丁琴(1998-),女,四川广安人,硕士研究生,从事固废处理研究工作。1725374299@qq.com |
收稿日期: 2021-06-30
修回日期: 2021-11-19
网络出版日期: 2022-06-17
基金资助
国家自然科学基金项目“动力扰动遇含夹塞体硐室散射引起的围岩动态应力集中与破裂规律”(12072376)
中山大学中央高校基本科研业务费专项资金(2021qntd15)
Study on Proportion and Mechanical Properties of Geopolymer Concrete
Received date: 2021-06-30
Revised date: 2021-11-19
Online published: 2022-06-17
混凝土是巷道支护过程中的重要建筑材料,然而混凝土在巷道施工中常常出现质量问题,为了不影响正常生产,需要对其进行修补。地聚合物混凝土凝结时间快,早期强度高,界面结合能力强,耐高温性和抗冻性强,耐腐蚀性良好,具有用作修补材料的潜力。以粉煤灰和矿粉为原料,Na2SiO3溶液和NaOH为碱激发剂制备地聚合物胶砂,研究不同的碱激发剂模数(1.0、1.2、1.4)和掺量(10%、15%、20%)对不同龄期胶砂力学性能的影响。结果表明:当碱激发剂模数为1.2,碱掺量为15%时,胶砂强度达到最大值。设计正交试验,研究了不同水胶比(0.45、0.50、0.55)、粉煤灰掺量(30%、50%、70%)和砂率(30%、35%、40%)对不同龄期地聚合物混凝土的工作性能和力学性能的影响。结果表明:粉煤灰掺量对抗压强度影响最为显著,水胶比次之,而砂率对强度发展几乎没有影响。最优的配合比为水胶比为0.50,粉煤灰掺量为50%,砂率为35%。
丁琴 , 陶明 , 李响 . 地聚合物混凝土配比及力学性能研究[J]. 黄金科学技术, 2022 , 30(2) : 243 -253 . DOI: 10.11872/j.issn.1005-2518.2022.02.082
Concrete is an important building material in roadway support,but there are often quality problems in roadway construction,such as honeycomb surface,cracks,holes and large area damage,which need to be repaired in order not to affect the normal production.Geopolymer concrete has the characteristics of fast setting time,high early strength,strong interface bonding ability,low permeability,high temperature resistance,frost resistance,corrosion resistance,excellent durability and low energy consumption,low pollution and low cost in the preparation process,and has the potential to be used as concrete repair materials.At present,there is no consensus on the proportion design of geopolymer concrete.The fly ash and slag were activated using sodium silicate and sodium hydroxide as alkalin-activator solution for the preparation of geopolymer mortar.The effects of different alkali-activator modulus (1.0,1.2,1.4) and content (10%,15%,20%) on the mechanical properties of mortar at different ages (3 d,7 d,28 d) were studied.The results show that the modulus and content of alkali-activator have a significant effect on the mechanical properties of geopolymers.Too large or too small alkali-activator modulus and content are not conducive to the strength development of geopolymer mortar.When the ratio of fly ash to slag is 1∶1,the modulus of water glass is 1.2,the content of alkali is 15%,the flexural and compressive strength of geopolymer mortar reaches the best value.The 28 d flexural strength is 7.6 MPa,the 28 d compressive strength is 72.3 MPa.In order to further explore the mechanical properties of geopolymer concrete with different mix ratios,the orthogonal experiment with three factors and three levels was designed to study the effects of different water-binder ratio (0.45,0.50,0.55),fly ash content (30%,50%,70%) and sand ratio (30%,35%,40%) on the workability and mechanical properties of geopolymer concrete at different ages (7 d,28 d).Taking the compressive strength as the evaluation index,the results show that fly ash content has the most significant effect on compressive strength,followed by water-binder ratio,and sand ratio has almost no effect on strength development.The results of variance analysis of 7 d and 28 d show that the content of fly ash has a highly significant effect on the compressive strength of geopolymer concrete,the water-binder ratio has a significant effect on the compressive strength of geopolymer concrete,but the sand ratio has no significant effect on the compressive strength of geopolymer concrete.Considering the workability and mechanical properties of geopolymer concrete,combined with the results of microstructure analysis,geopolymer concrete with water-binder ratio of 0.50 and fly ash content of 50% is a promising rapid repair material.
