The construction industry faces significant challenges in managing the insulation material waste, expanded polystyrene (EPS) and extruded polystyrene (XPS) due to their low density, contamination
issues, and the presence of hazardous flame retardants. This study investigates the feasibility and environmental impact of different end of life methods for EPS and XPS waste contaminated with various construction materials, including glue and mortar as well as bitumen. A practical approach is taken, aiming to tailor existing recycling technologies to the specific needs and constraints of construction practices, thereby increasing the industry’s recycling rate and reducing its environmental footprint.
This work explores the entire lifecycle of EPS and XPS, from production and application to waste generation and recycling, and proposes solutions. By focusing on practical solutions and industry-specific needs, this work facilitates a shift towards a more circular and sustainable model for EPS and XPS waste management in the construction industry, offering actionable recommendations for construction companies and waste managing companies to adopt more environmentally responsible practices.

The rapid development of infrastructure has led to various environmental, economic, and societal challenges. The pavement industry, in particular, is known for its high energy consumption, resource utilization, and pollution generation. Despite recent efforts to augment the sustainability and circularity of pavement infrastructure, there remains a lack of comprehensive assessment methods to evaluate the existing practices and technological advancements, which makes the implementation of innovations challenging. This study reviewed twelve existing circular economy indicators and frameworks to understand the challenges associated with their use in evaluating pavement infrastructure. The indicators included Material Circularity Indicator (MCI), Circular Economy Index (CEI), CB’23 framework, Environmental Sustainability and Circularity Indicator (ESCi), Circular Economy Indicator Prototype (CEIP), Material Reutilization Score (MRS), Value-based Resource Efficiency (VRE), Circular Economy Performance Indicator (CPI), Recyclability Benefit Rate (RBR), Reuse Potential Indicator (RPI), Product-level Circularity Metric (PLCM), and Building Circularity Indicator (BCI). These indicators cover different aspects of circularity and sustainability, such as resource efficiency, material circularity, product’s lifetime, preservation of product’s functions, and environmental and economic impacts. However, none of the indicators provide a comprehensive assessment tailored for pavements, encompassing circularity and all three aspects of sustainability. Considering factors such as data availability, overlap of conceptual and methodological approach, and the scope covered, six of the twelve circularity indicators were evaluated in this study, namely, MCI, CEI, CB’23, ESCi, CEIP, and MRS. Since these indicators were not originally developed to assess pavements, appropriate methodological modifications were proposed and validated using three different pavement construction and maintenance methods that are commonly adopted in the Netherlands. In order to map the road to sustainability, the analysis was complemented with the Environmental Cost Indicator (ECI, or in Dutch, MKI) and Net Present Value (NPV). The three case studies adopted in this study included: (a) resurfacing the pavement once in every 12 years with 25% Reclaimed Asphalt Pavement (RAP), hereafter referred as Business As Usual (BAU) scenario, (b) life-extension maintenance by rejuvenating the pavement in years 5 and 10 since construction followed by resurfacing, and (c) use of low-emission technology, i.e., Warm-Mix Asphalt (WMA) with higher RAP 3 percentage (50% by mass) in the mix. An analysis period of 36 years was chosen as per the Federal Highway Administration guidelines and the foreground data was collected from roadway stakeholders. Additional missing information was also gathered from Dutch asphalt product category rule, international databases, and existing literature. The results revealed the strengths and limitations of each indicator. MCI being a mass- based indicator captured the material circularity and product’s service life but failed to represent the environmental and economic impacts. Although CEI indirectly captures the environmental impacts as it is governed by market prices, which takes into consideration the societal and environmental taxes, it is volatile as it is can also be influenced by the supply and demand of raw materials and material quality, potentially overlooking the benefits of using higher percentages of recycled materials. CB’23 provides detailed information by classifying pavement components across different circular economy principles, which aids in targeted improvements but complicates the comparison of alternatives as a whole. ESCi combines MCI and MKI to incorporate circularity and environmental sustainability but requires extensive modelling and lacks economic and social considerations. CEIP, as a questionnaire-based indicator, covers a wide range of circularity principles, but the weighting and scoring of questions is subjective as it is based on the expert opinion leading to concerns of bias in decision making. MRS involves simplified mathematical computations, thereby serving as an attractive choice for quick decision-making. However, it is fundamentally biased to cover only the recycling strategy, and ignores the aspect of lifecycle use, thereby not accounting for durability of the asset. With regards to the case studies, MKI, MCI, ESCi, and MRS indicate that the WMA alternative was the most circular strategy. LCCA, CEI, and CEIP favour the rejuvenation alternative, while CB’23 may favour one alternative when the result of one sub-indicator is designated to be the criterion for decision making. However, since all the indicators cover different aspects of circularity, it is important to complement the results with environmental, economic, and social sustainability indicators for comprehensive and robust assessments. In practice, choosing different alternatives based on the selected indicators can lead to varying end result. Therefore, it is essential to handle these implications carefully and the scope, boundaries, methods, assumptions and any limitations must be clearly stated for transparent decision-making. Future research should focus on improving data quality and developing methods to integrate social sustainability, wherever feasible.

