Li Sifan, Mao Zhongyang, Deng Min
College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211800, China.
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing 211800, China.
Materials (Basel). 2023 Apr 5;16(7):2887. doi: 10.3390/ma16072887.
Due to its large volume and poor thermal conductivity, mass concrete is prone to temperature cracking caused by heat release during cement hydration after pouring. To address the issue of temperature cracking in mass concrete, this study utilized emulsion polymerization to prepare polybutyl acrylate (PBA) emulsions. At an optimal dosage of 1.5%, the addition of a PBA emulsion reduced the temperature rise of cement paste by 12.4%. The inhibitory mechanism of a PBA emulsion on cement hydration was analyzed by characterization techniques such as isothermal calorimetry, X-ray diffraction Rietveld full-profile fitting method (XRD), thermogravimetric-differential scanning calorimetry (TG-DSC), and mercury intrusion porosimetry (MIP). The results showed that the CS content in the cement specimens with 1%, 1.5%, and 2% PBA increased by 13.83%, 23.52%, and 34.65% compared to the blank group, respectively, while the CA content increased by 92.59%, 79.63%, and 96.30%, respectively. The addition of a PBA emulsion can slow down the hydration rate of CS and CA, thereby reducing the temperature rise and fall rate of cement hydration, reducing the peak heat release of the hydration reaction, and ultimately achieving the inhibition of the cement hydration reaction. In addition, the mechanical properties of PBA-modified cement-based materials were also tested. The results show that the addition of PBA can affect the early strength development of cement samples, but has no effect on the strength after 60 days. Therefore, PBA can be used as a hydration temperature rise control material to reduce the risk of temperature cracking in mass concrete.
由于大体积混凝土体积大且导热性差，浇筑后水泥水化过程中释放的热量容易导致其温度开裂。为解决大体积混凝土温度开裂问题，本研究采用乳液聚合法制备聚丙烯酸丁酯（PBA）乳液。在最佳掺量为1.5%时，添加PBA乳液可使水泥净浆的温升降低12.4%。通过等温量热法、X射线衍射全谱拟合方法（XRD）、热重-差示扫描量热法（TG-DSC）和压汞法（MIP）等表征技术分析了PBA乳液对水泥水化的抑制机理。结果表明，与空白组相比，掺1%、1.5%和2%PBA的水泥试件中CS含量分别增加了13.83%、23.52%和34.65%，而CA含量分别增加了92.59%、79.63%和96.30%。添加PBA乳液可减缓CS和CA的水化速率，从而降低水泥水化的温升和温降速率，降低水化反应的放热峰值，最终实现对水泥水化反应的抑制。此外，还测试了PBA改性水泥基材料的力学性能。结果表明，添加PBA会影响水泥试样的早期强度发展，但对60天后的强度无影响。因此，PBA可作为水化温升控制材料，降低大体积混凝土温度开裂风险。
