StonePanels International LLC

Projections and Forecasts for Acid Rain – Implications for Buildings

A new study, titled “Acidification of Earth: An Assessment Across Mechanisms and Scales\” was published in the journal Applied Geochemistry and recently reported on by Mother Nature Network (MNN). One of the key takeaways from the article by MNN is, “ … acidic runoff remains an issue in many areas where intensive mining takes place, even in wealthy countries, and ocean acidification from CO2 is a growing global issue.\”

Not only does acid rain remain a concern for the most developed areas of our globe, the problem of acid rain is primarily stemming from two things.

  • Increasing populations (and therefore use of resources that cause acid rain) across the globe
  • Less-developed countries are beginning to use resources (such as coal and nitrogen) that cause acid rain more and more

Acid rain is a growing concern for builders when they choose stone products for building materials – both stone for renovation and new construction. Cities are where the most acid rain occurs because of population density and use of resources. Cities are also where the most buildings are built. For these reasons, buildings are often in the most concentrated areas of risk for acid rain and builders have to factor in the effects of acid rain on building materials.

The Effects of Acid Rain and Need to Reinforce Materials
In order to best protect your building from the effects of acid rain, it\’s best to reinforce materials that are susceptible to the effects of acid rain with materials which are less susceptible. It is with this in mind that our StoneLite® product underwent rigorous testing. Stone Panels, Inc. conducted several accelerated aging by acid freeze-thaw procedures where the product was subjected to temperatures ranging from minus 10 degrees Fahrenheit to 170 degrees Fahrenheit while submerged in a 4 pH sulfuric acid bath. Our European accelerated aging procedure included UV exposure in addition to acid freeze-thaw conditions.

Tests were conducted on Stone Panels, Inc. samples that had been exposed to accelerated aging, and also on samples that had not been exposed for comparison of load capacity (flexural or bending strength) and bond of stone to honeycomb capacity (sometimes called tension capacity). Those tests were conducted after (following) acid bath accelerated aging. They found that the flexure or bending capacity in StoneLite® was reduced less than 10 percent; whether granite, limestone or travertine. When this type of exposure and testing is conducted on solid traditional travertine or limestone, there will be a reduction of around 80 percent in strength.

StoneLite® also underwent testing in Europe that was conducted by PARTEK in Finland. Our marble lightweight panels were subjected to 200 cycles of 4 pH acid rain, UV radiation exposure and temperature variations. The result of the tests was an average of less than six percent reduction in bond strength. Because of this testing, the technical committee for Finlandia Hall in Helsinki approved StoneLite® to replace existing dimensional stone systems that had warped and fallen from exterior walls.