicate solution for standing, and drying the obtained aggregate to obtain pretreated thermal-insulation aggregate; (2) uniformly mixing silica fume, calcium silicate powder, calcium hydroxide powder and water to form slurry; mixing the pretreated thermal insulation aggregate with the slurry, separating, airing the aggregate, and curing to obtain the primary thermal insulation aggregate. And (3) spraying water on the primary thermal insulation aggregate for wetting, then spraying ethanol containing a silane coupling agent, and airing to obtain the modified thermal insulation aggregate. And (4) uniformly mixing Portland cement, the modified thermal insulation aggregate, basalt fiber and a water reducing agent as raw materials, adding water, and uniformly stirring to obtain the mortar material. According to the invention, the water absorption rate of the porous lightweight aggregate is reduced, so that the adverse effect of the high water absorption characteristic of the aggregate on the mechanical properties of the mortar material is effectively reduced.

The invention discloses a high-salt-corrosion-resistant concrete pouring material and a preparation method thereof, and relates to the technical field of high-salt-corrosion-resistant concrete, and the high-salt-corrosion-resistant concrete pouring material comprises the following components in parts by weight: 5-10 parts of modified charcoal, 1.5-3 parts of a corrosion inhibitor, 320-360 parts of cement, 650-700 parts of river sand, 20-30 parts of silica fume, 0.3-0.6 part of super absorbent resin, and 0.2-0.8 part of a water reducing agent. According to the high-salt-corrosion-resistant concrete pouring material and the preparation method thereof, a protective film is formed on the surface of a reinforcing steel bar through the corrosion inhibitor, the anodic oxidation reaction is inhibited, the reinforcing steel bar is prevented from being corroded, eugenol releases corrosion inhibition molecules, a hydrophobic protective film is formed on the surface of the reinforcing steel bar, and electrochemical corrosion is inhibited; meanwhile, through the synergistic effect of a physical barrier and chemical passivation, the calcium-aluminum salt-eugenol composite corrosion inhibitor not only can block a corrosion path through physical film formation, but also can inhibit electrochemical reaction through chemical adsorption, so that the corrosion inhibition efficiency is improved.

The invention discloses a light high-strength fireproof decorative material as well as a preparation method and application thereof, belongs to the technical field of fireproof decorative materials, and aims at solving the technical problem that the fire resistance rating, the water absorption performance and the mechanical strength of a light fireproof material in the prior art need to be further improved. The lightweight concrete is specifically prepared from the following components in parts by weight: 80-100 parts of a silicon-calcium material, 8-10 parts of modified triphosphoric acid, 10-14 parts of a modified fiber reinforcement, 15-18 parts of modified lightweight aggregate, 5-8 parts of an adhesive and 2-3 parts of an additive, the modified triphosphoric acid is used as a flame retardant, the lightweight aggregate is pretreated, the fiber reinforcement is improved, and the lightweight high-strength fireproof decorative material is prepared through mutual cooperation with the additive, so that the fireproof performance and compressive strength of the material are improved, and the volume density of the material is reduced.

The application discloses a magnesium phosphate-based cement grouting material and a preparation method and application thereof. The raw materials of the magnesium phosphate-based cement grouting material include A component and B component; the raw materials of the A component include, in parts by weight, calcined magnesium oxide 140-200 parts, bentonite 0-30 parts, hydroxypropyl methylcellulose 0.2-0.5 parts, an additive 1-10 parts and water 70-140 parts; the raw materials of the B component include a first dihydrogen phosphate 70-100 parts, pretreated high-molecular water-absorbing resin 20-50 parts, sodium polyacrylate 0.5-2 parts and water 30-70 parts; the pretreated high-molecular water-absorbing resin is obtained by soaking the high-molecular water-absorbing resin in an aqueous solution of a second dihydrogen phosphate. The magnesium phosphate-based cement grouting material has the characteristics of low shrinkage, short and adjustable setting time, high compressive strength, simple construction, low cost, green environmental protection, good grout injection, good water dispersion resistance, good durability in a long-term soaking environment and the like.

