Monument MPM2036 - Dock floor, Dry Dock No.3 Portsmouth Historic Dockyard

Two concrete cores were drilled through the floor at the western end of Dry Dock No. 3 during geotechnical work in 2008. The foundation of the dock floor consisted of limestone blocks overlain by a single course of bricks on top of which was modern concrete. Timber was also encountered beneath the brick course in one core which was interpreted as indicting the presence of timber grillage (a framework of timber beams built to form a foundation).

Two concrete cores were drilled through the floor at the western end of Dry Dock No. 3 during geotechnical work in 2008. The cores revealed the thickness of the dock floor to be 1.40m, including modern concrete. The foundation of the dock floor consisted of limestone blocks overlain by a single course of bricks on top of which was modern concrete. Timber was also encountered beneath the brick course in one core which was interpreted as indicting the presence of timber grillage (a framework of timber beams built to form a foundation).

The first core recorded 0.23m of concrete beneath which was a single course of bricks 0.11m thick. At the bottom of the bricks, 0.34m below the dock floor, timber was encountered.

It was not possible to drill through the timber and subsequently a second core was drilled. This core recorded 0.23m of concrete overlying a single course of bricks and 0.03m of mortar 0.34m below the dock floor. Beneath the bricks 0.37m below the floor, four limestone blocks ranging between c0.15m to 0.40m thick were encountered. The blocks were recorded to a depth of 1.40m below the dock floor. Beneath the limestone blocks was a layer of grey silty clay recorded to 3m below the dock floor.

Sayer, Kathelen, 2009, Archaeological Monitoring of Geotechnical Works at the Portsmouth Historic Dockyard, Portsmouth, Hampshire (Unpublished document). SPM612.