Report on Tests of Waterproofing Preservative Materials on the Lime-Concrete Walls of Historic Buildings

Lombard, Jess

Originally established as a private fur trading fort in 1834, Fort Laramie evolved into the largest and best known military post on the Northern Plains before its abandonment in 1890. This “grand old post” witnessed the entire sweeping saga of America’s western expansion and Indian resistance to encroachment on their territories. The lime-concrete (grout) walls of the historic buildings and ruins at Fort Laramie National Monument are crumbling away under the influence of the weather. Moisture enters the walls at the top, on the sides, and rises by capillary action from the soil. Ice forms in the interstitial spaces and fragments from the size of sand grains to blocks of several hundred pounds are detached and fall. Aeolian erosion and sheet erosion from rains abrade the corners and bases and other surfaces. Unless some means of preventing the entrance of moisture into the walls and a means of binding the friable surface can be found, we will find the deterioration of these walls progressing in geometric proportion. With this problem in mind, various manufacturers of waterproofing compounds were contacted and samples of their products secured. The southwest end wall of the Noncommissioned Officer's Quarters ruin was selected as a site for a test application of these various preservatives. As seven different materials were obtained, seven rectangular spaces 30" wide and 36" high were laid out with light scratches at the corners. These were numbered one to seven by Roman numerals in black paint about 2" over the middle of the top of each block. The various preservative materials were then applied with a paint brush working the material in well. One coat only was used. Manufacturers directions in regard to mixing (if any), etc. were observed. The report found that "Hydrozo" seemed to be the best product as it did not discolor the surface, did not produce a gloss, did not crack or peel off and did provide protection by definitely waterproofing the surface and boding the friable wall surface. "Special Concrete Preservative" was found the second best, being only slightly less effective as a waterproofing agent and causing only a slight buff discoloration which would be unnoticed on a uniformly treated surface.

Report on Tests of Waterproofing Preservative Materials on the Lime-Concrete Walls of Historic Buildings

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