Antonio Bonati

Structural concrete aggregate can be substituted with sustainable alternatives from construction and demolition waste, such as reclaimed asphalt pavement (RAP). This contribution assesses the RAP aggregate production chain and aims to investigate the economic aspect of RAP aggregate, evaluating the costs associated with its production and comparing them with the ones necessary to produce NA and recycled concrete aggregate (RCA). This analysis aims to provide additional information on the possible advantages of RAP aggregate use in order to promote sustainable construction. The evaluation was developed using a four-step methodology consisting of (i) determining the RAP aggregate production procedure; (ii) selecting a case study; (iii) defining the mix design; and (iv) performing a cost evaluation and comparing it to the cost of NA and RCA production. The results of the cost analysis of three concretes containing different RAP percentages (0%, 30%, and 45%) demonstrated that RAP’s presence led to more expensive admixtures, with the RAP unit cost being higher than NA (+155.39%). Some strategies were proposed to diminish RAP’s cost, resulting in a reduction of −39.64% with respect to NA’s cost and ranging from 45.13% to 67.30% when compared to RCA’s cost.

Recycled materials from construction and demolition waste, such as recycled concrete aggregate, recycled brick aggregate, or recycled asphalt coming from the milling of road/motorway surfaces, are the key for a sustainable production of concrete. This paper reviews in particular the use of recycled asphalt pavement (RAP) aggregates in the production of concrete for structural uses. An overview is initially presented to describe the different areas of use of RAP, its definition and the limitations imposed by codes and standards. Relatively to the experimental data provided by the literature, a comparison with the Italian minimum requirements is also provided. Lastly, the influence of RAP on the characteristics of concrete such as compressive strength, flexural strength, Young’s Modulus and a study of durability are presented to define the possible applications of RAP in structural concrete in relation to the current allowable percentage of substitution.

Laminated glass, made by bonding glass plies together through polymeric interlayers, is a redundant system that allows for stress redistribution after partial failure. This study analyzes how the structural safety level of laminates made by two or three plies of annealed glass varies with the ratio between the thicknesses of the layers and their placement in the package. The probability of failure of laminated glass elements, in which the layers are arranged in different order, is statistically analyzed under gust wind loads, accounting for all the potential sequences of breakage for the plies. The gain obtainable from a tailored composition is quantitatively estimated through specific safety factors to be used in semiprobabilistic (Level I) design and calibrated through comparison in paradigmatic case studies with full-probabilistic (Level III) methods. Optimal laminated packages are thus determined as a function of the target probability of failure classified according to four distinct classes of consequences for malfunction or failure.