Customer Stories

Cracking 18th Century water tower

Substantial cracking brickwork to 18th Century water tower due to corroded mild steel – reinforce, remove corroding steelwork and make good

This building is an interesting 18th century purpose built water tower constructed to service a country estate with running water.

Problem: Cracking brickwork

AWT was contacted by the owners of the water tower with concerns about significant cracking to the brickwork.

On inspection we noted that there was indeed substantial cracking and distortion to the external brickwork, together with corresponding internal cracking.

The cracking noted appears to originate from the embedded mild steel.

Causation

The cracking noted was found to be progressive, mainly due to expanding corrosion from the mild steel RSJ’s lifting and cracking the brickwork and stone work, together with a combination of ageing, seasonal moisture, thermal expansion and contraction (i.e. hygrothermal).

Corrosion of the embedded mild steel resulted in the formation of ferrous oxide that expanded to several times the thickness of the metal it had resulted from, thus breaking out the brickwork and causing lifting and bowing of the walls.

Structural repair solution

Our proposed remedial scheme was to provide a viable repair by firstly removing the corroding mild steel, thus addressing the causation, and thereafter introducing bed joint reinforcement beaming, crack stitching, and lateral restraints to reconnect and restrain the brickwork, together with brickwork repairs to reinstate the uniformity of the wall and apply dry seal.

Starting at the top level and repeating to the lower levels we provided working platforms to accommodate the proposed works, installing temporary support with AWT developed props to brace the steel beams and allow for the removal of the embedded mild steel channels and RSJ’s, together with the removal of the surrounding brickwork.

We then replaced the removed channel with suitable bricks.

Once the brickwork was set the horizontal bed joint between the rebuilt and original brickwork was dry packed providing a supporting connection.

To maintain lateral restraining we drilled the masonry for, and resin bonded, stainless steel 12mm grip bars together with brickwork repairs.

To reconnect the brickwork we installed rows of twin 8mm stainless steel corded joint reinforcement, forming a deep masonry beam to stitch localised cracks and to add cohesion and tensile strength to the brickwork.