The invention discloses a plugging particle, a preparation method, application and a grouting material, the plugging particle is of a core-shell structure and comprises a force-bearing inner core, the force-bearing inner core is coated with an expansion functional layer, and the expansion functional layer is coated with a delayed hydrogel outer film layer; wherein the inner core is made of one or more of quartz sand, kaolin and inorganic fibers; the expansion functional layer comprises modified bentonite and a super absorbent polymer; the delayed hydrogel outer film layer comprises a water-soluble film; the particle size of the blocking particles is 0.5 to 2.5 mm; through material structure optimization and response mechanism design of the functional plugging particles and the special grouting liquid, the automatic plugging function in the grouting process without mechanical triggering, a chemical expanding agent and a complex plugging device is achieved; and the method is suitable for scenes with high requirements on plugging precision, construction efficiency and structural stability in complex rock mass crack grouting engineering.

This underwater sliding member is obtained by molding a resin composition which contains a thermoplastic resin that has water absorption resistance, and a granular inorganic filler and / or a plate-shaped inorganic filler, wherein the Mohs hardness of the inorganic filler is 5 or less.

The invention discloses a method for preparing a concrete curb by using detoxified fly ash and the concrete curb. The concrete curb is prepared from the following raw materials in parts by weight: 200-250 parts of cement; 0-60 parts of fly ash; 50-70 parts of mineral powder; 15 to 60 parts of detoxified fly ash; 1700 to 1900 parts of aggregate; 170 to 200 parts of water; and 2-5 parts of a water reducing agent. The detoxified fly ash can be effectively digested, the resource utilization rate is increased, meanwhile, the compressive strength of the product can be improved, and the water absorption performance and the freeze-thaw resistance both meet the requirements.

The invention discloses recycled aggregate concrete slurry and a prefabricated concrete laminated slab, and belongs to the technical field of prefabricated building materials. The recycled aggregate concrete slurry consists of a cementing material, aggregate, a functional additive, an additive and mixing water, the functional additive is selected from super absorbent resin, end hook type steel fiber and polypropylene fiber; the aggregate is composed of recycled coarse aggregate, natural gravel and medium sand; the additive comprises a water reducing agent. Concrete prepared from the recycled aggregate concrete slurry has excellent normal-temperature comprehensive mechanical properties, excellent high-temperature burst resistance, good workability and volume stability and certain economical efficiency and environmental friendliness. The recycled aggregate concrete slurry is used for preparing the prefabricated concrete laminated slab, and the obtained prefabricated concrete laminated slab has excellent durability and good safety.

The invention provides a capillary crystalline agent core material microcapsule and a preparation method and application thereof, and relates to the technical field of material science and engineering, the capillary crystalline agent core material microcapsule comprises a wall material and a core material; the wall material comprises a water-absorbing material, the water-absorbing material comprises at least one of sodium alginate and modified sodium alginate, and the mass of the water-absorbing material is not lower than 60% of the mass of the wall material; the core material comprises a capillary crystalline agent and a dispersing agent, and the mass of the capillary crystalline agent is not lower than 60% of the mass of the core material; the mass ratio of the wall material to the core material is (3: 7): (7: 3); and the particle size of the capillary crystalline agent core material microcapsule is 50-300 microns. The capillary crystalline agent core material microcapsule is applied to concrete repair, the crystallization reaction can develop along the depth of a crack, invasion of water and corrosive ions is inhibited for a long time, the service life of the structure is prolonged by 2-3 times, and the compressive strength / breaking strength of a repaired crack area can be recovered to 90% or above of that of original concrete.

The invention discloses a preparation method of an alkali-activated porous geopolymer wall material by using recycled fine aggregate to load an enhancer. The alkali-activated porous geopolymer wall material is prepared from the recycled fine aggregate, the enhancer, a cementing material, an alkali activator, a foaming agent and a water reducing agent. According to the method, slow-release carbonization strengthening of a porous geopolymer which takes water granulated slag and fly ash as binding materials, sodium hydroxide and water glass as alkali activators and hydrogen peroxide as a foaming agent is realized by utilizing a water-absorbing loading enhancer of recycled fine aggregate, so that the wall material with excellent performance is prepared; high-value utilization of building and industrial solid waste and low-carbon building wall manufacturing are achieved, and the problems that due to high water absorption and low hardness of recycled fine aggregate, the pore structure of an alkali-activated porous geopolymer wall material is distorted, the compressive strength is reduced, and an existing recycled fine aggregate strengthening technology has adaptability defects are solved.

