Biomass ash as supplementary cementitious materials: Characterization, application, and re-conditioning New types of supplementary cementitious materials (SCM) are in demand, due to the foreseen decrease in the availability of traditional SCM (i.e. coal fly ash and ground granulated blast furnace slags). Hence, this project investigated the potential of using biomass ashes as SCM. The studied ashes came from two different sectors, pulp and paper and energy producers, and from different plants in each case. Both fly and bottom ashes were investigated in terms of chemical composition and their evolution in time, mineralogy, reactivity, and participation in the hydration of cementitious binders. The re-conditioning of the ashes was also explored to limit the presence of undesired components, such as Cl and S. The use of blends of biomass ashes of different types and origins was investigated as well. Finally, mortar bars containing ashes in different proportions were cast to check their mechanical properties. The study revealed that the composition and overall properties of ashes did not change significantly in time (i.e. for different sampling dates), but that big differences could be found between different plants (because of differences in the production processes. Chlorine and sulphur could be washed away easily by simple immersion in water, but high alkali contents remained in some cases. Generally, fly ashes tend to be more reactive than bottom ashes, but exceptions were found Some ashes were found to be hydraulic reactive. Most samples exhibited a high LOI, resulting in some cases in high water absorption and poor hydration of the cement, which resulted in poor mechanical properties. The use of blends of ashes led to a reduction of the spread in reactivity and an increase in the average reactivity. The results showed that sufficient compressive strength could be reached in mortars containing biomass ash.

Concrete is the most used material in the world (buildings, infrastructure, transport) and its production is continuously increasing over the years because of the growth of the population, the urbanisation, and the infrastructure development. Unfortunately, the production of the main component of concrete, cement, causes inevitable CO2 emissions, accounting for 6% of the total anthropogenic CO2 emissions. The most efficient way to reduce this environmental footprint is to reduce the clinker factor in cement or to reduce the cement content in concrete, which is done by replacing a part of the cement by Supplementary Cementitious Materials (SCM). However, the most commonly used SCM (fly ash and ground granulated blast furnace slag) are only available in a low amount in Sweden. New SCM must be find.The objective of this project was to evaluate the potential of using Swedish clays as SCM. An inventory of available clays was performed in a first step. Then, as clays need to be activated before use with cement, different activation procedures were tested. A selection of clays was mixed with cement either in binary mixes (cement + activated clay) or in ternary mixes (cement + activated clay + limestone). The hydration properties and the microstructure of binder pastes were investigated, as well as the strength development of mortars. Finally, a life cycle analysis (LCA) was performed to evaluate the positive impact on the CO2 emissions when clays are used as SCM.The results of the project highlighted the good potential of using Swedish clays in concrete to decrease the environmental footprint due to the cement and concrete industries. In particular, the clays can be activated through mechanical and thermal treatment, depending on the type of clay. Thermal treatment in temperature ranges between 600-800 degrees is preferred for sedimentary clays, while a mechanical treatment by ball milling gives better results with marine clays. A satisfactory strength is achieved in mortar samples cast with calcined clays. This was achieved by replacing the cement with 30% of calcined clay and 15% of limestone. Finally, the LCA calculation shows that the use of clay in a ternary binder lead to a reduction of approx. 34% of the CO2 emissions.

