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Concrete is by far the most common building material in the world. Due to its good durability it is widely used in building envelopes. One major part of the embodied energy in concrete comes from the production of Portland cement that consumes around 3,500 MJ energy per each ton of cement. Globally 2.6 billion tons of Portland cement is produced and the consumption is increasing. Since concrete will be used as main building material also in future construction, it is reasonable to develop concrete building components with lower embodied energy.Using the example of an ultra-high performance concrete (UHPC) façade element, it is demonstrated how the embodied energy can be reduced by application of hydrothermal curing.
Ingress of moisture and harmful ions (e.g. Chloride, sulfate) into cementitious materials is one of the major factors in defining their durability. Modifications of building materials by targeted deposition of surface functional agents that make the surface hydro- and/or oleophobic aim to minimize moisture and ion ingress, and thus extend Service life of the cement based structures. Water repellent and easy-to-clean coatings for inorganic Substrates have gained strong attention during the last few years and various formulations based on silicones or alkylpolysiloxanes have been developed. Cementitious building materials are highly complex Systems with many components and changing properties in the course of a building’s Service life. The interactions between the Chemical agents and the cement based materials depend on many factors. The Chemical properties of the material Substrate appear to be the most important but in the context of their influence on the functionality of silanes and/or siloxanes these characteristics have not been well understood yet. The aim of this study was to evaluate the effect of different blended cements on water repellent agents’ performance. Two organosilicon compounds
were applied on fresh blended cements containing limestone (L), fly ash (F), slag (S) and trass (T), and investigated in terms of their functionality.
The surface properties of functionalized blended cements were studied based on wettability, i.e. contact angle measurements, before and after exposure to artificial and natural weathering. The first results indicate that slag and trass more distinctly affect the water repellent Surface performance after aging.
The goal of this study was to find a correlation between cleaning efficacy of substrates protected with anti-graffiti systems (AGS) and their porosity, surface roughness, and composition as well as usability of the Technical Testing Guideline for Anti-Graffiti Systems (TP-AGS, issued by BASt) for natural stone and brick/clinker masonry. The results showed that the cleaning efficacy mainly depends on the porosity of the substrate and the type of AGS. Also, higher surface roughness contributed to a lower cleaning efficacy. The results showed also that concrete panels and cement joints in masonry represented the worst case. The color change of all substrate materials compared to concrete was mostly within acceptable limits. Gloss changes were significant for a number of substrates. In particular, several of the wax-treated low-porosity substrates exceeded the threshold value of 10. The limit of water vapor permeability of the AGS prescribed in the TP-AGS might be too high for natural stone substrates. In general, the TP-AGS is useful for the determination of the efficiency factor of anti-graffiti agents on various substrates.