Concrete is a composite material made from Portland cement, water, and aggregates like sand, gravel, or crushed stone. This mixture hardens through hydration, forming a durable, rock-like substance. While hardened concrete is stable and widely used, its components and various stages of its lifecycle can pose hazards. Understanding these dangers is crucial for safety during its production, handling, and disturbance.
Hazards During Concrete Production
Concrete production involves handling dry components like cement powder and aggregates. Fine cement dust can irritate the respiratory system, causing coughing, wheezing, and shortness of breath. Prolonged exposure to this dust may lead to chronic bronchitis.
Some aggregates and cement naturally contain crystalline silica, a mineral that becomes a hazard when inhaled as fine dust. Inhaling this dust can cause lung inflammation and scarring. Cement also contains trace amounts of hexavalent chromium, which can trigger allergic contact dermatitis in sensitive individuals. This reaction can manifest as eczema and may recur with slight contact.
Risks of Wet Concrete Exposure
When mixed with water, concrete becomes a wet, workable material, and its hazards shift. Wet concrete is highly alkaline due to calcium hydroxide formation during hydration, with a pH up to 12.5, making it strongly caustic.
Direct and prolonged skin contact can result in severe chemical burns, often referred to as alkali burns. The caustic nature of wet concrete can also cause irritation and various forms of dermatitis. Eye contact can lead to severe damage, including potential blindness. The alkalinity can also alter the skin’s protective barrier, increasing absorption of other substances like hexavalent chromium.
Dangers from Cured Concrete Dust
When hardened concrete is disturbed through activities like cutting, grinding, drilling, or demolition, it generates fine dust. This dust contains respirable crystalline silica (RCS). These microscopic particles are approximately 100 times smaller than a grain of sand and can easily be inhaled deep into the lungs.
Inhaling RCS can lead to serious, long-term health conditions. Silicosis, an irreversible lung disease, causes lung tissue scarring and stiffening. Exposure to RCS also increases the risk of lung cancer, chronic obstructive pulmonary disease (COPD), and kidney disease. Symptoms, especially of silicosis, may not appear until many years after initial exposure.
Protecting Yourself and the Environment
Personal Protective Equipment (PPE)
Protecting against concrete hazards involves using appropriate personal protective equipment (PPE). Gloves, long-sleeved clothing, and safety goggles prevent skin and eye contact with wet concrete. Respiratory protection is needed when working with dry cement or disturbing cured concrete. An N95 respirator or a higher-efficiency particulate air (P100) filter can help filter out hazardous dust particles.
General Safety Practices
General safety practices are important for minimizing exposure. Using wet methods during activities like cutting or grinding concrete can help suppress dust generation. Proper ventilation in work areas also helps reduce airborne dust concentrations. For cleanup, wet sweeping or a HEPA-filtered vacuum is recommended; avoid compressed air as it aerosolizes harmful particles.
Hygiene and Environmental Responsibility
Good hygiene practices are also important. Wash hands thoroughly after handling concrete. Change work clothes and shower before leaving the worksite to prevent dust spread. Environmental responsibility also extends to managing concrete waste, particularly wet washout water. Preventing this alkaline washout from entering storm drains or waterways avoids harming aquatic ecosystems by altering water pH.