Concrete and asphalt paving in Pasadena, where older slabs meet heavy traffic

Decades-old driveways and what time does to them

A residential driveway that has been in service for thirty or forty years has been through a lot of wet seasons, dry summers and hurricane rains. Concrete of that age often shows a familiar set of symptoms: a few long cracks that have widened and shifted out of plane, a surface worn down enough that the sand and small stones show through, and joints that have lost whatever filler they once had and now hold grass and soil.

Older slabs in this part of the county were also built to the habits of their time. Some were poured thin, some have little or no steel in them, and some were placed on whatever native ground was there after the lot was cleared. Those details are not visible from the street, but they matter a great deal when deciding whether a crack is cosmetic or whether the slab has reached the end of its useful life.

A contractor looking at an older driveway should cut or core a small spot, or at least lift an edge where the slab is already broken, to see how thick it is and whether there is any reinforcement. That one observation often decides the whole conversation.

Clay that swells and shrinks under slabs that have seen it all

Much of the ground around Houston is expansive clay. It takes on water and swells during wet stretches, then dries and shrinks during long hot spells, and it does this over and over for the entire life of a driveway. On an old slab, the cumulative result is often visible as one panel sitting higher than its neighbor, a crack that opens in August and closes again after a rainy week, or an edge that has dropped where the soil beside it dries out faster than the soil beneath the middle.

Movement like this is not always a reason to tear out the concrete. A slab that has shifted a little but still carries cars without rocking can often be left alone or repaired at the joints. A slab that tilts toward the house, traps water or creates a real tripping edge usually needs more than a patch.

It helps to separate two kinds of problems. Driveway settlement caused by soil under the slab is a paving question. Cracking in the house itself, doors that stick or a garage slab that has dropped along with the foundation points to a foundation issue, and that is a separate specialty. So is lifting a sunken slab by pumping grout or foam beneath it. The paving contractor can tell you which one you are looking at and send you in the right direction.

Flat ground, heavy rain and water with nowhere to go

The land near the Ship Channel is close to flat. On a driveway or a parking area, that means the slope that moves rain toward the street or a drain has to be built in on purpose, because the ground will not provide it. Older pavement was not always given enough fall, and years of settling can flatten what little there was.

Standing water is hard on both materials. Under concrete, it keeps the clay wet and soft at the edges while the center stays drier, which encourages uneven movement. On asphalt, water sitting in a low spot works into small cracks, softens the base and, with traffic on top, turns into potholes much faster than the rest of the surface would fail.

When the ground is this flat, a replacement project is the best chance to fix drainage. That can mean regrading the base so the new surface falls toward the street, adding a trench drain across the end of a driveway that slopes toward the garage, or tying a parking area into an existing inlet. Any connection to a public storm drain or ditch is something to check with the city before the work is planned.

Commercial yards, truck routes and loads that residential slabs never see

Pasadena has a lot of commercial and industrial property, and the pavement serving it lives a harder life than a home driveway. Loaded trucks, forklifts, trailers parked on their stands and delivery vans turning in place all put heavy, concentrated weight on the surface.

For asphalt, that means thicker sections, a well compacted base and attention to turning areas where tires scrub the surface. For concrete, it means a thicker slab, proper reinforcement, joints spaced for the thickness and dowels or other load transfer where heavy wheels cross from one panel to the next. A trailer stand parked on thin asphalt in July will punch into it, so a concrete pad in the parking position is a common and sensible choice.

Many owners end up with a mix: concrete where trucks turn, park or load, and asphalt across the larger drive lanes and car parking. Sealcoating and restriping keep the asphalt portion in useful shape between larger projects.

Repair, overlay or replace on an older property

Old pavement tends to push owners toward replacement, but that is not always the right answer. The choice usually comes down to what is happening underneath the surface.

• Concrete with a few stable cracks and sound panels can often be cleaned, sealed at the joints and cracks, and left in service for years.
• Individual concrete panels that are broken, sunken or tilted can be cut out at the joints and replaced without removing the whole driveway.
• Asphalt with surface wear and fine cracking over a firm base is a candidate for crack sealing and sealcoating, or a mill and overlay if the wear is deeper.
• Asphalt with alligator cracking, soft spots or potholes that keep returning usually has a base problem, and those areas need full-depth repair before any overlay.
• Pavement that holds water across large areas usually needs the grade changed, which generally means removal and rebuilding rather than a new layer on top.

What a proposal for an older Pasadena property should cover

A useful proposal on an aged driveway or lot starts by describing what exists: thickness where it could be checked, the condition of the base, the drainage pattern and any areas of movement. It then states what will be removed, what will be kept and why.

For new concrete, look for the slab thickness, the reinforcement, the joint layout, how the base will be prepared and compacted, and how the finished surface will slope. For asphalt, look for the base depth and material, the compacted asphalt thickness, how edges will be supported and what happens at the transitions to the street and the garage. Cure and use times should be spelled out so nobody drives on new work too soon.

If the proposal cannot tell you where the water will go when it rains, ask. On flat east-side ground, that answer is at least as important as the surface material.

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