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LB2000沥青搅拌机设计【10张图纸】【优秀】

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LB2000沥青搅拌机设计【10张图纸】【优秀】.rar

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关键词：: LB2000 沥青搅拌机设计图纸 LB2000沥青搅拌机

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LB2000沥青搅拌机设计

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目　录

1 前言1

2 搅拌器设计数据3

2.1拌和桨叶对转轴安装角的选择3

2.2拌桨轴转速确定5

2.3叶桨式拌器参数确定7

2.4 搅拌器驱动功率计算13

2.5双轴式叶桨搅拌器的强度计算16

3 各零部件的参数计算21

3.1轴的参数计算21

3.2 齿轮参数计算22

3.3轴承的选取23

3.4桨叶的参数计算23

3.5桨背的参数计算23

3.6箱体的参数计算24

结论26

参考文献27

致谢28

附件清单29

摘要：为了提高产品的加工效率和质量，满足特定的加工要求，本课题设计研究了LB2000沥青搅拌机的总体构造，使得该沥青搅拌机在相同的要求下达到更好的使用效果，结构更加简便，使用更加方便。根据加工工艺要求进行设计,采用工序高度集中的原则，确定了搅拌机的整体布局方案，拟定了电机的传动路线，应用最优化方法布置零件、确定传动参数，设计了轴的结构，进行了齿轮、轴承等相关零件的强度校核计算。搅拌机采用微机程控和手动相结合的控制方法，大大提高了工作效率和安全，较好实现了设计要求。本沥青搅拌机具有优良的搅拌性能卓越的经济性能优秀的质量和稳定可靠的特性，模块化设计，运输安装快速：模块化和快速安装系统技术的采用，令运输与安装变的更加快捷。现在沥青搅拌机已经克服了无法加粉料和沥青老化的问题，同时由于具有生产设备简单，能力大；但是其仍然具有一些难于克服的缺点，主要有材料无法达到强制搅拌站的精确程度；精度误差比较大；对原料的含尘、水、超限料尺寸要求比较严格。关键词：沥青搅拌机；沥青混凝土搅拌设备；搅拌机；路面机械。

、论文内容及要求

⒈完成LB2000沥青搅拌机的总体设计

⒉完成搅拌器等主要零部件设计

⒊绘制部分零件和部装图

⒋设计说明书一份，说明字数不少于12000字

二、主要技术指标

1.根据使用需要，该沥青搅拌机性能的搅拌能力要达到2吨/批，生产效率达到

160吨/小时；

2.生产应是全自动进行的，生产速度为40秒/缸；

3.装配时以焊接为主，焊前应清除焊件表面铁锈，油污，水分等杂质，焊条必须要

烘干。为了防止空气侵入焊接区而引起气泡，裂纹，降低接头性能，应尽量采用短

弧焊；

4.热影响区应在高温停留时间不宜过长，以免晶粒粗大；

5.焊接角焊缝时，应对接多层焊的第一道焊缝和单层单面焊缝要避免深而窄的坡口

形式，以防止未焊透和夹渣的的缺陷；

6.多层焊时，应连续焊完最后一层焊缝，每层焊缝金属的厚度不大与5mm。

7.当焊件的刚性增大时，焊件的裂纹倾向也随之增大，故焊接刚性大的焊件宜采用

焊前预热和焊后消除应力的热处理措施。

三.毕业设计物化成果的具体内容及要求

1、图纸工作量

⒈总装图 1张

⒉搅拌中心 1张

⒊箱体 1张

⒋桨臂（左，右）旋 2张

⒌盘根密封器 1张

⒍连杆机构 1张

⒎双卧轴 1张

⒏齿轮 1张

⒐叶桨头 1张

⒉设计说明书要求

设计说明书1份，不少于12000字，且要符合规范要求。

⒊其他要求

绘制部分零件图、部件装配图两张、总装配图一张。主要参考文献：

1、张世英.筑路机械工程.北京：机械工业出版社，1998.

2、陈元机. 筑路机械设计技术.筑路机械与施工机械化，1991（4）-1992（1-5）.

