Concrete and masonry safety: cement burns, silica dust and heavy bags

1. Wet concrete burns

Wet portland cement is strongly alkaline (caustic). OSHA’s guide to working with portland cement says it can cause caustic “cement burns”, that they may not cause immediate pain or discomfort, and that in severe cases they can extend to the bone. Quikrete’s bags and data sheets carry the warning “Causes severe skin burns and serious eye damage”, and NRMCA’s guide to ordering ready-mix says fresh concrete can cause severe chemical burns to skin and eyes.

• Wear waterproof gloves — Quikrete specifies impervious gloves such as nitrile — and long sleeves and trousers.
• Keep it out of boots. Wear rubber boots high enough for the job, with trousers over the top (or taped) so concrete can’t run in. Kneeling in wet concrete without protection is how many serious burns happen.
• Protect your eyes. Splashes happen when mixing, pouring and screeding. Wear safety glasses or goggles.
• Wash promptly. If wet concrete gets on your skin or soaks through clothing, wash it off with clean water and change clothes. Don’t wait for it to sting. Get medical help for eye exposure or any burn.

Mortar, stucco, grout and self-leveler are cement-based too, and carry the same risk. The concrete calculator and post hole calculator both start you off — gear up before you open the first bag, whether it is ten bags for a pad or a whole truck.

2. Silica dust when cutting

Concrete, block, brick, stone and mortar contain crystalline silica. Cutting, grinding or drilling them makes respirable dust fine enough to reach deep into the lungs, and long-term exposure can cause silicosis, lung cancer and other disease. Dry mix dust is a lung hazard too: Quikrete warns that prolonged or repeated inhalation of dust may cause lung damage or cancer.

OSHA’s silica standard for construction (29 CFR 1926.1153) lists specific controls in its Table 1. For handheld and walk-behind saws cutting concrete or masonry, the control is a saw with an integrated water system that continuously feeds water to the blade — from a pressurized tank or a hose, with enough flow to keep visible dust down. Depending on how long you cut and whether you are indoors, a respirator may also be required.

• Cut wet whenever you can, or use a saw with a dust shroud and vacuum built for silica.
• Cut outdoors, with the wind behind you, and keep others away.
• Don’t dry-sweep the dust; wet it or vacuum it with a HEPA-filtered vacuum.
• Wear a properly fitted respirator for dusty work such as dumping bags of dry mix or chiselling.

Plan cuts out of the job where you can: lay out block walls in whole and half blocks — see 8×8×16 block actual size — and size fire pits and garden walls to the units, as in how many cinder blocks for a fire pit.

3. Heavy bags and heavy pieces

An 80 lb bag of concrete mix is heavier than most people should lift often. The NIOSH lifting equation uses 51 lb as its load constant — the most nearly all healthy workers should lift even under ideal conditions — and real lifts (twisting, reaching, from the ground) allow much less. A cubic yard of bagged concrete is 45 bags and 3,600 lb; a pallet of 80 lb bags is 3,360 lb. See how many 80 lb bags of concrete in a yard and how many bags of concrete on a pallet.

• Choose 50 or 60 lb bags if you are working alone, and use a hand truck or cart.
• Lift close to your body with your legs, and don’t twist while holding a bag.
• Have pallets and blocks delivered as close to the work as possible.
• Check your vehicle’s payload before loading bags — it adds up fast.
• Old slabs are heavy too: a 4 × 4 ft pad 4 in thick is about 770 lb — see how much does a 4×4 concrete slab weigh.

4. Before you dig

Call 811 in the US (or your local locate service) a few business days before digging post holes, footings or a slab base. Utility lines along property lines and roads can be shallow — mailbox posts are a classic case, see how many bags of concrete for a mailbox post — and so are chain-link fences along a lot line, see how much concrete for a metal fence post.

Gear checklist

• Waterproof (nitrile-coated) gloves, and spares — the concrete for even a small 3-step stoop is plenty to burn bare hands
• Safety glasses or goggles
• Rubber boots and long trousers
• A respirator for dusty work; a wet saw or vacuum-equipped saw for cutting
• Clean water on site for rinsing skin and eyes