Holistic Innovative Solutions for an Efficient Recycling and Recovery of Valuable Raw Materials from Complex Construction and Demolition Waste (HISER)

 

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higher recovery of raw materials from Construction and Demolition Waste
HISER
higher recovery of raw materials from Construction and Demolition Waste

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Inline quality assessment system based on laser-induced breakdown spectroscopy has been built and applied

Inline quality assessment system (TRL 4) based on laser-induced breakdown spectroscopy (LIBS) has been built and applied to recycled ceramic and concrete aggregates. TU Delft was responsible for this task. (3.1.3).

The first task is composed of two steps. First, classification model using input LIBS spectra based on partial least squares discriminant analysis has been built to differentiate between brick, cement paste and tile. To further distinguish between the clean bricks and bricks with attached mortar, a statistical sampling counter was established where more classified amount of cement paste was accounted for attached mortar more likely. This work was conducted on three batches of construction and demolition waste materials received at TU Delft from GAIKER:

•    Clean red bricks (15 kg).
•    Bricks with mortar attached (3 kg).
•    Floor/wall tiles (10 kg).

The next step of quality inspection of the red ceramic batch is to predict the contamination level quantitatively based on the LIBS spectra. To that end, several freshly casted red bricks sent by VITO were received at TU Delft. They were first crushed and milled down into powders and then mixed with 1.0 to 10 weight percentages of gypsum and cement, respectively. These two separate calibration sample sets were employed to study the LIBS quantitative analysis. Three LIBS quantitative analysis methods to predict gypsum and cement contents were developed and compared as follows:

•    Calibration curves using LIBS emission line intensities of major elements (e.g., Fe II 263 nm, Si I 288 nm, Ca I 616 nm and S I 921 nm).
•    Partial least squares regression model using full LIBS spectral wavelength range.
•    Plasma Physics model using LIBS emission line intensities of major elements based on local thermal equilibrium assumption.

To be consistent, these samples have been sent to VITO as substitutes for raw materials to produce new bricks up to 10 wt%. Further mechanical strength tests are to be conducted on these new bricks and their results are to be correlated with the LIBS data before April 2016.

For the inspection of concrete aggregates, LIBS feasibility test on prepared batches of 2-8 mm concrete aggregates mixed with contaminants such as ceramics, glass, wood, plastics, metals, gypsum was successfully performed. Four batches of concrete aggregates (4-16 mm) with varying contamination levels complied with Dutch norms for concrete aggregates and limit values agreed between HISER partners are being prepared and to be measured with LIBS . They are then to be sent to MEBIN for production of concrete test cubes for strength testing after 7 days and 28 days of curing in February 2016. MEBIN will choose the cement and recipe to produce a middleclass strength concrete (e.g. Dutch class C20-28) with 100% course aggregate replacement. Their final analysis results are to be correlated with the LIBS data before April 2016.

The project has received funding from the European Union's  Horizon 2020 research and innovation program under grant agreement No 642085.

 

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