3、陈大先.机械设计手册（第1至5卷）.北京：化学工业出版社，2002 .

4、陈秀宁. 机械设计课程设计.浙江：浙江大学出版社，1995 .

5、辛德刚等.高速公路沥青路面材料与结构，北京：人民交通出版社，2002 .

6、化工设备设计全书编委会.化工设备设计全书2搅拌设备与设计.上海：上海科学

技术出版社，1985 .

7、陈志平等.搅拌与混合设备设计选用手册. 北京：化学工业出版社，2004 .

8、王凯等.编搅拌设备. 北京：化学工业出版社，2003 .

9、冯忠绪.混凝土搅拌理论与设备.北京交通出版社，2001 .

10、搅拌设备3 . 北京：化学工业出版社，2003 .

内容简介：: 毕业设计开题论证报告专业机械设计制造及其自动化学生姓名班级学号指导教师完成日期课题名称：LB2000沥青搅拌机设计一、课题来源、课题研究的主要内容及国内外现状综述课题来源：企业设计内容：LB2000沥青搅拌机设计，根据使用要求，该沥青搅拌机的搅拌能力要达到2吨/批，生产效率达到160吨/小时。国内外现状：借助公路发展的良机，机械行业大发展的势头已经有所显现。去年筑养路机械全行业保持高速增长，主要表现在产品产量以及销售收入比往年都好，固定资产投资增加，先进的数控设备明显增多，产品质量也有进一步提高。他强调，国产品牌的声誉迅速提升，已经和国外品牌并驾齐驱，其中沥青搅拌机、沥青摊铺机、压路机、平地机四大筑路机械在国内市场已占绝对优势地位。本沥青搅拌机具有优良的搅拌性能卓越的经济性能优秀的质量和稳定可靠的特性，模块化设计，运输安装快速：模块化和快速安装系统技术的采用，令运输与安装变的更加快捷；虽然现在沥青搅拌机已经克服了无法加粉料和沥青老化的问题，同时由于具有生产设备简单，能力大，生产费用低，因此得到了很多用户的认可；但是其仍然具有一些难于克服的缺点，影响其在国内使用，主要有骨料级配无法达到强制搅拌站的精确程度；油石比精度误差比较大；对原料的含尘、水、超限料尺寸要求比较严格等。二、本课题拟解决的问题完成LB2000沥青搅拌机的总体设计；完成搅拌机的主要零部件的设计；绘制部分零件图和部装图；设计说明书。三、解决方案及预期效果 1.通过企业生产第一线的参观了解整个工作流程，熟悉相关构件的作用和存在的问题； 2.通过庞大的网络数据系统，阅读相关的材料和数据，进行初期的资料整理； 3.首先完成搅拌机以及搅拌中心等主要元件的设计，从大处着手； 4.在零部件的设计方面多查设计手册，作到切实可行，不能依靠一成不变的理论数据，要联系实际，多动脑筋，要理论联系实际； 5.在4月分完成主要零件的初步设计以及图纸的绘制，在5月上旬进一步完成主体部件的设计，下旬完成各附属部件的设计。四、课题进度安排3月6日3月17日毕业实习阶段。毕业实习，查阅资料，到多个公司实践，撰写实习报告。3月18日3月31日开题阶段。提出总体设计方案及草图，填写开题报告。4月1日5月10日设计初稿阶段。完成总体设计图、部件图、零件图。5月11日6月4日中期工作阶段。完善设计图纸，编写毕业设计说明书，中期检查。6月5日6月7日毕业设计预答辩。6月8日6月13日毕业设计整改。图纸修改、设计说明书修改、定稿，材料复查。6月14日6月16日毕业答辩。6月17日6月18日材料整理装袋。五、指导教师意见年月日六、专业系意见年月日七、学院意见年月日3盐城工学院毕业设计说明书 2006LB2000沥青搅拌机设计摘要：为了提高产品的加工效率和质量，满足特定的加工要求，本课题设计研究了LB2000沥青搅拌机的总体构造，使得该沥青搅拌机在相同的要求下达到更好的使用效果，结构更加简便，使用更加方便。根据加工工艺要求进行设计,采用工序高度集中的原则，确定了搅拌机的整体布局方案，拟定了电机的传动路线，应用最优化方法布置零件、确定传动参数，设计了轴的结构，进行了齿轮、轴承等相关零件的强度校核计算。搅拌机采用微机程控和手动相结合的控制方法，大大提高了工作效率和安全，较好实现了设计要求。本沥青搅拌机具有优良的搅拌性能卓越的经济性能优秀的质量和稳定可靠的特性，模块化设计，运输安装快速：模块化和快速安装系统技术的采用，令运输与安装变的更加快捷。现在沥青搅拌机已经克服了无法加粉料和沥青老化的问题，同时由于具有生产设备简单，能力大；但是其仍然具有一些难于克服的缺点，主要有材料无法达到强制搅拌站的精确程度；精度误差比较大；对原料的含尘、水、超限料尺寸要求比较严格。关键词：沥青搅拌机；沥青混凝土搅拌设备；搅拌机；路面机械。 The design of LB2000 pitch mixerAbstract: In order to improve the processing efficiency and quality of the products , satisfied the specific processing demand, this subject designs the overall structure of studying LB2000 pitch mixer, make this pitch mixer reach better result of use under the same demand . The structure is more simple and more convenient,and more convenient to use. Design according to the process, The principle with