Alkali-activated material prepared by the silicon aluminum solid wastes are commonly considered as the low-carbon cementitious material, which has important significance for promoting the sustainable development of construction materials. The mechanical properties, reaction mechanisms, and microstructure evolutions of Alkali-activated Ultra High Performance Concrete (AAUHPC) matrix with 7 design parameters were comprehensively studied through testing the fluidity, 28 days compressive strength, 28 days flexural strength, hydration heat, and microstructures. The environmental impacts including carbon emissions and energy consumption are evaluated. Appropriately increasing NaO dosage, silicate modulus (Ms), and granulated blast furnace slag (GBFS) to fly ash (FA) mass ratio (GBFS/FA) and decreasing silica fume (SF) content and water to binder ratio (W/B) are conducive to accelerating the early reaction of AAUHPC. High NaO dosage, Ms, SF content, and W/B are not conducive to increasing the 3 days reaction degree of AAUHPC, while the moderate GBFS/FA is corresponding to the higher 3 days reaction degree of AAUHPC. The optimal NaO dosage, Ms, GBFS/FA, SF content, sand to binder ratio (S/B), fine sands content in quartz sands, W/B are 8 %, 1.4, 4.5:1, 10 %, 1.0, 50 %, and 0.34 for the 28 days mechanical properties. The acquired AAUHPC matrix with fluidity of 218 mm and the lowest porosity has 28 days compressive strength of 114.8 MPa and 28 days flexural strength of 10.6 MPa, whose microstructure has more high polymerization degree C(N)-A-S-H gels with higher Al/Si, lower Na/Al, and lower Ca/Si molar ratios. Compared to the traditional Ultra High Performance Concrete (UHPC), the environmentally friendly AAUHPC can reduce the carbon emission by 42%–52 % and the energy consumption by 5%–18 %. The total CO emission of per unit compressive strength (1.0 MPa) of concrete per cubic meter (CI) is in range of 2.5–3.7 kg, which is significantly lower than the traditional UHPC (6.98 kg/MPa•m).

中文翻译：

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不同设计参数环保型碱激发超高性能混凝土（AAUHPC）基体的力学性能、微观结构及环境影响研究


利用硅铝固体废弃物制备的碱活化材料被普遍认为是低碳胶凝材料，对于促进建筑材料的可持续发展具有重要意义。通过测试流动性、28天抗压强度、28天抗折强度、水化热和微观结构，全面研究了具有7个设计参数的碱激活超高性能混凝土（AAUHPC）基体的力学性能、反应机制和微观结构演化。评估了包括碳排放和能源消耗在内的环境影响。适当提高NaO用量、硅酸盐模量（Ms）和粒化高炉矿渣（GBFS）与粉煤灰（FA）质量比（GBFS/FA），降低硅粉（SF）含量和水胶比（W/B）有利于加速AAUHPC的早期反应。高NaO用量、Ms、SF含量和W/B不利于提高AAUHPC的3天反应度，而适度的GBFS/FA则对应较高的AAUHPC 3天反应度。最佳NaO用量、Ms、GBFS/FA、SF含量、砂胶比(S/B)、石英砂中细砂含量、W/B分别为8%、1.4、4.5:1、10%、1.0、50 %，28天机械性能为0.34。获得的AAUHPC基体流动性为218 mm，孔隙率最低，28天抗压强度为114.8 MPa，28天抗弯强度为10.6 MPa，其微观结构具有较高聚合度的C(N)-A-S-H凝胶，Al/Si较高，较低的Na/Al和较低的Ca/Si摩尔比。 与传统的超高性能混凝土（UHPC）相比，环保的AAUHPC可减少42%–52%的碳排放和5%–18%的能源消耗。混凝土每立方米（CI）单位抗压强度（1.0MPa）的CO总排放量在2.5-3.7kg范围内，显着低于传统UHPC（6.98kg/MPa·m）。