Californian cement companies are reportedly working with state transportation officials on a pact to lower the level of greenhouse gas (GHG) emissions produced during cement manufacturing in the state, by using a blended limestone cement. However, the California Department of Transportation (Caltrans) remains unconvinced a major switch in the formulation for cement used in road-building to achieve the emissions reductions would result in safe roads, according to a Caltrans source.
Industry representatives consider the new formulation to be critical to meeting the Cal/EPA-led Climate Action Team’s (CAT) targeted 70 per cent reduction in emissions from cement manufacturing, which is a significant source of GHG emissions in the state.
Cement industry and Caltrans officials are scheduled to meet next week to develop a testing program to measure GHG emissions from a cement formula that adds limestone to blends used in road building, sources said. The program would investigate appropriate amounts of limestone to add during road building, in order to both reduce emissions and maintain a durable product.
Despite these potential emission benefits, Caltrans officials are reluctant to support such a change until they can prove roads built using limestone-supplemented cement retain their strength, durability and longevity, the Caltrans source said. Preliminary indications appear to show a five per cent reduction in road strength for every 2.5 per cent of limestone in cement, but more study is needed, the source said. Cement makes up about 11% of the concrete used to build roads in the state.
Industry representatives continue to seek a full five per cent replacement of kilned cement with limestone, since the CAT final report cites this blend in the recommended 70 per cent reduction in emissions from the industry. Acceptance of this blend is vital to the industry’s ability to achieve the 70 per cent emissions reductions target from the CAT report, the second industry source said.
National ASTM standards already allow up to five per cent limestone in cement, making Caltrans’ reticence to accept the five per cent standard seem overly protective, the source said.
The CAT report, which predicts 2025 GHG emissions from cement manufacture at around 15Mt, is seen as a critical tool for lawmakers and Schwarzenegger Administration officials to reduce GHG emissions in the state. Cement manufacturers’ switch to limestone in road cement is seen as a "cost-effective" GHG reduction strategy, according to the report.
Cal/EPA officials have said that interaction between Caltrans and cement manufacturers shows why it is important that multiple agencies be involved in state programs to reduce GHG emissions. A Cal/EPA spokeswoman said she is unaware of any ongoing negotiations over cement formulations that currently involve the agency. "It is a concept that has been brought up, but there is no movement on it at this time" by Cal/EPA officials, the spokeswoman said.