Engineering Investigations and Durability Problems of the Construction Materials of the Roman Babylon of Egypt

Abstract

The Babylon of Egypt was constructed in the Roman period (300 AD), in the old Cairo area. It is one of the most distinguished monuments in the universal architectural heritage. The present study introduces the characteristics of roman and byzantine bricks and their joining structural mortars used in the roman fortress in order to risk assessment and to define the necessary characteristics of the intervention retrofitting new materials, which will be used in the ongoing preservation work of this fortress. To achieve such, several analyses and laboratory tests like ultra-sonic pulse method testing (ultrasonic pulse velocity, dynamic modulus of elasticity), uniaxial compression test and Brazilian splitting tension test, were carried out to determine their basic, mechanical and engineering properties, along with the microstructural properties determination using Mercury porosimeter. On the other hand, the morphological description, petrography, mineralogical and microstructural properties were determined using scanning electron microscope equipped by EDS, polarizing light microscopy, XRD and XRF. The obtained results indicated that the joining structural mortars are ranging from medium to stiff, low compacted, having hydraulic properties due to the use of natural furnace slag, brick powder, brick fragments and aggregates that match with the pozzolanic properties and also rich in active silica and alumina. The examinations reveal the use of limestone fractions as coarse aggregates or fillers. On the other hand, the Roman bricks consist mainly on quartz and feldspars embedded in a matrix of iron oxide and burnt clays. Also the obtained results indicated that old bricks were of low apparent specific density (1.4 - 1.7), medium absorption (10% - 20%) and low uniaxial compressive strength (2 - 10 MPa), with Young’s modulus 1.2 to 3 GPa. The ultra-sonic wave velocity is 1.7 to 2 km/s, with dynamic modulus of elasticity 2.4 to 4 MPa. The shear modulus is 917 to 1500 MPa. These results may be due to large pores and cracks into their matrix. Due to their surface roughness, the adhesion with the lime mortars was relatively high.