DOMING (BOWING) OF FINE-GRAINED MARBLE TABLETS INSIDE AN 1894 CIVIL WAR MONUMENT IN DOWNTOWN CLEVELAND: CONSTRAINING THE FACTORS THAT CAUSE MARBLE TO WARP

It is well know that the use of thin (~2.5 cm) marble slabs on the exterior of buildings is a bad idea because of warping, also know as bowing or dishing (and what we term doming). What is NOT well known is that such thin slabs can also warp INSIDE structures. We have examined the doming of marble tablets inside Clevelands Soldiers and Sailors Monument, completed in 1894. Thirty-eight 23 x 11 x 0.25-dm marble tablets line the interior walls of the monument. The stone is a very fine-grained (average length = 0.2 mm), granoblastic-textured white marble.

We have quantified tablet doming using a simple homemade measuring tool patterned after a carpenter's contour gauge. Warping is variable: maximum vertical bowing of tablets ranges from about 6 to 27 mm. We have not been able to determine timing of doming. However, one panel has been partially replaced by a 0.5-m-high segment, probably at least several decades after the original tablets were put in. At the time of replacement a lunate section of the original tablet was ground off so that the replacement piece would blend in with the original tablet. Thus most, but probably not all, of the bending occurred in the early decades of the monument's existence.

The structure has been heated by radiators (at first electric, but replaced by steam in 1921) located directly below the tablets, heating the room as well as the space behind the tablets. Measurements made on two accessible slabs show a temperature increase from front to back and from top to bottom. Doming is convex towards the cooler, interior of the building, and concave toward the warm brick wall behind the marble. The typical pattern reported for building exteriors is outward bowing, e.g., convex toward solar radiation.

Doming of marble inside the Monument shows that bowing can occur under restricted temperature ranges (still high, but less than those experienced by exterior cladding in temperate climes), with relatively low amounts of moisture, no freeze-thaw, and no direct solar radiation. This is not the only case of interior marble warping: nineteenth-century reports allude to bowing in white marble fireplace mantels, and monument companies and others continue to address marble warping in mausoleums. Thus it is likely that there are many unreported examples of warped interior marble.