Pre-demolition concrete waste stream identification: classification framework

Demand for high quality recycled concrete aggregates (RCA) to offset the use of primary materials is significantly rising due to circular economy goals and high-value reuse of concrete. The quality of RCA significantly affects their availability for new concrete production due to the variability of parent concrete streams. The optimization of...

Time-dependent reliability assessment of existing concrete bridges with varying knowledge levels by proof load testing

In the evaluation of existing bridges and viaducts, relying solely on a desk study is often inadequate for determining their structural reliability. Performing a proof load test provides valuable field data that offers detailed information about the structural integrity. However, the relation between the magnitude of the load and the...

Non-destructive screening methodology based on handheld XRF for the classification of concrete: cement type-driven separation

The utilization of locally available concrete waste for producing recycled concrete aggregates is recognized as one of the most sustainable ways of satisfying the growing demand for concrete production. However, the quality of concrete waste depends on its origin and it may significantly differ from one concrete structure to another. Knowing the...

Categorization of formulas for calculation of crack width and spacing in reinforced concrete elements

Over the last century, over one hundred crack width formulas have been developed to calculate the width and spacing of cracks in reinforced and prestressed concrete elements. It is unclear which formulas are the most accurate. An extensive comparison study is required to determine which formulas accurately describe the crack patterns,...

Energy consumption of a laboratory jaw crusher during normal and high strength concrete recycling

This paper presents the measurement and analysis of energy consumption of a laboratory jaw crusher during concrete recycling. A method was developed to estimate the power requirements of a lab-scale jaw crusher. The impact of material properties on the crusher performance is studied. Eight concrete strength classes (C20/25–C80/95) were...

Developing a new acoustic emission source classification criterion for concrete structures based on signal parameters

Acoustic emission (AE) signal parameters can be used to classify the source type in concrete structures. However, signal parameters are influenced by the wave propagation from the source to the receiver, leading to wrong source classification results, especially for monitoring large concrete structures. This paper experimentally evaluates the...

Reliability assessment of existing reinforced concrete bridges and viaducts through proof load testing

In the assessment of existing infrastructure performing only a desk study is often not sufficient to determine the structural reliability of a bridge or viaduct. For concrete structures gathering field data by performing a proof load test offers detailed information about the structural performance. However, the relation between the magnitude...

Selectief slopen van betonconstructies: Ontwikkeling in-situbetonidentificatietechniek

Momenteel wordt gerecycled beton meestal toegepast als wegfundering en daarmee 'gedowncycled'. Dat komt onder meer doordat er geen informatie beschikbaar is over de kwaliteit van het gesloopte beton. Hoogwaardig hergebruik van gerecyclede toeslagmaterialen in nieuwe betonconstructies vereist een strengere kwaliteitscontrole. Aan de TU Delft...

Monitoring structural responses during proof load testing of reinforced concrete bridges: A review

Proof load testing can be an interesting method to assess existing bridges for which analytical methods are unable to provide an accurate assessment. In a proof load test, a load representative of the factored live load is applied to the bridge. If the bridge can carry this load without distress, the proof load test is success-ful, and the...

Using particle packing technology for sustainable concrete mixture design

The annual production of Portland cement, estimated at 3.4 billion tons in 2011, is responsible for about 7% of the total worldwide CO2-emission. To reduce this environmental impact it is important to use innovative technologies for the design of concrete structures and mixtures. In this paper, it is shown how particle packing technology can be...

Design of ecological concrete by particle packing optimization

The goal of this research project on Ecological Concrete was to reduce the CO2-emission of concrete and to reuse secondary materials form concrete production and other industries simultaneously. This also minimizes the use of natural resources and the production costs. To replace cement in concrete in a safe way, the main question answered in...

The use of particle packing models to design ecological concrete

Ecological concrete can be designed by replacing cement with fillers. With low amounts of cement it becomes increasingly important to control the water demand of concrete mixtures. In this paper a cyclic design method based on particle packing is presented and evaluated on the basis of experiments on cement pastes combined with quartz powder....

Design of self compacting concrete by particle packing optimization

Measuring water demand or packing density of micro powders: Comparison of methods