1. What is Unreinforced Masonry?
Unreinforced Masonry or URM was a prevalent construction type in New Zealand in the past,
comprising of stone, brick, or concrete blocks, without the presence of steel reinforcement and only
bonded with mortar and ties. CSI offers the following service in regard to URM:
- Concrete and URM scanning,
- Identifying ties and spacing in existing URM structures.
- Identifying cavities and thickness of existing URM structures.
- Identifying mortar compaction.
- Scanning nearby RC prior to use as structural connection.
- In situ measurement of masonry mortar joint shear strength
- Prism or masonry unit compression testing.
- Anchor testing.
- Camera and drone survey.
- Scratch testing.
2. When would you use Unreinforced Masonry?
It is well known that URMs perform poorly during large earthquakes. New Zealand Society of Earthquake Engineering (NZSEE) recommends that URM buildings with no previous strengthening being carried out, be categorised as potentially earthquake prone without entering into a formal assessment process. Retrofitting of URM is now widely accepted as required. URM testing can be engaged early during the design phase for retrofitting; which provides the required information of in-situ condition of the targeted structures.
3. What are the Benefits of Unreinforced Masonry?
URM structures are non-homogeneous; the quality depends highly on workmanship for both the masonry unit and bonding mortar, in addition to the advanced age of most URMs in New Zealand. It is paramount that the existing component conditions and properties are tested so that an effective retrofitting design can be applied.