highly centralized process is adopted in the design. The whole overall arrangement scheme of the mixer is confirmed. The transmission route of the electrical machinery is designed, use optimize the method and assign the part is optimized. The parameter of the transmission is decided, the structure of the axle is designed , the intensity of carrying on such relevant parts as gear wheel , bearing ,etc. is checked and calculated. The mixer adopts the programmable controlled and manual control method to combine together according to computer, which improved the working efficiency security greatly , and realizes the designing requirement better. This asphalt mixer has fine stirs the performance remarkable economical performance outstanding quality and the stable reliable characteristic, the modular design, the transportation installment fast: The modulation and fast installs the system technology the use, the command transports and the installment changes even more quickly. Now the asphalt mixer already overcame has been unable the question which added the powder material and the asphalt got older, simultaneously because had the production equipment simply, the ability was big; But it still had the shortcoming which some difficulty with overcame, mainly had the material to be unable to achieve forced to stir the station the precise degree; The precision error quite is big; Contains the dust, the water ultra to the raw material, limits the material size request quite to be strict.Key word: Pitch mixer designs; Mixing equipment of bituminous concrete; Mixer; Road surface machinery.参考文献1 张世英、陈元基主编. 筑路机械工程 . 机械工业出版社.19982 王戈、王贵慎、张世英主编. 工程机械. 1990(2-7)3 陈元基主编. 筑路机械设计技术. 筑路机械与施工机械化. 1991(4)-1992(1-5)4 黄宗益、薛瑞祈、阎以诵主编.工程机械CAD.上海工业出版社, 19915 黄继昌主编. 实用机械机构图册. 北京. 人民邮电出版社. 19966 徐锦康主编. 机械设计. 北京. 机械工业出版社. 2001(8)7 吉卫喜主编. 机械制造技术. 北京. 机械工业出版社.20018 王化培主编. 机械设计方法学. 重庆. 重庆大学出版社. 1996(8)9 陈大仙主编. 机械设计手册. 化学工业出版社 . 199410 陈秀宁主编. 机械设计课程设计. 浙江. 浙江大学出版社. 1995(8) 毕业设计任务书课题： LB2000沥青搅拌机设计专业机械设计制造及自动化学生姓名刘洪班级 B材机011 学号 B0110120107 指导教师倪文龙专业系主任发放日期 2006 年3月6日一、论文内容及要求完成LB2000沥青搅拌机的总体设计完成搅拌器等主要零部件设计绘制部分零件和部装图设计说明书一份，说明字数不少于12000字二、主要技术指标1.根据使用需要，该沥青搅拌机性能的搅拌能力要达到2吨/批，生产效率达到160吨/小时；2.生产应是全自动进行的，生产速度为40秒/缸；3.装配时以焊接为主，焊前应清除焊件表面铁锈，油污，水分等杂质，焊条必须要烘干。为了防止空气侵入焊接区而引起气泡，裂纹，降低接头性能，应尽量采用短弧焊；4.热影响区应在高温停留时间不宜过长，以免晶粒粗大；5.焊接角焊缝时，应对接多层焊的第一道焊缝和单层单面焊缝要避免深而窄的坡口形式，以防止未焊透和夹渣的的缺陷；6.