机制骨料技术指标及其对混凝土性能的影响研究

Research on Technical Indicators of Mechanical Aggregate and Its Influence on Concrete Properties

本文以第六届和第七届全国砂石骨料大赛的机制骨料数据为依据,分析其整体质量水平,并参照GB/T 14685—2022《建设用卵石、碎石》和GB/T 14684—2022《建设用砂》的要求进行评价,同时探究机制骨料对混凝土工作性能和抗压强度的影响。结果表明:相较于第六届全国砂石骨料大赛,第七届全国砂石骨料大赛的机制骨料质量有了很大的提升,压碎指标的改善情况最为显著,达到GB/T 14685—2022《建设用卵石、碎石》Ⅰ类要求的比例从54.5%提高到了86.7%;第七届全国砂石骨料大赛机制砂的4项技术指标中,达到GB/T 14684—2022《建设用砂》Ⅰ类要求的比例较第六届有所提高,其中,石粉含量由65.2%提高到了100%,压碎指标达到Ⅰ类要求的比例从69.6%提高到了93.3%,同时第七届的机制砂颗粒级配明显得到改善,整体都达到了Ⅱ类及以上要求;机制骨料对混凝土拌合物的和易性影响较大,其中,G-08组和G-09组石子的粒形好,机制砂吸附性低,且为钙质石粉,颗粒级配好,混凝土拌合物的工作性能好;虽然15组机制骨料的质量水平参差不齐,但对混凝土抗压强度的发展影响并没有对混凝土和易性的影响显著,15组C40混凝土的28 d抗压强度均高于48 MPa,其中,G-14组混凝土的28 d抗压强度最高,达到了77.3 MPa。

This article is based on the mechanism aggregate data of the 6th and 7th National Sand and Gravel Aggregate Competition.It analyzes its overall quality level,and evaluates it according to the requirements of GB/T 14684-2022 Sand for Construction and GB/T 14685-2022 Pebble and Crushed Stone for Construction.At the same time,it explores the inf luence of mechanism aggregate on the workability and compressive strength of concrete.The results show that compared to the 6th National Sand and Gravel Aggregate Competition,the quality of mechanism aggregates in the 7th National Sand and Gravel Aggregate Competition has been greatly improved,the improvement of the crushing index is the most significant,with the proportion of meeting the Class I requirements of GB/T 14685-2022 Pebble and Crushed Stone for Construction increasing from 54.5%to 86.7%.Among the four technical indicators of the mechanism sand in the 7th National Sand and Gravel Aggregate Competition,the proportion that meets the Class I requirements of GB/T 14684-2022 Sand for Construction has increased compared to the 6th competition;among them,the stone powder content has increased from 65.2%to 100%,and the crushing index that meets the Class I requirements has increased from 69.6%to 93.3%;at the same time,the particle size distribution of the mechanism sand in the 7th competition has been significantly improved,and overall meets the Class II and above requirements.Mechanized aggregates have a significant impact on the workability of concrete mixtures.Among them,the G-08 and G-09 groups have good particle shapes of stones,low adsorption of mechanism sand,and are calcium stone powder with good particle size distribution,resulting in good workability of concrete mixtures.Although the quality level of the 15 sets of mechanism aggregates varies,their impact on the development of compressive strength of concrete is not significant for its workability.The 28 days compressive strength of the 15 sets of C40 concrete is all higher than 48 MPa,among which the G-14 set of concrete has the highest 28 days compressive strength,reaching 77.3 MPa.