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Rajarambapu Institute of Technology, Rajaramnagar

DEPARTMENT OF CIVIL ENGINEERING

Seminar on

“Masonry Structure – Discoloration and Weakening”Project by,

OMKAR MUNGURDEKAR-1424003

Under the Guidance ofProf. P D Kumbhar

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 blocks2

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

Cause of weakening of masonry4

Weakening of masonry due to moisture and weathering action 5

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

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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

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F. Iron compounds are found naturally in stone which can oxidize and cause the stone to turn yellowish brown.

E. Calcium hydroxide in the mortar bed reacts and becomes calcium carbonate which causes grey color formation.

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Formation of calcium carbonate which causes grey color of stone

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

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Entering liquid from top surface causes discoloration

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