The safety and stability of concrete chimneys as an integral part of industrial buildings are directly related to the smooth conduct of the entire production process. However, as a result of prolonged exposure to the natural environment and production conditions, concrete chimneys are likely to experience various forms of damage and ageing, which need to be reinforced. This paper details several common ways of strengthening concrete chimneys and analyses their characteristics and applications。
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I. Carbon fibre reinforcement
Carbon fibre consolidation is an advanced technology widely applied to concrete chimney consolidation. The method significantly enhances the carrying capacity of the chimney and its resilience to earthquakes by pasting carbon fibres on the surface of the chimney, using such characteristics as high intensity and high modulus of carbon fibre. Carbon fibre consolidation has the advantage of being simple, effective and durable, especially in the case of cracks or localized damage to the chimney surface。
In the process of carbon fibre consolidation, the cleaning and grinding of chimney surfaces is first required to ensure that the surface is flat, oil-free and impurities. It is then painted with adhesive glue on the surface of the chimney, so that the carbon fibre sheet is attached to the chimney. When pasting is complete, carbon fibre sheeting needs to be compacted and sequestered to ensure that it is closely integrated with the chimney surface. Finally, strengthened chimneys are tested for quality to ensure that they meet the requirements for use。
Ii. Street strengthening
The strengthening of steel plates is a method of connecting steel plates by welding or bolting on the surface of the chimney, increasing the cross-section size and carrying capacity of the chimney. The method applies in the case of larger cracks or severe damage to chimneys. The strengthening of steel plates has the advantage of speed of construction and a marked increase in carrying capacity, but attention needs to be paid to the corrosive treatment of steel plates and connection to the original concrete。
The consolidation of steel plates will first need to be based on the actual condition of the chimney and the size of the steel plate. It is then drilled or cut out of a steel plate and is then installed to weld or bolt to the chimney surface. When the connection is completed, the steel plate needs to be preservative to improve its useful life. Finally, strengthened chimneys are tested for quality to ensure that they meet the requirements for use。
Iii. Preliminary strengthening
Pre-resilience reinforcement is a method of pre-pressure treatment of chimneys to improve their carrying capacity and stability by setting up pre-responders within or outside the chimney. The methodology applies in cases where the chimney's overall structure is stable but local carrying capacity is insufficient. The pre-resilience reinforcement has the advantage of having a significant hardening effect and a low impact on the original structure, but construction is relatively difficult and requires a professional construction team and equipment。
The pre-resilience reinforcement will first need to determine the location and number of pre-resilience bands according to the actual condition of the chimney. It is then installed inside or outside the chimney or where pre-receptions are cut, which are installed and stretched. Upon completion of the zhang pull, the pre-resilience bands are anchored and fixed to ensure long-term pre-resilience. Finally, strengthened chimneys are tested for quality to ensure that they meet the requirements for use。
Iv. Spray concrete reinforcement
The injection of concrete reinforcement is a way of increasing the cross-section size and carrying capacity of the chimney by spraying a new layer of concrete on its surface. The method applies where the chimney surface is less damaged or requires overall reinforcement. The injection of concrete consolidation has the advantage of speed of construction and significant reinforcements, but attention needs to be paid to the problems of connection between old and new concrete and to the homogeneity of jet concrete。
In the case of injection concrete consolidation, the cleaning and grinding of chimney surfaces is first required to ensure that the surface is flat, oil-free and impurity. Then, a new layer of concrete is sprayed on the surface of the chimney to ensure that the concrete is closely integrated with the surface of the chimney. Attention needs to be paid to the homogeneity and condensity of concrete during the jetting process, avoiding holes and cracks. Finally, strengthened chimneys are tested for quality to ensure that they meet the requirements for use。
V. Other strengthening
In addition to the common enhancements described above, there are other enhancements that deserve attention. For example, the coating of special protective coatings on the outer walls of the chimney can prevent external water infiltration and chemical corrosion; the addition of structural support points on the chimney to increase its tensile and shear strength; and the coating of glue on the chimney to reduce gaps in maintenance and extend its useful life. These enhancements can be selected and combined according to the realities of the chimney。
In conclusion, the concrete chimney is strengthened in a variety of ways, each with its characteristics and applicable scenes. A combination of considerations and analysis based on the actual circumstances of the chimneys is needed to select the most appropriate enhancements to ensure the safety and stability of the chimneys. At the same time, reinforcement work needs to be carried out with regard to the quality and safety of construction to ensure that the reinforcement achieves the desired results。
