冷再生混合料中最佳乳化沥青用量的方法研究

冷拌乳化沥青混合料最佳沥青用量与旧沥青含量有关,通过100%RAP(RAP为再生沥青路面材料,Reclaimed Asphalt Pavement)和0%RAP两种乳化沥青混合料的60℃马歇尔试验、25℃马歇尔试验及25℃劈裂试验,探讨了确定冷拌乳化沥青混合料最佳乳化沥青用量方法的区别与联系.     

几种不同材质钢锭模的试验研究

本文针对10.5英寸浸水冷却的钢锭模试验研究了灰铁、蠕铁、稀土灰铁三种材质,并对其性能、影响因素进行了分析比较。     

锌熔法回收废硬质合金混合料中锌的测定—原子吸收法

硬质合金混合料中锌含量的高低,对硬质合金性能的影响很大,在回收废硬质合金生产工艺流程中,需要严格控制锌的含量。我们进行了原子吸收法测定废硬质合金混合料中的锌的试验,对这种大量钴、     

昆钢铁矿粉烧结特性试验研究

为研究昆钢目前使用的3种粉矿的成矿性能,针对其原料特点设计正交试验方案,进行大量系统的烧结杯试验。通过试验数据分析,得到每种矿混合料平均粒度以及烧结矿转鼓强度表达式。利用单因素分析法和极差法研究了配碳量和碱度对烧结矿FeO、转鼓强度、成品率以及利用系数的影响。试验结果得到每种矿的最佳配碳量和碱度配比。分析发现,配碳量对3种矿烧结指标的影响大于碱度的影响。     

圆筒混合机制粒性能优化研究

在烧结生产中,优化圆筒混合机工艺参数、强化混合料制粒效果是改善料层透气性、提高烧结矿产量和质量的重要措施。通过对圆筒混合机制粒性能影响因素的研究,确定了最佳制粒工艺条件,结果表明:实验室最优混合料制粒水分宜控制在7.5%～7.8%之间;延长制粒时间有利于烧结混合料的混匀制粒过程,适宜的混合料制粒时间为5 min;实验室条件下适宜的圆筒转速为18 r/min,即弗劳德准数在5.23×10~(-3)左右;填充率不低于10%;较高生石灰配比对烧结混合料的制粒效果有显著的促进作用,原料的种类和配比对制粒效果有一定影响。     

褐铁矿对钒钛磁铁矿烧结性能的影响

由于褐铁矿烧结影响因素多,烧结性能差,技术经济指标恶化。考察了褐铁矿配比、料层、水分、燃料配比4个关键因素,运用混合水平均匀设计法,试验次数少代表性强。采用"6水平3因素+4水平1因素"仅试验12次,通过对试验结果直观择优与建模寻优,找出了4个参数的最优组合,对指导现实生产具有重要意义。使用褐铁矿后烧结矿强度与利用系数下降,固体燃耗上升,矿物组成变好,软熔性能变差,低温还原粉化性恶化,但还原性改善。采用均匀设计方法进行方案设计,通过实验室试验、回归分析和模型寻优,确定出褐铁矿对钒钛磁铁矿烧结性能影响的最佳组合。中褐粉综合评价最优组合参数为:配比6.02%,焦粉配比5.14%,水分7.07%,料层592 mm。     

正交试验法在钼矿石浮选试验中的应用

用正交试验法合理地设计了钼矿石浮选条件试验方案,并用数理统计的方法对试验结果进行数据处理,表明在钼矿石浮选试验研究中,利用正交试验设计方法可以简便、有效地指出各因素对浮选指标的影响,确定最佳条件组合,为进一步研究提供可靠的参数。     

国产环氧沥青混合料施T控制与强度增长特性

通过室内试验研究了国产环氧沥青混合料在低温环境条件下的施工和易性、容留时间范围,以及强度增长规律等施工控制特性.选取芯样空隙率和试件马歇尔稳定度作为评价施工质量的性能指标;通过轮碾试验模拟实际施工过程中的碾压成型过程;选择马歇尔试验和布氏粘度试验研究强度增长特性.试验结果表明:国产环氧沥青混合料可以在10℃的低温环境条件下进行施工;混合料在120℃的容留温度条件下最长容留时间达到70min;在国产环氧沥青混合料完全固化以前,混合料强度随着时间和温度的增长而不断增长.最后,用有机化学理论分析了国产环氧沥青混合料强度增长规律的理论依据.     

