Today, we're talking about natural pavements and, more generally, roads, to delve into a fundamental and equally important topic: the choice of aggregates . While experts know how crucial they are, those less aware are those who are new to the field. For them, the word "aggregate" might even suggest, etymologically, something "passive" or irrelevant. Well, that's not the case: the choice of aggregates plays a crucial role in the construction industry , as these materials are found in large quantities both in traditional road surfaces and in "simple" concrete, both ecological and otherwise. So, let's delve deeper into the topic, discovering how and why the choice of aggregates affects the performance, resistance, and durability of natural pavements and roads.
What are inert materials?
Humans have been using natural raw materials since time immemorial, and many of these are used in traditional construction projects. So, where do aggregates fit into the vast array of construction materials ? To understand this, we must first begin with the definition of inert material.
Aggregates , also known as inert materials , are materials used in construction to assemble, for example, roadbeds or embankments. Their main characteristic is that they do not participate in the reactions of the binder used (hence the name), but maintain their physical state unchanged over time. They are usually mixed with other materials, such as asphalt, cement, and so on. Aggregates serve many purposes, including reducing the risk of cracks within the structure and increasing the mix's plasticity.
For this reason, the aggregates must be composed of non-freezing or friable elements and must be free of organic, chalky, silty or clayey substances or possess such quantities that they do not become an obstacle to the hardening and durability of the conglomerate.
Origin and classification
Aggregates can have various origins . Usually extracted from open-pit quarries , this large collection of materials includes ligneous rocks, metamorphic rocks, and sedimentary rocks. For sustainability reasons related to the transportation of materials, aggregates can also be extracted in situ , that is, by taking aggregates from the site and soil where the work is carried out. Or, again, we can deal with recycled aggregates , that is, deriving from the disposal of other construction works, both road and otherwise. In short, the origin is varied, as is their grain size : usually, the choice of aggregates depends on both the physical characteristics and the "size" of the material itself. In particular, based on their grain size, aggregates—which are obtained from crushing rocks—are classified into sand (fine, medium, and coarse), gravel (fine, medium, and coarse), and crushed stone (fine, medium, and coarse).
Choice of aggregates: each work has its own material
The quality and type of aggregates is crucial to determining how they will be used and, therefore, the final construction project in which they are used. The characteristics of each material contribute to the durability and performance of the structure itself in terms of resistance and functionality. For example, if aggregates are used with binders, it is necessary to choose types that can adhere perfectly to the component being used. Some aggregates, in fact, have a greater affinity for water, others react to the presence of alkalis, causing cracks and a loss of cohesion in the structure.
Choice of aggregates for roads and natural paving
What can be said, however, about the choice of aggregates for roads and natural pavements ? A surface of this type, in fact, not only fits perfectly into its context (integrating with it not only from a landscape and historical perspective), but also helps prevent environmental pollution, while also adhering to the principle of hydraulic invariance.
Terra Solida , an industry leader in natural paving, typically uses on-site aggregates for its green roads and surfaces , reducing environmental impact in terms of emissions related to material transportation. The choice of aggregates , which can also be quarried or recycled, is accompanied by the use of eco-friendly technologies . For example, the products in the City Open Paving line use a specific mix of single-granular aggregates characterized by a composition that ensures the paving has high drainage capacity of up to 2240 l/m2 x min thanks to a void ratio between 15 and 20%.
The Villa Fine Flore line , on the other hand, combines beauty, elegance, and functionality to create eco-friendly and beautiful architectural concrete flooring . In this case, aggregates such as marble, porphyry, granite, and semi-precious stone chips of small and medium size, both irregular and rounded, are used.
In short, the world of aggregates is very vast and their choice is essential to create durable and resistant flooring. If sustainability is also added to this, the objective has been achieved from every point of view.