Experimental research into the spalling behaviour of mortars and if it is possible to predict the spalling resistance. Research is divided into spalling experiments with varying parameters and experiments to analyse and characterize the pore structure. By combining both results, a first step is taken into a formula that is able to predict the spalling behaviour of cement based materials.

The increasing traffic load on highway bridges provides a need for replacement or improvement of the bridge decks. The design of a new bridge deck using fibre-reinforced polymer (FRP) bridge decks raises questions on the connection of a FRP bridge deck to a steel superstructure. At the Tu Delft a bolted connector injected with steel reinforced resin (iSRR) is developed for the connections between steel superstructure and FRP bridge deck. Steel reinforce resin (SRR) is a combination of steel shot (SS) and resin. The steel shot is added to achieve higher stiffness and reduce the total production cost. The iSRR connection can be produced using multiple methods. For all production methods, the SRR in the connector is produced by pouring SS around the bolt followed by the injection of the resin. The iSRR connector should accompany the fatigue resistance of the FRP bridge deck. A better understanding of crack propagation can help to increase the life expectancy of iSRR connections. However, no standardized method for the testing of crack propagation in SRR exists. This research attempts to find a crack propagation testing method for SRR by investigating the use of compact tension (CT) and semi-circle bending (SCB) testing for the SRR material. For the production 5 different casting methods were compared. From these methods, the closed mould injection casting and ring mould injection casting showed the most promising production method for the production of complicated forms in SRR. From this testing the need to use modified forms of CT and SCB was found, resulting in the use of a doubly tapered compact tension specimen (2TCT) and the design of the short tapered notched beam specimen (STNB). The modified specimen forms are tested under varying loading types. The 2TCT specimen is tested under load controlled, and displacement controlled loading. From this, the incremental increasing loading type was suggested. This loading type was used in the testing of STNB specimens. Lastly with the use of FEA the stress intensity factors for the modified test forms were validated. The validation was done on the analytical formulas provided by literature for the unmodified forms. From this research, it can be concluded that the closed mould injection casting and ring mould injection both achieve good results for the production of complicated shapes with SRR. The incremental increasing displacement loading method leads to more stable crack growth. The 3 point bending testing type leads to the most promising results for crack propagation. With a linear correlation in the small range of K = 20-60 resulting in a Paris Law with 𝐶 = 4.3𝑒 − 7 and 𝑚 = 2.41. It is recommended for further crack propagation testing to produce specimens with the least amount of voids. The voids are expected to have a high contribution to the big spread of data found during the testing. For better insight, the voids in the tested specimens could also be investigated.