Um Denkmäler zu bewahren und Altbauten für eine zeitgemäße Nutzung instand zu setzen, sind Lösungen notwendig, die den Eigenschaften und dem Erhaltungszustand der Gebäude angepasst sind. Dazu ist ein Grundwissen über historische Baustoffe erforderlich. Reparaturmaterialien interagieren physikalisch und chemisch mit dem Bestand. Falsche Reparaturversuche können Schäden verschlimmern oder neue Schäden hervorrufen. Dieses Buch ist eine Baustoffkunde der seit Jahrtausenden gebräuchlichen Materialien Lehm, Kalk, Gips, Naturstein und Ziegel. Behandelt werden außerdem Zementmörtel und historische Betone sowie unterschiedliche Farben und Pigmente. Ein Kapitel ist dem Asbest gewidmet. Der Autor beschreibt die Geschichte der Entstehung oder Herstellung dieser Baustoffe, ihre stoffliche Zusammensetzung und die Materialeigenschaften. Ein wesentlicher Teil des Buches befasst sich mit naturwissenschaftlichen Grundlagen und Analysemethoden, mit denen Materialzusammensetzungen bestimmt und Schadensursachen aufgeklärt werden können. Dieses Grundwissen benötigen Planer, damit sie baustoffkundliche Untersuchungen gezielt beauftragen und fundierte Entscheidungen für Maßnahmen zum Schutz, zur Konservierung oder zur Instandsetzung treffen können. Das Buch ist Teil der Reihe »Erhalten historisch bedeutsamer Bauwerke - Empfehlungen für die Praxis«. Diese Buchreihe stellt in thematisch abgegrenzten Einzelbänden konzeptionell-entwurfliche und bautechnisch-konstruktive Methoden für einen behutsamen Umgang mit historischer Bausubstanz vor, bei dem Eingriffe auf das wirklich Notwendige beschränkt werden. Sie gründet auf einer gleichnamigen, vor genau 20 Jahren von Fritz Wenzel und Joachim Kleinmanns herausgegebenen Publikationsreihe, in der die Ergebnisse des Sonderforschungsbereichs 315 »Erhalten historisch bedeutsamer Bauwerke - Baugefüge, Konstruktionen, Werkstoffe« veröffentlicht wurden. 

The report presents an investigation of the role of the sulfate balance in blended binders with slag (ground granulated blast furnace type, GGBS) or fly ash (low calcium type) in achieving improved sulfate resistance (SR) when using non-SR CEM I. The investigation involved experiments with sulfate-doped vs. undoped blended binders, pastes and mortars with and without exposure to sulfate attack, which was induced by immersion in Na2SO4 solution using a laboratory method. The results reveal the benefit of a sulfate level adjustment to promote improved behaviour during sulfate attack: doped blends yielded lower expansion during sulfate attack and reduced internal damage compared to undoped alternatives. Sulfate-doping increased the potential of slag and fly ash to mitigate sulfate attack with non-SR cement.

The Swedish construction industry is generating a save and affordable built environment for transport, work and living but it is faced with a huge challenge: drastic reduction of greenhouse gases and an increase of circularity in their production cycles. One material, which has inherently embodied CO2, is limestone, which is needed for the production of Portland cement, the essential ingredient in concrete. The CO2 emission during cement production can be drastically compensated by so called supplementary cementitious materials (SCM), which replace cement components causing CO2 emissions. SCM can be used by incorporating them into Portland cement or can be used directly by mixing into concrete. However, traditionally used SCM such as ground granulated blast furnace slag or fly ash are only available in limited amounts in Sweden, not matching the domestic cement production. An alternative to those more traditional SCM is activated or calcined clay, which reacts similar to blast furnace slag or fly ash. Calcined clay is created from natural clays by heating up to 700 ° - 800 °C, where it become very reactive. In this roadmap the state-of-the-art about activated clays is shown from a Swedish perspective. It also shows challenges and needs that have been formulated for a future implementation of activated clays as a component of low carbon concrete.

Concrete is the worldwide most utilized construction material because of its very good performance, forming ability, long-term durability, and low costs. Concrete is a brittle material prone to cracking. Extensive cracking may impact durability and performance over time considerably. The addition of a small amount of carbon nanotubes (CNT) increases the concrete's overall electrical conductivity, enabling internal structure condition monitoring (self-sensing). This article presents the mechanical and self-sensing properties of regular and high-performance concrete (HPC) with multi-wall carbon nanotubes (MWCNT). The stress detection was investigated in cyclic compression, while damage detection was assessed by means of wedge splitting tests combined with the digital image correlation (DIC) method. The results proved that a small addition of MWCNT (0.05% and 0.10%) enhances the stress detection capabilities and enables the monitoring of microcracking.