多层焊时，应连续焊完最后一层焊缝，每层焊缝金属的厚度不大与5mm。7.当焊件的刚性增大时，焊件的裂纹倾向也随之增大，故焊接刚性大的焊件宜采用焊前预热和焊后消除应力的热处理措施。三.毕业设计物化成果的具体内容及要求1、图纸工作量总装图 1张搅拌中心 1张箱体 1张桨臂（左，右）旋 2张盘根密封器 1张连杆机构 1张双卧轴 1张齿轮 1张叶桨头 1张设计说明书要求设计说明书1份，不少于12000字，且要符合规范要求。其他要求绘制部分零件图、部件装配图两张、总装配图一张。四、毕业论文进度计划起讫日期工作内容备注2006.03.062006.03.07布置任务下达任务书06.03.0606.03.17调查研究，收集资料，熟悉课题,毕业实习06.03.1806.03.31总体设计，方案论证06.04.0106.05.10部件、零件设计阶段06.05.1106.06.04编写说明书06.06.0506.06.07毕业设计预答辩06.06.0806.06.11修改整理毕业设计材料06.06.1206.06.13材料评阅06.06.1406.06.16毕业答辩06.06.1706.06.18材料整理装袋五. 主要参考文献：1、张世英.筑路机械工程.北京：机械工业出版社，1998.2、陈元机. 筑路机械设计技术.筑路机械与施工机械化，1991（4）-1992（1-5）.3、陈大先.机械设计手册（第1至5卷）.北京：化学工业出版社，2002 .4、陈秀宁. 机械设计课程设计.浙江：浙江大学出版社，1995 .5、辛德刚等.高速公路沥青路面材料与结构，北京：人民交通出版社，2002 .6、化工设备设计全书编委会.化工设备设计全书2搅拌设备与设计.上海：上海科学技术出版社，1985 .7、陈志平等.搅拌与混合设备设计选用手册. 北京：化学工业出版社，2004 .8、王凯等.编搅拌设备. 北京：化学工业出版社，2003 .9、冯忠绪.混凝土搅拌理论与设备.北京交通出版社，2001 .10、搅拌设备3 . 北京：化学工业出版社，2003 .六、其他完成指导老师指定的资料查阅、毕业实习、毕业实习小结、总体设计方案比较论证等工作。5 外文翻译专业机械设计制造及其自动化学生姓名班级学号指导教师 .发泡的沥青混合-混合设计程序K M Muthen译者刘洪摘要: 提取发泡的沥青代表沥青产业的驱动往省能源，环境友好和有效的解答为路大厦。发泡的沥青提到路大厦聚集体和发泡的沥清一个沥青混合物，由一个冷的混合过程生产。虽然沥清过程被开发了超过40年前并且由研究员赞美世界，它被相信缺乏规范化的设计程序对技术的有限的实施在南非贡献了，当实习者倾向更加熟悉和更加有大量文件证明的产品。最近有重大兴趣在产品上，特别是在建筑原地方法，并且需要对于一个标准混合设计程序现在变得根本。也许被证明是障碍到标准化发泡的沥青技术的一个元素是各种各样的私有的沥清起泡沫的技术诞生关键词:泡沫沥清，发泡的沥青，膨胀的沥青，膨胀的沥清1介绍1.1引言一种基本成分在南非路面产业的成功是被承受的研究，新和供选择的路大厦方法的发展和实施，由经济和路面材料缺乏原因刺激。它是通常承认的土壤加固法技术为升级品质差材料是适当的，以便这些材料能使用到他们的潜能在路面结构。沥清土壤加固法技术是导致被提炼的混合设计程序为产品例如ETBs最近研究主动性的焦点等沥清材料。沥清土壤加固法的一个共同的方面是少量的并网黏合剂，在一个冷的混合的做法，哪浩大地增加剪(内聚)力量，疲劳被对待的材料的抵抗和防潮性。虽然冷混合沥青产品用于南非在研究主动性之前，他们的用途和好处在产业之内现在获得增加的支持。对发泡的沥青的用途，一个供选择的冷的混合做法，在路路面的建筑在南非也有有限的应用。然而，规范化的混合设计程序不是可利用的。虽然发泡的沥清过程被开发了超过40年前并且由研究员赞美世界，它被相信缺乏规范化的设计程序对这技术的有限的实施在南非贡献了，倾向更加熟悉和更加有大量文件证明的产品的实习者。1.2目标和范围这个项目宗旨将开发和核实混合设计程序为发泡的沥青。本文在发泡的沥青包含出版研究研究结果文学回顾。信息从早先研究和当前实践用于开发指南为发泡的沥青混合设计用于南非。1.3发泡的沥青的定义“泡沫沥青”，如用于本文，提到路面建筑聚集体和发泡的沥清混合物。发泡的沥清，或膨胀的沥清，由水被注射入热的沥清的一个过程生产，造成自发起泡沫。沥清的有形资产临时地被修改，当被注射的水，在联络与热的沥清，把变成在数以万计被困住微小的沥清泡影的蒸气。然而泡沫在较少比一分钟和沥清恢复它原始的物产消散。为了生产起了泡沫沥青，沥清必须被合并到聚集体里，当仍然在它发泡的状态时。2发泡的沥青的概要和好处2.1引言1956年发泡的沥清潜力为使用作为土壤黏合剂首先发挥了由博士。 Ladis H. Csanyi，在工程学实验驻地在衣阿华州立大学。从那以后，发泡的沥青技术在许多国家成功地使用了，以原始的沥清起泡沫的对应的演变过程作为经验在它的用途被获取了。原始的过程包括注射蒸汽入热的沥清。蒸汽起泡沫的系统为沥青植物是非常方便的，蒸汽是欣然可利用的，但它证明不切实际的为在原处起泡沫的操作，由于对特别设备的需要例如蒸汽锅炉。 1968年， MOBIL油澳洲，哪些获取了专利权为Csanyi的发明，通过加冷水修改了原始的过程而不是蒸汽入热的沥清。沥清起泡沫的过程因而变得更多实用和经济为一般用途。起泡沫增加沥清的表面和可观地减少它的黏度，使它非常合适为混合与冷和潮湿聚集体。