The leading voice for the crushed stone, ready mixed concrete, sand and gravel, and cement industries' community.
PELA is a 10-month hybrid program with online and in-person educational sessions and networking opportunities.
Careers in the Aggregates, Concrete & Cement Industries
The Pennsylvania Aggregates and Concrete Association (PACA) is the industry’s unified voice, representing more than 200 member companies across the state.
Creating a unified and strong voice for our industry.
PACA monitors and analyzes local, state and federal regulations and advocates for a balanced approach by the regulators.
PACA builds a bridge between our members and our partners at PennDOT, and the Pennsylvania Turnpike Commission along with Pennsylvania’s construction industry to further the use of our materials to the benefit of the commonwealth.
One of the most effective tools in government relations for an industry is a robust advocacy/grassroots strategy.
In the last legislative session, we contributed over $275,000 to our political champions.
November 2025 at Hotel Hershey in Hershey, PA (PACA members only event).
PACA offers comprehensive concrete certification programs for ACI, NRMCA, and PennDOT in the central Pennsylvania area.
Membership has its privileges - most of PACA's events are open to PACA members only.
PACA conducts numerous education and training events during the year.
Choose concrete for your next parking lot project.
Streets built with concrete are built to last, consider concrete for your next project.
Concrete's strong, resilient and the choice for your next building or bridge.
PACA works with the National Ready Mixed Concrete Association (NRMCA) to convert your parking lot or building project to concrete without hurting your bottom line.
PACA drives a member-approved strategic plan to increase market share and engages specifiers and owners on the value of concrete in their projects.
This program provides free continuing education to the design and specifying communities. There are currently four courses available, ranging from 30 minutes to 60 minutes focused on the cement, aggregates and concrete industries. You'll receive a certificate of completion once you pass a quiz. The bookmarking feature allows you to leave the course and resume where you left off when you return.
The disposal of municipal solid waste (MSW) is a nationwide challenge. According to the EPA, total MSW in 2018 amounted to 292.4 million tons. That’s almost five pounds per person per day!
Less than a third of this waste gets recycled or composted. Fully half goes to landfills. A key component of MSW is the ash left over from incineration. It is commonly referred to as incinerator bottom ash (IBA).
Ultimately, the use of IBW in concrete diverts the material from landfills. When properly processed, the ash can actually enhance concrete’s desirable qualities. In one study, researchers found that 5% IBA improves strength while reducing permeability.
The production of Portland cement is a carbon-intensive process. Supplementary cementitious materials (SCMs) reduce the percentage of Portland cement in concrete. In turn, this reduces the industry’s carbon emissions.
Coal fly ash has been a popular SCM for some time now. Ash from municipal incineration is another potential SCM. However, contaminants pose a problem. Incinerator ash may contain heavy metals, chlorides, sulfates and organic compounds. In concrete, these impurities can inhibit curing, reduce compressive strength and cause volume expansion.
SCMs have been prominent in high-profile projects for some time now. Consider the concrete used at One World Trade Center and its companion towers. Various admixtures included fly ash, slag cement, and silica fume. The massive Tappan Zee Bridge is another example. Its two cable-stayed decks are 3.1 miles long, and its eight towers are 419-ft high. SCMs replaced 55-65% of the Portland cement (OPC) in the concrete used. For some concrete projects, SCMs now replace as much as 70-80% of the OPC.
The key benefit of processing incinerator bottom ash so it is a safe SCM is clear. It reduces the use of Portland cement which lowers the industry's carbon emissions.
Diverting incinerator ash to concrete plants also keeps it out of the nation’s landfills. The Environmental Protection Agency (EPA) maintains a database of these sites. There are more than 2,600 landfills receiving municipal solid waste (MSW). As of March 2022, Pennsylvania has 38 operational facilities.
The possible presence of contaminants is IBA’s biggest drawback. Common heavy metals found in IBA include gold, silver, platinum, copper, stainless steel, zinc and lead. Proper removal safeguards human health and the environment.
Various methods address the problem of contaminants. One study suggests that biotreatment reduces the concentration of copper and cadmium by 75% and 69%, respectively. However, biotreatment is not effective in immobilizing zinc. Microbiologically induced calcium carbonate precipitation (MICP) is another option. It induces calcium carbonate precipitation to reduce the impact of heavy metals.
