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Deterioration Assessment & Mix Design. A client has recently purchased a workshop building and a separate boiler house unseen at auction. These were built in 1970 are located on the promenade at St Annes, Lancashire and the client has since discovered a number of issues regarding their condition which require further investigation and remediation. The concrete frame is painted internally in all but in one small location which shows the natural surface of the concrete has a dark grey to almost black appearance. A spalled concrete panel is located at roof level on the boiler house. This appears to be a long-term problem and other sections of the same panel have become cracked. The spalled concrete appears normal in all respects except for evidence of rust staining. In light of the building conditions, carry out the sequence of steps you would take in order to assess the deterioration and arrive at a likely diagnosis and suggest the suitable concrete mix design in order to resolve the issues in the building. b. Each Student Group will submit the solution in the form of comprehens To assess the deterioration of the workshop building and the boiler house, and arrive at a likely diagnosis and suitable concrete mix design to resolve the issues, the following sequence of steps can be taken: 1. Visual Inspection: Conduct a thorough visual inspection of the workshop building and boiler house. Take note of any visible signs of deterioration, such as cracks, spalling, rust staining, discoloration, and any other anomalies in the concrete surfaces. 2. Documentation: Document the observed issues with photographs, notes, and sketches. This will help in analyzing and discussing the problems effectively. 3. Historical Information: Gather any available historical information about the building, including construction documents, maintenance records, and previous repairs. This can provide insights into the original design, materials used, and any previous issues that have been addressed. 4. Structural Assessment: Engage a structural engineer to assess the overall structural integrity of the workshop building and the boiler house. They will examine the concrete frame, identify any signs of structural distress, and evaluate the load-carrying capacity of the elements. 5. Concrete Analysis: Collect concrete samples from various locations, including the dark grey to almost black area and the spalled concrete panel with rust staining. Conduct laboratory tests on the samples, such as compressive strength testing, chloride content analysis, and carbonation depth testing. This will help determine the condition of the concrete and identify any potential causes for deterioration. 6. Moisture and Environmental Analysis: Assess the moisture levels within the building, particularly in the areas showing signs of deterioration. High moisture levels can contribute to concrete deterioration, so it is essential to identify potential sources of water ingress or inadequate ventilation. 7. Corrosion Evaluation: If rust staining is observed on the spalled concrete panel, conduct a corrosion evaluation to determine the extent of steel reinforcement corrosion. This can be
done through techniques like half-cell potential mapping, corrosion rate measurement, and concrete resistivity testing. 8. Diagnosis and Remediation: Based on the findings from the previous steps, the likely diagnosis of the deterioration issues can be made. It could be due to factors like carbonation, chloride ingress, poor construction practices, water ingress, or corrosion of steel reinforcement. Once the cause is identified, suitable remediation measures can be proposed. 9. Concrete Mix Design: Develop a concrete mix design that addresses the specific issues identified in the building. The mix design should consider factors such as required strength, durability, resistance to chloride ingress, and appropriate cover for steel reinforcement. 10. Repair and Rehabilitation Strategy: Develop a comprehensive repair and rehabilitation strategy based on the identified issues. This may involve techniques such as localized concrete repair, corrosion control measures, waterproofing systems, protective coatings, or strengthening measures based on the structural engineer's recommendations. It's important to note that this is a general sequence of steps and the specific details and actions required may vary based on the actual conditions of the workshop building and boiler house. Engaging professionals such as structural engineers, concrete specialists, and experienced contractors will be crucial in accurately assessing the deterioration and developing an appropriate solution. 1. Visual Inspection: During the visual inspection, pay close attention to the extent and severity of cracks, spalling, and discoloration. Note the location, size, and patterns of these issues. Look for any signs of water stains or moisture-related problems. Also, examine the surrounding areas for signs of corrosion or rusting. 2. Documentation: Take clear photographs of each observed issue from different angles to capture the full extent of the deterioration. Make detailed notes describing the observed conditions, including the size, shape, and location of each problem. Use sketches or diagrams to illustrate specific areas of concern. 3. Historical Information: Review any available construction documents, such as architectural drawings, structural plans, and specifications. Gather maintenance records or previous repair reports that may provide insights into past issues and repairs. This information can help in understanding the original design intent and any modifications made over the years. 4. Structural Assessment: Engage a qualified structural engineer to assess the integrity of the concrete frame. They will evaluate the condition of load-bearing elements, such as columns, beams, and slabs. The engineer will check for signs of distress, such as excessive deflection, uneven settlement, or visible signs of structural instability. 5. Concrete Analysis: Collect representative concrete samples from different areas of the building, including the dark grey to almost black area and the spalled concrete panel with rust staining. Send these samples to a laboratory for testing. The laboratory tests may include compressive strength testing, chemical analysis to determine chloride content, carbonation depth testing, and petrographic examination to identify potential causes of deterioration.
6. Moisture and Environmental Analysis: Use moisture meters or sensors to measure the moisture content of the concrete in various locations. Identify potential sources of water ingress, such as leaks, condensation, or inadequate waterproofing systems. Consider the environmental conditions, including exposure to saltwater, humidity, or harsh weather conditions. 7. Corrosion Evaluation: Engage a corrosion specialist or a materials testing laboratory to evaluate the extent of steel reinforcement corrosion. They can perform tests such as half- cell potential mapping, corrosion rate measurement, and concrete resistivity testing. These tests will help determine the severity and extent of corrosion and its impact on the concrete's condition. 8. Diagnosis and Remediation: Based on the findings from the previous steps, analyze the data to arrive at a likely diagnosis of the deterioration issues. Possible causes could include carbonation of concrete due to exposure to atmospheric CO2, chloride ingress from de-icing salts or coastal environment, poor-quality concrete mix, inadequate cover to reinforcement, or insufficient waterproofing measures. With a clear diagnosis, develop an appropriate remediation plan that addresses the identified issues. 9. Concrete Mix Design: Collaborate with concrete experts or materials engineers to develop a mix design that addresses the specific issues discovered. This may involve using high-performance concrete with enhanced durability properties, such as low permeability, reduced water-cement ratio, appropriate cementitious materials, and additional admixtures for corrosion resistance. 10. Repair and Rehabilitation Strategy: Develop a detailed repair and rehabilitation strategy based on the identified issues and recommendations from the structural engineer and concrete specialists. The strategy may include localized concrete repairs using suitable repair mortars or grouts, application of protective coatings or sealants to prevent water ingress, installation of corrosion control systems like cathodic protection or corrosion inhibitors, and strengthening measures such as external post-tensioning or carbon fiber reinforcement. Remember that this is a general outline, and the actual steps and actions needed will depend on the specific conditions and findings at the workshop building and boiler house. Consulting with professionals experienced in concrete assessment and repair is crucial for an accurate diagnosis and effective remediation plan.
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