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Reducing CO2 emission is now extremely urgent. At the current level of emission in only 7 years we will exceed the level of CO2 in the atmosphere deemed to lead to warming of 1.5°C. LC3 is a technology which can make a major contribution to reduction. In this presentation I will describe how we came up with this innovation, how we went about implementing it in the field and what remaining barriers we need to overcome to realize the full potential.

Wet curing improves OPC concrete durability and strength by increasing total hydration, densifying microstructure and decreasing concrete permeability. In general, wet curing is recommended for ordinary portland cement (OPC) concrete curing until it gains >70% of the designed compressive strength, typically at least 7 days. Calcium sulfoaluminate (CSA) cement may allow for decreased curing time requirements due to its rapid hydration, hardening, and strength gain. This study investigated a variety of curing durations and curing solution compositions to understand their effects on CSA hydration, strength development, and shrinkage. The results demonstrate that curing for 2 days promotes adequate strength gain and completion of hydration reactions and that CSA can be cured using similar methods as used for OPC, including application of fog or limewater. Additionally, curing CSA samples even for 1 day in 100% RH led to lower shrinkage than 7-day cured OPC samples, and may reduce cracking in concrete pavements.

The production of ordinary portland cement (OPC) is very carbon expensive, and with an increased focus on application of eco-friendly cementitious materials, interest in alternative cements has grown. One of these alternatives is calcium sulfoaluminate (CSA) cement. The manufacturing of CSA cement emits about 50% less carbon per lb. of cement produced and has other advantages such as rapid hardening due to a greater formation of ettringite when compared to OPC. However, there are a limited number of studies concerning the freeze-thaw resistance of CSA cement systems in cold environments. This study directly compares Type I OPC and CSA cement paste and mortar mixtures at water-to-binder ratios (w/b) of 0.40, 0.45, and 0.50 to determine the differences in freeze-thaw durability. This study implements thermomechanical analysis (TMA) to quantify the frost-induced damage in CSA and OPC systems with micron-scale resolution. Additionally, water absorption, bulk electrical resistivity, and porosity measurements along with microstructure characterization were performed to relate the freeze-thaw performance to the microstructural and mass transport properties of CSA systems.

It is well known that the concrete industry is at a watershed towards sustainability, focused on reducing its environmental impact and improving the performances and the service life of concrete structures. One of the main causes of the huge environmental impact of mortars and concretes is portland cement, an energy-intensive binder characterized by strong greenhouse gases emissions and high natural raw materials consumptions. For this reason, several low-environmental impact alternative binders to portland cement have been proposed in recent years. However, it is clear that the massive volumes required by construction industry, together with technological limitations, inconsistency of properties and price issues, make the replacement of significant portions of portland cement in concrete production practically impossible. Nevertheless, alternative “green” binders may play a fundamental role in the formulation of special mortars and concretes due to their peculiar properties at fresh and hardened state. This paper presents different “special” applications of alternative binders (alkali activated materials, calcium sulphoaluminate clinker-based blends) such as expansive concretes for jointless slabs on ground, heat-insulating reinforced plasters for seismic and energy retrofitting of poor-quality masonry structures, cement-free renders for structural applications on existing buildings and pervious concretes made only with recycled raw materials.

The most recent advancements in the field of the concrete industry don’t only represent the possibility to satisfy the demand of an ever-changing market demand but could also be the opportunity to reach important improvements in terms of holistic sustainability which is an essential topic nowadays. In view of this, the current work investigates the case of nanofunctionalized Ultra High-Performance Concrete (UHPC) to address also the potential advantages coming from the better structural and durability performances when exposed in specific aggressive environmental scenario. The benefits of adding alumina nanofibers or cellulose nanofibrils/crystals in terms of enhanced crack control, reduced autogenous shrinkage and improved durability self-healing capacity will be quantified in a life cycle perspective, also considering the impact and cost of the nano-particle production. In this framework a holistic assessment perspective will be provided through the Life Cycle Assessment methodology, employed to quantify such advantages on a local, regional, and global scale using the worldwide recognized 10 CMLA impact categories to also show how such procedures, being employed within an “a priori” de-sign phase, can help to drive the sector to more conscious choices.

Earlier, a simplified, excel based tool was developed based on extensive experimental data by innovative/new test methods to do durability-based performance evaluation of conventional coal ashes in HPC. The aim was to offer the contractor an easy-to-use tool to predict the durability performance of the concrete mixes in terms of ASR, chloride-induced corrosion, freeze-thaw damage, and shrinkage-based cracking potential during the mix design development stage. Some uncommon coal ashes (e.g., blended ash, bottom ash, harvested ash, etc.) were subsequently evaluated through (i) detailed characterization including reactivity measurements, and (ii) durability-based performance evaluation using the developed tool with selective validation testing. The merits of an easy-to-use tool for rapid durability-based performance evaluation of some of these uncommon coal ashes will be highlighted.