How to evaluate and improve the effect of concrete pavement leveling through quality inspection?

For any kind of mechanical equipment, in the process of long-term high-load operation, parts will inevitably be worn or damaged. This is no exception for concrete laser leveling machines, because the performance status of parts is directly It is related to the working efficiency and service life of the entire concrete laser leveling machine, so it is very necessary to master the replacement and maintenance methods of each component of the leveling machine. Next, our professional technicians will teach you how to correctly replace the various parts of the concrete laser leveling machine. ▼Laser leveler / leveling  piston and piston ring replacement skills Pistons marked with an upward arrow on the top should be installed in the direction specified by the mark; if there is no mark, the vortex pit on the top of the piston or the small gap next to the pit should face the side of the injector to ensure uniform gas mixing. When assembling piston rings, those with "UP" and "UP" marks on the top should face up; for twisted rings without marks on the top, their inner circular grooves or chamfers should face down; chrome-plated rings (shine shell) should be In a piston ring groove, the openings of each ring should be staggered by 120~180 degrees to ensure its sealing effect. ▼Laser leveling  machine cylinder head gasket replacement skills If there is an oil hole, align it with the corresponding oil passage hole on the body of the concrete laser leveling machine and the cylinder head, so as not to cause friction on the gas distribution mechanism on the cylinder head due to oil cut-off. If there is no oil passage hole and the front and back shapes are the same, it is determined by the material of the cylinder head: for the aluminum alloy cylinder head, the curled side of the cylinder head should face the cylinder block; for the cast iron cylinder head, the curled side of the cylinder head should face the cylinder head . ▼Replacement skills of main bearing cap, bearing bush and bushing of laser leveling / leveling  machine The main bearing cap and the bearing housing of the concrete laser leveling machine are processed by paired boring. They should be seated according to the matching marks. Do not exchange or change the assembly direction at will, so as not to damage the coaxiality and dimensional accuracy of the main bearing housing hole. Bearing bushes or bushes with oil holes should be aligned with the corresponding oil passage holes on the bearing housing and bushing holes to ensure smooth oil passage. ▼Replacement skills of connecting rod and connecting rod cover of laser leveler / leveling The connecting rod of the horizontal diesel engine is split at 45 degrees, and the section should face down to change the stress on the connecting rod bolts. The matching marks are on the same side to ensure that the roundness and cylindricity of the connecting rod bearing meet the specified requirements. Have you learned the methods and techniques for correctly replacing the concrete laser leveling machine piston, piston ring, cylinder head gasket, main bearing cap, bearing bush, bushing, connecting rod and connecting rod cover today? If you don't understand something, you can call directly for consultation, and we will have professional and technical personnel to answer your questions in time.

    When the hydraulic oil temperature of your power trowel is too high, you can check and implement the following solutions one by one in the order from simple to complex: These steps can be carried out quickly on the construction site, aiming to control the situation immediately. Immediately stop the polishing operation, lift the polishing disc and let the equipment idle for a few minutes without load. This can quickly relieve system pressure and reduce heat generation. This is one of the most immediate methods. The vast majority of power trowel use air-cooled coolers. Please immediately use compressed air or a low-pressure water gun to blow and wash from the inner side to the outer side of the cooler fins to thoroughly remove the dust, cement powder lumps and debris adhering to them, ensuring smooth ventilation. After the machine stops, check the oil level gauge of the hydraulic oil tank. Low oil level (insufficient oil volume) can cause the oil pump to suck air and have insufficient cooling circulation, resulting in high temperatures. If the oil level is too high, the foam inside the fuel tank will be difficult to dissipate, which will also affect heat dissipation. Make sure the oil level is between the upper and lower marks on the dipstick. Move the equipment to a cool and well-ventilated place and avoid continuous operation under direct sunlight or in an environment with extremely high temperatures. If the problem persists or recurs after emergency measures are taken, a more in-depth inspection is required. Oil type: Ensure the use of anti-wear hydraulic oil of the grade and viscosity level specified by the equipment manufacturer. Excessively high viscosity will increase flow resistance and generate heat, while excessively low viscosity will intensify internal leakage, leading to a decrease in pump efficiency and heat generation. Oil quality: If the hydraulic oil has turned black, has a burnt smell or produces a large amount of foam, it indicates that the oil has oxidized and deteriorated, and its lubricating and heat dissipation performance has sharply declined. The oil must be completely replaced with new oil, and the oil tank should be cleaned and the hydraulic oil filter element replaced at the same time. Cooling fan: Check whether the motor driving the cooling fan is working properly and whether the circuit is intact. If it is belt drive, check whether the belt is loose, slipping or broken, and adjust or replace it