稀土复合助剂在胶粉改性路面沥青中的应用研究

将稀土复合助剂添加到胶粉改性沥青中,研究了添加量、整体配比对沥青性能的影响。研究表明,稀土复合助剂的微量加入,有助提高沥青高紫外线吸收性能。据此制成的沥青路面更能适应北方日照时间长的自然条件。     

水洗洁净处理对钢渣SMA性能影响的研究

介绍了路用钢渣集料洁净技术,利用洁净工艺前后的钢渣集料分别配制了钢渣沥青玛碲脂碎石混合料(SMA),得到用水清洗后钢渣最佳配合比为:1号(钢渣10~16mm)∶2号(钢渣5~10mm)∶3号(玄武岩3~5mm)∶4号(玄武岩3mm)∶5号(石灰岩矿粉)=38∶36∶8∶8∶10,最佳油石比为6.4;没有用水清洗钢渣最佳配合比为:1号∶2号∶3号∶4号∶5号=34∶38∶10∶8∶10,最佳油石比为6.4。研究了钢渣洁净技术对钢渣SMA性能影响,发现洁净技术有利于发挥钢渣SMA性能。     

Engineering Properties of Fiber Reinforced Cold Asphalt Mixes

A laboratory investigation consisting of Marshall, as well as static and cyclic triaxial tests, was undertaken to study the effect of the addition of randomly distributed synthetic fiber on the mechanical response of a cold-mixed densely graded asphalt mixture. The properties included density, air voids, Marshall stability and flow, elastic, and resilient moduli. The asphalt mixture was treated according to weight with 0.1, 0.25, and 0.50% staple polypropylene fibers 10, 20, and 40 mm long. In the first stage, Marshall tests were carried out in order to determine the optimum length and content of the fiber. The testing data supported that slit film fibers 40 mm long and fiber contents of 0.10 and 0.25% gave the best overall results, from a road engineering perspective. In the second phase, test specimens prepared at the optimum combination were subjected to conventional and cyclic triaxial tests. The results show that the addition of fiber is responsible for a small variation in mixture strength parameters, as well as for substantial drops in the mixture resilient moduli when compared to plain mixtures.     

钒钛钢渣配制AC-13型沥青混合料的研究

钒钛钢渣具有较好的力学和表面特性,研究了其作为AC-13型沥青混合料集料的可行性。结果认为,钒钛钢渣可以作为AC-13型沥青混合料的集料,该沥青混合料的配合比设计为:钒钛钢渣(4.75~13.2 mm)、钒钛钢渣粉(0.075~4.75 mm)、矿粉三者之比为58∶40∶2,外配油石比最佳比例为4.9%。     

泥浆泵内衬材料的磨损特性试验研究

本文通过一种泥浆喷射装置研究了聚氨酯、硫化弹性体、橡胶三种弹性衬套材料的泥浆磨损特性,试验表明橡胶具有最好的耐泥浆特性。     

Performance of Polymer Modified Asphalt Bridge Expansion Joints in Low-Temperature Regions

Conventional asphalt bridge expansion joints used in low-temperature regions generally show cracking within the first 2?years. To improve the low-temperature performance of these joints, the commercial MEIJIA asphalt binder commonly used in bridge expansion joint construction was modified with two polymers: thermoplastic rubber and rubber. The goal is to find an optimum combination of polymers, binders, and aggregates to improve the performance of asphalt expansion joints in low-temperature regions. The polymer modified binders and mixtures were evaluated for their low-temperature properties using ductility, penetration, indirect tension, and bending tests. The study indicates that performance of these joints at low temperature can be enhanced significantly with the right combinations of polymers, binders, and aggregates. Four expansion joints made with the polymer modified asphalt mixtures were installed on two bridges in a cold region. A construction procedure was also developed to install these joints properly to minimize low-temperature cracking along the interface between the joint and bridge deck. After 7?years of service, the four joints show good performance without any visible cracking or rutting.     

