Masonry Problem

Our client wanted to investigate possible methods of improving the load bearing capacity of their building in Brighton. The property would soon be having a new addition; a pent house apartment built on to the existing 1960s structure, suspended off a steel frame with loads of up to 60 tonnes directed to each base plate and distributed through the building.

Core samples were taken around the areas to receive these extra stress/loads and sent to the laboratory for testing, tests showed that the brick was hard and sound but beyond the masonry was sort /friable with fractures. Mortar joints had also become soft and poorly cemented.

Proposal

WEBAC 1660 is designed for sealing, bonding and stabilising building components. WEBAC 1660 is also suitable for filling cavities and gravel nests and is especially designed for structural crack repairs e.g. of dry cavities in quarry stonework and unconsolidated rock, for static strengthening of brickwork and for injection procedures via injection methods.

  • Compressive strength (after 7 days) approx. 65 MPa (N/mm²)
  • Bending and tensile strength (after 7 days) approx. 85 MPa (N/mm²)
  • Core samples clearly showing signs of successful permeation of resin

Injection Procedure

The injection material is injected until the pores are closed by saturation of the joints and the material can be seen emerging from the masonry into the area of the adjacent packer.

In the event of leaks, interrupt the injection procedure and patch any cracks and lose joints. As the mortar in the bed joint is usually more porous than the bricks are, it is necessary to primarily fill the masonry joints with injection material during pressure injection. In doing so, the permeation depth is very high, particularly in the area between mortar and masonry. Consequently, the injection material displaces the water in the capillary system. Leaks, cracks and cavities can thus be sealed in one process, solving the problem of moisture penetration. During the injection procedure, the material penetrates the capillary structure creating a continuous, horizontal active level. A secondary injection must be carried out within the application time of the injection material in order to complement capillary migrated material.

Result

On completion, further core samples were taken and sent to our lab for a full analysis of the core compressive strength, tested to destruction by mechanical loading carried out following curing to EN771, EN772-1 and BSEN12504-1: 2009 Standards. The results far exceeded the requirements for our client and allowed the steel work to commence a week ahead of program to the delight of our client’s customer.

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