in time. Upgrade cooling capacity: For old equipment or devices operating under extremely harsh conditions, if the original cooler's capacity is insufficient, it is advisable to consider installing a larger-capacity or independently driven air-cooled cooler. If the set pressure of the relief valve is too high or the valve core is stuck in the pressure relief state, it will cause high-pressure oil to continuously return to the oil tank through the relief valve. This is a common cause of a sharp increase in oil temperature. It is recommended that professional maintenance personnel use a pressure gauge to detect the system pressure and readjust the relief valve according to the specified value. If the valve core is damaged, it needs to be cleaned or replaced. Hydraulic pump: Internal wear of the hydraulic pump (such as wear of the plunger, gears or blades) can lead to severe internal leakage. High-pressure oil leaked inside the pump into the low-pressure area, generating a large amount of heat. It is usually accompanied by phenomena such as weak machine power, slow movement and increased noise. Professional personnel are required to conduct efficiency tests. After confirmation, maintenance or replacement should be carried out. Control valve group: The wear of the valve cores of each control valve (such as directional control valves) can also lead to internal leakage, causing local high temperatures. One can touch the surface of the valve block to feel if there are any abnormal hot spots to assist in the judgment. Prevention from the perspective of usage habits is fundamental. Arrange the construction rhythm reasonably to avoid the equipment running at full load for a long time without interruption. When the working conditions are particularly heavy, it is necessary to consciously arrange intermediate rest periods to allow the hydraulic system to "catch its breath" and cool down. Daily: Clean the exterior of the cooler after work. Weekly: Check the hydraulic oil level and quality. Every six months or according to the working hours: Replace the hydraulic oil and filter element regularly as recommended by the manufacturer. This is the most effective means to prevent system contamination and oil deterioration. Solving the problem of excessively high hydraulic oil temperature in the power trowel machine is a systematic process. Please follow the principle of "start from the outside to the inside, from the easy to the difficult" : Begin with external factors such as cleaning the cooler and checking the oil level, as these often solve most problems. If it is ineffective, further investigate the core parameters such as the quality of the hydraulic oil and the setting of the relief valve. Finally, complex maintenance such as internal leakage of hydraulic pumps and valve groups should be considered. Adhering to standardized operation and regular maintenance is the fundamental way to prevent such problems from happening.   Note: The parameters provided in this document are for reference only and are not mandatory. Due to differences in technical characteristics between different brands and models of laser levelers, please consult the manufacturer for a suitable solution before actual operation. This reference document assumes no responsibility for any issues arising from failure to follow the manufacturer's instructions.    

    Technical objective: Through standardized technical management, precise process control, and scientific risk prediction, quality and safety hazards such as collapse, cracking, and leakage in concrete projects are eliminated from the technical level, ensuring the safety of personnel, equipment, and structures during the construction process, and guaranteeing that concrete projects comply with the "Code for Acceptance of Construction Quality of Concrete Structures" (GB50204) and relevant safety production regulations. ​ Scope of application: This measure is applicable to the entire life cycle of concrete engineering, including all links such as the selection of concrete raw materials, mix proportion design, mixing and transportation, pouring and vibration, curing and formwork removal, covering various concrete structure projects such as housing construction, municipal works, Bridges and tunnels. ​ Raw material selection and inspection: Strictly screen raw materials such as cement, sand and gravel, admixtures, and admixtures. Select cement products that meet the design strength grade (such as P.O42.5 and above), and the sand and gravel gradation should comply with the specification requirements (the particle size of the gravel is determined based on the structural dimensions, with the maximum particle size not exceeding 1/4 of the minimum cross-sectional size of the component). After each batch of raw materials arrives at the site, a third-party testing institution is entrusted to conduct performance tests (such as cement strength and stability, mud content and crushing value of sand and gravel, water reduction rate and setting time of admixtures). Only after passing the tests can they be used. ​ Technical requirements for raw material storage: Cement should be stored in a closed warehouse, stacked in zones according to the batches entering the site, and kept at least 30cm above the ground to prevent moisture and caking. The sand and gravel yard is hardened and treated, with rain shelters set up. Sand and gravel of different specifications are stored separately to avoid mixing. Admixtures are stored in dedicated tanks and labeled to prevent confusion with other materials. ​ Customized mix ratio: According to the type of engineering structure (such as beams, slabs, columns, foundations), strength grade (such as C30, C40), construction environment (temperature, humidity) and construction technology (pumping, self-compaction), entrust a qualified laboratory to design a special mix