浅谈SBS改性沥青配合比的设计与施工

在良好的设计配合比和施工条件下,SBS沥青能使沥青路面的耐久性和高温稳定性明显提高。根据赣州市红旗大道东延道路工程的设计情况,简要讲述SBS改性沥青的设计及施工技术要求。     

Prediction of Clean-Bed Head Loss in Crumb Rubber Filters

Crumb rubber media have been beneficially invented for ballast water and tertiary wastewater treatment. There is a critical need for precise prediction of clean-bed head loss for engineering design purposes. Pilot crumb rubber filters were tested to study their clean-bed head loss under the influences of three design and operational parameters (media size, media depth, and filtration rate). Data from the filtration tests were used to evaluate the application of the Kozeny and Ergun equations in crumb rubber filters and to develop a statistical model for examination of the effects of each parameter and for clean-bed head loss prediction. Results showed that both the Kozeny and Ergun equations had limitations for crumb rubber filters, especially when the data of compressed media depth were unavailable from the filtration tests. The statistical model developed by the multiplicative power-law relationship was proved to be valid, and it could be used to predict clean-bed head loss in crumb rubber filters.     

Thermoelastic Enhancement of Damping of Sand Using Synthetic Ground Rubber

This paper examines the possibility of introducing synthetic rubber in constructed earthen systems to improve their vibration attenuation. The results of a series of controlled laboratory tests—aimed to investigate the improvement of low-strain dynamic properties of Ottawa sand by mixing ground rubber of similar size—showed a simultaneous increase in both the shear modulus and the damping ratio of the sand specimens up to an optimum volume proportion of the rubber. Predictions using Hertzian particle contact effects and mechanical damping, resulting from thermoelastic effects between the dissimilar particles, were employed to discern the observed behavior. It is postulated and examined through the available data that the large difference between the elastic modulus of the two materials results in the increase in contact area of the sand and rubber particles and consequently the increase in the stiffness matrix. Similarly, the large difference between the coefficient of thermal expansion of sand and rubber may effectively lead to high thermoelastic enhancement of damping in the sand-rubber mixture.     

Prediction of Creep Stiffness of Asphalt Mixture with Micromechanical Finite-Element and Discrete-Element Models

This study presents micromechanical finite-element (FE) and discrete-element (DE) models for the prediction of viscoelastic creep stiffness of asphalt mixture. Asphalt mixture is composed of graded aggregates bound with mastic (asphalt mixed with fines and fine aggregates) and air voids. The two-dimensional (2D) microstructure of asphalt mixture was obtained by optically scanning the smoothly sawn surface of superpave gyratory compacted asphalt mixture specimens. For the FE method, the micromechanical model of asphalt mixture uses an equivalent lattice network structure whereby interparticle load transfer is simulated through an effective asphalt mastic zone. The ABAQUS FE model integrates a user material subroutine that combines continuum elements with viscoelastic properties for the effective asphalt mastic and rigid body elements for each aggregate. An incremental FE algorithm was employed in an ABAQUS user material model for the asphalt mastic to predict global viscoelastic behavior of asphalt mixture. In regard to the DE model, the outlines of aggregates were converted into polygons based on a 2D scanned mixture microstructure. The polygons were then mapped onto a sheet of uniformly sized disks, and the intrinsic and interface properties of the aggregates and mastic were assigned for the simulation. An experimental program was developed to measure the properties of sand mastic for simulation inputs. The laboratory measurements of the mixture creep stiffness were compared with FE and DE model predictions over a reduced time. The results indicated both methods were applicable for mixture creep stiffness prediction.     

KR法铁水脱硫过程铁水混合现象的水模型

摘要：为了优化铁水脱硫操作工艺,利用水模型研究搅拌桨转速和浸入深度对搅拌效果的影响。针对210t的铁水包,建立1∶7的比例模型,研究示踪剂注入位置、搅拌桨转速和浸入深度对混匀时间的影响,用混匀时间实验衡量液相混合效果。结果表明,随着搅拌桨转速从110r/min增加310r/min,混匀时间缩短了45%,浸入深度为229mm时有利于液相混合。对于210t的实际铁水包,KR搅拌的最佳操作参数是搅拌桨转速100r/min,浸入深度1600mm。