The invention discloses a long-distance pressure tunnel positioning method based on inner wall feature texture auxiliary identification, and the method is based on the fact that the inner wall of a long-distance pressure tunnel presents different feature textures at different times due to the non-uniform water absorption of the inner wall material. Meanwhile, in combination with the difference of characteristic textures such as pores, gaps, denudation, damage, aging and attachments of concrete structures at different parts of the tunnel and the relevance of the characteristic textures at the same position and at different time, the characteristic textures of the inner wall are associated with the specific position by adopting a mode similar to fingerprint identification based on a panoramic database constructed in a non-pressure period and an emptying period; and finally, comprehensive, accurate and rapid positioning of the underwater non-defect area and the defect area in the'pressure period 'in the long-distance pressure tunnel is achieved.

The invention discloses a construction evaluation method for building masonry, which comprises the following steps: establishing a stratum acquisition area in a construction area, acquiring a soil sample, and dividing the soil sample into a hard soil layer and a soft soil layer according to the water absorption of the soil layer; according to parameters of different stratums, design parameters of a foundation pile and a foundation ground beam are formulated, the foundation pile and the foundation ground beam serve as a foundation of a construction building masonry, a simulation model is established according to data of the foundation pile and the foundation ground beam, and stress needing to bear the building masonry is applied to the simulation model. And evaluating the stability of the foundation piles, the foundation ground beams and soil layers and rock stratums under the foundation, and giving construction suggestions. According to the scheme, detailed stratum test data and a comprehensive stability analysis method of construction analogue simulation are combined, so that the safety and the reasonability of the construction design scheme of the building masonry are ensured, and a solid foundation is provided for construction safety and smooth service.

The invention discloses a freeze-thaw damage self-repairing foam concrete material and a preparation method thereof, and relates to the technical field of building materials. The fly ash with high hydration activity can induce in-situ self-repairing of original defects of the cement stone microstructure. The concrete initiates microcracks under initial freezing and thawing, the proper humidity in the concrete is maintained by adding the fly ash, initiating hydration and adding the water-absorbent resin material, and the cracks are sealed by generated hydration products, so that the compactness of the concrete is recovered. The water-absorbent resin material can continuously absorb and release water in a freeze-thaw cycle, and the process can be triggered circularly, so that the self-repair of multiple freeze-thaw damages is realized. The carboxymethyl cellulose is used for preparing the water-absorbent resin, and the carboxymethyl cellulose has good water absorbability, so that the water absorbability of the water-absorbent resin is improved. Calcium carbonate is added into the water-absorbent resin to form a cross-linked network, so that the stability in the concrete is improved.

This application relates to a foundation pit structure and its construction method, comprising a foundation pit main body with a support structure installed. The support structure includes a reinforcement component and a drainage component. The drainage component is installed on the reinforcement component and includes a fall arrest net and a drainage pipe. The drainage pipe is installed inside the reinforcement component. One side of the fall arrest net is connected to the reinforcement component. The fall arrest net has multiple water storage channels inside. The bottom of the fall arrest net is in contact with the bottom of the foundation pit main body. The bottom of the fall arrest net is provided with a water-absorbing fixing component, which is driven into the bottom of the foundation pit main body. The reinforcement component includes corner reinforcement components and vertical reinforcement components. The corner reinforcement components are fixed at the corners of the foundation pit main body and fit against the corner walls of the foundation pit main body. The vertical reinforcement components are connected to the corner reinforcement components. The foundation pit structure of this application is robust, less prone to lateral collapse, and facilitates drainage.

The utility model relates to strip cleaning technical field, concretely is a kind of strip cleaning after quick removal residual moisture device, including mounting seat, two rows of high-speed fan are fixedly installed on the mounting seat, two rows of high-speed fan are used for passing through for strip between, the air outlet of high-speed fan is fixedly installed with the air scoop of output port alignment strip, the drying box of being located in the upper and lower sides of strip is fixedly installed on the mounting seat, a side for being used to contact with the dry towel of strip is wrapped on the drying box. By setting high-speed fan, most of the moisture on the surface of strip is blown away from the strip, the residual moisture is wiped off by the subsequent dry towel, the moisture can be completely removed from the surface of strip, the production efficiency is improved, and the dry towel can be dried, so that the dry towel always maintains good water absorption performance. Even if the strip keeps full-speed operation, the drying quality can still be guaranteed, the subsequent coating process is facilitated, and the quality of the strip is guaranteed.

