It depends on whether the slab has moved. Cracks that are tight, level across the break, and stable year to year are usually repairable — cleaned out, filled, and sealed. Once one side sits higher than the other, the crack is wide enough to see into, or the slab is broken into several pieces that rock underfoot, the base beneath has failed and patching will not hold. At that point replacement of the affected section, with the base properly recompacted first, is the repair that actually lasts.

That is spalling, and in the Philadelphia area the usual causes are freeze-thaw cycling and de-icing salt. Water soaks into the concrete surface, freezes, and pushes the top layer apart from within; road and sidewalk salt accelerates it sharply by drawing more moisture in and attacking the cement paste. Concrete finished too wet or troweled too early is more vulnerable because the surface layer ends up weaker than the slab beneath it. Repair means removing the failed surface and resurfacing, then avoiding salt on the new work.

Often, yes, and it is worth asking about because it costs less and takes less time than removal and repour. Slabs sink when the fill underneath washes out or compresses, leaving a void; if the slab itself is still structurally sound and in one or two pieces, it can frequently be lifted back to level and the void filled. If the slab is cracked into multiple pieces, badly spalled, or the drainage problem that caused the washout is ongoing, replacement is the better spend because raising it will only buy a few seasons.

Some cracking in new concrete is normal and expected — concrete shrinks slightly as it cures, and that shrinkage has to go somewhere. That is what control joints are for: deliberate grooves that give the slab a planned place to crack so it does not do so randomly. Fine hairline cracks within the first months, particularly along or near those joints, are usually cosmetic. What is not normal is a wide crack, a crack with vertical displacement, or one crossing the slab diagonally — those point to base or reinforcement problems rather than curing.

Fresh concrete needs to stay above freezing while it gains initial strength, so pours in the Philadelphia area generally run spring through late autumn. Cold-weather placement is possible with blankets, heated enclosures, and mix adjustments, but it adds cost and risk, and a hard freeze on green concrete can permanently weaken the surface. If you are dealing with a broken step or trip hazard in winter, the practical approach is making it safe now and scheduling the permanent repair for the first reliable stretch of warm weather.

K&S Masonry Restoration is based in Brookhaven, PA and works throughout Delaware County and the Philadelphia suburbs, including Philadelphia, Havertown, Springfield, Drexel Hill, Chester, Wayne, Radnor, and Ardmore, plus Montgomery and Chester Counties. If you are unsure whether your address is in range, call (610) 990-1379 and ask — it is a quick answer.