Performance of green concrete pipes made exclusively from carbon-activated steel slag

混凝土管是一种重要的基础设施产品，传统上由波特兰水泥制成。生产一吨水泥需要1.8吨原生材料，如石灰石和粘土，消耗1400千瓦时的能源当量，排放0.8吨二氧化碳（CO2）。为了使混凝土管负碳“绿色”产品，在此过程中，波特兰水泥被替代的环保粘合剂所取代是至关重要的。钢渣是炼钢过程中产生的废弃物，由于其水力性能较差，在建筑产品生产中从未被视为独立的粘结剂。麦吉尔大学开发的方法使用碳化活化技术使钢渣成为建筑应用的主要粘合剂。使用钢渣作为建筑产品的初级粘结剂，将消除波特兰水泥的使用，减少二氧化碳的排放，将工业废物转化为增值产品，将二氧化碳封存为稳定的碳酸盐，并且消耗零自然资源。已成功应用于Carbicrete公司的砌块生产中。该联盟项目探讨了使用碳活化钢渣系统生产混凝土管道的可能性。传统上，混凝土管是用钢筋加固的，市场比砖石砌块大得多。提出的研究将开发一种在柔性外壳中低压碳化高坍落度渣基混凝土的新工艺。将对材料的微观结构进行表征，并通过腐蚀试验和抗硫酸盐试验评估渣基管道的耐久性。碱活化对提高碱度保护钢筋和促进碳化后水化的能力进行了研究。渣基混凝土的浸出行为也将进行研究。

Concrete pipe is an important infrastructure product and is traditionally made of Portland cement. Production of one tonne of cement requires 1.8 tonnes of virgin materials, such as limestone and clay, consumes 1,400 kWh energy equivalent, and emits 0.8 tonnes of carbon dioxide (CO2). To make concrete pipe carbon negative "green" product, it is crucial that Portland cement be replaced by an alternate environment-friendly binder in the process. Steel slag is a waste generated from steel refining process and has never been considered as a stand-alone binder in the production of construction products due to its poor hydraulic properties. The method developed at McGill University uses the carbonation activation technique to make steel slag a primary binder for construction application. The use of steel slag as a primary binder in construction products will eliminate the use of Portland cement, reduce carbon dioxide emissions, convert industry wastes into value-added products, sequester carbon dioxide into stable carbonates, and consume zero natural resources. It has been successfully applied to masonry block production marketed by Carbicrete Inc. This Alliance project investigates the possibility of producing the concrete pipes using carbon-activated steel slag system. The concrete pipes are traditionally reinforced by steel and have a much larger market than masonry blocks. The proposed research will develop a new process for a high slump slag-based concrete carbonated at very low pressure in a flexible enclosure. The microstructure of the material will be characterised and durability of the slag-based pipe will be evaluated through the corrosion tests and the sulfate resistance tests. Alkali activation will be examined for its ability to enhance the alkalinity to protect steel reinforcement and promote post-carbonation hydration. Leaching behaviour of slag-based concrete will also be examined.