An Evaluation of Dampness in Masonry Walls in Old Buildings and Repair Methods

Rising damp in masonry walls results in serious issues the buildings, especially for historical buildings. Upward movement of water by capillary action is called rising of damp. It is one of the main problem affecting historical structures all over the world. It creates a problem for the structural stability as well as the aesthetic view of the building. Aesthetic degradation and structural damage to the exterior part of the building are serious issues due to the rising of damp.

Moisture penetration in walls of old buildings which are in direct contact with the ground leads to a migration of soluble salts responsible for many issues in the building. Even though the construction field and research field has developed immensely over the last few decades still we are lack with the proper solutions for the rising of damp. So many researches have been conducted over past few years and they have found some solutions but their solutions seem to be not effective especially in the case of old historical buildings where renovations should be done in a special and more careful manner. Those techniques are not effective when dealing with the walls of considerable thickness and heterogeneous materials. The scarcity of effective and proper rectification measures creates a need for an effective and efficient technique. In this paper, we are discussing the researches and experiments carried out in the past and the effectiveness of the techniques that they have proposed. We feel that many of the techniques that are currently used to minimize rising damp are not effective. So there is much need for a better solution. A better solution must be proposed. Rising dampness in masonry walls causes vexatious issues to the old buildings, especially for historical buildings. Upward movement of moisture through the walls by capillary action is called rising of damp. Rising of soluble salts due to dampness may lead to lots of pathologies. Aesthetic degradation and structural damage to the exterior part of buildings are serious effects due to this issue. This creates an unpleasant environment for the people who are living there. Rising of damp is a serious issue especially in historical buildings.

Even though the construction field has developed immensely over the past few decades this issue is still there in newly built buildings. So there is a need for a proper rectification method for rising of damp. Presence of moisture in buildings may occur due to various ways such as infiltration from roofs, pipe leakages, condensation, and capillary rise from the soil, flooding, and poor drainage. Rising damp is one of the most widespread phenomena responsible for the presence of moisture in buildings. It is one of the persistent problems which requires much effort and financial resources for its rectification. Removal of rising damp in historically important building and old structures is extremely difficult and undeniably a challenging task due to the restrictions related to historical buildings, characteristics of masonry and aesthetic constraints. Removal of rising damp from historical buildings still remains a challenging task and the authorities related to these buildings are still short of efficient and reliable techniques to treat the rising of damp. The techniques that are already in use are ineffective so an effective reliable technique for dehumidification of masonries is much needed. This research is to propose a best reliable and practically applicable technique to treat the rising of damp. Rising of dampness is a major issue in old buildings. Over past few decades, several types of research were carried out to find the solution for this problem and they have found some rectification methods to overcome this issue but still, authorities related these old buildings are not satisfied with the techniques they have proposed.

The rectification techniques that they have proposed are creating a physical or chemical barrier, creating a potential against capillary potential, applying atmospheric drainage, applying a coating with controlled porosity. Especially in the case of old historical buildings techniques, they have proposed seems to be unsuitable. Still, these authorities are short of better and effective treatment methods for rising of damp. Further research can be done on this and practically suitable method for treating damp should be identified. In the case of historical buildings, it is much needed for a new solution for this issue. Evaluation of mortar samples obtained from UK houses treated for rising damping was done by some researchers. They collected mortar samples from a variety of dwellings in the UK with the majority from houses with rising damp. They evaluated the mortar attributes and its influence on damping.This research was done with the aim of developing a proper relationship between rising damp and mortar characteristics. The mortar samples were obtained from walls in different places. If it is not possible to obtain mortar from wall jointing in that cases drilling dust or render pieces were used. After that aqueous suspension of each mortar was produced by crushing 5g of mortar mixing the powder with 50g of deionized water. Then it was kept for 24hrs and pH was measured.(Hanna instruments; pH 209).The different suspensions from pH study were then filtered and analyzed for water-soluble salts by inductively coupled plasma (ICP) analysis.

By the help of sorptivity, the water uptake of the samples was determined. Sorptivity is the gradient of the graph of the volume of water absorbed per unit area with regard to the square root of time. Before taking a sorptivity measurement the mortar was dried at 55C to get constant weight. After that pieces of dried mortar were made to contact with water on lower surface only. The weight increase as a function of time was then measured and a plot of the volume of water absorbed per unit area was produced. The experiment was done using flat pieces of 2cm × 2cm. These are some of the useful research data from this research. These data were obtained from the above stated practical. From these experimental results, they came to any conclusions. The most of the mortars collected there to show a pH value of 9-12 in that range with a typical value of 9 new mortars show a higher pH value and reduction with time can be due to carbonation.

The main parameter that controls dampness is the sorptivity. In the collected samples they showed values between 0.2 to 14mm min-1/2 older mortars showed some high sorptivity values. This shows that rise of damp is very high in older mortars than in new mortars The number of soluble salts found in mortar also increased with the age of mortar. New mortar is found with less amount of soluble salts whereas old mortars are found with the high amount of soluble salts. These findings have developed a better relationship between the character and nature of mortar. These characteristics can be used to find a replica mortar that can be used in the case of rising damp. There are several techniques used to treat the rising of damp and they seem to be ineffective. So some researchers did some research on this ineffective and the problem of using those techniques