发泡的沥清可以使用与各种各样的材料，范围从常规优质被分级的材料和被回收的路面材料到少量的材料例如有的那些一个高可塑性索引。发泡的沥青可以被制造在原处或在一棵中央植物中。黏合剂内容根据混合设计，并且被确定作为为混合(由重量)要求的百分比有最宜的物产。2.2发泡的沥青混合的好处发泡的沥青的以下好处是有大量文件证明的：发泡的黏合剂增加切变强度并且减少颗粒状材料的湿气感受性。发泡的沥青方法的力量特征那些被巩固的材料，但发泡的沥青是灵活和疲劳抗性。泡沫治疗比其他冷的混合过程可以使用与大范围集合类型。减少的黏合剂和运输费用，起泡沫沥青比冷混合的其他类型要求较少黏合剂和水。挽救及时，因为发泡的沥青立刻变紧密并且可能几乎运载交通，在击实完成之后。能量守恒，因为需要加热仅沥清，当聚集体被混合，当寒冷和潮湿时时(对干燥的没有需要)。起因于挥发性的蒸发的环境副作用从混合从治疗被避免不导致挥发性发行发泡的沥青可以储备没有黏合剂决赛或水蛭吸血的风险。因为发泡的沥青保持可使用在非常延长的期间，通常时间限制为达到击实，塑造和完成层数被避免。发泡的沥青层数在有害天气情况可以被修建，例如在冷气候或小雨，没有影响实用性或完成的层数的质量。3设计考虑3.1引言在发泡的沥青进行的实验室试验应该评估对变形的抵抗，并且在内聚和力量上的变化以湿气和温度。因为发泡的沥青混合力量对湿气情况是极端敏感的，在测试方法应该考虑到这些。由于发泡的沥青混合可能承担范围从颗粒状材料的特征到那些高质量沥青材料，选择的测试方法应该能处理大范围物质类型。关联领域表现以实验室试验结果为了开发适当的指标值(标准)是适当的为实验室被测量的物产。3.2沥清物产发泡的沥清，也指膨胀的沥清，是从液体临时地被转换了成泡沫状态被水的一种热的沥青黏合剂(典型地2%)的小百分比加法。发泡的沥清被描绘根据扩展比率和半衰期。一旦泡沫消散了，泡沫的扩展比率被定义作为比率在泡沫状态达到的最大体积和黏合剂之间的最后的容量。半衰期是时间，在几秒钟内，在片刻之间泡沫达到它消散到最大体积的一半的最大体积和时间。3.2.1起泡沫的潜力在发泡的沥青生产期间，混合的阶段沥清的起泡沫的特征扮演一个重要角色。它可以期望最大化的扩展比率和半衰期在混合之内将促进黏合剂分散作用。佛朗哥和Wood (1983)发现任何沥清，不问等级或起源，能起泡沫以喷管类型的一个适当的组合，水，空气和沥清射入压力。然而， abel (1978)发现了：包含硅树脂的沥清可能减少了起泡沫的能力;沥清以更低的黏度比沥清欣然起了泡沫并且有更高的泡沫比率和半衰期以更高的黏度，但对高黏性沥清的用途导致优越聚集涂层; 反剥离的代理增强了沥清的起泡沫的能力，并且可接受起泡沫只达到了在温度在149C之上。3.2.2发泡的沥清内容(BC)在起泡沫沥青混合最宜的沥清内容不可能清楚地经常被确定，它能在情况下热混合沥青。的黏合剂内容的范围可以使用(BC)在混合的稳定限制由损失在范围的上端和由水感受性在末端。看起来一个重大参量是黏合剂内容比与罚款内容， i.e. 黏合剂罚款灰浆的黏度在混合稳定扮演一个重大角色(参见第3.3部分)。表3.1也许用于作为指南选择根据混合的罚款内容的适当的黏合剂内容。 akeroyd和Hicks (1988)也提出了对比例黏合剂罚款关系的用途选择黏合剂内容，范围从3,5%黏合剂黏合剂内容为5%罚款内容对5%黏合剂内容为20%罚款内容。然而这种方法可能不是可适用的为材料的所有类型，由于罚款的变化的黏合剂吸收特征，反过来，取决于来源(父母)材料。超过475mm（）超过0075mm（）泡沫沥青（） 10 4.5 50(沙子) 35 3.557.5 47.510 4.5 10 53.3聚集物产研究表示，大范围聚集体也许使用与起泡沫沥清，范围从被击碎的石头到沙子和对矿石跟踪，如表3.2所显示。土壤的某些类型也许要求石灰治疗和分级的调整使他们令人满意地执行。图3.1显示MOBIL泡沫安定分级的图(Akeroyd， 1988)。材料符合图的区域A被发现适当的为泡沫治疗为沉重被交易的路。材料符合区域B为轻微被交易的路是适当的，但能对区域A材料被调整被粗糙的分数的加法。除非罚款增加，材料在区域C在罚款上是短少并且为泡沫安定不是适当的。3.4湿气情况湿气含量在混合和击实期间由许多研究员认为最重要的混合设计准则为发泡的沥青混合。在聚集体要求湿气变柔和和故障附聚，援助在沥清分散作用在混合期间和为领域击实。 ruckel等(1982)建议湿气密度关系在试验混合的公式化被考虑。不足的水在黏合剂的不充分的分散作用减少混合和结果的实用性，当许多水加长治愈时间时，减少变紧密的混合的力量和密度，并且可以减少聚集体的涂层。最宜的湿气含量(OMC)变化，根据被优选的混合物产(力量，密度，吸水性，胀大)。然而，因为湿气为混合和击实是重要的，这些操作，当优选湿气含量时，应该考虑。3.5治疗适应研究表示，发泡的沥青混合不在击实以后开发他们充分的力量，直到混合的湿气的大百分比丢失。这个过程被命名治疗。治疗是过程，藉以发泡的沥青逐渐获取对湿气含量的减少随着时间的过去陪同的力量。 ruckel等(1982)认为，湿气含量在治疗的期间有一个重大效果在混合的强度极限。然而，李(1980)提供建议的实验证据一个前提对于在发泡的沥青上的力量获取混合的干耗。哪些案件，实验室混合设计程序将需要模仿治疗过程的领域为了关联实验室制作的混合物产与那些领域混合。因为治疗发泡的沥青在领域混合发生在几个月，再生产治疗条件在实验室里的实际领域是不切实际的。需要治疗做法的一个加速的实验室，在哪些力量获取特征可以关联以领域行为，特别是与早期，被获得的中间和强度极限。