During the past winter the temperature in our area didn't get above 0°F for 2 weeks or above 32°F for 8 weeks. Consequently some residential driveways built in November didn't get much chance to cure before they were put into use. Then during December, January and February they were exposed to a lot of salt that dripped off the cars and definite ruts 1/4 to 3/4 inch deep developed. The concrete was the standard mix used in this area—4 70 pounds of cement per cubic yard and air-entrained—which normally produces 2500- to 3000-psi compressive strength at 28 days. It was cured with a membrane curing compound. The owners demand new driveways. Can these be repaired satisfactorily so that they do not need to be replaced?
Although the questioner mentions curing in November, he doesn't say whether the driveways were protected from the freezing temperatures during curing. Protection (see ACI 306 "Recommended Practice for Cold Weather Concreting" for the amount of protection required) can make a great difference in the amount of strength actually developed before the slab is exposed to cold weather. It can be anticipated that strength development will resume to some degree when more favorable curing conditions resume in the spring. Furthermore, the damage experienced is not excessively deep. It would thus seem advisable to grind or scarify the surface to make it uniformly flat and provide an attractive slip-resistant surface as a bonus. This method would be far more satisfactory than patching. An application of linseed oil would help make the driveway resistant to deterioration next winter. The linseed oil treatment should be renewed about every two years. Linseed oil does darken the surface. If the darkened color is undesirable a good quality clear sealer such as copolycarvitol could be applied. In either case the best results are obtained if the treatment is done when the temperature of the concrete is 70°F or warmer for better absorption. In future driveway construction it would be best to use a mix that produces at least 3500-psi strength, as recommended by ACI Committee 302. Furthermore, one should avoid the use of curing compounds on exterior slabs placed during the late fall in northern climates where deicers are used to melt ice and snow. Use of these compounds under these conditions may prevent proper airdrying of the concrete, which is necessary to enhance resistance to deicer scaling. This drying period should be at least one month in duration after curing if possible. Sheet membranes such as polyethylene film are preferable because they can be removed entirely when the curing period has ended. However, polyethylene will not hold much heat in the concrete; additional appropriate protection, such as insulating blankets or bats, should be placed over the poly membrane to hold the curing temperature in the concrete well above freezing (50°F is recommended).