The Ministry of Energy and Health has issued a statement on details of the technical status report on Mater Dei Hospital.

The Ministry said that while investigating options for the extension of the Accident and Emergency (A&E) building at the Mater Dei Hospital, concrete cores were taken from columns to confirm the concrete strength of the existing structure.

The results of these tests suggested that the concrete strength was low and below specification.

In September 2014, following this initial investigation, Arup was commissioned by the Ministry to conduct an independent structural assessment of the A&E building and audit of the concrete strength.

Immediately following the appointment, Arup conducted an inspection which gave assurance that the building is currently structurally sound to safely function on an ongoing operational basis.

Independent concrete core tests were undertaken and an analysis by a certified international test laboratory comprehensively concluded that the strength of the concrete in parts of the A&E building was significantly below the originally specified design.

The Ministry said that laboratory tests identified that the samples taken included both hard and softer limestone aggregate, along with high porosity and high levels of carbonation. This was consistent with observed corrosion of reinforcing steel to columns in untreated undercroft zones.

The impact of the below specification concrete was assessed within a structural model of the building Arup developed. Arup also assessed the seismic resilience of the A&E building. Arup’s assessment highlighted that remedial measures are required to address performance under seismic conditions.

Remedial designs for the A&E building are currently being finalised by Arup, the Ministry said, and the requirements will shortly be issued for contractor/s to deliver the works. Remedial works include reconfiguration of roof plantrooms to reduce loads together with new bracing, the introduction of additional shear walls to provide enhanced stability, concrete repairs to poor condition columns and verification of ties to the external façade.

Due to these findings and the importance of the hospital as a public facility, the Minister further commissioned Arup to review all of the other buildings across the hospital campus.

This review is currently underway. To date, assessment of the Oncology is complete. The concrete strength is in line with the design specification and the building structural design has been verified, with the conclusion that no remedial work is required.

Below strength concrete has been identified in Block D and structural analysis has concluded that remedial works are required to address seismic conditions. The remedial works design is ongoing.

For the remaining buildings test results confirm that the concrete strength is close to the specified design. Arup continues to undertake structural design analysis and verification, including for the steel frame Block F, with conclusions expected in the coming months.

Additional information regarding the concrete core testing undertaken:

• A&E Building: 22 additional cores were taken from columns. An assessment of past and current core data concluded that 18 MPa is an appropriate characteristic value for the strength of the concrete; significantly lower than the 30 MPa specified design strength.

• Block D: An assessment of past and current core data concluded that 23 MPa is an appropriate characteristic value for the strength of the concrete; significantly lower than the 30 MPa specified design strength.

• Oncology Building: 16 number cores from columns in the Oncology give a characteristic cube strength of 35MPa, compared with 35MPa specified.

• Remaining buildings: 100 cores were taken from columns across the remaining blocks to assess the concrete strength the results of which are being considered in the ongoing assessment.

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