The impact of urbanization on construction minerals
Construction minerals (sand, gravel and crushed stone used in the production of concrete) are among our most plentiful mineral resources by volume. Increasing quantities of these materials are required for construction within urban areas. However, continuing and accelerating suburbanization is rapidly making unusable deposits of these minerals due to zoning and other restrictions. In addition, the low intrinsic value of mineral aggregates and their bulkiness make the economics of the industry extremely sensitive to location. Mathematical programming is used to investigate the economic impact of urbanization on the production and distribution of construction minerals.
Geomaterials as construction aggregates: a state-of-the-art
Construction aggregates derived from primary resources either by crushing of sound rock masses (crushed stone aggregates) or from naturally occurring unbound clastic sediments (natural sand and gravel aggregates) make the most voluminous mineral raw material exploited by humans nowadays (Fookes 1991; Přikryl 2017). Extremely low perunit cost of the extracted raw material (Přikryl et al. 2016) makes aggregates highly sensitive to transport distance from a quarry to the construction site. According to this basic relationship, constructional aggregates quarries should be preferably located close to their markets—construction sites. Aggregates belong to the essential materials needed for the development and maintenance of the infrastructure and built environment of our civilization. They can also be considered as one of the critical materials securing standards of our well-being. Various aspects of aggregates desire research interest from at least three research communities: geologists (including engineering geologists) who participate in the evaluation of aggregate deposits and quality of aggregates, civil engineers who utilize them, and environmental scientists who increasingly face the problems related to impacts of extensive aggregate exploitation. Lack of sound and detailed investigation of rock materials aimed as a source of construction aggregates (often consequence of apparent cheapness of the raw material and the products—constructional aggregate) can have serious consequences: both in terms of safety of the built environment and its durability (Fookes 1997; van Loon 2002). Necessity of premature maintenance or even replacement of deteriorating built structures inevitably involves substantial additional cost. Aggregates thus deserve much more attention from geologists than it was common in past decades (Prentice 1990; Bobrowsky 1998; McNally 1998; Primel and Tourenq 2000; Smith and Collis 2001; Lorenz and Gwosdz 2003; Bustillo Revuelta 2021). It is evident that geologists became to be more and more involved in the evaluation of causes of premature damage of civil engineering structures by using their standard tools— microscopy and related analytical techniques (Verhoef and Van de Wall 1998, French 1991; Ingham 2009, 2011, 2019; Poole and Sims 2016).
The genus Pseudolithophyllum (Corallinaceae) in the Gulf of Maine
SummaryThis is the third of a series of papers covering the anatomy, morphology, systematics and ecology of the crustose corallines of the Gulf of Maine. Pseudolithophyllum orbiculatum, the only species of this genus in the region, is treated in this paper.