I would like to ask about the specific methods for installing emery floor surfaces

1) Base surface requirements: The underlying concrete must be hard in texture, with a slump range of 75–110 being optimal. Concrete with the lowest water-cement ratio should be used, and it must be fully compacted during pouring; its compressive strength should be above 25 N/mm2. 2) Construction method and tools: An automatic spreader with a laser scraper is used: after leveling, emery is evenly spread over the concrete in one go at a rate of 5 KG/M2. 3) Manual application: Once the water on the surface has evaporated, spread the emery uniformly over the concrete of the leveling layer in two applications (3 KG/M2 for the first application, and 2 KG/M2 for the second). Care should be taken when applying the powder to prevent pits from forming on the concrete surface. The total amount used in construction is 5 KG/M2; failing to pay attention or scattering emery more than 2 meters away from the application points will reduce the quality of the final surface. 4) Compaction: After spreading the first batch of material on the floor, immediately spread the second portion of emery. Emery makes the concrete surface harden faster than usual; care should be taken to shape the adjacent edges and corners that are about to be poured, to smooth the surface, seal the pores, and level it out. 5) Construction precautions: The application of dry powder agents should be carried out in areas with wind or strong air currents. Characteristics of the concrete surface, such as moisture content and cement quality, can cause slight color differences. Color changes during the drying process are normal and expected. Due to the natural variations in the concrete surface, dry-applied hardeners may result in some color differences in the final finish of the entire concrete floor. At low relative humidity, there is a risk of weathering; at high relative humidity, water will precipitate, slowing down the curing and hardening process. Delay the smoothing operations. Protection measures: When working in a enclosed workshop, it is necessary to ensure adequate ventilation and stay away from open flames, including welding. To avoid minor allergic reactions, butyl or nitrile rubber gloves should be used. Change contaminated work clothes, and wash hands during breaks and after completion of work. The health and safety recommendations indicated on the packaging label must be followed.

From the internet. For educational purposes only: http://b.co188.com/content/233_119224_1.html Techniques for constructing second-stage emery floor surfaces. Keywords: emery, concrete pouring, grouting, leveling, construction techniques. In the Jiangsu South region, with the investment of numerous Taiwanese-owned electronics companies, the construction of high-standard floor surfaces in industrial buildings on a large scale and within a short timeframe is crucial for ensuring the economic and social benefits for the construction firms involved in such projects. For a plastic factory floor constructed by our company, the use of one-time molding floor construction technology not only ensured quality but also shortened the construction period and saved costs, resulting in excellent outcomes. I. Project Characteristics: This plastic factory building is designed to meet the requirements arising from frequent changes in process equipment, minor vibrations, and regular use of forklifts for transportation. Additionally, the production process does not allow for dust, so the following floor specifications are required: 1) Design load of 10 kN per square meter ； 2) Surface Mohs hardness of 6.0 or above ； 3) The surface flatness, as measured with a 3m square aluminum straightedge, is less than 3mm ； 4) No cracks, no moisture absorption, no dust generation, and resistant to wear. To meet the above requirements, the following measures are taken: 1) A 20 cm thick layer of C25 concrete is used at the base layer, with 12 mm steel bars arranged in two layers and in both directions at intervals of 250 mm each; the thickness of the protective layer around the steel bars on the surface layer is 5 cm. The construction is carried out using a pump-driven continuous pouring method. 2) High-precision horizontal control of double-nut channel steel. 3) Construction method for mechanically troweled emery surface layer. II. Construction Process 1. Subgrade preparation, steel bar binding, and everything is ready. 2. No horizontal control: The surface flatness requirement for this project is 3 mm/3 m, which is twice as high as China’s current standard of 5 mm/2 m; therefore, high-precision double-nut channel steel is used for horizontal control. Channel steel serves as a marker for leveling with a straightedge; they are placed every 3 meters, with 5-meter-high channel steel pieces laid on their sides and fixed to L12mm screws, the screws being spaced 2 meters apart. The screw is embedded in the cushion layer and pre-fixed with concrete, while also being welded firmly to the reinforcement in the surface layer; the top of the screw is l cm below the ground level. Level the upper surface of the channel steel using a level, and adjust the nuts to ensure that the entire floor is level and reaches the required elevation. The support screws should be installed and properly fixed before the rebar is tied together, and the number of channel steels installed should be sufficient to allow for replacement during concrete pouring. 