In general, SCMs are not always available in the quantities required in a given locale. Long-distance transport is not always a viable option. Transporting IBA comes at a price, both economically and environmentally. Consider the experience of the precast concrete sector, and its embrace of fly ash from coal-fired power plants. As plants close, supplies dissipate. This map shows the uneven distribution of the remaining coal-fired power plants.
Fortunately, incineration does not alter the properties of metals commonly found in IBA. Consequently, recoverable metals can replace virgin metals, preserving natural resources and reducing emissions. For example, by 2016, European metal recycling from bottom ash was reducing GHG emissions by an estimated 3.2 million tons per year.
Recycling rates in modern IBA processing facilities can exceed 80%. Methods like the use of eddie current (EC) separators recover metals which are then sold to refiners. There are both wet and dry IBA processing technologies. Crushing ash residues may further enhance metal recovery. Dry processing requires 4-6 weeks of aging to reduce moisture content below 10%. Some fine metals get lost in a dry recovery process.
Research also demonstrates the promise of electrodialytic remediation (EDR). It uses modest electric currents to separate suspended particulates into different electrolyte solutions. Acidification releases ionized metals that migrate in the electric field. EDR recovers valuable metals while also removing soluble salts. When combined with other methods, EDR makes incinerator ash a more viable SCM.
One company already specializes in processing IBW across three continents. Meanwhile, a South Korean company plans a pilot project to demonstrate the viability of IBA as an SCM.
Pasadena-based Blue Phoenix Group is the world’s largest ash processor. It specializes in processing IBA from the U.S. to Australia, and from the U.K. to Europe. In the U.S., it is dedicated to unlocking the potential of IBW as a recycled aggregate. In the process, the company recovers valuable raw materials that keep them out of landfills.
Ash emanating from U.S. energy-from-waste plants is often a mix of bottom ash, fly ash, and boiler ash. Processing this combined ash presents special challenges. For example, the fly ash makes the combined ash fine and compact. This inhibits the efficacy of standard processing equipment. In response, Blue Phoenix has developed solutions customized for this combined ash. For example, advanced ballistic processing ensures “recovery of a majority of all ferrous and non-ferrous metals.”
In July 2022, SK Ecoplant announced plans to launch an IBA pilot project. The goal is to use up to 60% IBA to replace Portland cement. The plan is to use IBA to induce an exothermic reaction in the presence of expansion-reducing reactants and non-sintered inorganic binders. This will increase compressive strength. Ecoplant believes its product will be price competitive.
The Pennsylvania Aggregates and Concrete Association (PACA) monitors industry innovation worldwide. PACA commits to promoting technologies that move the industry toward carbon neutrality.
For answers to your questions about your upcoming concrete project, please contact us.
February 22, 2024
Proficient carbon calculations are increasingly important as “Buy Clean” legislation proliferates. New York and Colorado are among the states that now require carbon calcs for public projects. An estimated 40% of emissions are from the built environment. According to one estimate, the planet’s total building floor area will double by 2060. This makes the concrete industry a key player in the quest for net-zero emissions products and projects.
February 15, 2024
The Natural Resources Defense Council (NRDC) notes that cement production is “so carbon intensive that even though cement makes up less than 15% of concrete by weight, it accounts for 90% of concrete’s carbon footprint.” The use of fossil fuels to fire cement kilns is a key source of these carbon emissions.
February 08, 2024
In the quest for reduced greenhouse gas (GHG) emissions, everyone has a role to play. In the concrete industry, this includes everyone from manufacturers to contractors, and from trade associations to governments. Here is a review of some of the major initiatives impacting concrete’s sustainability.
February 01, 2024
Ordinary Portland cement (OPC) requires high-temperature calcination of limestone. It is possible to use various emissions-reducing pozzolans in concrete. Fly ash comes from coal-fired power plants. Ground granulated blast furnace slag (GGBFS) comes from steel mills. Another SCM is metakaolin derived from kaolin.
The program is delivered in one (1) module and it should take approximately 30 minutes to complete. You will receive a certificate of completion once you pass the quiz. The bookmarking feature will allow you to leave the course and resume where you left off when you return.