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利用魔角旋转核磁共振(29Si MAS-NMR)测试技术从机理上分析了不同掺量粉煤灰(30%～70%)对水泥基材料强度发展和溶蚀条件下性能退化的影响规律。结果表明:随着粉煤灰掺量的增加,水泥硬化浆体强度逐渐下降,但掺量为50%时,强度下降率最小,超过这个掺量强度下降率增大;与此对应,水化硅酸钙(C-S-H)中Q1和Q2含量相应减少,特别是Q1的变化令人关注。粉煤灰掺量从0增加到50%时,Q0,Q1,Q2信号峰强度均较溶蚀前下降,但Q1信号峰下降幅度更大;当粉煤灰掺量为70%时,Q1信号峰已不明显,Q2也相应减少,此时引起强度降低和溶蚀后性能退化显著。溶蚀后Q(21Al)信号峰强度增大,粉煤灰掺量50%时最为明显。研究表明,Q1具有很强的工程特性,其变化对粉煤灰适宜掺量的确定起着关键作用。
The effects of different dosages of fly ash (30% ~ 70%) on the strength development of cement-based materials and the performance degradation under dissolution conditions were analyzed mechanistically using the magic atom rotation nuclear magnetic resonance (29Si MAS-NMR) test technique. The results show that with the increase of fly ash content, the strength of hardened cement paste decreases gradually, but the strength decrease rate is the smallest when the content of fly ash is 50% The content of Q1 and Q2 in the calcium silicate (CSH) decreases correspondingly, especially the change of Q1 is a cause of concern. When the content of fly ash increases from 0 to 50%, the peak intensities of Q0, Q1 and Q2 are lower than those before corrosion, but the amplitude of Q1 decreases more. When the content of fly ash is 70%, the peak of Q1 signal It is not obvious that Q2 is correspondingly reduced. At this moment, the strength is reduced and the degradation of performance is obvious after dissolution. After the corrosion, the peak intensity of Q (21Al) signal increases, and the most obvious is when the content of fly ash is 50%. Research shows that Q1 has strong engineering characteristics, and its change plays a key role in determining the proper dosage of fly ash.