3. Pouring of the base concrete: The pumping process for the base concrete requires thorough preparation to ensure continuous pouring. It is also necessary to conduct tests on the setting time of the concrete, in order to determine the time from initial setting to final setting, and to ensure that this time fits within the required timeframe for carrying out the necessary procedures for applying the emery surface layer. When pouring concrete, use the pre-installed channel steels as markers to fill the space between them with concrete; after vibrating it until it is compact, use a trowel to level the surface against the channel steels. Once the concrete has stopped flowing, remove the fixing nuts and take out the channel steels. Then fill the area again with concrete, compact it, and level it, before handing it over to the surface finishing crew for further work. 4. Construction of emery surface layer: The emery surface layer is a premixed product whose main components are highly strong and tough aggregates with tightly packed particles, along with additives formulated specifically for this purpose. The construction is carried out during the initial setting stage after the fresh concrete has been poured; the product is spread in two stages, followed by completion using specialized machinery. The formed emery surface layer forms a single unit with the underlying concrete, possessing extremely high strength and hardness as well as dust-resistant properties. The main construction steps are as follows: 1) Remove the floating slurry and apply the material for the first time: Sprinkle 2/3 of the specified amount of emery before the base concrete has set to about 5–60% dry, then compact it using a disc sander and rub it to ensure that the emery penetrates into the surface layer of the concrete. 2) Fine leveling, second application of material: After a certain period of time, the remaining 1/3 of emery is spread in the same manner, and the surface is polished as a whole using a disc sander and a metal trowel. 3) Mechanical troweling: Perform at least three passes with a blade grinder, depending on the degree of concrete hardening. 4) Surface finishing grinding: The final surface treatment is carried out using a mechanical trowel or a manual trowel. 5) Maintenance: Apply a maintenance agent for preservation depending on the weather conditions. 6) Cutting of expansion joints and filling with PU sealant. 7) Waxing and handover. III. Precautions For the successful construction of large-area, high-standard emery floor surfaces through one-time molding, it is essential to pay attention to the following points: 1) It is necessary to conduct tests on the setting time of concrete, and select an appropriate concrete mix ratio as well as cement admixtures. If concrete sets too quickly, it becomes impossible to apply the emery surface layer; if it sets too slowly, a large amount of cement slurry bubbles up during the application of emery, affecting the surface quality. 2) A reasonable concrete pouring procedure must be established to ensure continuous pouring and coordination with the construction speed of the surface layer. 3) It is necessary to select appropriate surface material as required, strictly control the entry of materials into the project, and it is strictly prohibited to use quartz sand in place of emery to reduce the surface hardness. 4) Personnel with construction experience must be selected to carry out specialized level control and surface finishing work to ensure quality. 5) It is necessary to enhance the awareness of finished product protection, especially for colored emery floor finishes. Quality control for one-time formation of large-area concrete emery floors. Guangzhou Siwei Heavy Industry Co., Ltd. is located at No. 5 Dongjiang Avenue, West Area of Guangzhou Economic and Technological Development Zone. This project consists of a production workshop, a power workshop, and storage areas. The production workshop uses a rack structure, while the power workshop features a reinforced concrete frame structure; the upper part of the production workshop is supported by steel roof trusses, with the building having one floor in most areas and four floors in some sections. The total construction area is approximately 10,125 m2, and the building height is 16.72 m ； The power workshop has a construction area of 200.5 m2 and a building height of 6 m ； The area of the reception room is 51.27 m2, with a building height of 3.5m ； There’s another bunch of fields. The floors of the production workshops and storage areas are constructed by applying emery concrete in a single coating; the thickness of the base concrete is 300 mm, with a design strength of C30. The