阅读说明：本技术 一种用于评价机制砂综合性能的基准砂 (Reference sand for evaluating comprehensive performance of machine-made sand ) 是由 黄法礼 李化建 袁政成 易忠来 王振 靳昊 谢永江 温浩 袁静怡 谢清清 刘勇 于 2020-06-17 设计创作，主要内容包括：本发明公开了一种用于评价机制砂综合性能的基准砂,所述的基准砂是以石英岩为原料,经机械破碎、筛分、整形制成的粒径小于4.75mm的颗粒,其中二氧化硅含量不小于98%,表观密度不小于2600kg/m<Sup>3</Sup>,烧失量不超过0.4%,含水率不超过0.2%,圆形度不小于0.850,15min累计吸水量不超过3.0g/kg,30min累计吸水量不超过5.0g/kg,24h累计吸水量不超过10.0g/kg。实施本发明,可以通过测试胶砂需水量比或流动度比,对机制砂的颗粒级配、颗粒形貌、吸水率和石粉吸附性等指标进行综合评价,也可以通过测试胶砂抗压强度比和抗折强度比,对机制砂力学性能进行综合评价,为其工程适用性提供有效判据。本发明还用于混凝土用复合矿物掺合料流动度比、减水剂水泥胶砂减水率、混凝土膨胀剂抗压强度等的测定。(The invention discloses reference sand for evaluating the comprehensive performance of machine-made sand, which is particles with the particle size of less than 4.75mm and prepared by taking quartzite as a raw material through mechanical crushing, screening and shaping, wherein the content of silicon dioxide is not less than 98 percent, and the apparent density is not less than 2600kg/m 3 The loss on ignition is not more than 0.4 percent, the water content is not more than 0.2 percent, the circularity is not less than 0.850, the cumulative water absorption in 15min is not more than 3.0g/kg, the cumulative water absorption in 30min is not more than 5.0g/kg, and the cumulative water absorption in 24h is not more than 10.0 g/kg. By implementing the method, indexes such as particle grading, particle morphology, water absorption, stone powder adsorption and the like of the machine-made sand can be comprehensively evaluated by testing the water demand ratio or the fluidity ratio of the mortar, and the mechanical property of the machine-made sand can be comprehensively evaluated by testing the compressive strength ratio and the flexural strength ratio of the mortar, so that the engineering sand is obtainedApplicability provides an effective criterion. The invention is also used for measuring the fluidity ratio of the composite mineral admixture for concrete, the water reducing rate of the water reducing agent cement mortar, the compressive strength of the concrete expanding agent and the like.)

1. A reference sand for evaluating the combination properties of machine-made sand, characterized by: the quartzite is used as a raw material, and particles with the particle size of less than 4.75mm are prepared by mechanical crushing, screening and shaping, wherein the content of silicon dioxide is not less than 98%, the apparent density is not less than 2600kg/m3, the loss on ignition is not more than 0.4%, the water content is not more than 0.2%, the circularity is not less than 0.850, the cumulative water absorption in 15min is not more than 3.0g/kg, the cumulative water absorption in 30min is not more than 5.0g/kg, and the cumulative water absorption in 24h is not more than 10.0 g/kg.

2. The reference sand for evaluating the comprehensive performance of machine-made sand according to claim 1, wherein the grain composition satisfies the following requirements: the accumulated oversize of a 2.36mm square-hole sieve is 30 +/-5%, the accumulated oversize of a 1.18mm square-hole sieve is 50 +/-5%, the accumulated oversize of a 0.6mm square-hole sieve is 65 +/-5%, the accumulated oversize of a 0.3mm square-hole sieve is 78 +/-5%, the accumulated oversize of a 0.15mm square-hole sieve is 88 +/-5%, and the accumulated oversize of a 0.075mm square-hole sieve is 95 +/-1%.

Technical Field

The invention belongs to the field of building materials, and particularly relates to reference sand for evaluating comprehensive performance of machine-made sand.

