---
title: "Deterioration and preservation of stone"
subject: "Civil Engineering Materials"
chapter: 2
key: "semester_3/civil_engineering_materials:deterioration-preservation-stone"
source: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/deterioration-preservation-stone
site: BCT Engineering
---

# Deterioration and preservation of stone

Civil Engineering Materials · Chapter 2: Building Stones

- Asked in: 2072 Chaitra, 4 marks; 2076 Asoj, 2 marks (asked 2 times)
- Video: [Deterioration of Stones](https://www.youtube.com/watch?v=56zsygZbszY) — Mounika Ganta
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/deterioration-preservation-stone
- Whole chapter: https://www.bctengineer.com/md/semester_3/civil_engineering_materials/chapter-2

## Question

What is the deterioration of stone and how is it preserved?

## Short answer

Deterioration is the gradual decay of stone from weathering and chemical attack, losing strength and appearance. Preserve by using dense, seasoned stone, placing bed perpendicular to load, smooth dressing, proper drainage, and applying protective coatings like silicone or baryta water, along with regular cleaning and pointing.

## Answer

**Deterioration of stone** is the gradual decay of stone in which it loses strength, colour and surface because of weathering and chemical action over time.

#### Causes
- Rain, moisture and frost action in the pores.
- Acid gases (SO₂, CO₂) in the air forming acids that dissolve limestone and sandstone.
- Temperature changes causing expansion and contraction.
- Crystallisation of salts in the pores and growth of lichen or roots.
- Wind abrasion and wrong laying of the natural bed.

#### Preservation
1. Select dense, low-porosity stone and season it.
2. Dress the surface smooth and provide proper drainage and projections.
3. Place stratified stone with the bed perpendicular to the load.
4. Coat the surface with oil paint, linseed oil or wax, or silicone water repellents; use Baryta water or alum-soap solution to fill the pores.
5. Maintain the stone by regular cleaning and good pointing.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Deterioration of stone is:
   A. Gradual loss of strength, colour and surface due to weathering and chemical action
   B. Sudden breaking during quarrying
   C. Cutting by tools
   D. Hardening with age
   Answer: A. It is the gradual decay over time. (Key point: Definition)

2. Which gases form acids that dissolve limestone and sandstone?
   A. N2 and He
   B. SO2 and CO2
   C. H2 and Ar
   D. O2 and N2
   Answer: B. SO2 and CO2 form sulphuric and carbonic acids. (Key point: Acid gases)

3. Stratified stone should be placed with its bed:
   A. Parallel to the load
   B. Vertical in walls
   C. Perpendicular to the load
   D. Inclined at random
   Answer: C. This gives strength and prevents water entering layers. (Key point: Bed placement)

4. Which coatings help preserve stone?
   A. Cement slurry only
   B. Bitumen mixed with sand
   C. Plain water
   D. Oil paint, linseed oil, wax or silicone water repellents
   Answer: D. Such coatings seal the pores and repel water. (Key point: Coating)

## Related in Civil Engineering Materials

- [Causes of deterioration of stone](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acauses-deterioration-stone) — Civil Engineering Materials, chapter 2, asked 4×
- [Methods of preserving stone](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Apreservation-of-stone) — Civil Engineering Materials, chapter 2, asked 4×