减水剂对水泥浆体横向弛豫时间曲线的影响

Effect of Superplasticizer on Transverse Relaxation Time Curve of Cement Paste

研究了初凝前的水泥浆体在质子共振频率23 MHz下的横向弛豫时间(T2)分布,主要对纯水泥浆体和掺减水剂的水泥浆体在水化5,30,60,90,120 min时的弛豫时间进行了测试和分析。结果表明:测试到的水泥浆体的弛豫时间分布曲线出现了3个T2弛豫峰;第1弛豫峰处于0.01 ms至0.20 ms之间,与水泥浆体中的物理结合水相对应;第2弛豫峰在0.21 ms至1.20 ms之间,由嵌入水泥絮凝结构中的水引起的,其峰面积和峰位置对水化时间的变化不敏感,减水剂的掺加使其峰面积有一定程度的减少;第3弛豫峰在1.21 ms至20 ms之间,认为是由填充在水泥颗粒周围的水引起的,减水剂的掺加使峰位置向长弛豫时间方向偏移。

The transverse relaxation time T2 distribution of the cement paste hydration before the initial of setting was studied under 23 MHz proton nuclear magnetic resonance,using pure cement paste and the cement paste with superplasticizer,then obtaining the relaxation time curve at different hydration time（5,30,60,90,120 min）.It is found that the relaxation time distribution curves sys-tematically exhibits three T2 relaxation peaks;the first one,between 0.01ms and 0.20 ms,whose value is very small and which may be the physical bond water,or caused by the noise of the spectrometer;the second one,between 0.21 ms and 1.20 ms,which is quite insensitive to hydration time（before initial setting time）,using the superplasticizer can reduce its area.It is attributed to water em-bedded in flocculated cement grains before setting occurs;the third one,between 1.21 ms and 20 ms,which is the main peak of the curve.The effect of superplasticizer on the peak is that the peaks shift gradually to the long T2 value.It can be attributed to bulk water surrounding cement grains.