SMA混合料设计某些问题的探讨

SMA作为一种新型路面材料,其优良的路用性能已为众多道路工作者所认同,虽然国外已有较为成熟的SMA混合料配合比设计方法,但并不是十分完善,本文中就SMA混合料设计中的某些问题提出自己的建议,供同行商榷。     

LiF对水泥基材料性能的影响

在20℃长期养护条件下,当碱含量为2.5%时,掺加Li/Na摩尔比0.6的LiF能长期有效抑制碱集料反应嘭胀.研究发现:集料活性越高,LiF对膨胀抑制效果越好.对于沸石化珍珠岩砂浆,在有效抑制碱集料反应膨胀的前提下,随着Li/Na摩尔比进一步的增加,LiF对碱集料反应膨胀的抑制效果并没有得到相应的提高.此外,掺加LiF一定程度上降低了砂浆的抗压强度和抗折强度,掺量越大,强度降低越多.在相同碱含量条件下,掺加LiF能缩短水泥的凝结时间,且Li/Na摩尔比越大,凝结时间越短.     

钢渣作沥青混凝土集料的研究

研究了钢渣的化学成分与稳定性的关系,检测了钢渣的物理力学性能,并进行钢渣沥青混合料配合比设计与性能检验,研究结果表明该钢渣是一种具有优良路用性能的矿质集料,可用于高等级公路面层。     

钢渣作耐磨集料的研究

研究了武钢钢渣的化学成分与稳定性、耐磨性的关系,以及三炼钢尾渣代替部分河沙作细集料对混凝土耐磨性能的影响,研究结果表明该存放期为半年的三炼钢尾渣是一种优质耐磨矿质集料。     

碎砖在混凝土中的应用

将碎砖作为混凝土的粗骨料 ,能够减少污染和减少天然骨料的使用。研究表明 ,碎砖粗骨料混凝土的性能与花岗岩粗骨料混凝土相当 ,将碎砖用作混凝土粗骨料是可行的     

三峡工程花岗岩人工骨料碱活性试验研究

对花岗岩休工骨料从宏观到微观,用多种试验方法进行了大量的试验研究,研究结果表明,用现有标准判断,花岗岩为非活性骨料,砂浆长度法试验结果表明,花岗岩砂浆经14例的膨胀已基本趋于稳定,而且在碱含量低的条件下,也没有出现危害性的膨胀,从三峡工程的重要性及混凝土耐久性方面全面考虑,工程应严格控制水泥含碱量及混凝土中的总碱量。     

西安混凝土骨料碱活性研究--灞河卵石碱活性的研究

采用ASTM C1260－94,CECS48：93和岩相法综合研究了西安灞河卵石的碱活性。通过对构成该卵石的主要岩石碱活性以及卵石各岩种混凝土碱活性的研究,得出了对灞河卵石碱活性的初步看法。     

集料有效密度测试方法研究

沥青混合料体积设计法成功的关键在于集料的密度参数能反映集料在沥青混合料中的实际情况 ,集料有效密度参数是最能反映实际情况的密度指标。通过分析集料有效密度的影响因素 ,对多种试验方案结果进行了比较 ,提出了简便、合理的有效密度测试方法。     

Mechanical and acoustic absorption properties of lightweight fly ash/slag-based geopolymer concrete with various aggregates

Acoustic absorption and thermal insulation play a key role in modern buildings to make living comfortable and energy-saving. This paper aims to study the workability, physical and mechanical properties, thermal conductivity, and acoustic absorption of modified geopolymer concrete (GPC) with various types of lightweight aggregates (LWA) such as extruded polystyrene foam beads waste (EPS), vermiculite, or lightweight expanded clay aggregate (LECA). The mixtures of geopolymer concrete have been modified by substituting for the ordinary aggregates (dolomite) by volume with various ratios of 0, 25, 50, 75, and 100% for each type of LWA. Besides, the mechanisms of specimens were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and mapping. The results illustrated that the compressive strength values range between 8.5 and 47.50 MPa. The hardened density of concrete was between 1500 and 2450 kg/m³, and thermal conductivity was between 0.45 and 1.16 W/m.K. Geopolymer concrete was considered an acoustic absorption and thermally insulating material. Geopolymer concrete was considered an acoustic absorption and thermally insulating material. EPS, vermiculite, and LECA will be beneficial for applications in lightweight geopolymer concrete due to their capability to reduce weight and excellent thermal conductivity, and the property of improving acoustic absorption. The mechanical results indicated that 25% LECA was the best compared with the ratios of other LWA and gained 35.0, 2.7, and 4.3 MPa of compressive, splitting tensile and flexural strength, respectively. It had positive workability; the thermal conductivity was 1.1 W/m.K, and hardened density was decreased to 10% compared to the control. In addition, LECA is considered the superior and suitable material for acoustic absorption compared with other aggregates.     

煤矸石骨料及其改性技术研究进展

煤矸石作为煤炭开采和洗煤过程中产生的废弃物,大量堆放会给生态环境带来巨大的压力,以煤矸石为骨料生产混凝土符合绿色可持续发展理念。煤矸石骨料具有孔隙率大、针片状颗粒含量高的特性,会对混凝土性能产生较大负面影响。本文简述了煤矸石骨料的基本物化特性,综述了煤矸石骨料对混凝土工作性能、力学性能、耐久性以及界面过渡区的影响;在此基础上,针对煤矸石骨料存在的缺陷,重点综述了煤矸石骨料改性技术(表面包覆、水玻璃改性、热活化和微生物矿化等技术)的研究现状,指出了每种改性技术目前存在的问题及解决方法,并对其在混凝土中的研究方向进行了展望,以期推动煤矸石骨料在混凝土的应用与发展。