Potentialities of magnesium phosphate cement-based ultra-high-performance concrete in extremely cold weather construction

IF 7.4 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials Pub Date : 2024-11-22 DOI:10.1016/j.conbuildmat.2024.139297

Jie Yuan , Xin Huang , Xin Chen , Zipeng Zhang , Qian Ge , Yang Liu

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Abstract

The aim of this study was to design serviceable ultra-high-performance concrete (UHPC) based on magnesium phosphate cement (MPC) in severely cold weather and investigate the effects of different temperature conditions on UHPC performance, including constant temperatures, natural temperatures, and variations from sub-zero to normal-temperature conditions. The MPC composition was first modified for higher early-age performance, and then the mix proportion of MPC-UHPC was designed based on the modified MPC. Compared with the water content calculated based on the complete consumption of phosphates, optimal mechanical properties were achieved with the lowest water content necessary for acceptable moulding. The designed UHPC was prepared and cured under various low-temperature conditions to investigate its strength development and microstructural maturation. It developed 120 MPa above compressive strength and 24 MPa above flexural strength after 28 d under constant −10 ℃ or the daily fluctuating temperatures of the freezing Harbin winter (−27 to 3 ℃). At low temperatures, the strength was attributed to a combination of MPC hydration, pore solution freezing, and steel fibre reinforcement. However, this study was the first to discover degradation in flexural strength and impact ductility when frozen specimens were moved to warm environments, even though the microstructure was continuously maturing, presenting an increase in hydration products and a decrease in capillary porosity. This paradox was attributed to freezing regression. Finally, the shrinkage and durability of UHPC were tested and verified to meet the requirements of the relevant standards. These findings convincingly demonstrate that MPC-UHPC with an appropriate mix proportion is ideal for winter construction in severely cold regions.

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磷酸镁水泥基高性能混凝土在极寒天气施工中的潜力

本研究的目的是设计在严寒天气下使用的基于磷酸镁水泥（MPC）的高性能混凝土（UHPC），并研究不同温度条件对UHPC性能的影响，包括恒温、自然温度以及从零下到常温条件的变化。为了提高早期性能，首先对MPC的组成进行了改进，然后在此基础上设计了MPC- uhpc的配合比。与基于磷酸盐完全消耗计算的含水量相比，在可接受的成型所需的最低含水量下实现了最佳的机械性能。对所设计的UHPC进行了制备，并在不同的低温条件下进行了固化，研究了其强度发展和微观结构成熟度。在恒定−10℃或哈尔滨冰冻冬季（−27 ~ 3℃）的日波动温度作用下，28d后，其抗压强度高于120 MPa，抗折强度高于24 MPa。在低温下，强度归因于MPC水化、孔隙溶液冻结和钢纤维增强的综合作用。然而，本研究首次发现，即使微观结构不断成熟，水化产物增加，毛管孔隙率降低，但当冷冻试样移至温暖环境时，其抗弯强度和冲击延性也会下降。这一悖论归因于冻结回归。最后，对UHPC的收缩率和耐久性进行了测试验证，满足相关标准的要求。这些结果令人信服地表明，适当配比的MPC-UHPC是严寒地区冬季建筑的理想选择。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Construction and Building Materials 工程技术-材料科学：综合

CiteScore

13.80

自引率

21.60%

发文量

3632

审稿时长

82 days

期刊介绍： Construction and Building Materials offers an international platform for sharing innovative and original research and development in the realm of construction and building materials, along with their practical applications in new projects and repair practices. The journal publishes a diverse array of pioneering research and application papers, detailing laboratory investigations and, to a limited extent, numerical analyses or reports on full-scale projects. Multi-part papers are discouraged. Additionally, Construction and Building Materials features comprehensive case studies and insightful review articles that contribute to new insights in the field. Our focus is on papers related to construction materials, excluding those on structural engineering, geotechnics, and unbound highway layers. Covered materials and technologies encompass cement, concrete reinforcement, bricks and mortars, additives, corrosion technology, ceramics, timber, steel, polymers, glass fibers, recycled materials, bamboo, rammed earth, non-conventional building materials, bituminous materials, and applications in railway materials.