这个描述特性是特别重要的，当结构容量分析，基于实验室被测量的力量价值，需要。大多早先调查采取了治疗做法的实验室由Bowering (1970) 提议，例如，治疗在温度的3天烤箱60C。这个做法导致稳定在大约0%到4%的湿气含量，哪些代表最干燥的状态可达成在领域。如此被治疗的样品的力量特征是在职状态的代表近似地一年在建筑。关心被表达了对也许发生在一个固化温度60C.的黏合剂变老。并且，因为这个温度上述那软化点共同的路品级沥清，在沥清分散作用上的变化在混合之内在治疗期间是可能的。在实验室检验阶段这项研究期间，这些问题将被论及。刘易斯建议的一个可选择方法(1998)将烘干发泡的沥青对恒定的大量，在低温(40 C)。4 结论起了泡沫冷的混合在大众化获取由于他们的好表现的沥青，建筑和兼容性舒适与大范围集合类型。和与所有沥青混合，有一个适当的混合设计程序为发泡的沥青混合为了优选可利用的材料用法和优选混合物产是根本的。幸运地，为发泡的沥青混合，混合设计可以完成由相对地简单测试规程和通过遵守某些制约关于用于的材料。在这项研究中，早先经验与发泡的沥青材料在世界的其他地区被巩固了入混合设计指南用于南非。混合设计指南跟随一个逐步程序，从通过原材料的描述特性到最后测试变紧密的样品。保重保证被采取的规程是与标准测试方法和当前被接受的实践兼容。除沥清起泡沫的植物之外，混合设计可以达到用标准设备可利用在沥青实验室。中央哲学在混合设计是优选混合力量特征在最坏的操作环境，例如，在被浸泡的情况下。间接抗拉强度测试提供如此评估变紧密的发泡的沥青样品一个方便方式。样品使用标准马歇尔击实用具在一个被浸泡的情况变紧密然后被测试。通过举办测试在黏合剂内容的范围，最宜的黏合剂内容可以被选择。其他测试，例如韧性模数，动态蠕动和混合，也被举办为了核实选择的最宜的混合和保证混合的充分表现。许多新的技术被开发达到起泡沫沥清。然而，因为混合设计在优选混合物产此中提出了集中，它相等地很好与所有泡沫沥青混合一起使用，不问用具的种类曾经生产发泡的沥清Foamed Asphalt Mixes - Mix Design ProcedureK M MuthenAbstract Foamed asphalt epitomizes the asphalt industrys drive towards energy efficient, environmentally friendly and cost-effective solutions for road-building. Foamed asphalt refers to a bituminous mixture of road-building aggregates and foamed bitumen, produced by a cold mix process. Although thefoamed bitumen process was developed more than 40 years ago and lauded by researchers the world over, it is believed that the lack of standardized design procedures has contributed to the limited implementation of the technology in South Africa, with practitioners favouring more familiar and well documented products. Recently there has been significant interest in the product, especially in the in-situ method of construction, and hence the need for a standard mix design procedure has now become essential. One element of foamed asphalt technology which may prove to be an impediment to standardization is the emergence of various proprietary bitumen foaming techniquesKey words foamed bitumen, foamed asphalt, expanded asphalt, expanded bitumen1 INTRODUCTION1.1 GeneralAn essential ingredient in the success of the South African pavement industry is the sustained research, development and implementation of new and alternative road-building methods, motivated by reasons of economy and the scarcity of pavement materials. It is generally accepted that soil stabilization techniques are suitable for upgrading