ratio. Clarify key parameters such as water-binder ratio, sand ratio, and admixture dosage (for example, the slump of pumped concrete should be controlled at 120-160mm, and the spread of self-compacting concrete should be ≥550mm). ​ Mix proportion optimization technology: By adding admixtures such as fly ash and mineral powder, the amount of cement is reduced, the heat of hydration is lowered, and temperature cracks in mass concrete are avoided. For winter construction, early-strength admixtures should be added to the mix proportion to ensure the early strength growth of concrete. During summer construction, adjust the dosage of retarder, extend the initial setting time, and prevent the initial setting of concrete during transportation. ​ Plan formulation and review: Prepare a special construction plan for concrete projects, clearly defining the construction process, technical parameters (such as the thickness of each pouring layer, vibration time, and curing period), and quality and safety control points. For special projects such as large-volume concrete (pouring volume ≥1000m³ or thickness ≥1m), ultra-high pumping concrete (pumping height ≥100m), and special-shaped structure concrete, experts are organized to conduct technical arguments on the plans, with a focus on reviewing temperature control, support systems, and distribution methods, etc., to ensure the scientific and feasible nature of the plans. ​ Technical briefing and Training: After the plan is approved, a comprehensive technical briefing will be conducted for technical personnel and construction teams, detailing the mix ratio requirements, pouring sequence, vibration key points, and emergency response measures. Organize technical training for operators, conduct practical exercises on key procedures such as the use of vibrators and the connection of pumps and pipes, and only allow them to take up their posts after passing the assessment. ​   Technical supervision of the mixing process: The mixing plant adopts a fully automatic metering system to ensure that the metering deviation of raw materials complies with the specification requirements (the metering deviation of cement and admixtures is ≤±1%, and that of sand and gravel is ≤±2%). The mixing time should be strictly controlled (for ordinary concrete, the mixing time should be ≥90 seconds; for concrete with admixtures or admixtures, it should be ≥120 seconds). During the mixing process, technicians should be arranged to inspect and observe the workability of the concrete (such as slump, cohesion, and water retention). If problems such as segregation and bleeding occur, the mix proportion should be adjusted immediately or the mixing should be stopped. ​ Technical support during transportation: Special tank trucks are used for concrete transportation. The inner walls of the tank trucks are thoroughly cleaned to prevent residual concrete from affecting the quality of fresh concrete. The transportation route should be planned in advance to avoid congested sections and ensure that the transportation time is ≤ the initial setting time of the concrete (≤2 hours at normal temperature and ≤1.5 hours at high temperature). During transportation, the tanker should maintain a low rotational speed (2-4r/min) to prevent concrete segregation. After the concrete arrives, technicians will test the slump on site. If the deviation exceeds ±20mm, the laboratory will issue an adjustment plan. It is strictly prohibited to add water at will. ​ Pouring sequence technical optimization: Follow the principle of "layered pouring, symmetrical advancement, and continuous operation". The concrete pouring of beams and slabs should be advanced from one end to the other, while the concrete pouring of columns and walls should be done layer by layer, with each layer thickness ≤500mm (when using insert-type vibrators), to avoid local accumulation causing overloading of formwork supports. The "inclined plane layering" pouring method is adopted for mass concrete, with a layering thickness of 300-500mm. The pouring speed is controlled (generally ≤2m/h) to reduce internal temperature stress. ​ Vibration Technical:  Specification The type of vibrator should be selected based on the slump of the concrete (high-frequency vibrators should be used for a smaller slump, and medium-frequency vibrators for a larger slump). When using an insertable vibrator for vibration, the spacing between the vibration rods should be no more than 400mm, and the insertion depth should be 50-100mm to the lower layer of concrete. The vibration time should be controlled at 15-30 seconds (until the concrete surface shows slurry and no air bubbles escape). Over-vibration (to prevent aggregate segregation) or missed vibration (to avoid honeycomb and pitted surfaces) is strictly prohibited. During the vibration process, avoid the vibration rod touching the steel bars, formwork and embedded parts to prevent structural deformation or displacement of embedded parts. ​ Temperature control for bulk concrete: The "internal reduction and external protection" technical measure is adopted. Temperature measurement tubes are pre-embedded inside (with one temperature measurement point set every 50-100 square meters) to monitor the internal and surface temperatures of the concrete in real time, with the temperature difference controlled at ≤25℃. Circulating cooling water can be introduced inside to lower the core temperature. The surface is covered with thermal insulation cotton and plastic film to reduce heat loss and prevent temperature cracks. When the temperature difference exceeds the limit, add insulation layers or adjust the flow rate of cooling water. ​ Conventional concrete moisture control: Within 12 hours after the concrete pouring is completed, cover it with moisture-retaining materials (such as gunny bags, geotextiles). During the hot summer, water it in