Provided are a method for producing a recycled water-absorbing resin which achieves reduction in deterioration of water absorption performance and reduction in coloration, and a method for producing a water-absorbing resin with use of the recycled water-absorbing resin. An embodiment of the present invention relates to, for example, a method for producing a recycled water-absorbing resin from a used absorbent article, the method including: a urea removal step of removing urea so that a urea content in the recycled water-absorbing resin becomes 2 mass% or less; and a recovery step of recovering a water-absorbing property.

The invention discloses a multi-parameter joint evaluation method for transmission performance of ultra-high performance concrete, and belongs to the technical field of concrete durability evaluation. The multi-parameter joint evaluation method comprises the following steps: preparing an ultra-high performance concrete test piece with a gradient function; calculating a steel fiber distribution coefficient; obtaining a slice test piece; performing a gas permeation test on the test piece with the undamaged slices; performing a capillary water absorption experiment on the test piece with the undamaged slices; carrying out a splitting tensile strength test to obtain slice test pieces with different damage degrees; performing a gas permeation test and a capillary water absorption test on the damaged slice test piece; and calculating and fitting the experimental results to obtain a concrete transmission performance multi-parameter joint evaluation equation set under the steel fiber distribution coefficient. According to the method, the gas transmission performance and the capillary water absorption are tested at different slice positions of the ultra-high performance concrete test piece with a certain mixing ratio, the evaluation process of the concrete transmission performance is obtained, the process of permeability evaluation through multiple parameters is introduced, and the accuracy of the evaluation result is improved.

The invention discloses a multi-solid-waste high-strength baking-free brick and a preparation method thereof, and belongs to the technical field of resource utilization of copper smelting slag. The multi-solid-waste high-strength baking-free brick is prepared from the following raw materials in parts by weight: 56 to 72 parts of copper smelting slag, 4 to 12 parts of red mud, 4 to 12 parts of ardealite, 5 to 10 parts of Portland cement, 10 to 15 parts of slag, 15 to 20 parts of water, 0.5 to 1 part of calcium sulphoaluminate and 1 to 2 parts of sodium silicate. A synergistic excitation mechanism of the red mud and the ardealite is innovatively provided, the composite excitation effect of the calcium sulphoaluminate and the sodium silicate is combined, a multi-solid-waste gelling system is constructed, and an economical and efficient absorption approach of comprehensive utilization of various solid wastes such as the copper smelting slag, the red mud and the ardealite is achieved. And the prepared multi-solid-waste high-strength baking-free brick has high strength, high water resistance and low water absorption.

This utility model discloses a fireproof hollow insulation board, comprising an insulation board, and relates to the technical field of insulation boards. This fireproof hollow insulation board, by installing water-resistant plates on the contact surfaces of the front and rear sides of the insulation board, allows the water-resistant plates to form water-resistant gaps between the insulation board and the wall, and between the insulation board and the external cement slurry, effectively maintaining the insulation performance and structural stability of the insulation board. Secondly, raised dots are provided on the surface of the front water-resistant plate, ensuring the integrity of the mortar and preventing its flow, thus avoiding significant mortar spillage onto the ground during the bonding process with the wall. Furthermore, an inner circular groove is provided inside the front water-resistant plate, and an opening smaller than the inner circular groove is provided on the front side, allowing the mortar to fill the interlayer between the inner circular groove and the opening. After the mortar solidifies, the above combination improves tensile strength and enhances overall robustness.

The application provides a building curtain wall and a construction method and application thereof, and the building curtain wall comprises the following raw material components by weight: cementing material 100 parts, admixture 5-40 parts, additive 0.1-10 parts, superabsorbent polymer 0.1-5 parts, conductive polymer 0.1-10 parts, water 10-40 parts, aggregate 10-30 parts and electrode material 10-30 parts. The application adopts traditional cementing material-based building material to construct a building curtain wall with energy storage function, a self-luminous system based on the building curtain wall utilizes photoelectricity and thermoelectricity to generate electricity, and additional electricity from a power grid is not needed, a photoelectron system is based on solar power generation, a thermoelectron system effectively utilizes a large amount of waste heat generated in a photovoltaic cell power generation process, the whole power generation process does not involve carbon emission, and the electricity generated by the power generation system is stored in the building curtain wall and used for supplying power to the luminous system at night, so that energy is saved and consumption is reduced.

