Abstract
The growing environmental sensitivity and the reduction of natural resources create, in Italy and other developed countries, an increasing interest in the search for alternative materials to be used in road construction works. In recent years, the problems related to environmental sustainability have made it increasingly difficult to remove natural aggregates from quarries and, at the same time, the regulations for the management of waste dumps are more and more restrictive. For this reason, the use of recycled aggregates is experiencing a continuous increase in the civil construction sector. This paper deals with the study of construction and demolition waste (CDW) in the field of road construction, in particular for the construction of embankment, road subgrades, foundation layers and unbound bases for flexible superstructures. Three different particle size fractions were used to prepare the mixtures: the first having a coarse size and designation 0–63 mm, the second intermediate size with aggregates of 0–31.5 mm grain size and the third with the finest aggregates having a grain size of 0–4 mm. The study was carried out by analyzing three granulometric fractions, verifying the best application for each of them. Subsequently, the mix-design was investigated, operating in compliance with the requirements imposed by UNI 11531-1, EN ISO 14688, EN 13242 and EN 13285. For the unbound layers of subgrade, foundation and base, which require greater resistance to fragmentation, the use of CDW alone has shown some limitations. Therefore, in the experimentation, it was decided to mix the CDW with a granulated slag coming from the steel production in the electric arc furnaces (EAF) and with an additional CDW (0–31.5 mm) coming from the recovery of concrete with slag. EAF granulated slag was used in small quantities, due to its relatively high cost. Four eco-friendly and recycled mixtures were studied, with low economic impact and high environmental sustainability, suitable for the construction of unbound layers of road superstructures.
Highlights
Construction and demolition waste constitute a very wide and varied range of materials.The fraction that contains concrete and bricks is the more suitable to be employed as a replacement for natural aggregates in several applications, including fillings, subgrades, foundation layers and bases of road pavements [1].The purpose of this paper is to define the optimal mix design of the mixtures to be used in road embankments, foundations and unbounded bases, according to the UE standards
This study evaluates the use of recycled aggregates (construction and demolition waste (CDW) with eventual
The designed mixture suitable to be used in road construction bringsbrings significant advantages in environmental and landscape in road construction significant advantages in environmental and terms, because it allows both a reduction the quantity of waste to be landfillsof and landscape terms, because it allows both ainreduction in the quantity of disposed waste to of beindisposed in the amount of virgin material to be taken from the loan quarries
Summary
Construction and demolition waste constitute a very wide and varied range of materials.The fraction that contains concrete and bricks is the more suitable to be employed as a replacement for natural aggregates in several applications, including fillings, subgrades, foundation layers and bases of road pavements [1].The purpose of this paper is to define the optimal mix design of the mixtures to be used in road embankments, foundations and unbounded bases, according to the UE standards. Construction and demolition waste constitute a very wide and varied range of materials. The fraction that contains concrete and bricks is the more suitable to be employed as a replacement for natural aggregates in several applications, including fillings, subgrades, foundation layers and bases of road pavements [1]. The purpose of this paper is to define the optimal mix design of the mixtures to be used in road embankments, foundations and unbounded bases, according to the UE standards. This study evaluates the use of recycled aggregates (construction and demolition waste (CDW) with eventual. Sci. 2020, 10, 3465 addition of electric arc furnaces (EAF) slag) as partial substitutes for natural aggregates to achieve environmentally sustainable mixtures
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