05 November 2024
Raising The Bar Guidance - Concrete Extrusion Machine Equipment Requirements
The Concrete Extrusion Machine is specialized equipment used to construct continuous concrete barriers, curbs, gutters, and other structures by extruding wet concrete into pre-defined shapes. This machine is widely used on highway and road construction projects for creating durable, uniform barriers efficiently. Due to the complexity of handling wet concrete and the machine’s potential impact on traffic and site safety, National Highways’ "Raising the Bar 1" guidelines provide specific operational and safety standards for the safe use of concrete extrusion machines on all projects.
General Minimum Requirements
The General Minimum Requirements (GMR) provide the baseline safety and operational standards for all equipment, including concrete extrusion machines:
Daily Inspections: Concrete extrusion machines must undergo thorough pre-use inspections each day. Operators should complete a checklist to detect any potential issues, such as leaks, wear on extrusion moulds, or issues with the hydraulic or conveyor systems.
Compliance with Legislation: All extrusion machines must meet UK regulatory standards, including UKCA certification and compliance with the European Commission Machinery Directive (2006/42/EC), with a declaration of conformity.
Safety Decals and High-Visibility Markings: Safety decals should be legible and visible on the machine. High-visibility markings must be applied to handrails, steps, and other high-traffic points to support safe access and handling.
Hearing Protection: Due to noise generated by the extrusion machine, operators and nearby personnel should wear hearing protection whenever the machine is in use.
Public Highway Compliance: When used on or near public highways, extrusion machines must be marked with warning signage, lights, and flashing amber beacons, as specified in Chapter 8 of the Traffic Signs Manual.
Equipment-Specific Safety and Compliance Standards
The unique characteristics of concrete extrusion machines, including the need for precision in concrete extrusion and management of the wet concrete mix, require specific safety standards:
Amber Beacon and Seat Belt Indicator: An amber beacon must be installed to increase visibility. An external green light should also indicate when the operator’s seat belt is engaged; this green light may be turned off when operating near public highways if required by lighting regulations.
360° Visibility Standards: Concrete extrusion machines must meet 360° visibility standards, which can be achieved with mirrors, cameras, or other visual aids to provide the operator with a full view around the equipment, especially when operating close to traffic or pedestrians.
Reversing Alarm: A directional, white-noise reversing alarm is required to alert nearby personnel when the machine is reversing. This alarm must be clearly audible outside the machine to enhance safety.
Hydraulic and Pressure System Safety: The hydraulic systems used to move concrete through the extruder must be fitted with a pressure relief system to prevent over-pressurization, which can cause leaks or bursts in the hydraulic lines.
Concrete Hopper Guard: The concrete hopper should be fitted with a guard to prevent accidental contact with the rotating parts. Operators should avoid placing any body parts near the hopper and ensure that it is filled carefully to prevent spills.
Anti-Vibration Measures: Anti-vibration measures should be in place to reduce operator fatigue and prevent equipment damage from prolonged vibration, especially during continuous extrusion operations.
Emergency Stop Buttons: Clearly marked emergency stop buttons must be accessible to both the operator and any assistants. These buttons should halt all machine operations immediately in case of an emergency.
Extrusion Process and Concrete Management Standards
The extrusion process requires careful handling of wet concrete and precision in positioning, necessitating specific operational standards:
Concrete Mix and Consistency Control: Operators must ensure that the concrete mix is of the correct consistency and strength for extrusion. A mix that is too dry or too wet can compromise structural integrity and clog the machine.
Controlled Extrusion Speed: Extrusion speed should be monitored and adjusted based on ground conditions and the project’s requirements to ensure a consistent concrete flow and prevent machine jamming.
Hydraulic System and Pressure Checks: Operators should monitor hydraulic pressure gauges to prevent overloading, which could damage the machine or create uneven extrusion.
Load Distribution on Inclined Surfaces: When operating on slopes or uneven terrain, operators should monitor the concrete load distribution to ensure consistent extrusion and prevent tipping or sliding.
Clear Path for Continuous Extrusion: The extrusion machine’s path should be free of obstacles, with marked areas for clear access. This prevents disruptions to the extrusion process and reduces risks for nearby personnel.
