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.
PurposeThis paper aims to report a case study regarding the combined use of several non‐destructive techniques (NDTs) as a tool in the management of diagnosis and refurbishment of a damaged reinforced concrete building.Design/methodology/approachFour types of NDTs have been selected and carried out on the pillars of the building: visual inspection, electromagnetic rebar location, sonic test and rebound hammer test. The campaign has been planned and run in order to get the highest amount of reliable data about materials degradation and structural safety with limited costs and limited interference with the functionality of the building.FindingsThe diagnostic campaign highlighted the usefulness of the selected techniques in the diagnosis of the type and the amount of degradation, thus permitting a plan of refurbishments to be defined, and to get a realistic estimation of restoration costs.Practical implicationsNDTs' ability to specifically identify a type of damage may be viewed as a reliable tool in assessing and managing the structural life‐cycle cost.Originality/valueThe presented case study highlighted that NDTs are very likely to locate and quantify the damage of materials and buildings, so that they can be considered as one of the most important parts of health monitoring of civil structures and infrastructures.
The results of an experimental investigation on cracking of fifteen reinforced recycled concrete slabs are presented in this paper. Five different recycled aggregates replacement percentages have been used for different mix design. First, the values of tensile strength, cylindrical compressive strength and modulus of elasticity of the concrete mixes have been determined. Then the deflection-load curve of the simply supported slabs have been obtained. The limit of the linear part of this curve determines the experimental cracking load. Its comparison with the theoretical value shows good agreement. Recycled concrete slabs show a similar performance to those made with ordinary concrete.
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