利用金属切削废料制作低成本金属3D打印粉末
近期,印度科学研究所(IISc)的研究人员发现,金属加工领域产生的切屑废料在精炼后的性能与常见气雾化粉末一样好,能够满足金属增材制造(SLM技术)的使用要求。
切屑通常作为废品丢弃。它通常呈细丝状,就像金属碎片一样,但它有时候也会呈现出完美的球形颗粒。由机械工程系助理教授Koushik Viswanathan领导的IISc研究小组发现,这小部分球形粉末颗粒是由于在切削过程中表面层的氧化(放热反应)产生的高热而熔化的结果。然后,他们改进了这一工艺以生产大量球形粉末,这些粉末被收集并进一步加工,用作增材制造的原料。他们的研究表明,这些颗粒在金属增材制造方面的性能与商业气体雾化粉末一样好。该工艺可用作生产金属粉末的替代技术。
IISc产品设计和制造中心的博士生、该研究的作者之一Priti Ranjan Panda补充说:“我们有一种替代的、低成本和可调控的制造金属粉末的方法,以及保证最终粉末的高质量。与传统的气体雾化粉末相比,这似乎非常具有竞争力。”
Viswanathan解释说:“最近人们对采用金属增材制造产生了浓厚的兴趣,因为从本质上讲,它可以实现大量定制并允许设计自由。然而,现有金属粉末的高昂成本一直是绊脚石。我们希望我们的工作将为制造更便宜、更容易获得的金属粉末打开新的大门。”
机械系博士生Harish Singh Dhami(本研究的参与者)补充说:“降低增材制造工艺的成本(通过经济的粉末)可以扩大材料范围,例如制造生物医学植入物,这可能变得更便宜、更容易获得。”
研究人员表示,使用磨损制造金属粉末在其他高性能应用中也具有潜力,例如飞机发动机,在这些应用中需要高度的特异性和复杂性。
用于3D打印的传统金属粉末存在缺陷。AM的主要来源材料是金属粉末,主要使用称为雾化的技术生产,其中熔融金属流使用空气或水射流分解成细小液滴。
然而,尽管它被广泛使用,但雾化的产量很低,价格昂贵,而且它可以处理的材料类型不灵活。然而,这种新技术回避了这些问题。
http://www.goldsci.ac.cn/article/2022/1005-2518/1005-2518-2022-30-2-243.shtml
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|
曹向阳,杨建森,2020.地聚合物及其混凝土的胶凝性质概述[J].硅酸盐通报,38(7):9.
|
范飞林,许金余,李为民,等,2008.矿渣—粉煤灰基地质聚合物混凝土的基本性能研究[J].混凝土,(6):58-61.
|
刘德军,左建平,刘海雁,等,2020.我国煤矿巷道支护理论及技术的现状与发展趋势[J].矿业科学学报,5(1):22-33.
|
罗新春,汪长安,2015.钙含量对偏高岭土/矿渣基地聚合物结构和性能的影响[J].硅酸盐学报,43(12):1800-1805.
|
任进阳,2016.粉煤灰地聚物混凝土的力学性能研究[D].银川:宁夏大学.
|
单仁亮,彭杨皓,孔祥松,等,2019.国内外煤巷支护技术研究进展[J].岩石力学与工程学报,38(12):2377-2403.
|
尹明,白洪涛,周吕,2014.粉煤灰地质聚合物混凝土的强度特性[J].硅酸盐通报,33(10):2723-2727.
|
张春光,2009.矿用高性能聚合物改性混凝土研究[D].焦作:河南理工大学.
|
章定文,王安辉,2020.地聚合物胶凝材料性能及工程应用研究综述[J].建筑科学与工程学报,37(5):13-38.
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