This document summarizes a seminar on masonry structure discoloration and weakening. It discusses how masonry, commonly used for building walls and monuments, can weaken due to factors like weathering, porous stone, and temperature variations. It also explains how moisture and weathering can cause masonry to weaken. The document outlines various causes of stone discoloration, including water penetration from the top surface or rising moisture from minerals in the stone, contamination from mortar, and reactions between compounds in the mortar and stone that cause gray or yellow-brown coloring.

1. 1
Rajarambapu Institute of Technology,
Rajaramnagar
DEPARTMENT OF CIVIL ENGINEERING
Seminar on
“Masonry Structure – Discoloration and Weakening”
Project by,
OMKAR MUNGURDEKAR-1424003
Under the Guidance of
Prof. P D Kumbhar

2. INTRODUCTION
Masonry structure: Masonry is an assembly of bricks,
blocks or stone held together with mortar. Commonly used
for the walls of buildings, retaining walls and monuments.
Famous structure of stonemasonry include Taj Mahal,
Egyptian Pyramids and Stonehenge.
The common materials of masonry construction are :-
•Brick
•Stone
•Concrete blocks
2

3. Weakening of stone
The construction of stones bonded together with
mortar is termed as stone masonry. Stone masonry is
generally used in construction of retaining walls, docks,
buildings, etc
Common causes of weakening of stones are;
•Weathering of stone
•Due to porous nature of stone
•High coefficients of expansion and contraction due to
large temperature variations
•Use of bad quality mortar 3

4. Cause of weakening of masonry 4

5. Weakening of masonry due to moisture
and weathering action 5

6. Discoloration of Stones
• All stones are more or less porous in nature.
• Discoloration of the stone produced by a staining
agent that was actually absorbed by the stone.
• Water is masonry's worst enemy. Discoloration is
caused by water penetration or is an indication that
water is entering but evaporating in masonry.
• Extreme weather can cause degradation and
weakening of stone masonry wall
6

7. Causes of discoloration of stones
A. Entering liquid from top surface.
B. Rising moisture from minerals contained in the natural
stone
C. Contamination carried up from the mortar bed
D. Moisture from the grouting compound which discolors
stone edges
7

8. E. Calcium hydroxide in the mortar bed reacts and becomes
calcium carbonate which causes grey color formation.
F. Iron compounds are found naturally in stone which can
oxidize and cause the stone to turn yellowish brown.
8

9. Formation of calcium carbonate which causes grey color of
9
stone

10. Iron compounds oxidize and cause the stone to turn
yellowish brown.
10

11. 11
Entering liquid from top surface causes discoloration

12. 12