Chemistry & Microanalysis

The microanalysis laboratory uses the latest tools to carry out chemical composition and mineralogical studies of all types of building materials, soils, rocks and artefacts.

In addition to the traditionally adopted methodologies in analytical chemistry, Geolab is equipped with instrumentation such as atomic absorption spectrometry, fluorescence X-ray spectrometry, X-ray diffractometry, optical microscopy on thin section and scanning electron microscopy. This enables us to conduct a complete characterization of materials defining their compositional and microstructural profile.

The microanalysis represents the tip element for degradation diagnosis in materials, structures and monuments. The PANalytical X'Pert Pro system for X-ray diffraction (XRD) provides the quantitative analysis of the different crystalline phases constituting a sample. It applies to all types of solid samples, and is ideal for the study of corrosion products, the study of hydration of the cement, and the quantification of reactive amorphous phases in the aggregates. The PDF-4 database contains 200,000 crystalline compounds and allows identification of all the components of the sample.

The tool for scanning electron microscopy (SEM) Fei Quanta 200 provides images at very high magnifications, allowing a detailed study of the shape, size and texture of the particles that compose a sample. The simultaneous elemental microanalysis EDAX provides the local chemical composition. The possibility of working in low vacuum (ESEM) prevents the influence of physical state and hydration on the sample during analysis.

The Philips PW2400 spectrometer for X-ray fluorescence (XRF) provides extremely accurate analysis of the chemical composition, ideal for the quantification of chlorides, sulphates, heavy metals, sodium, potassium, etc. in all solid matrices. The same analysis is carried out on samples of water using the atomic absorption spectrometer (AAS) and flame PerkinElmer AAnalyst 200.

For the preparation of the samples, the preliminary examination, and the investigation of modified bitumens, two Leica optical microscopes complement our laboratory instrumentation, covering magnifications from 5x to 1000x. They work in reflected light, transmitted light and fluorescence.

The chemistry lab and microanalysis provides services for sectors dealing in raw materials, semi-finished and finished products used in modern buildings. The chemical, mineralogical and microstructural characterization of raw materials, semi-finished and finished products in modern buildings and civil engineering is fundamental for both, the quality control in production processes, and the evaluation of performance and durability. The analyzed materials include land and water for concrete, natural and artificial aggregate, premixed mortars, and ceramic bodies in a state of green bricks. They also carry out analysis with a scanning electron microscope to search for asbestos fibres.

Diagnosis of the deterioration of concrete structures

The knowledge of the causes of deterioration of a concrete structure is crucial to the choice of the most appropriate intervention techniques for its restoration. For this purpose, the survey must be carried out with mineralogical - petrographic methods, such as X-ray fluorescence spectrometry, X-ray diffractometry, optical microscopy in transmitted and reflected light, optical microscpia in fluorescent light and scanning electron microscopy.

Through mineralogical - petrographic analysis, it is possible to obtain information about the compositional and micro structural characteristics that govern the behaviour of the material. This enables identification of the products degrading the materials, even if they are present only in the embryonic stage. In particular, we are equipped to carry out the following analyses:

• Indication of the compositional characteristics of the cement hardened paste including lithologic characteristics, grain size, morphological and microstructural aggregate, fine and coarse aggregate

• Identification of pozzolanic materials and fibres, their distribution and interaction with the cement paste

• Determination of the quantity, distribution, and pore size entrapment of air bubbles

• Identification and description of bleeding structures 

• Determination of capillary porosity

• Distribution, development and orientation of macro and micro cracks

• Depth and distribution of carbonation 

• Identification and evaluation of the outcomes of alteration caused by alkali reaction, sulphate attack and chlorides input

• Degree of corrosion of metal reinforcements

Evaluation of stone artefacts of historic and artistic interest

As part of the evaluation of stone artefacts of historical and artistic interest for their conservation, one needs to begin with characterizing the constituent materials. This allows one to understand the causes that have produced the deterioration and choose the best conservation work.

The laboratory of chemistry and microanalysis has highly qualified personnel and instrumentation for the characterization of natural and artificial stone materials and the study of their alterations such as mortars, terracotta, stone tiles, glass paste, baked enamel, paint layers, etc.

Archaeometric studies of stone materials of archaeological interest

The archaeometric study of natural and artificial stone materials of archaeological interest relies on the traditional characterization methodologies, geochemical, mineralogical and petrographic. This helps in defining the origin, distinguishing local productions, identifying processing methods and obtaining information about the origin of raw materials.

These analyses can be carried out in Geolab’s laboratories by conducting chemical analysis of major, minor and trace materials. We use fluorescence spectrometers, X-ray diffractometry, polarizing optical microscope and SEM investigations to conduct the mineralogical, petrographic and textural characterization of the constituent materials.

We can make modifications once the compositional and micro-structural properties of stone materials have been identified and subjected to restorative treatments, cleaning, protection and consolidation.

The effectiveness of a restoration method can only be assessed by means of preliminary tests carried out directly in the component. The choice of materials and the method to use is made on the basis of appropriate tests in the laboratory. The checks may be carried out not only in view of the preservation of a certain product, but also with the purpose of qualifying potential new products and new methodologies. In particular, in our laboratories, we can check for:

• content of soluble salts and dosage of individual chemical species

• water absorption by capillarity

• permeability to water vapour

• depth and distribution of the consolidating material produced by means of optical and electron microscopy

• artificial aging tests (wet-dry cycles, cycles of crystallization of the salts)

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