Fan Chuanhe, Qian Jueshi, Sun Huaqiang, Fan Yingru
College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China.
School of Advanced Manufacturing, Fuzhou University, Quanzhou 362200, China.
Materials (Basel). 2023 Jun 18;16(12):4452. doi: 10.3390/ma16124452.
Knowing and promoting the strength development of concrete at an earlier age is essential for accelerating formwork circulation of the on-site construction and precast product manufacture. The strength development rate at earlier ages of less than the initial 24 h was investigated. The effect of measures of adding silica fume, calcium sulfoaluminate cement, and early strength agent on the strength development of earlier concrete at ambient temperatures of 10, 15, 20, 25, and 30 °C was studied. The microstructure and long-term properties were further tested. It is shown that the strength increases exponentially first and then logarithmically, different from what is commonly recognized. Increasing cement content exhibited a certain effect only above 25 °C. When the cement content increased from 420 to 460 kg/m, the strength only increased from 6.2 to 6.7 MPa after 12 h at 25 °C. The early strength agent could increase the strength significantly, the strength could be increased from 6.4 to 10.8 MPa after 20 h at 10 °C and from 7.2 to 20.6 MPa after 14 h at 20 °C. All measures for promoting earlier strength did not have an evident negative effect. The results could be potentially referred for the formwork removal at a suitable moment.
了解并促进混凝土早期强度发展对于加快现场施工和预制产品制造中的模板周转至关重要。研究了初始24小时以内的早期强度发展速率。研究了添加硅灰、硫铝酸钙水泥和早强剂措施对10、15、20、25和30℃环境温度下早期混凝土强度发展的影响。进一步测试了微观结构和长期性能。结果表明，强度先呈指数增长，然后呈对数增长，这与通常的认识不同。增加水泥用量仅在25℃以上表现出一定效果。当水泥用量从420kg/m增加到460kg/m时，在25℃下养护12小时后，强度仅从6.2MPa增加到6.7MPa。早强剂可显著提高强度，在10℃下养护20小时后强度可从6.4MPa提高到10.8MPa，在20℃下养护14小时后强度可从7.2MPa提高到20.6MPa。所有促进早期强度的措施均未产生明显负面影响。研究结果可为适时拆模提供潜在参考。
