The Mausoleum RG3

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Remarks on the building process and the struc- tural layout

The building phases can be reconstructed as fol‐

lows: construction of the concrete walls faced with bricks, up to the height of the impost of the vaults of the arcosolia. This level was sealed with a bonding course of bipedales. Construction of the solid‐brick vault above the arcosoliasimultaneously with the exterior walls, which bond to the vaults. At 56° the impost ( fig. 3.82) was a second course of bipedales that was necessary to strengthen the wall above the haunches. At the impost of the cloister vault was a recess used to support the centering along the side walls. In fact putlog holes such as the ones in RG1 are missing. Construction of the first section of the vault, up to a height of 60 cm, including the relieving flat arches and the concrete on the extrados of the vault. The construction was carried out without cen‐

tering. Construction of the brick shell from the haunches to the crowning, above a centering.

Completion of the vault with the concrete layer set on the vault extrados. Two points should be made regarding the vaults. The first is that the arches cov‐

ering the arcosoliawere thicker (30 cm) than the cloister vault covering the room (20 cm). The reason for this is that the arches had to support the weight of the structure above and divert the weight to the abutments, while the upper vault had only to bear its own weight.

The second is that the bricks used for the cloister vault were different from the ones used for the wall facing and for the vaults above the arcosolia, mean‐

ing that they were produced on purpose, to obtain a brick shell lighter than one made with 30 cm thick bricks. This made it possible to use a lighter center‐

ing. The reduced thickness of the brick shell sug‐

gests that the brick‐vault was used as a permanent centering for concrete set on its extrados and that the centering was a very light construction.

The use of the relieving flat arches, of the bonding courses and the building technique which places the cut surface of the bricks on the facing of the wall‐

facing give indicate an attention in the construction not found in the square mausoleum RG1. The large brick (80x80x6.5 cm) does not correspond to the standard bipedalissize. It was used under the reliev‐

ing flat arches but not for the bonding courses of the walls, that had regular 60 cm bipedales. Similar sized bricks can be found also in tomb RG4 and other sites in the Peloponnese and outside of Rome.

For instance in the “Tempio di Venere” in Baia and in the “Tempio di Apollo” by the Averno Lake, both dating to Hadrian, unusual sized bricks were used for the relieving arches (54x54 cm) together with bricks ca. 80 cm long in the interior niches, while the wall facing was made with bessales(20 cm)⁹⁸. This mausoleum is larger than the others in

Fig. 3.83Troezen. Sketch plan of mausoleum RG3

Roman vaulting and construction in the Peloponnese: case studies 89

2.00x0.75 m). The building is preserved to its full original height, although most of the exterior walls and the roof have undergone considerable rebuilt‐

ing with a different masonry. Also the windows on the west and east side are not original; the arches of the two doors entering the west corridor and the central room have been reconstructed. Only the windows opening at the centre of the side corridors are original.

Description

Walls. All the walls are 60 cm thick, except the two abutments of the higher central vault, which are 90 cm thick. They were built with mortared rubble faced in the exterior walls with bricks (M=61 cm), cut in triangular shape from square bricks (bessales 22x22x4 cm), while the facing of the interior walls was differentiated between the wall in front of the entrance (fig. 3.85), also made with brick facing, and

Fig. 3.84Troezen. Sketch sections with construction details of the mausoleum RG3

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the other walls, made with opus mixtumof rubble and courses of square uncut bessales (fig. 3.86).

Opus mixtum had bands of six brick courses (fig.

3.84), that did not go through the thickness of the wall. At the corners were large squared limestone

blocks, of irregular dimension. Putlog holes (12x12 cm) were set regularly into the north and south ex‐

terior walls and passed from side to side of the wall (fig. 3.87‐A). The central room had marble veneer.

Smaller barrel vaults. The north and south corri‐

dors were covered by barrel vaults running from one end to the other. They spanned 1.20 m and the crowning was at 2.91 m from the floor level. The section from the impost to the haunches was made with six courses of bricks laid in horizontal layers (fig. 3.88). Just above the impost were putlog holes 25x25 cm) regularly spaced in which were inserted the beams which supported the centering (fig. 3.87‐

B). Centering was used only for the construction of the remaining section of the vault (crowning). The imprints of four boards are partially preserved (fig.

3.87‐C).

Large barrel vault. The central room and the west corridor were covered by a larger vault, spanning 4.25 m. The wall dividing the west corridor from the central room was only a partition wall which was not load‐bearing. In fact it has been partially re‐con‐

structed without damaging the vault (fig. 3.89‐ dot‐

ted lines). The building technique was similar to the one used for the smaller vaults, with six courses of bricks above the impost and the remaining section built with mortared rubble. The difference is that the centering was most probably set directly on the floor, since the putlog holes used in the side corri‐

dors are missing.

In the west corridor the vault abutted on the pas‐

sageway to the lateral corridors. For this reason at the height of the imposts stone lintels were laid on a stone corbel towards the exterior wall and in‐

serted into the wall on the interior (fig. 3.84, below).

Above the stone lintel was a section faced with bricks in which a relieving arch made of bessales was inserted.

Remarks on the vaults

The structural layout was characterised by the strong abutments of the vaults, being those of the central room thicker (3 RF= 90 cm) than the vaults covering the side corridors (2 RF= 60 cm). The side vaults contributed to the static stability of the con‐

Roman vaulting and construction in the Peloponnese: case studies 91

Fig. 3.85 Troezen. Mausoleum RG3. Brick lining of the wall fa‐

cing the entrance in the west corridor

Fig. 3.86Troezen. Mausoleum RG3. Opus mixtumof the interior facing of the west wall

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Fig. 3.87Troezen. North corridor of mausoleum RG3. A) opus mixtumwall; B) holes for the timber beams of the centering; C) concrete vault. Dotted line shows impost of the barrel vault

Fig. 3.88Troezen. South corridor of mausoleum RG3

Fig. 3.89Troezen. Central room of mausoleum RG3. Dotted line marks reconstructed walls

Roman vaulting and construction in the Peloponnese: case studies 93

crete vault with its counteracting thrust.

In the west corridor the vault abutted on the stone lintel covering the passageway to the north and south corridors. Since the stone lintel was too thin to support the vault the builders diverted its weight by means of a relieving arch passing right through the thickness of the vault. The stone lintel eased the construction process because it did not need any centering.

The six horizontal brick courses at the impost were

Description

This nearly square mausoleum is located close to another mausoleum (RG3) on the east side of the city (fig. 3.63). It has undergone radical transforma‐

tion in a later period, probably after it collapsed.

Few remains of the vault survive. The plan of the mausoleum can be reconstructed to 7.10x7.32 m, with an entrance (1.18 m wide) facing south, to‐

wards mausoleum RG4. The two mausoleawere not aligned, but rather located at right angles to one an‐

other. They do not seem to face a road.

The walls were made with mortared rubble and were 90 cm thick. Up to 1.60 m from the hypotheti‐

cal level of the floor the wall was made with large rubble (ca. 20x35 cm), with courses of smaller stones every 30 cm. Putlog holes (10x11 cm) courses were ca. 90 cm apart.

The vault was oriented south/north. It was a barrel vault spanning 5.30 m. A section made with the same rubble masonry as the wall, but curved to fol‐