The Inevitable Question and the choice that everyone has to make..

How do I repair a building when the original building materials are no longer available? Will it matter if the repair is not visible or can it be conveniently covered by appropriate coatings?
The Inevitable Question and the choice that everyone has to make..

Poor Renovation Work

These are just some of the questions that we must ask ourselves when we are faced with this type of dilemma; replacing sand:cement render with a plaster derivative or vice versa may work for a simple, small patch, but add in any complications such as London brick, non-standard sand:cement ratios, unusual sands and cements and the repair becomes unstable & unpredictable. Add heat, cold & moisture and we have a recipe for disaster.

The only way to make a legitimate, sustainable repair is to use, as best we can, the original building materials in their original proportions. Isolating and quantifying the different components (Sand:Cement:Lime, etc.) is relatively straightforward chemical analysis, characterising the insoluble residue and its morphology is also relatively easy; finding a local supply of the specific materials is more difficult.

The application of water soluble polymers, co-polymers and wetting agents to the surface of a repair and/or included in the repair mixture may improve the incompatibility between the original and repair matrices, thus facilitating a suitable repair, but it doesn't change the thermo-dynamics properties of the original and repair materials. The relative difference in the thermo-dynamics of the materials is the cause of the problem, thermal-expansion and permeability work against a sustainable repair; initially this may manifest itself as severe cracking around the repair, longer term the repair may fail totally, separating itself from the underlying sub-structure as indicated in the picture.

Services to Test Hardened Concrete, Mortar, Render & Screed

Carbonation Depth Measures the degree of degradation in a concrete, mortar or render.
Cement Content of hardened concrete. The determination of constituent components in a concrete, mortar or render to identify the materials and their concentration.
Chlorides Quantification of chlorides in hardened concrete, mortar or render.
Rapid HAC in Concrete Identification of High Alumina Cement (HAC) in buildings and infrastructures.

The only way to make a proper repair to an older or historic building is to analyse the existing concrete, mortar, render or screed and initially determine if there is any degradation in the infrastructure and then make an informed decision on how best to proceed based on the information available; this may involve further analysis to determine the concentration, type and morphology of the constituent parts of the concrete, mortar, render or screed.

This is just a small part of the building and infrastructure services offered by WoB, specifically focusing on the testing of hardened concrete and mortar, a full range of our Building Services are available here. If you require any additional information please do not hesitate to Contact Us.

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