poor quality materials so that these materials may be used to their full potential in the pavement structure. Bitumen soil stabilization technology has been the focus of recent research initiatives which have resulted in refined mix design procedures for products such as GEMS and ETBs, i.e. bitumen emulsiontreated materials. A common aspect of bitumen soil stabilization is the incorporation of small amounts of binder, in a cold mixing procedure, which vastly increases the shear (cohesion) strength, fatigue resistance and moisture resistance of the treated materials. Although cold mix bituminous products were used in South Africa prior to the research initiatives, their use andbenefits are now gaining increased acceptance within the industry.The use of foamed asphalt, an alternative cold mix procedure, has also had limited application in the construction of road pavements in South Africa. However, no standardized mix design procedure is available. Although the foamed bitumen process was developed more than 40 years ago and lauded by researchers the world over, it is believed that the lack of standardized design procedures has contributed to the limited implementation of this technology in South Africa, practitioners favouring more familiar and well documented products.1.2 Aim and ScopeThe objective of this project is to develop and verify a mix design procedure for foamed asphalt. This document contains a literature review of published research findings on foamed asphalt. Information from previous research and current practice was used to develop guidelines for foamed asphalt mix design for use in South Africa.1.3 Definition of Foamed AsphaltThe term foamed asphalt, as used in this document, refers to a mixture of pavement construction aggregates and foamed bitumen. The foamed bitumen, or expanded bitumen, is produced by a process in which water is injected into the hot bitumen, resulting in spontaneous foaming. The physical properties of the bitumen are temporarily altered when the injected water, on contact with the hot bitumen, is turned into vapour which is trapped in thousands of tiny bitumen bubbles. However the foam dissipates in less than a minute and the bitumen resumes its original properties. In order to produce foamed asphalt, the bitumen has to be incorporated into the aggregates while