entire foundation consists of 732 pedestals of different sizes, along with floor slabs connecting these pedestals, covering an area of 12,845 m2 – a fairly large area ； Since the factory is located at the confluence of the Pearl River and the Dongjiang River, where water levels are high during high tides, there is a need for waterproofing when producing floors. Therefore, it is necessary to develop effective plans to control the quality during its construction process and after the ground is formed. I. Crack control The main reason for cracks that may occur during the pouring of the base concrete is the high strength grade of the base concrete, which results in high heat of hydration ； During winter construction, the ambient temperature is low (in Guangzhou, it is around 10°C from December to January), resulting in a large temperature difference between the concrete and the ambient air ； Improper curing, such as suddenly applying cold water for curing when the concrete is at a high temperature, can also result in multiple irregular micro-cracks; severe cracks can lead to leakage in the bottom slab. To prevent cracks, it is necessary to incorporate expansion joints and post-cast strips in the design, and to make cuts in the emery floor once it is completed. During construction, it is important to improve the construction techniques, reduce the thermal stress on the concrete, and enhance the concrete’s inherent strength – all of these factors need to be taken into consideration. 1. Mix proportion design and trial mixing: To reduce the thermal stress in concrete, the best approach is to lower its hydration heat; therefore, it is essential to carry out proper mix proportion design and trial mixing for the concrete. 1.1 Selection of raw materials 1.1.1 Cement: Low-hydration heat fly ash silicate cement is used to minimize the amount of cement required. Grade 425 fly ash cement is used in this project. 1.1.2 Fine aggregate: Medium sand from Zone II is recommended, as using medium sand reduces the amount of water and cement required compared to fine sand. 1.1.3 Coarse aggregate: Under pumping conditions, stones with a continuous gradation ranging from 5 to 20 in particle size are used to reduce concrete shrinkage and deformation. 1.1.4 Clay content: If the aggregate contains a high amount of clay, it not only increases the shrinkage deformation of concrete but also significantly reduces its tensile strength, posing a serious risk of cracking. Therefore, on-site sampling and testing of the aggregates are necessary; the clay content in stones should be kept below 1%, while the clay content in sand should be kept below 2%. 1.1.5, Admixtures: The use of fly ash addition technology is applied. Fly ash incorporated into concrete not only reduces the amount of cement used, lowers the heat of hydration, and improves the workability of the concrete, but it also significantly enhances the later strength of the concrete; moreover, the 28-day strength of such concrete can approach the standard strength value for concrete. 1.1.6, Admixtures: The UEA micro-expansive admixture technology is employed. Add about 10% UEA to the concrete. Tests have shown that when UEA is added to concrete, the expansion stress generated within the concrete can compensate for its shrinkage stress, thereby improving the concrete’s crack resistance. 1.1.7 Determination of trial mix and construction mix proportions: Based on the laboratory-designed mix proportions, for each cubic meter of concrete, 275 kg of Type 525 cement is used, 1031 kg of continuously graded crushed stone (with particle sizes ranging from 5 to 20 mm), 73 kg of admixtures, 5.28 kg of additives, 185 kg of water, and the slump range is 140–160 mm. 2. Since the thickness of the base concrete is only 300 mm, ordinary covering, watering, or spraying for curing can be employed to ensure that the temperature difference between the inside and outside of the concrete (between the center and the surface, and between the surface and the outside environment) remains below 25°C. 3. Issues to note during construction: 7 to 10 days after the emery floor is completed, corner cracks often appear at the junctions between the floor and columns. This is mainly due to changes in stiffness; structural vertical cracks form at the corners where the surface shape of the base concrete changes, with these cracks extending from the top downward and being wider at the top and narrower at the bottom. Such cracks arise as a result of combined effects such as shrinkage stress, settlement, and temperature stress, which cause concentrated stresses at the corners that exceed the tensile strength of the concrete. To prevent cracks in the concrete at corners, in addition to designing the structure to minimize the use of uneven surfaces and employing structural measures such as additional rebar at those corners, it is also necessary to ensure high quality in the concrete construction at those areas during construction. The concrete should be covered promptly, watered, or treated with a curing agent for proper curing, and the timing of form removal should be controlled so that it is not done too early. 