What are concrete batch plants, and why are they in Houston?

A TexCon Ready Mix concrete batch plant in Fifth Ward.

Aldine residents hold up signs in opposition to a proposed concrete batch plant during a public TCEQ meeting at the East Aldine Management District building on April 7, 2022.

The TexCon Ready Mix concrete batch plant in Fifth Ward.

Houston led the U.S. in new home construction in 2023, and that expansion has driven a heavy demand for concrete.

The spinning drums of racing ready-mix trucks are a common sight along city thoroughfares, and while fumes and the occasional spill from the fleets irk residents, the urban batch plants that fill the trucks have proven much more controversial. City and county authorities have pointed to research showing batch plants' connection to a range of serious health problems.

The Houston area is home to more than 100 of these small industrial operations, and new permit applications are common.

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Concrete batch plants are different from cement kilns, such as the proposed facility Lt. Gov. Dan Patrick decried after a visit to Grayson County, or concrete crushers, like the operation slated to be built across from Houston's Lyndon B. Johnson General Hospital. Both of these create powders or small bits that can be used in future concrete batching.

A concrete batch plant is a facility where water is mixed with a slew of dry ingredients to form wet concrete, which is then transported to a job site. They can either be combined in a central mixer, or dropped straight into a truck with a rotating drum that continues to mix the material as it races off to pour the thick liquid.

Concrete begins hardening after it is mixed. This means trucks are on a clock, and cannot be filled hours away from a job site. While drying times vary based on the temperature and composition of each batch, the American Society for Testing and Materials specifies that ready-mix concrete should be poured no more than an hour and a half after it is combined.

According to the National Ready Mixed Concrete Association, the material "remains in a fluid condition for about four to six hours which permits transporting, placing and finishing in its final location, then the mixture starts to harden."

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The final step in making ready-mix concrete, performed at facilities called concrete batch plants, is to combine the ingredients into a truck equipped with a rotating cement mixer that can drive to a job site.

Houston has no zoning regulations, so concrete batch plants are not restricted to specific industrial areas. As a result, they have popped up across the city, prompting strong pushback from residents in areas that are already jam-packed with polluters.

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More than 100 concrete batch plants in Harris County have sprung up disproportionately in low-income, Hispanic, and Black areas, according to a study published last year. Researchers' conclusions mirrored a previous analysis by the Chronicle and frustration from local leaders over the increasing number of facilities in residential communities.

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Open-air concrete plants generate airborne pollution, and its components, including particulate matter and crystalline silica, are linked to a range of health issues including lung problems, asthma, bronchitis, heart disease and cancer.

While technologies used at these plants to control pollution can help reduce how much gunk neighbors breathe in, Houstonians have grown increasingly vocal over the years about their concerns with low pollution standards and their reliance on self-policing.

Concrete batch plants have to follow emissions and production rules dictated by the Texas Commission on Environmental Quality.

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Trade groups consider the industry to be highly regulated, though local officials have challenged the efficacy of those rules in court and the U.S. Environmental Protection Agency has been investigating them.

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The TCEQ recently updated its standard permit rules for batch plants, with additions that increase buffer zones, constrain stockpile sizes, restrict annual production limits and revisit dust emission controls. These changes will not have an immediate impact for many communities because they apply to existing facilities only when their current permits expire.

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