Introduction - Geomaterials: Under the Microscope - page 2

The economic importance of geomaterials and their
contribution to the global construction industry cannot
be overestimated. For example, the ex-works value of
raw materials production for the construction industry
in Britain alone was estimated as being £2,105,000,000
in 2004 (Taylor et al ., 2006). Table 1 lists the quantities
of different geomaterials produced for construction in the
British Isles.
Testing of construction materials to ensure that they
are fit for purpose has been an essential part of the
construction process since the early 19th century. The
second half of the 19th century saw the emergence of
independent materials testing companies (Doran &
Cockerton, 2006). Since the 1920s there has been a
growing cooperation between civil engineers and
geologists to develop the knowledge of geomaterials in
the construction industry. During the last 40 years,
geomaterials practice has evolved into a discipline in its
own right. Today, geomaterials practitioners apply
geological and materials engineering knowledge to
construction and civil engineering projects, ranging from
new building and infrastructure developments through
to monitoring, maintenance, refurbishment, and
conservation of existing structures. They are involved in

the full lifecycle of built assets with tasks typically
comprising:
• Location of new construction material resources.
• Evaluation of materials proposed for use in
construction.
• Routine quality control testing and monitoring
during construction.
• Investigation of deterioration during service.
• Screening existing structures for potential problems.
• Monitoring repair and restoration programmes.
• Expert witness service.

Clients of the geomaterials engineer may include
architects, engineers, specifiers, surveyors, commercial
property owners/managers, domestic property owners,
manufacturers, contractors, and government agencies.
Petrographic examination is one of the most powerful
investigative tools available to the geomaterials engineer.
It involves using the polarizing microscope to examine thin
sections or polished surfaces of samples, in the same way
that geologists examine rock samples. This may be
supplemented by various other microscopical techniques,
chemical analysis, and simple physical tests. First used for
examination of rock in 1849, petrography was soon applied

Table 1 Production of construction geomaterials in the United Kingdom, 2004 (Taylor et al., 2006)
Material

Type Quantity

Building stone Igneous rock 189,000 tonnes

Sandstone 439,000 tonnes

Limestone 226,000 tonnes

Dolomite 8,000 tonnes

Slate 763,000 tonnes

Aggregate Concrete aggregate 81,293,000 tonnes

Roadstone 47,768,000 tonnes

Rail ballast 3,630,000 tonnes

Armourstone 333,000 tonnes

Construction fill 39,313,000 tonnes

For glass making 5,011,000 tonnes

Cement Finished product 11,405,000 tonnes

Concrete Ready-mixed 22,856,000 cubic metres

Brick Clay brick 2,707,000,000 bricks

Gypsum For plaster products 1,686,000 tonnes