Town of Amherst CPAC Presentation Town Hall Steps

Town of Amherst CPAC Presentation Town Hall Steps Slate Roofs

Town Hall FRONT and SOUTH STEPS RESTORATION PROJECT Field Conditions

Mortar Detachment and Deterioration Although generally considered permanent, masonry is subject to deterioration, esspecially in the mortar joints. The Town Hall Front Steps are currently suffering from both deterioration of mortar and detachment of the granite blocks. The detachment of the stone is a result of the deterioration of mortar but likely began with the differential settlement of the stone due to an inadequate substructure.

Mortar Detachment and Deterioration

Efflorescence and Spalling Efflorescence is characterized by white stains and is often a result of rising moisture, which occurs when groundwater is drawn up into the base of the stone and masonry. As moisture migrates and gets trapped in the stone, crystalized salt are deposited and can be seen leeching out of the stone and masonry. When the stone become more deteriorated through this process, the outer surfaces of the stone can become damaged and lead to spalling. Spalling occurs when trapped salts and moisture are subjected to the freeze-thaw cycle and moisture trapped beneath the surface forces out breaking pieces of the stone off.

Efforescence and Spalling

Inadequate Substructure The monolithic granite stones used for the steps sideways and steps are applying an enormous amount of pressure on the substructure (fountain, stem wall, and fill). Over time differential settlement occurs and the stone will begin to shift. Depending on the fountain and fill, this shifting could be relatively minor or could lead to an extreme case of catastophic failure.

Inadequate Substructure

Insensitive Repairs