The invention discloses low-carbon reclaimed sand concrete as well as a preparation method and application thereof, and belongs to the technical field of concrete materials. The invention provides low-carbon recycled sand concrete. The low-carbon recycled sand concrete is prepared from the following raw materials in parts by weight: 60-80 parts of recycled mixed aggregate, 80-100 parts of coarse aggregate, 15-20 parts of Portland cement, 5-10 parts of volcanic ash and 0.5-1 part of a water reducing agent, the preparation method of the recycled mixed aggregate comprises the following steps: A1, mixing the large-particle-size aggregate and the recycled fine aggregate to obtain mixed aggregate; a2, transferring the mixed aggregate into a curing box filled with carbon dioxide, and curing for 30-50 hours to obtain regenerated mixed aggregate; the key problems of low strength and poor water absorption of the recycled concrete are effectively solved through the synergistic effect of multiple components, and the compressive strength of the concrete is improved by constructing a'microfiber-nanoparticle 'multi-stage reinforcing system.

The invention belongs to the field of solid waste brickmaking quality detection and analysis, and relates to a solid waste brickmaking quality detection and analysis method.The solid waste brickmaking quality detection and analysis method comprises the multiple key steps that firstly, test blocks are randomly extracted and grouped to conduct compressive strength, water absorption, durability and heat conductivity tests, then all test data are collected, and the test data are stored in a database; comprising compressive strength, water absorption, durability and thermal conductivity indexes, then various performance coincidence coefficients, such as compressive strength, water resistance, durability and thermal conductivity, of the test block are calculated by deeply analyzing the data, finally, the quality coincidence indexes of the test block are evaluated by integrating the various coincidence coefficients, and whether the quality of the solid waste brick is qualified or not is judged according to the indexes. And if the quality does not reach the standard, an early warning mechanism is triggered immediately, so that the product quality is strictly controlled, the quality of solid waste brick making is controllable, and the reliability and the safety of the product are improved.

This invention provides a non-fired magnesia-calcium brick and its preparation method, belonging to the field of refractory materials. Its raw materials include aggregates, fine powder, graphite, binders and composite additives, wherein the composite additives contain calcium nitrate tetrahydrate. The non-fired magnesia-calcium brick of this invention has the following beneficial properties: (1) The composite additives are uniformly distributed in a network in the non-fired magnesia-calcium brick. Due to the dehydration reaction of calcium nitrate tetrahydrate in the composite additives during the brick drying process, a uniform network crack is formed in the finished brick, thereby improving the thermal shock resistance of the product; (2) The calcium nitrate formed by the dehydration of calcium nitrate tetrahydrate has strong water absorption, effectively protecting the CaO in the brick from hydration and improving the hydration resistance of the product; (3) During the high-temperature use of the finished non-fired magnesia-calcium brick, the calcium nitrate undergoes melting and decomposition to transform into highly active CaO, and reacts with SiO2 introduced in the composite additives to form a combined phase, improving the medium-temperature performance of the non-fired magnesia-calcium brick.

The present application relates to a kind of preparation methods of modified waste concrete recycled aggregate, comprising: after crushing waste concrete, screen suitable particle size as the raw material of recycled aggregate, water washing is carried out by oscillation screen to remove part of edge and the corner that will soon fall off, using nano-silica, water-soluble silicate etc. Modification solution carries out gelation reaction, the micro-pore on the surface of concrete particle is plugged and repaired, makes its structure complete and densification, enhances the mechanical strength of aggregate, reduces porosity and water absorption, again by phenolic resin coating further reduces water absorption and enhances mechanical strength. Using the modified waste concrete recycled aggregate, mixed with cement, zeolite powder etc. And is pressed into blank, after carbonization maintenance, obtain the artificial stone with excellent mechanical properties and low water absorption rate.The method of the present application has good application prospect and environmental protection significance.