4. Surface Treatment 4.1 Introduction to emery: Floor hardeners can be divided into two types – non-metallic floor hardeners and metallic floor hardeners. Both types are composed of non-metallic or metallic aggregates along with standard Portland cement and other binding materials, and can be used immediately after being unpacked. It boasts high strength and wear resistance, is dust-proof, effectively enhances the oil resistance of the surface, and shortens construction time. It is generally used for industrial floors that require wear resistance and dust protection. Its 28-day strength ； Non-metallic floor hardener floor 80mpa ； Metal floor hardener – floor strength of 91 MPa. Walking may be allowed 48–72 hours after construction is completed; light trucks can drive after 7–10 days ； It can be used normally after 28 days. 4.2 Construction method for emery floor: Vibrate the base concrete promptly; first vibrate the concrete in the middle of the mixture to create a natural slope, and then vibrate the entire area. To increase the ultimate tensile strength of concrete, prevent cracks caused by concrete settlement, reduce internal micro-cracks, and improve the density of concrete, a secondary vibration method is also employed. When the vibrator is moved, the concrete can still close on its own without leaving voids in it; this is the appropriate time to apply secondary vibration, but over-vibration should be avoided to prevent segregation. Due to the thick layer of cement on the surface of the pumped concrete, it should be initially leveled using a long trowel within 3–4 hours after the pouring of the base concrete. Before the concrete starts to set, it should be rolled twice with an iron roller, and then smoothed and compacted with a wooden trowel in order to prevent surface cracking and reduce water loss from the concrete surface. Finally, a specialized finishing machine with a disk is used to further smooth the concrete, ensuring that its surface is even and dense. After the concrete has begun to set but before it fully sets, the hardener is applied, while a trowel and disk are used to compact and smooth it out. The surface grooves are completed 24 hours later to prevent the formation of cold cracks. After about 1 to 2 hours, repeat the spreading and compacting process ； Finally, polishing and sealing are carried out using a polisher with blades, while the edges and corners are repaired manually ； Finally, apply a curing agent or cover with a film to prevent cracking caused by rapid evaporation of moisture. From concrete leveling to covering and curing, all operations are completed within 24 hours. Walking can be allowed 2 to 3 days after construction is completed, and cracks should be cut in the finished surface to prevent cold cracks. 5. Maintenance measures: Ordinary watering for maintenance is adopted. 6. Improve construction organization and management: While formulating technical and quality control measures, an organizational command system was also established, with technical instructions conveyed at each level to ensure thorough implementation and smooth progress of the work. 7. Issues to be noted during construction 7.1. Minimize the transportation time of concrete, arrange the pouring sequence properly, and unload the material promptly ； Before pouring, rinse the formwork with water to cool it down ； The pump pipe is wrapped in burlap to prevent it from heating up due to exposure to sunlight ； 7.2 Ensure thorough vibration; strictly control the vibration time, movement distance, and penetration depth to prevent both insufficient vibration and excessive vibration ； 7.3 Ensure a steady supply of concrete, and avoid creating construction joints arbitrarily ； 7.4 Ensure proper on-site coordination and organizational management, with sufficient human and material resources to guarantee that construction proceeds smoothly as planned. II. Control of flatness and surface finish: The surface of the floor in this factory is made of plain concrete to which a hardening agent is added to increase its surface hardness. During construction, the concrete is simply treated by leveling it with a long scraper and rolling it with rollers; before it sets, the surface is polished using specialized machinery. After curing, the surface achieves a hardness sufficient to withstand heavy loads without being damaged. For such an approach, on the one hand, it saves costs associated with an additional 20-mm-thick cement mortar finish on the floor surface, thereby reducing investment expenses; on the other hand, since the thickness of the structural layer remains unchanged, the thickness of the cement mortar finish is reduced by 20 mm, which in turn increases the clear height of the room by 20 mm. On the other hand, such approaches reduce the difficulty of design. Since the delta area is mostly characterized by soft soil foundations, the bearing capacity of these foundations is relatively low. The cost associated with improving the bearing capacity of the foundations is high compared to the