Environmental sustainability has become a pervasive topic of conversation, speculation, skepticism, and confusion. The driving force behind the move toward sustainable technologies and products are innumerable, but the move towards sustainability in any given industry is based on a heightened awareness of the nonsustainable ways in which current resources are being allocated and applied.
In California, as with most states, resource sustainability has become a main focus of consideration in the construction industry. These resource issues are manifested in the escalating cost of construction materials and the community impact of producing and transporting these materials to construction sites.
When addressing the current and future state of aggregate production and delivery to California’s ever growing infrastructure needs, the time has come to consider alternative technologies available to sustain growth, while protecting from environment destruction.
The technology that has emerged as a proven solution to these issues of both economic and environmental sustainability is the process of replacing unsustainable aggregate resources with the highly sustainable chemical stabilization process. The process of chemical stabilization addresses these sustainability issues of escalating material cost and community impact in ways that have been clearly defined, with a proven track record of over 30 years in California.
California has had a relatively strong experience with chemical stabilization for decades, but has been fragmented and non-standardized in its overall approach. Even with this, the soil stabilization process has seen tremendous growth the last several years. This growth is motivated by the realization that chemical stabilization is providing value beyond its engineering advantages. The chemical stabilization process has now been realized as a solution to sustainable growth of California’s infrastructure.
There is no clearer benefit provided by the stabilization process than in the design and construction of roadways, foundation structures, water resource and environmental remediation projects. Chemical stabilization provides the ability to deliver equivalent engineering properties of materials that otherwise would have been imported to construction sites.
Environmental sustainability in California’s construction industry starts with proper resource allocation. The current and projected construction environment (i.e. high projected growth coupled with aggregate shortages) makes chemical stabilization’s engineering, environmental, and economic benefits a necessary and timely option to the public and private construction markets by directly addressing the need for sustainable resources.
Chemical stabilization significantly reduces the construction impact on the surrounding community and infrastructure. This impact is initially realized by the reduction of construction traffic on neighborhood roads leading to construction sites. The stabilization option reduces the traffic impact by reducing imported aggregate materials at a replacement ratio of 40 to 1. This significant ratio is even greater when considering projects that also require exporting of native soil to allow for grading balance.
From an environmental perspective, the practice of exporting/importing increases truck emissions, road wear-and-tear, traffic congestion, and strain on landfills. As California becomes more urbanized, in-fill projects create more congestion on already busy roadways. Also, life cycle acceleration of existing pavements occur within a few months of servicing a project.
How bad is the aggregate shortage in California? California has now turned to importing aggregate materials from other countries, such as Canada and Mexico, to supplement the ever-growing need for crushed stone.
Statewide, approximately one-third of the aggregate resources required to meet the next 30 years of demand has been permitted. New quarries that do come online tend to be far from populated areas, thus additionally impacting the infrastructure system and emissions.
The demand for durable rock continues to be prioritized, the strongest of which is used in the production of concrete and asphaltic concrete. The quality of aggregate stone used for road base continues to decrease in weight, which is a key factor in durability of the rock used.
California, along with many states, continues to supplement the demand for aggregate with recycled materials. Although recycled aggregates can be used in a variety of road construction applications, product variability and strength characteristics usually limit their use to road base sections. The chemical stabilization process can substantially increase the durability and strength of these materials.
Whether the aggregate comes from other countries, new quarries, or recycled plants, it does little to reduce the trucking aspect of transporting heavy materials from various sources to various locations throughout California.
The concept of chemistry being the solution to environmental concerns is nothing new. When a concrete pad is poured, it arrives by truck in the form of a mixture of chemicals that become activated and converted into high strength compounds upon the introduction of water. Few think much more about it after the concrete is set and the permanent reactions have taken place. This example uses the same chemistry that is the basis of chemical soil stabilization. When the appropriate reagent is used and processed properly, these relatively innocuous construction chemicals form cementitious, non-reverting, extremely stable, strength-bearing compounds that can last long beyond their performance design life.