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0 Introduction Since
1990s, with the rapid development of science and technology and the continuous investment in national infrastructure, China has formed a huge construction steel structure industry chain. Take Shanghai as an example, from the construction of Shanghai Center, Shanghai Disney, Shanghai's tallest Twin Towers Star Harbor International Center, to Shanghai Hongqiao Integrated Transportation Hub, Pudong International Airport and shanghai World Expo China Pavilion, and so on, representative buildings are emerging.
in order to avoid corrosion damage to the atmospheric environment during service, coatings are often used to protect building steel structures
. Coatings have been proven to be one of the most cost-effective ways to protect steel structures in buildings. In general, coating systems often provide a shorter period of protection than construction steel structures, so the relevant parties must consider the possibility of repair and reconstruction during the planning and design phases.
, many construction steel coatings fail to varying degrees during service. And most of the construction steel structure during the service period did not establish a perfect post-maintenance data. Early steel construction units are often not post-maintenance/maintenance units, resulting in a lack of professional planning and guidance before maintenance. In the maintenance often appear in the repair paint and the old coating is not compatible with the situation, substrate surface treatment without professional specifications, resulting in premature failure of the late maintenance coating and so on.
therefore, it is important to study how to carry out regular inspection and evaluation of construction steel coatings in order to develop maintenance plans.
1
Experimental Part
1.1 Determination of corrosion environment
According to ISO12944-2, "Color paint and varnish protective paint system corrosion protection of steel structure Part II corrosion environment classification", the construction steel structure is located in the environment of the main categories listed in Table 1.
1 Corrosion Environment Classification
1.2 Project Area Division
which collects and records engineering data (including construction records, project drawings, construction support, etc.).
the project drawings and preliminary observation on the site, we understand the structural distribution, construction area, etc. of the whole steel structure project and divide the project into several areas. Such as top, column, main structure, walking platform, railings and so on.
1.3 On-site coating appearance inspection
in accordance with the relevant standards, specifications, the quality of the coating appearance of the project, mainly for peeling, cracking, foaming, rust rating (see Table 2), other defects can be recorded at the same time assessment, for auxiliary reference. During the on-site inspection, the location, degree and percentage of the area of the main damage of the coating will be described, recorded, and analyzed to determine the failure aging and cause.
2 Peeling, Cracking, Foaming, Rust Rating
1.4 Field Coating Performance Check
spot checks of the coating performance of the project, mainly for the measurement of coating thickness.
the thickness of the coating is measured by an electronic dry film thickness gauge to analyze the cause of the failure of the coating. For example, the film thickness is super thick to produce cracking or coating film thickness does not meet the design requirements of the early corrosion.
2
on-site evaluation and discussion of steel structures
In May 2019, on-site inspection and evaluation of anti-corrosion coatings of construction steel structures was carried out at the first phase of the plant of Hang Xiao Steel Construction Co., Ltd.
2.1 Project Background
Table 3 Project Background
2.2 Field Assessment Report
Based on the project background (Table 3), the site assessment site is an internal column beam, as detailed in Table 4 and Figure 1.
Table 4 Internal column beam site assessment report
Figure 1 field picture
after on-site assessment, the degree of corrosion is light, it is recommended that the rust area polished to the substrate, grade St3, and pull the original coating out of the crack. Pay attention to cleaning before treatment, it is recommended to rinse with high pressure water. Plant is an open area, pay attention to the temperature and humidity during construction.
3
Conclusion
Through on-site inspection and evaluation of the construction steel structure, the main degree of corrosion of the anti-corrosion coating of the reaction steel structure is: foaming, peeling, cracking and rusting. The rating of these defects visually reflects the "health" of the coating in part or overall of the steel structure, effectively maintaining them and carrying out appropriate repair and maintenance plans.
References (slightly)
For more information, please refer to Coatings and Protection No. 12 of 2019
Author/ Muze, Hu Xiaozhen
(Shanghai Jianke Inspection Co., Ltd./National Construction Materials Quality Supervision and Inspection Center, Shanghai 201108)
.