Background

With the rapid development of infrastructure construction in China and the increasing emphasis on ecological environment, the resources of natural sand capable of being exploited and utilized are less and less, and the preparation of concrete by machine-made sand instead of river sand becomes a necessary trend for improving the green index of concrete and realizing the sustainable development of the concrete industry. The basic construction engineering of China has wide distribution range and large span, so the facing machine-made sand parent metal is very different. In addition, the machine-made sand manufacturers have different good and bad effects on selecting the base materials for the machine-made sand and controlling the crushing processing technology of the machine-made sand, and different machine-made sand manufacturers, even different batches of finished sand of the same manufacturer, have larger difference between physical and chemical performance indexes, so that the applicability of the machine-made sand engineering is poor.

In order to standardize the machine-made sand for construction engineering, regulations on a plurality of technical indexes such as the grain composition, the stone powder content, the harmful substance content, the firmness and the like of the machine-made sand are increased in the national standard GB/T14684 issued in 2011. But these indicators have little guidance for the formulation of concrete from machine-made sand. Therefore, the local standard of Guangdong province published in 2016 DBJ/T15-119 of the pre-mixed concrete machine-made sand application technical specification, and the local standard of Jiangxi province published in 2019 of the highway water transport engineering concrete machine-made sand production and application technical specification DB 36/T1153-2019 of the Jiangxi province local standard published in 2019, and the national building industry standard of high-performance concrete aggregate JG/T568-2019 published in 2019 increase the regulation on the water demand ratio of machine-made sand, namely the water demand ratio of machine-made sand and ISO continuous graded standard sand under the specified cement mortar fluidity deviation, and the water demand ratio serves as an index for comprehensively judging the machine-made sand grading, grain shape, water absorption rate and absorption performance. However, the natural quartz sea sand with the ISO standard sand of 0.8 mm-2.0 mm is prepared by screening and washing, and the characteristic that the natural quartz sea sand contains partial stone powder and has the maximum particle size of 4.75mm is obviously different from the machine-made sand, and the water requirement of the machine-made sand is not reasonable when the natural quartz sea sand and the machine-made sand are close to each other in fluidity. In addition, ISO standard sand is expensive, and counterfeit and shoddy products are more in the market, which puzzles the authenticity and accuracy of detection results.

Disclosure of Invention

The water demand ratio or the mortar fluidity ratio of the machine-made sand is used as a comprehensive index for evaluating the grading, morphology, water absorption and stone powder adsorption of the machine-made sand, and the compressive strength ratio and the flexural strength ratio of the machine-made sand are used as a comprehensive index for evaluating the mechanical property of the machine-made sand, and can be used for guiding the engineering applicability of the machine-made sand. The invention aims to provide the reference sand which has stable performance, reasonable gradation and low price and is used for measuring technical parameters such as the water demand ratio or the mortar fluidity ratio of machine-made sand.

In order to achieve the purpose, the invention adopts the following technical scheme: a reference sand for evaluating the combination properties of machine-made sand, characterized by: the quartzite is used as a raw material, and particles with the particle size of less than 4.75mm are prepared by mechanical crushing, screening and shaping.

The machine-made sand for evaluating the comprehensive performance of the machine-made sand is characterized in that the content of silicon dioxide is not less than 98 percent, and the apparent density is not less than 2600kg/m³The loss on ignition is not more than 0.4 percent, the water content is not more than 0.2 percent, the circularity is not less than 0.850, the cumulative water absorption in 15min is not more than 3.0g/kg, the cumulative water absorption in 30min is not more than 5.0g/kg, and the cumulative water absorption in 24h is not more than 10.0 g/kg. The machine-made sand for evaluating the comprehensive performance of the machine-made sand is characterized in that the particle size distribution meets the requirements of table 1.

Table 1 machine-made sand grain composition.

The invention has the beneficial effects that: (1) the problem that the machine-made sand has insufficient water demand ratio, glue sand fluidity ratio and glue sand strength ratio is solved, and support is provided for scientific judgment of comprehensive performance of the machine-made sand; (2) the machine-made sand disclosed by the invention has the advantages of stable quality, reliable test result and low cost.

Detailed Description

In order to better understand the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.