The present application relates to the technical field of railway subgrade disease, and discloses a construction process for treating railway subgrade disease by adopting bed closure and subgrade body grouting, which comprises the following steps: step one: according to requirements, carry out the extraction of the sleeper and the square sleeper, the excavation of the bed and the bed, and the laying of the thick crushed stone cement layer at both ends of the bed and the surface layer of the bed, and the mixing of the super water-absorbing resin and the silica gel desiccant in the thick crushed stone cement layer; the water-absorbing stone cement layer is laid on the top of the thick crushed stone cement layer, the porous structure of the water-absorbing stone cement layer is used to quickly absorb water, and the water is discharged from the side of the bed through the water outlet pipe, so that the water is prevented from accumulating in the bed; the super water-absorbing resin and the silica gel desiccant are mixed in the thick crushed stone cement layer, the super water-absorbing resin and the silica gel desiccant are used to increase the water absorption performance of the thick crushed stone cement layer, and after the completion of water absorption, the silica gel desiccant can be reused by evaporating the moisture in the silica gel desiccant through high temperature.

A method of analyzing an auxiliary cementitious material (SCM) may include obtaining a sample comprising the SCM; immersing the sample in an alkaline or acidic aqueous solution, thereby subjecting the sample to dissolution; determining the ion concentration in the alkaline or acidic aqueous solution for a predetermined time after the sample is immersed; and predicting reactivity of the SCM in the gelling mixture based on the ion concentration. In another embodiment, a method of analyzing SCM may include obtaining a sample including SCM; placing the sample on a porous substrate in contact with a water source; measuring a change in water level of the water source as the sample absorbs water passing through the porous substrate; and determining the water absorbency of the sample. The hydroscopicity may predict yield stress and / or viscosity of a gelling mixture including the SCM.

The application relates to an artificial intelligence technology and discloses a ceramic product performance detection method, which comprises the following steps: measuring the first weight of a ceramic product, measuring the drainage volume of the ceramic product after being immersed in a water pool to calculate the density of the ceramic product, measuring the second weight of the ceramic product after being immersed in the water pool, calculating the water absorption performance according to the first weight and the drainage volume, calculating the wear resistance of the ceramic product by measuring the weight of the ceramic product after being polished, testing the compressive strength of the ceramic product by using a pressure loading device to obtain the maximum compressive strength, and judging whether the ceramic product meets preset performance indexes according to the measured density, water absorption performance, wear resistance and maximum compressive strength. The application further discloses a ceramic product performance detection system. The application can improve the efficiency of ceramic product performance detection and make the detection more comprehensive.

The application discloses a kind of freeze-thaw damage self-repairing foam concrete materials and preparation method thereof, it is related to building material technical field.The fly ash with higher hydration activity can induce in-situ self-repairing of microstructure primary defect of cement stone.The microcrack is initiated in concrete under initial freeze-thaw, the fly ash is added in the application, hydration is triggered, the water-absorbing resin material is added to maintain the suitable humidity inside concrete, the generated hydration product seals the crack, so that the density of concrete is restored.The water-absorbing resin material can continuously absorb and release water in freeze-thaw cycle, and the process can be triggered cyclically, thereby realizing the autonomous repair of multiple freeze-thaw damage.The carboxymethyl cellulose is used to prepare water-absorbing resin in the application, and the carboxymethyl cellulose has good water absorption, which improves the water absorption performance of water-absorbing resin.Calcium carbonate is added in water-absorbing resin to form a crosslinked network, which improves the stability in concrete.

The invention discloses self-compacting concrete with synergistically optimized fluidity and volume stability, and belongs to the technical field of concrete materials, the self-compacting concrete is prepared from the following components by weight: 834-849 parts of coarse aggregate; 950 to 968 parts of artificial sand; 322 to 345 parts of ordinary Portland cement; 142 to 150 parts of water; 55 to 75 parts of modified hollow ceramic microbeads; 14 to 18 parts of an expanding agent; 5 to 9 parts of a super absorbent resin-montmorillonite composite material; and 5-11 parts of a water reducing agent. According to the self-compacting concrete disclosed by the embodiment of the invention, the contradiction between the fluidity and the volume stability can be fundamentally coordinated, and the shrinkage deformation is remarkably reduced while the excellent self-compacting performance is ensured, so that the self-compacting concrete is suitable for narrow space lining projects such as water delivery tunnels and the like which have extremely high requirements on structural integrity and long-term safety.