新拌水泥砂浆和混凝土中矿物掺合料的定量测定

Quantitative Determination of Mineral Admixtures in Fresh Cement Mortars and Concretes

基于GB/12960—2007的要求,发展了一种新拌水泥砂浆和混凝土中的矿物掺合料掺量测定的方法。研究了水化时间、粉煤灰80μm筛余、砂和卵石的含泥量和减水剂对测定新拌水泥砂浆和混凝土中矿物掺合料的影响。结果表明:在拌水后的前3 h内,粉煤灰和矿渣还未开始水化,水泥熟料的水化和掺加减水剂对胶凝材料中矿物掺合料的测定没有影响,而20%的粉煤灰80μm筛余使得粉煤灰测定值P与实际掺量P1的比值P/P1达0.8,使得矿渣测定值S与实际掺量S1的比值S/S1达0.9,而粗细骨料中的含泥量分别使得P/P1达2.44和2.92,使得S/S1达1.52和1.71。采用本文提出的方法测量的新拌水泥砂浆和混凝土中的矿物掺合料掺量的测定值与实际掺量值偏差在2%以内。

Based on GB/12960-2007 for quantitative measurement of mineral admixtures in cement,a method was developed for quantitative determination of mineral admixtures in fresh cement mortars and concretes.The effects of several factors,such as the hydration time,80 μm-residue of fly ash on sieve,silt content of fine and coarse aggregates and water-reducing agent on the meas-urement were studied.Experimental results indicated that,during the first 3 h,the hydration time did not show effect on measurement results,but the residues of fly ash on 80 μm sieve and silt contents of aggregates demonstrated significant effect on the measured re-sults.There was a good linear correlation between measured and actual contents after the consideration of residue and silt in the de-veloped method.Therefore,the method developed in this paper can be used for effective measurement of mineral admixtures in fresh cement mortar and concrete.