The development of an efficient and sustainable transportation system is crucial for the effective functioning of economies. Concrete, a widely used material for road construction, poses significant environmental challenges. A sustainable alternative is to use alkali-activated concrete (AAC) for road construction. However, the aggregates used in AAC are generally mined, contributing to the negative environmental impact. To address this concern, municipal solid waste incineration (MSWI) ashes, specifically MSWI bottom ash (BA), can be utilised to replace natural aggregates. Thus the construction of pavements using sustainable concrete facilitates its growing demand without burdening the environment. This research focuses on the utilisation of municipal solid waste incineration bottom ash (MSWI BA) aggregates in AAC for potential application in pavements. The study was divided into five phases: aggregate characterisation, mechanical performance evaluation, long-term performance study, microstructure analysis, and life cycle assessment (LCA) analysis. The physical properties of MSWI BA aggregates indicated that the aggregates are porous and weak. Nonetheless, these aggregates showed comparable properties to natural aggregates and can still be used for pavement application. However, the metallic aluminium in the MSWI BA aggregates releases hydrogen gas leading to concrete cracking and swelling, thus, hindering its use in various applications. To address this concern, alkaline pre-treatment using sodium hydroxide solution was employed in this research. An optimal replacement level of 30% was chosen based on the effectiveness of the pre-treatment in removing metallic aluminium and the compressive strength of AAC containing MSWI BA aggregates. In the next phase of the research, the mechanical and long-term performance of AAC with optimum replacement level was evaluated. The results demonstrated that the concrete satisfied the mechanical performance requirements for pavements. However, the freeze-thaw resistance of the AAC was below the norm requirement due to the air voids and associated cracking, which was confirmed through scanning electron microscopy (SEM) and X-ray computed tomography analysis. SEM analysis revealed reactive phases in the MSWI BA aggregates and poor aggregate-matrix bonding for the coarser fraction compared to the finer aggregate fraction, leading to decreased mechanical performance. Despite these findings, the AAC containing MSWI BA aggregates satisfied the majority of the norm requirements, indicating its potential for road pavement application. However, evaluating the environmental impact of adding MSWI BA aggregates in concrete is essential. The life cycle assessment analysis demonstrated that the optimal MSWI BA sample exhibited better environmental effects, indicated by a lower environmental cost indicator value compared to AAC and ordinary Portland cement concrete samples with similar performance. In conclusion, the pre-treatment method utilised in this research is optimal for a replacement level of 30% of gravel with MSWI BA aggregates. The AAC with 30% replacement level meets all the mechanical property requirements stipulated by the norm for pavement application, exhibits good air void distribution, and has limited environmental impact owing to the lower ECI value. This study evaluated the feasibility of applying MSWI BA aggregates in AAC for pavement application and showed promising results.

In 2016 the Paris agreement was adopted by 196 parties. The main goal of this agreement is to obtain a climate-neutral world in 2050. The CO2 emissions should decrease as soon as possible to achieve this goal. Concrete is the world's most used building material, and with good reason, it provides cheap, solid and reliable products used for over 200 years. However, concrete is responsible for 5-10 % of the yearly CO2 emissions worldwide. These emissions are mainly because of cement production, the binding agent of concrete. Therefore, to lower the CO2 emissions from concrete, it is most effective to opt for an alternative binder. This research focuses on alkali-activated materials (AAMs), where an alkali-activated binder has replaced cement. This binder consists of a precursor and an alkaline activator. The materials most commonly used as precursors are blast furnace slag and fly ash, waste products. The production of these materials is not nearly enough to replace cement. Therefore, there is a need for alternative precursors. Volcanic materials can be an alternative precursor, and some have been successfully applied in AAMs before. However, since volcanic materials come in different forms, validation of a wide range of volcanic materials. This research has investigated four European aluminosilicate volcanic materials: trass, phonolite, perlite and pumice. Each of these materials has been assessed on their particle size, chemical composition and microstructure to determine whether they exhibit (pozzolanic or latent hydraulic) reactivity. All four materials classify as inert. For trass and phonolite, the lack of reactivity is most likely because of their lack of amorphous phases (around 30% and 5%, respectively). For perlite and pumice, it is because of the too coarse particles. The reactivity of trass and phonolite is enhanced by calcination, and the reactivity of perlite and pumice is enhanced by grinding. Determination of the reactivity shows that calcination had no or a negative effect on the reactivity of trass and phonolite. Most likely because of the lack of calcium and magnesium in these materials. Ground pumice does show an increase in reactivity. However, not sufficient to be classified as reactive. Ground perlite does show reactive behaviour and is classified as pozzolanic, less reactive. Ground perlite and BFS are used as precursors in mortar to assess the contribution of perlite to compressive strength development. It shows that perlite contributes to the strength of mortar when combined with a sodium silicate and sodium hydroxide activator. Likely, the sodium silicate is necessary to delay the alkalinity of the mixture. This alkaline delay makes that perlite does not form a layer of hydration products over the particles, making it impossible for perlite to react further and contribute to the compressive strength. TGA measurements found that because of the silicates that perlite contributes to the mixture, the hydration products become denser, which seem to cause higher strength. However, it is also found that silicates from sodium silicate solution are more effective in providing silicates than perlite is. Of all four materials, only perlite seems to be reactive enough to contribute to the strength of alkali-activated binders as precursors. Volcanic materials cannot be considered to be one material, and each one has to be assessed individually.