time for maintenance to keep the surface moist. During winter construction, methods such as covering with electric blankets and steam curing should be adopted to ensure that the curing temperature is ≥5℃. The curing time should be carried out in accordance with the specifications (≥7 days for ordinary concrete, ≥14 days for concrete with retarding admixtures or with impermeability requirements) to prevent shrinkage cracks caused by rapid water loss in the concrete. ​   The determination of formwork removal time: The formwork removal time is determined based on the strength of the concrete test blocks under the same curing conditions. For bending members such as beams and slabs, formwork removal can only be carried out when the strength of the test blocks reaches 75% (for spans ≤8m) or 100% (for spans > 8m) of the designed strength. For vertical components such as columns and walls, the side formwork can be removed when the strength of the test block is ≥1.2MPa. Before formwork removal, technicians should issue a formwork removal application, which can be implemented after approval by the supervision unit. It is strictly prohibited to remove formwork in advance, which may cause structural cracking or collapse. ​ Technical Specifications for formwork removal operations: Formwork removal follows the principle of "install first and then remove, install later and then remove first, from top to bottom". Rough formwork removal is strictly prohibited. When removing large formwork, a crane should be used for hoisting, and a dedicated person should be assigned for command. No one is allowed to stand under the formwork. After formwork removal, promptly clean up the residual concrete on the surface of the formwork, check the flatness and deformation of the formwork, and repair the damaged parts before putting it back into use. ​ Structural entity inspection: 28 days after the concrete pouring is completed, a third-party inspection agency is entrusted to conduct structural entity inspection, including concrete strength rebound, steel bar cover thickness inspection, structural dimensional deviation inspection, etc. Conduct core drilling and sampling tests on large-volume concrete and important components (such as frame columns and main beams of Bridges) to ensure that the concrete strength meets the design requirements. For the parts that fail the inspection, a special treatment plan shall be formulated and implemented after being approved by the design unit (such as reinforcement by high-pressure grouting, external concrete coating, etc.). ​ Defect repair technology: For defects such as honeycomb, pitted surface and exposed bars on the concrete surface, the "surface treatment method" is adopted for repair: Clean the loose concrete at the defect area, rinse it clean with a high-pressure water gun, apply an interface agent, and then repair it with fine aggregate concrete or mortar in the same proportion as the original concrete. After repair, cover and maintain it. For crack defects, the repair method should be selected based on the crack width (surface sealing method for width ≤0.2mm, pressure grouting method for width > 0.2mm). During the repair process, technical records should be kept well to ensure the repair quality. ​ Establish technical archives for concrete engineering, collect and organize raw material inspection reports, mix proportion notices, construction logs, temperature measurement records, curing records, formwork removal applications, physical inspection reports and other materials to ensure that the materials are complete, accurate and traceable. Technical archives are filed and preserved in accordance with the prescribed requirements, serving as an important basis for project acceptance and later maintenance. ​ Regularly review and analyze the technical data of concrete engineering, summarize the technical problems during the construction process (such as the optimization effect of mix proportion and the accuracy of temperature control), form a technical summary report, provide technical references for subsequent similar projects, and continuously improve the safety production technology level of concrete engineering. ​   Emergency technology for concrete supply interruption: If the supply of concrete is interrupted due to a malfunction of the mixing plant or traffic congestion, immediately stop pouring, vibrate and compact the surface of the already poured concrete, and cover it with moisture-retaining materials. When the interval time exceeds the initial setting time of the concrete, handle it according to the requirements of the construction joint (set up a vertical construction joint, clean the surface floating slurry and loose aggregates, and apply an interface agent). After the concrete supply is restored, re-pour to ensure that the construction joint is tightly combined. ​ Emergency techniques for structural cracks: If early cracks are found on the concrete surface during the pouring process, stop pouring immediately, check the width and depth of the cracks. If they are surface dry shrinkage cracks, cover them with water in time and strengthen moisture retention and maintenance. If it is a temperature crack, add an insulation layer and adjust the temperature control measures. If the cracks continue to develop, immediately organize the evacuation of personnel, entrust the design unit to formulate a reinforcement plan, and adopt technical measures such as temporary supports and grouting sealing to prevent the cracks from expanding and causing structural safety accidents.   Instructions for Use: This plan is a general template. Before the specific implementation of each project, it should be refined and supplemented according to the characteristics of the project (such as super-high, super-heavy, large-span structures, etc.), especially the control measures for major hazard sources.