Concrete possesses an intrinsic chloride binding capacity. Chloride ions from the environment bind with the hydrated cementitious phases in the form of bound chlorides. The contribution of chemically bound chlorides toward increasing the service life of concrete structures is vital as they help in slowing down the chloride diffusion in the concrete thereby delaying reinforcement depassivation. The authors attempt to increase the chloride binding capacity of concrete by adding a small amount of Mg–Al–NO2 layered double hydroxides (LDHs) with the objective to delay reinforcement corrosion and by this to considerably extend the service life of concrete structures situated in harsh environments. This study presents numerical and experimental analysis of the action of LDH in concrete. Formation factor is used to determine the effective chloride diffusion coefficient. In addition, the chloride binding isotherms together with Poisson–Nernst–Planck equations are used to model the chloride ingress. A comparable chloride binding is observed for concrete with and without Mg–Al–NO2, depicting only a slight chloride uptake by Mg–Al–NO2. Further investigations are conducted to understand this behavior by studying the stability and chloride entrapping capacity Mg–Al–NO2 in concrete. © 2020 The Authors.

Construction and Demolition Waste (CDW) accounts for approximately 25-30% of all waste generated across Europe each year. However, Waste Framework Directive 2008/98/EC requires from all EU member states to achieve at least 70% re-use, recycling or other recovery of non-hazardous CDW by 2020. In response, the Horizon 2020 RE4 Project (REuse and REcycling of CDW materials and structures in energy efficient pREfabricated elements for building REfurbishment and construction) consortium was set up. Its main aims are to assess the quality of various CDW fractions (e.g. mineral aggregate, timber, plastics, silt & clay), improve the quality of mineral aggregates and develop different building elements/components which contain at least 65% of CDW. Innovative building concepts will also be developed in an effort to improve recycling rates of future buildings through the use of prefabrication and modular design. The developed products and technologies will be assessed in a number of test sites by building 2-storey demonstration houses.

Foreword All transport systems have a certain capacity determined by its configurations. For cars the most efficient current form is constant speed driving, e.g. the motorway. Its capacity is limited by the time separation between vehicles. Any transport system that stops because of congestion or other causes by definition sees its capacity reduced to zero. Hence traffic jams are hugely disruptive. Public transport operates on a model inherited from the 19 th Century. Vehicles (buses, trams, railways, metros) run on a regular (timetabled) basis and stops at every station (bus stop). Since there is no pre-booking and the need of transport is hard to foresee, the vehicles are often almost empty, at other times hugely congested. The NuMo technology emerges from decades of work across the whole transportation industry. Autonomous electric vehicles (AEVs) equipped with vehicle-to-vehicle (V2V) communication can safely keep shorter distances. In practical terms this means that a platooned car system has the same capacity in one lane as a double-lane motorway. Automated intelligent controls ensure that the NuMo systems never stops, thus achieving the highest capacity. Instead of waiting for the mass deployment of fully automated vehicles, NuMo starts with dedicated networks that integrate tightly with existing infrastructure for step-wise smooth transition to fully automated transport system. NuMo includes an on-demand public transport system which only runs when it is needed. The system will take advantage of close-spacing possible with robot controls – vehicles can run close together and also use less road width by less wiggling. Equally importantly stations and access to the normal road network is arranged such that the traffic flow never stops. The urban impact can be imagined by understanding the impact of modern public transport systems currently under construction. Some of them are underground to avoid disrupting the street patterns. Some are elevated, some rely on physical separation at grade. One interesting option is to use tunnels underground or in water to further reduce disruption. Many cities are abandoning the traditional port infrastructure giving huge opportunities to again regard water as a connector rather than something to cross. The NuMo system uses all of those techniques and detailed design studies are under way for each of those options. NuMo will make an important contribution to environmental sustainability in many respects. Firstly, it will accelerate adoption of electric propulsion; secondly it will encourage vehicle sharing; and thirdly by only running when needed will save on unnecessary movements and finally its construction costs will be less than conventional systems. Sketches of NuMo networks are presented on places as diverse as Stockholm, Gothenburg and New York. Naturally the system will also be crucial in the development of new cities. This report is a summary of the studies performed within the project “New urban infrastructure support for autonomous vehicles” financed by Vinnova through the Strategic Innovation Program InfraSweden2030. The aim is to explore the infrastructure support to accelerate the introduction of autonomous electric vehicles for future mobility.

The sustainability of concrete infrastructures is highly dependent on the durability. A longer service life with low repair work reduces the resource use and hence the greenhouse gas emissions. New admixtures based on nanomaterials have the possibility to increase the service life. However, it is also important to consider the embodied impact of the material and safety issues concerning new nanomaterials. Here we present an overview on the latest developments on the safety and sustainability of some novel admixtures.