Tasks
Task 1
This task dealt with the procurement, production and analysis of the recycled aggregates.
Afterwards, preliminary concrete mixes were designed, in order to define the four concrete mixtures - a reference mixture, and three mixtures with different recycled aggregates incorporation ratios, one of which containing superplasticizer. The concrete mix design considered common practices of the construction sector.
The four concrete compositions were comprehensively tested, in the fresh and hardened states, and the results were analysed and compared, as well as benchmarked with other investigations.
Task 1 also included the material characterization of structures made with the four previously designed mixtures. Since these structures were built by construction workers in an actual construction site, rather than in a laboratory, the tests performed (compressive strength on standard cube specimens made and cured onsite and of concrete cores taken from the structures, ultrasonic pulse velocity tests and rebound hardness number) evaluated whether the use of recycled aggregates concrete significantly affected the properties of concrete, when compared with execution quality.
In total, Task 1 produced two ISI publications, a Masters dissertation and six reports.
Task 2
Task 2 comprised structural tests on four full-scale concrete structures. The structural tests performed were: dynamic characterization tests, vertical load tests and static nonlinear horizontal destructive load tests.
The structures were designed following Eurocode specifications and it was intended to verify whether the use of recycled aggregates changed the behaviour of the structures significantly. To guarantee a ductile behaviour during the horizontal destructive tests, nonlinear models were used in the design of the structures and of the tests setup. Since structural concrete is dependent not only on the properties of concrete, but also on the properties of the reinforcing bars, it was expected that the effect of recycled aggregates incorporation would be more reduced in the structural behaviour evaluated in Task 2 than in the concrete properties tested in Task 1.
The dynamic characterization tests evaluated the natural frequencies of the structures when subjected to ambient vibrations and when vibrating after impulses. A triaxial seismograph and unidirectional accelerometers were used to evaluate horizontal and vertical vibration modes. The natural frequencies of the structures allowed the estimation of global Young's moduli by finite element modelling.
The vertical load tests required the execution of masonry walls (60 cm height) and the slabs of the structures were filled with water. Displacement transducers were used to measure the deformations of slabs and beams.
The horizontal destructive load tests allowed the evaluation of the load capacity, displacements, ductility, cracking and behavioural pattern of the structures when in nonlinear behaviour. The test setup used cables, grip hoists, load cells, a topographic station, and a surface microscope. The softening of the structures was captured. The structural behaviour was analysed and compared. The load capacities and displacements were compared with numerical models and the loads associated with cracking, yielding and post-yield stiffening of the rebars were compared with numerical and algebraic models.
Task 2 resulted in three ISI publications, a Masters dissertation, five reports, and an award.
This task dealt with the procurement, production and analysis of the recycled aggregates.
Afterwards, preliminary concrete mixes were designed, in order to define the four concrete mixtures - a reference mixture, and three mixtures with different recycled aggregates incorporation ratios, one of which containing superplasticizer. The concrete mix design considered common practices of the construction sector.
The four concrete compositions were comprehensively tested, in the fresh and hardened states, and the results were analysed and compared, as well as benchmarked with other investigations.
Task 1 also included the material characterization of structures made with the four previously designed mixtures. Since these structures were built by construction workers in an actual construction site, rather than in a laboratory, the tests performed (compressive strength on standard cube specimens made and cured onsite and of concrete cores taken from the structures, ultrasonic pulse velocity tests and rebound hardness number) evaluated whether the use of recycled aggregates concrete significantly affected the properties of concrete, when compared with execution quality.
In total, Task 1 produced two ISI publications, a Masters dissertation and six reports.
Task 2
Task 2 comprised structural tests on four full-scale concrete structures. The structural tests performed were: dynamic characterization tests, vertical load tests and static nonlinear horizontal destructive load tests.
The structures were designed following Eurocode specifications and it was intended to verify whether the use of recycled aggregates changed the behaviour of the structures significantly. To guarantee a ductile behaviour during the horizontal destructive tests, nonlinear models were used in the design of the structures and of the tests setup. Since structural concrete is dependent not only on the properties of concrete, but also on the properties of the reinforcing bars, it was expected that the effect of recycled aggregates incorporation would be more reduced in the structural behaviour evaluated in Task 2 than in the concrete properties tested in Task 1.
The dynamic characterization tests evaluated the natural frequencies of the structures when subjected to ambient vibrations and when vibrating after impulses. A triaxial seismograph and unidirectional accelerometers were used to evaluate horizontal and vertical vibration modes. The natural frequencies of the structures allowed the estimation of global Young's moduli by finite element modelling.
The vertical load tests required the execution of masonry walls (60 cm height) and the slabs of the structures were filled with water. Displacement transducers were used to measure the deformations of slabs and beams.
The horizontal destructive load tests allowed the evaluation of the load capacity, displacements, ductility, cracking and behavioural pattern of the structures when in nonlinear behaviour. The test setup used cables, grip hoists, load cells, a topographic station, and a surface microscope. The softening of the structures was captured. The structural behaviour was analysed and compared. The load capacities and displacements were compared with numerical models and the loads associated with cracking, yielding and post-yield stiffening of the rebars were compared with numerical and algebraic models.
Task 2 resulted in three ISI publications, a Masters dissertation, five reports, and an award.