Carbon dioxide can be used during concrete production, which leads to stronger concrete as well as a sequestration method for CO2. While these technologies are developed quite far, they are currently not being used within society nor is there any systemic overview of the system and a reason why these technologies are not used. This thesis performs a Technological Innovation System analysis to investigate the Dutch concrete system and find barriers to the transition from conventional to carbon-cured concrete. The three located barriers are knowledge exchange, guidance of the search and the formation of markets. Intervention tools are presented to decrease the barriers and stimulate the technology within the system to enable further growth.

The increasing demand for sand in the construction sector underscores the need for sustainable alternatives to natural sand. This bachelor's thesis explores the application of Fine Recycled Concrete Aggregate (fRCA) produced by Heating air and classification system (HAS) from the Concrete To Cement and Aggregate (C2CA) technology as a sustainable substitute for natural sand. fRCA consists of pure sand and cementitious material, with the removal of extraneous substances such as timber and steel. While fRCA finds applications in various sectors, the challenges in its use in mortar include property variations, cost considerations, and the absence of quality control standards. Addressing these challenges would be crucial for the wider adoption of fRCA in mortar applications. This research aims to characterize fRCA properties, enhance fRCA quality through acid treatment and milling, determine optimal milling parameters, investigate the influence of the water-cement (W/C) ratio on mortar workability, and assess the compressive and tensile strength of mortar with fRCA. The central inquiry pertains to identifying the optimal approach for enhancing fRCA properties and integrating it into concrete mixes for civil engineering applications. The study is exploring the effects of untreated fRCA, milled fRCA, and acid-washed fRCA on mortar properties. It is also determined the ideal quantity of milled fRCA to replace natural sand in mortar mixtures. The theoretical evaluation of sustainability in mortar mixes utilizing this specific fRCA have been conducted. This research did not investigate the chemical properties of fRCA. Notably, the quality of fRCA differs from that of Natural Aggregate (NA), characterized by distinct particle size distributions and water absorption properties. While fRCA can effectively replace NA in mortar mixtures, it does affect compressive strength due to higher water absorption and the partial retention of cementitious material. However, by milling or treating it with ACID, the quality of fRCA can be improved, making it possible to use fRCA as a replacement for NS in mortars. The optimal substitution rate of NA with fRCA is identified as 25%, with the possibility of an increase to 100%, depending on the specific application. The integration of fRCA in concrete holds potential for sustainability by reducing reliance on natural resources and curbing waste generated by the construction industry.

Construction and demolition waste form a significant problem in terms of environmental pollution and material depletion. Concrete, as part of construction and demolition waste, is already responsible for 9% of the total anthropogenic carbon dioxide emissions. Consequently, it is important to alleviate the environmental stress of concrete by replacing virgin aggregates and cement by recycled aggregates and liberated cement. This study determines how the properties of recycled aggregates and virgin (new) aggregates compare for using recycled aggregates in a new concrete mixture.
Recycled aggregate properties are examined by performing a variety of experiments, namely
water absorption and specific gravity, Los Angeles abrasion, flakiness and shape index and
compressive strength. Each experiment describes a different characteristic of the aggregates
creating a clear picture of their properties. The properties of virgin aggregates have been
obtained from literature.
In addition, a milling method has been examined as a possible new step in the recycling chain
for liberating cement paste from the fine recycled aggregates.
Water absorption and interfacial transition zone formed problems for the recycled aggregates,
but they show excellent properties in terms of compressive strength, resistance to abrasion,
grain interlocking and shape characteristics.
While very different from each other, recycled aggregates show very good properties when
compared to virgin aggregates giving them potential to be used in new concrete mixtures.