Recycling concrete construction waste is a promising way towards sustainable construction. Indeed, replacing natural aggregates with recycled aggregates obtained from concrete waste lowers the environmental impact of concrete constructions and improves natural resource conservation. This paper reports on an experimental study on mechanical and durability properties of concretes casted with recycled aggregates obtained from two different parent concretes, belonging to two structural elements of the old Cagliari stadium. The effects of parent concretes on coarse recycled aggregates and on new structural concretes produced with different replacement percentages of these recycled aggregates are investigated. Mechanical properties (compressive strength, modulus of elasticity, and splitting tensile strength) and durability properties (water absorption, freeze thaw, and chloride penetration resistance) are experimentally evaluated and analyzed as fundamental features to assess structural concrete behavior. The results show that the mechanical performance of recycled concrete is not related to the parent concrete characteristics. Furthermore, the resistance to pressured water penetration is not reduced by the presence of recycled aggregates, and instead, it happens for the chloride penetration resistance. The resistance to frost–thawing seems not related to the recycled aggregates replacement percentage, while an influence of the parent concrete has been assessed.

An in-situ experimental testing campaign on stone masonry walls performed in the Volterra (Pisa, Italy) hospital complex is described herein. The test-site is a disused building, dated back to the early 1930s, which offered the opportunity to perform destructive and non-destructive tests with multiple purposes: the masonry mechanical characterization of a wide group of nearby similar buildings, the comparison of several testing methods applied on masonry with chaotic texture and the development of the innovative twin panel test procedure. In this context, the failure mode for panels under shear and compression forces was interpreted and, through the results obtained from different techniques (flat-jack test, drilling test, diagonal compression test and shear compression test), a safety domain shear vs. compression for the rubble masonry type was also drawn up. The cross validation of several testing methods can suggest strategies to determine shear strength, deformation properties and ductility capacity of stone masonry walls with highly irregular texture.

This paper investigates the out-of-plane behavior of masonry walls interacting with roofs. Often, collapses of masonry portions supporting roofs may occur due to the roof thrust, which generates a destabilizing effect over motion. Nevertheless, the roof weight can produce a positive stabilizing effect for rotation amplitudes smaller than the critical value. The dynamics of a rocking masonry block interacting with roofs is discussed, by properly modifying the Housner equation of motion of the free-standing single degree-of-freedom block. The dependence of the restoring moment on the rotation angle is investigated and the minimum horizontal stiffness is calculated so that the same ultimate displacement as the system without roof thrust is obtained. Two case studies are presented as applicative examples of the proposed method: an unreinforced masonry structure tested on shaking table and a spandrel beam subjected to roof thrust that survived the Emilia Romagna earthquake. Inertia moments and radius vectors of different failure mechanisms are also provided to solve the equation of motion for different block shapes. Finally, a parametric analysis of a trapezoidal rocking block has been carried out by changing its geometrical shape. This analysis shows that the influence of the shape is relevant for the calculation of the failure load, although is not possible to determine an a priori most critical shape

The paper deals with the use of vibro-compressed units with bio-natural components on construction. The proposed mix design of vibrated blocks consist of cork granules and/or hemp shives, with the aim to substitute polymeric elements or expanded clay, together with the use of natural hydraulic lime (NHL) as binder. An experimental campaign is presented, with mechanical tests to evaluate the influence of each component on flexural and compression behavior. The proposal is also investigated from a productive point of view, considering how it can be harmonized in the productive process of lightweight aggregate concrete units without modifications in the productive process. The tested elements could perform a certain reduction of the carbon impact, maintaining interesting mechanical properties. The application of the proposed units in several contexts, as separating elements joined with structural components, is considered to improve rehabilitation or to obtain higher performances in buildings.

Experimental tests and constructive assessments are presented for a simple bamboo framed structure with innovative low-cost and low technology joints, specifically conceived for small buildings in developing countries. Two full scale one-storey bamboo frames have been designed by using the simplest joints solution among three different tested typologies. The entire building process is based on low-technology and natural materials: bamboo canes, wooden cylinders, plywood plates and canapé rods. The first full scale specimen (Unit A) is a one-storey single deck truss structure subjected to monotonic collapse test; the second full scale specimen (Unit B) is a one-storey double deck truss structure used to evaluate the construction time throughout assembling tests. The first full scale specimen showed ductility in collapse and ease in strengthening; the second one showed remarkable ease and speed in assembling structural elements. Finally several constructive solutions are suggested for the design of simple one-storey buildings; they are addressed to four purposes (housing, school, chapel, health center) by the composition of the proposed full scale bamboo frames. Ease of use and maintenance with a low level of technology contribute to application in developing countries although not exclusively.

The retrofitting of existing masonry buildings is now a crucial problem for Europe. Indeed, structural safety and energy efficiency should represent the target of any renovation. The proposal of a new synthetic performance parameter is presented and discussed. Following this approach, in this paper, after a review of the main studies available in the literature, a proposal of a new performance parameter approach is presented and discussed. It is capable of taking into account both the structural and thermal aspects of masonry retrofitting. An emblematic set of reinforcements and energy improvements for masonry walls is examined. An example, generalized formulas, and a simultaneous evaluation of the role of multiple structural and thermal parameters on masonry buildings are proposed, with a view to optimize several categories of costs related to the intervention.