石英質和長石質的砂料是否适用于水工混凝土,取决于这类砂子的顆粒級配;同时,砂内硫酸化合物和云母的含量不得超过苏联国定标准的定額。用代表性的砂样在干燥状态下加以篩分,可以确定砂料的顆粒級配;然后再求定砂的粒度模数。从水泥用量的观点来看,粒度模数是鑑定砂料的基本因素。在大部分采砂地区,不論在篩分后的石英顆粒之間,或在薄片状的顆粒上,都附有粉末粘土状的微粒(为氢氧化鉄所膠結起来)。但这些有害的杂質,当砂 The suitability of quartz and feldspathic sand for hydraulic concrete depends on the particle size distribution of such sand; at the same time, the content of sulphate and mica in the sand must not exceed the quotas of the Soviet Union’s national standard. A representative sample of sand is sieved in a dry state to determine the particle size distribution of the sand and then to determine the particle size modulus of the sand. From the point of view of the amount of cement used, the particle size modulus is the basic factor to identify the sand material. In most areas where sand is milled, powdered clay-like particles (cemented with hydroxide) are attached to the sieved quartz grains or to the flaky grains. But these harmful impurities, when the sand