Rocks

Question 1

Are the different rocks isotropic or anisotropic?

Answer 1

Magmatic: isotropic
Sedimentary: anisotropic
Metamorphic: anisotropic

Question 1

How can you classify rocks?

Answer 1

• Compositional classification
  Monomineral
  Poly-mineral
• Depending on the region of origin
  Endogenous
  Exogenous
• Depending on the genesis = petrographic
  Magmatic (igneous)
  Sedimentary
  Metamorphic

Question 2

Name som different rocks

Answer 2

Porphyry: Magmatic rock
Travertine: Sedimentary rock
Marble: Metamorphic rock
Gneiss: Metamorphic rock

Question 3

What are some critical issues to be considered with rocks?

Answer 3

• Source = quarry: Non renewable source
• Transportation: often long transportations, needs to be considered in the LCA
• Alteration of natural balance and ecosystem
• Impact on the environment

Question 4

What is the difference between natural or artificial agglomerate stone materials?

Answer 4

Natural stones are stone materials without addition of binding agents

Artifical agglomerate stone materials are rock fragments or stones bound toghether by cement or synthetic resins

Question 5

Describe the commercial classification

Answer 5

Commercial classification is different, not related to the origin:
4 classes marble, granites (partially magmatic and partially metamorphic), stones (all the rest), travertine.

Question 6

Explain artificial agglomerates

Answer 6

Since they are combined rock fragments or stones they can be seen as a sort of recycling of stone materials.

Used for paving, flooring, internal claddings etc.

Question 7

Which are the main techniques for rock extracting?

Answer 7

The main cutting categories are:
* Primary cutting: related to extracting
* Squaring: obtain final products

Question 8

Which are the primary cutting techniques?

Answer 8

• cutting by using explosive and dynamic splitting
• diamond wire
• chain saw
• flame jet
• high-pressure water jet

Question 9

Name the techniques for surface working and treatments for stones

Answer 9

• Quarry-plaine or split surface: natural block
• Bush hammering: minimize slippering
• Trimming
• Ruling
• Flame treated surface: high temperature
• Polishing by using diamond grinders
  Improvs resistant to agents and degradation
• Agin treatment: gives ancient appearance
• Laser technology: to control microroughness, expensive

Question 10

Which techniques can be used for squaring?

Answer 10

• Diamond Wire
• Dynamic splitting
• Water-jet

Question 11

What is used for surface treatment?

Answer 11

*Impregnation with resin:
Used for brittle and defective materials but still strong enough to just impregnate
*Plastering:
Typically for travertin

Question 12

How can we choose the right stone?

Answer 12

By following standards and normal recommendations.

Also to consider the key things:
* aesthetic reason
* physical and technological properties
* time-dependent behavior

Question 13

What does the standards say?

Answer 13

• Describe the petrographic classification
• Assessments of the characteristics due to the environmental interaction - important for degradation

Question 14

What is the flow chart of the analyses and main analytical techniques?

Answer 14

A chart that shows the typical process fro analyzing a material

1. Macroscopic and aesthetic characterization:
   Analyzes visible features of the material with naked eye evaluation.
   Type of rock
   Mineral phase: secondary phases
   Color
   Degradation critical: Presence of coating, surface roughness, presence of defects
2. Mineralogical characterization: Identyfies the mineral phases present in the material by using techniques.
   Optical microscopy
   Scanning electron microscopy (SEM)
   EDXS
   XRD
3. Evaluation of technical characteristics
   Density
   Porosity: the more pores - more degradation
   Gelivity
   Resistance to salt crystallization
   Compressive strength
   Elastic Modulus E
   Resistance to mechanical shocks
   Wear
   Hardness
   Thermal conductivity
   Thermal expansion coefficient alpha

Question 15

When doing an X-ray doffraction, what do you identify?

Answer 15

X-rays is to identify the minerals present in a stone by seeing a unique diffraction pattern.

• Qualitative analysis: type of crystalline phase, Braggs law
• Quantitative analysis: phase amount and crystal size

Question 16

How does porosity affect the stone? How can we solve problem with porosity?

Answer 16

The more porosity - the more degradation
E-modulus gets lower with more pores

Use water repellent impregnation substances, such as polymeric solution. They form a barrier on the surface so water cannot enter.

Question 17

When is gelivity of stone material negligible?

Answer 17

if, after 20 freezing-thaw cycles (performed according to appropriate standard), the reduction of sigma,comp is < 25 % in comparison to the untreated material.

Question 18

How can heat be transferred in stones?

Answer 18

Heat is transferred through phononic vibrations

Question 19

What problems can be cause if we dont pay attention to the thermal expansion coefficient alpha?

Answer 19

Due to unavoidable thermal expansion and/or the effect of different values of alpha, thermal stresses at the interface between the elements could be generated → micro-sized surface cracks that progressively go towards the material core

High difference between aplha of two material close to each other can cause problems:
* Loss of adhesion and interfacial stresses can cause structural collapse.