Lubbock, TX · Guide
Caliche, Clay and the Base Under Lubbock Concrete
The ground under a Lubbock yard can change from soft topsoil to hard caliche within a foot. That variation explains many cracked slabs and how to avoid them.
01 — What this covers
The work itself
- What caliche is
- Sandy loam and clay pockets
- Why mixed ground cracks slabs
- Excavation and base
- Using caliche as base
- Water and caliche
- Steel and joints
- Questions to ask
02 — Detail
What caliche is
Caliche is a layer of soil or sediment cemented together by calcium carbonate, the same mineral as limestone. It forms in dry climates when water carrying dissolved minerals evaporates and leaves them behind, and it is common across the Llano Estacado and much of West Texas.
It can be soft and crumbly or nearly as hard as rock, and its depth varies from right below the grass to several feet down.
Caliche is also used as a road base material in the region, because it is locally abundant and compacts well when dry.
03 — Detail
The mix under a typical yard
Above and around the caliche, Lubbock yards have sandy loam topsoil and, in places, clay that swells and shrinks with moisture. A single driveway can sit on all three.
Sandy soil drains well but can wash out from under slab edges. Clay pockets move with the seasons. Caliche can be firm when dry but soften when water sits on it.
A slab that rests on supports with different behavior bends where they meet, which is why many cracks follow a line across a driveway.
04 — Detail
Building a uniform base
The goal of base preparation is even support. That means removing topsoil, organic material and loose fill, and building a compacted layer of select material across the whole slab area.
Where caliche is close to the surface and solid, it may be trimmed and compacted as part of the subgrade. Where it is broken or mixed with clay, it is removed or blended to avoid hard and soft spots.
Excavating hard caliche takes more time and equipment, which can affect the price.
05 — Detail
Water is the key variable
Caliche and clay both behave worse when wet. Rain running under slab edges, downspouts emptying beside a driveway and sprinklers spraying the base all change the ground under the concrete.
Grading the area so water flows away from slabs, sealing joints and directing downspouts away protect the base for years.
On the flat South Plains, getting water off a slab sometimes requires channel drains or regrading the yard.
06 — Detail
Steel and joints
Rebar on chairs, placed in the middle of the slab, holds pieces together if cracks form and keeps them level. Mesh lying on the ground does little.
Control joints at proper spacing guide cracking into straight lines. Expansion joints separate slabs that move differently.
These details do not stop the ground from moving, but they make the concrete tolerate it.
07 — Detail
Questions to ask your contractor
Ask how deep they will excavate, what base material they will use and how it will be compacted. Ask whether rebar or mesh is included and how it will be supported.
Ask how they plan drainage around the slab and whether the mix is air-entrained for winter.
A contractor who answers clearly is one who plans for Lubbock ground.
How we work
Step by step
- 01
Inspect the ground: topsoil, clay, caliche and drainage.
- 02
Excavate to firm, uniform support.
- 03
Place and compact the base.
- 04
Set forms and steel on chairs.
- 05
Pour, finish, cut joints and cure.
What it costs
Excavating caliche, removing soft soil and adding base material affect the price but determine how long the concrete lasts.
Questions
Caliche, Clay and the Base Under Your Concrete — asked and answered
Is caliche good under concrete?
Solid, dry caliche can be a good support, but mixed or wet caliche needs care.
Why did my driveway crack in a straight line?
Often where support changes, for example from caliche to clay or fill.
Does hard caliche cost more to dig?
Yes, excavation takes longer and may need heavier equipment.
What base should be used?
A compacted layer of select material that gives even support across the slab.
Do I need rebar?
Rebar on chairs is strongly recommended for driveways in Lubbock.
Next step
Concrete services in Lubbock
Concrete Driveways
New and replacement concrete driveways in Lubbock, including alley-entry drives, approaches at the street and…
Stamped Concrete
Stamped concrete patios, walks, entries and pool decks in Lubbock, with colors suited to West Texas light…
Concrete Patios
Concrete patios in Lubbock, from new back patios and extensions to slabs for covered patios, windbreaks and…
Concrete Repair
Concrete repair in Lubbock for winter scaling, cracked driveways, broken sidewalk panels, chipped steps and…
Concrete Leveling
Concrete leveling in Lubbock with polyurethane foam or slurry, to lift sunken driveways, walks, patios and…
Polished Concrete
Polished and ground-and-sealed concrete floors in Lubbock garages, workshops, barns and homes, using the…
Service area