Green ultra-high performance concrete with very low cement content

The development of Green Ultra-High Performance Concrete (GUHPC) has become a hotspot of concern in the construction industry. GUHPC with very low cement content can be prepared based on the combined optimization of the physical and chemical effects of the binder materials. On this basis, this paper proposes to prepare a new GUHPC by further enhancing chemical effects of the binder materials through the addition of nanomaterials and chemical activator. Series of experiments are designed to investigate the mechanical properties and environmental impact in respect to embodied CO2-emissions of GUHPC. The hydration characteristics and the pore structure of GUHPC are evaluated by employing thermogravimetry analysis and mercury intrusion porosimetry. The results show that GUHPC with good mechanical performance and very low environmental impact can be prepared with very low cement content (no more than 370 kg/m3). The high initial packing density of GUHPC can be achieved by application of multi-scale particles system, especially in the presence of nano-scale particles. Chemical activator can effectively improve the reactivity of binder materials and promote the hydration of GUHPC. The GUHPC has lower porosity and finer pore size than UHPC.