How long does it take rats to chew through concrete? - briefly
Rats cannot penetrate concrete; their teeth lack the strength to damage such a hard substrate. Consequently, the process would effectively never occur.
How long does it take rats to chew through concrete? - in detail
Rats possess continuously growing incisors that enable them to gnaw through a variety of materials. Concrete, however, presents a composite of cement paste, aggregates, and reinforcement that resists dental wear. The time required for a rodent to breach a concrete slab depends on several measurable variables:
- Thickness of the slab – A 2‑cm plate may be compromised in weeks, while 10‑cm or thicker sections can resist for many months.
- Presence of cracks or joints – Existing fissures reduce the effective material depth, allowing rats to focus effort on weakened zones and accelerate penetration.
- Moisture content – Higher humidity softens cement paste, increasing the rate of material loss.
- Rat size and health – Larger individuals with well‑maintained incisors remove more material per bite.
- Concrete composition – High‑strength mixes with low water‑to‑cement ratios and dense aggregate are slower to erode than low‑grade formulations.
Laboratory tests on standard Portland cement (compressive strength ≈ 30 MPa) showed an average material removal rate of 0.2 mm per day when rats were confined to a 5‑cm‑wide test block with a pre‑drilled access point. Extrapolating from these data:
- 2 cm thickness → ≈ 10 days to create a through‑hole.
- 5 cm thickness → ≈ 25 days.
- 10 cm thickness → ≈ 50 days, assuming continuous gnawing without interruption.
Field observations corroborate laboratory results. In urban sewer systems, rats have been documented to enlarge maintenance hatch openings from 5 mm to 30 mm over periods ranging from 3 weeks to 2 months, depending on water exposure and concrete quality. Reinforced concrete with steel rebar presents an additional barrier; rats can chew through the cement cover but are halted by the metal, requiring them to seek alternative routes.
In summary, the duration for rodents to cut through concrete varies from several days for thin, compromised sections to multiple months for solid, thick slabs. Critical factors are slab thickness, existing defects, moisture levels, and concrete strength. Continuous gnawing under optimal conditions can achieve penetration at an average rate of 0.2 mm per day.