Avoiding Overhead Obstructions: Operators must be mindful of overhead structures or power lines when positioning the extrusion machine, especially if the machine has an extendable arm for positioning concrete.
Operator Competency and Requirements
Operator training and competency are essential to the safe and efficient use of concrete extrusion machines, given the technical nature of the extrusion process and the machine’s high-pressure systems:
Licensing and Certification: Operators must hold the appropriate certification to operate an extrusion machine, especially if the equipment is used near public roads.
Extrusion Machine-Specific Training: Operators should receive machine-specific training covering the operation of the extrusion system, hydraulic controls, and emergency procedures.
Understanding of Concrete Consistency and Pressure Control: Operators must understand the impact of concrete consistency on extrusion quality, as well as the importance of pressure monitoring to avoid equipment malfunctions.
Ground Condition Assessment: Operators should assess ground stability and slope before beginning extrusion, particularly when working on sloped or uneven surfaces to maintain a consistent output.
Emergency Procedures: Operators must be trained in emergency response, including how to engage the emergency stop, manage hydraulic failures, and control sudden concrete overflow.
Desirable Features
Additional features are recommended to improve safety, efficiency, and environmental compliance for concrete extrusion machines:
Automatic Pressure Monitoring System: An automatic pressure monitoring system alerts operators to sudden pressure changes, helping prevent equipment damage or inconsistent concrete flow.
Stage V Emission Compliance: For environmentally conscious projects, Stage V-compliant engines are recommended to reduce emissions, particularly in urban or environmentally sensitive areas.
Remote Control System: Remote control capability allows operators to control the extrusion machine from a safe distance, providing added flexibility, especially in confined or high-risk areas.
360º Camera System: A 360º camera system enhances visibility, helping operators avoid obstacles, personnel, and other equipment, especially when manoeuvring in complex construction zones.
Anti-Vibration Seating: Anti-vibration seating can reduce operator fatigue and improve comfort during long shifts, enhancing focus and reducing the risk of errors.
Concrete Flow Monitor: A flow monitor provides real-time feedback on concrete consistency and volume, alerting operators to any variances that may impact extrusion quality.
Hazard Identification and Mitigation
Operating a concrete extrusion machine involves specific risks, and proper mitigation is essential for safe operation:
Over-Pressurization and Hydraulic Failure: The high-pressure hydraulic systems used in concrete extrusion can fail if overloaded. Pressure relief systems, regular inspections, and consistent monitoring are essential to prevent accidents.
Concrete Spill Hazards: Wet concrete can spill during loading or extrusion, creating slip hazards and potentially impacting nearby equipment. Operators should control concrete flow and ensure proper hopper filling.
Noise and Vibration Exposure: The machine generates noise and vibration, which can impact operator health over time. Hearing protection, anti-vibration measures, and ergonomic seating help reduce this exposure.
Obstacles and Restricted Paths: The extrusion process requires a clear, uninterrupted path. Operators should establish exclusion zones and maintain a clear work area to prevent interference during extrusion.
Overhead Obstruction Hazards: When working near overhead power lines or structures, operators should use caution and establish height restrictions to prevent accidental contact.
Hopper and Rotating Part Hazards: The hopper and other moving parts pose a risk of entrapment. Operators should avoid direct contact with these areas, and hoppers must have guards to prevent accidental contact.
Summary
The Concrete Extrusion Machine is a specialized tool for constructing continuous concrete structures efficiently and with precision. However, due to its high-pressure systems, moving parts, and concrete handling requirements, strict adherence to National Highways' "Raising the Bar 1" guidelines is essential. Following key protocols, such as daily inspections, extrusion speed controls, visibility standards, and emergency stop functions, ensures safe and effective operation. Additional safety features like automatic pressure monitoring, remote controls, and anti-vibration measures can further enhance the safety and operational efficiency of concrete extrusion machines.
This article provides a comprehensive overview of the critical safety standards, operator requirements, and hazard management strategies for concrete extrusion machines, ensuring compliance with National Highways’ standards for safe and efficient project execution.