overall cost of the project. Assuming a density of 2000 kg/m3 for cement mortar, reducing the weight of a 20 mm thick mortar coating would result in a reduction in the structural weight per square meter of 1×1×0.002×2000 = 40 kg. The design standard value for the uniform load on the floor of this factory building is 3000 kg/m2; thus, the load is reduced by 40/3000 = 1.33%. This reduction leads to lower costs for foundation treatment, thereby decreasing the investment required by the construction party as well as the design challenges faced by the design team. Furthermore, it is easy to construct. Compared to shear wall structures in residential buildings, when using a disc sander with a diameter of 1 meter for grinding emery floors, large-span factories provide sufficient working space; mechanical processing can be carried out throughout, except at the areas where the floor meets the factory columns, which require manual finishing. This reduces the accuracy issues that can arise from workers’ insufficient skill levels. Analysis of the construction difficulties of one-piece cast concrete floors 1.1 The current standards do not specify any quality acceptance criteria for one-piece cast concrete floors. According to the \"Code for Acceptance of Construction Quality of Concrete Works\", the required levelness for concrete floors (rough floors) is 8 mm, a requirement that is generally met. However, the only acceptance standard that can be used as a reference during construction is that related to the levelness of mortar-covered floors as specified in the \"Code for Acceptance of Construction Quality of Building Floor Works\" (4 mm). As a result, for construction companies, the difficulty of constructing concrete floors in one go increases compared to using mortar-covered floors. 1.2 Due to design requirements that the ground must be formed in one go before the construction of the superstructure can proceed, there is a high risk of damaging the already formed ground during the construction process. During the construction of columns, ring beams, and steel roof trusses, as well as during the setup and dismantling of formwork, the existing ground surface can be damaged, which leads to increased costs for technical measures aimed at protecting the products and greater difficulties in management. Control measures: After the rebar is tied together, a level is placed around the site; the elevation is determined using control points. A rebar bar perpendicular to the ground is welded every 4m×4m along the floor’s rebar structure. The rebar bars are cut at the height corresponding to the desired floor elevation. During concrete pouring, the exposed ends of the rebar bars are used to ensure that the floor reaches the correct elevation. The concrete is poured to a thickness slightly greater than that of the rebar bar ends, after which it is vibrated to achieve compactness. Subsequently, the levelness is checked using these rebar bar ends as references, and the elevation is verified again after leveling with a long straightedge, ensuring that the elevation error remains within 4mm. After the concrete has begun to set, work begins on preparing the emery floor; at the locations where vertical rebar will be placed, a wooden trowel is used to rub and smooth the surface. Emery is mixed with concrete paste to ensure a tight bond between the layers. After the emery floor is formed, technical measures for product protection must be implemented; watering for curing is required within 2 to 3 days once the floor reaches a strength suitable for human use, and 2 to 3 layers of plastic film should be applied to prevent rapid loss of moisture while also protecting the floor. During the subsequent construction of the main structure, materials must be lifted manually; dropping them is strictly prohibited. When lifting the steel roof trusses, since the truck crane must be driven into the factory building, it is required to lay 20 mm thick sand on the ground, and place two layers of 10×10 wooden planks crosswise under the crane’s support frames to prevent the ground from being damaged by excessive concentrated loads. Conclusion: Upon on-site inspection, no temperature-induced deformation cracks were found in this foundation, and the levelness and smoothness of the surface are generally satisfactory. Practice has shown that by adopting effective technical measures in areas such as optimizing mix design, improving construction techniques, enhancing construction quality, and strengthening curing, as well as by maintaining strict construction organization and management, it is entirely possible to control the occurrence of concrete temperature cracks and construction cracks, thereby achieving good self-waterproofing and impermeability properties ； Enhancing management efforts and thoroughly implementing the established technical measures can effectively control the surface flatness and smoothness of one-piece formed emery floors, thereby meeting the requirements for using such floors in industrial facilities. This post was last edited by zhangya*ong on 2009-3-18 16:56]