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AN
EVALUATION OF DAMPNESS IN MASONRY WALLS IN OLD BUILDINGS AND REPAIR METHODS

 

S.Guneshan

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Abstract: 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 problem for the structural stability as well as the
aesthetic view of the building. Aesthetic degradation and structural damage to
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. Scarcity of effective and proper
rectification measures creates a need for an effective and efficient technique.
In this paper we are discussing about 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.

Keywords:
Rising damp, Dehumidification,Damp,Capillary,masonry

 

1.   
Introduction

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 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 construction field has developed immensely over 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 soil, flooding, and poor drainage. Rising
damp is one of the most wide spread phenomenon

 

responsible
for the presence of moisture in buildings. It is one of
the persistent problem which requires much effort and financial resources for
it’s 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 is
still remains as 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 techniques 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 researches 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 efficient 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 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 was used. After that aqueous suspension of each mortar was
produced by crushing 5g of mortar mixing the powder with 50g of deionised
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 analysed for water soluble salts by
inductively  couple plasma (ICP) analysis.
By the help of sorptivity the water uptake of the samples was determined.
Sorptivity is the gradient of the graph of volume of water absorbed per unit
area  with regard to the square root of time.
Before taking 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 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 many conclusions.The most of the mortars colllected there 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 carboation.                                    

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 amount of soluble salts found in mortar also increased with the age of
mortar. New mortar are found with less amount of soluble salts where as old
mortars are found with high amount of soluble salts. These findings have
developed a   better relationship between the characteristic
and nature of mortar. These characteristic 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

 

 

                                                                                              

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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