Sustainable Urban Drainage Systems (SUDS) are useful tools to manage rainwater and reduce pollutants in urban environments. Their use, as sustainable solutions, can mitigate the effects of climate change and urbanization. The existence of different definitions of performance is one reason for delaying more implementation of SUDS. Deciding on the Key Performance Indicators (KPIs) is one of the objectives of this thesis. WaterStreet, the chosen study area, is a living lab that permits the implementation, presentation, and testing of newly designed SUDS with the goal of facilitating their entrance into the market. WaterStreet could benefit from using sensors to provide the KPIs and other indicators of performance, but the sensors already implemented do not achieve that objective fully. So, the objective of this thesis is, to develop a comprehensive set of KPIs that describe the performance of SUDS and propose a monitoring network to measure the performance of SUDS implemented in WaterStreet.
To achieve that objective, information on the study area’s characteristics, like soil types, design of SUDS, and groundwater levels were gathered to find how water flows in, out, and around the study area including the SUDS. Additionally, the key stakeholders were determined with a stakeholder analysis, and literature was researched on the important indicators used to reflect the performance of SUDS for water quality and quantity. Interviews were performed to include the view of the key stakeholders on the indicators found in the literature. The two approaches explained above provide the data that need to be monitored on WaterStreet. Criteria for the quality of data that would be provided by the sensors are set, before concluding on suggestions. The suggested sensors and their limitations are based on results of published studies and reports.
Based on the findings of this thesis a distinction between the Key Performance Indicators (KPIs) and Indicators of Performance (IP) is made. In the first category, the indicators of overflowing volume, duration, and frequency are included along with rainfall and overflow from upstream drainage areas. In the second category the indicators, infiltration in the soil and through the first layer of SUDS, and storage in the soil and system are included. Both categories of indicators are suggested to be monitored in the study area of WaterStreet to increase the value of WaterStreet as a living lab. Indicators for water quality are not concluded due to the lack of information on the existing pollutants and their removal and remobilization mechanisms. Reduction of Total Suspended Solids (TSS) and Total Phosphorus (TP) are two possible indicators that are also considered as a proxy in Germany. Changes in pH and temperature are two indirect indicators that are found to affect the reduction and remobilization mechanisms and are therefore important to consider as well.
An acoustic disdrometer to measure rainfall, a sonar pulse sensor to measure groundwater levels, divers in an observation pipe in the system to measure the water level in the system and the infiltration in the soil, and lastly divers in a controlled volume downstream of the SUDS to measure the overflowing water downstream the SUDS, were the proposed sensors. The disdrometer and two of the sonar pulse sensors are already installed on WaterStreet while it is suggested to put divers in the individual systems and two more sonar pulse sensors. For the indicators, overflowing water from upstream and the rate of water entering the SUDS research on the runoff coefficient and the use of water balance are suggested, respectively.
An important consideration in this thesis is the characterization of hydraulic isolation from the top and bottom of the system, allowing the interpretation of the data from monitoring, to represent only one system’s response. Suggestions to include a controlled volume to capture the overflow downstream of the SUDS and a drainpipe to ensure a drainage depth of 0.5 m, are made, to help ensure hydraulic isolation from top and bottom respectively. Based on this study, only half of the systems placed on WaterStreet are isolated, not considering the possibility that the groundwater table can get even higher resulting in even fewer systems isolated. Additionally, from analyzing the hydraulic response on the SUDS in WaterStreet, it was concluded that all 5 studied systems out of 8 total were being over-dimensioned, meaning that the storage in the SUDS would not be full even with rainfall of once in 100 years. From the same analysis, it was also concluded that the infiltration through the first layer is the prevalent overflowing mechanism of 3 out of 4 studies SUDS. Both the previous findings are important to realize a hydraulic response to rainfall proportionally to real implementations. This is an essential consideration from living labs because they try to bring lab and real implementation closer. Lastly, pollutants to be used as KPIs for water quality performance of SUDS should be researched more based on the principle of not shifting problems downstream.

This thesis adopt existing methodologies for flood-risk assessment in other civil infrastructure (such as dams or urban flooding) and apply them in road type infrastructure in order to quantitatively assess flood vulnerability and risk in project locations where historical closure data is not available and the complex global network-approach usually implemented cannot be used for road risk management issues. By looking from a designer/ manager perspective, the aim is to deal directly with the specific road-segment under hydrological threat, shifting the interest to a more detailed comprehension of: the hazards likelihood of occurrence, the system (road pavement and bridges) response, the potential failure modes involved, and the expected consequences derived from a failure. Doing so, the proposed methodology has proven to be useful to support decision making and prioritization of risk reduction actions during and after the completion of the road design works in a case study considering climate change effect.