Antifreeze is a mixture of water and glycol, typically either ethylene glycol or the less-toxic propylene glycol, used to regulate engine temperature. Ethylene glycol is highly poisonous, and its sweet taste makes spills especially dangerous for pets and wildlife. When spilled on concrete, this liquid poses a dual problem because it is both a toxic substance and a tenacious stain. Concrete is a porous material, meaning the liquid quickly soaks into its microscopic structure, necessitating quick action before it fully cures and creates a deep-seated hazard.
Immediate Safety and Preparation
Before beginning cleanup, prioritize personal safety and gather all necessary supplies. Antifreeze is a toxic chemical, so wear protective gear, including chemical-resistant gloves and safety eyewear. You will need an absorbent material (like clay kitty litter or specialized oil dry absorbent), a stiff-bristled scrub brush, a commercial degreaser, and a secure, sealable container for waste disposal. A water source for rinsing is helpful, but avoid flushing the spill into storm drains.
Initial Spill Containment and Absorption
The immediate action for any wet spill is to contain the liquid and absorb the bulk material to prevent it from spreading or soaking deeper into the concrete. Use a damming material to block the spill’s path. Then, liberally cover the entire affected area with a highly absorbent granular product like clay cat litter or sawdust. Allow the absorbent material to sit for 15 to 20 minutes to pull liquid from the concrete surface. Once the liquid has been fully absorbed, carefully sweep or shovel the contaminated material into a sealable container.
Deep Cleaning and Residue Removal
After removing the bulk liquid, address the residue and any stain that has penetrated the concrete’s pores. Antifreeze is water-soluble, so apply a cleaning solution designed to break down the remaining glycol compound. Effective choices include powdered laundry detergent, a commercial concrete degreaser, or trisodium phosphate (TSP) mixed with hot water. Scrub the cleaning agent vigorously into the stain using a stiff-bristled brush to agitate the pores and lift the embedded material.
Poultice Method for Deep Stains
For deep-seated stains, a poultice method is necessary to draw the stain out of the concrete. Create a paste by mixing the powdered absorbent material with the chosen chemical cleaner or solvent. Spread the poultice over the stain, overlapping the edges, and cover it tightly with plastic sheeting to prevent evaporation. The paste dissolves the stain, and as it slowly dries over 12 to 24 hours, the absorbent powder wicks the dissolved glycol residue upward. Once the poultice is completely dry, remove the covering, scrape up the dry powder, and rinse the area with clean water.
Safe Disposal of Contaminated Materials
All cleanup materials, including contaminated absorbent, used rags, and rinse water, must be treated as hazardous waste due to the toxicity of the glycol. Antifreeze should never be poured down storm drains, into sinks, or onto the ground. Seal the contaminated solid waste in a plastic bag or container. Contact your local waste management facility or a household hazardous waste collection site. These facilities are equipped to handle the proper disposal or recycling of used antifreeze.