still in its foamed state.2 OVERVIEW AND ADVANTAGES OF FOAMED ASPHALT2.1 GeneralThe potential of foamed bitumen for use as a soil binder was first realised in 1956 by Dr. Ladis H. Csanyi, at the Engineering Experiment Station in Iowa State University. Since then, foamed asphalt technology has been used successfully in many countries, with corresponding evolution of the original bitumen foaming process as experience was gained in its use. The original process consisted of injecting steam into hot bitumen. The steam foaming system was very convenient for asphalt plants where steam was readily available but it proved to be impractical for in situ foaming operations, because of the need for special equipment such as steam boilers. In 1968, Mobil Oil Australia, which had acquired the patent rights for Csanyis invention, modified the original process by adding cold water rather than steam into the hot bitumen. The bitumen foaming process thus became much more practical and economical for general use.Foaming increases the surface area of the bitumen and considerably reduces its viscosity, making it well suited for mixing with cold and moist aggregates. Foamed bitumen can be used with a variety of materials, ranging from conventional high-quality graded materials and recycled pavement materials to marginal materials such as those having a high plasticity index. Foamed asphalt can be manufactured in situ or in a central plant. Binder contents are based on the mix design, and are determined as percentage (by weight) required for the mix to have optimum properties.2.2 Advantages of Foamed Asphalt MixesThe following advantages of foamed asphalt are well documented: The foamed binder increases the shear strength and reduces the moisture susceptibility of granular materials. The strength characteristics of foamed asphalt approach those of cemented materials, but foamed asphalt is flexible and fatigue resistant. Foam treatment can be used with a wider range of aggregate types than other cold mix processes. Reduced binder and transportation costs, as foamed asphalt requires less binder and water than other types of cold mixing. Saving in time, because foamed asphalt can be compacted immediately and can carry traffic almost immediately after compaction is completed. Energy conservation, because only the bitumen needs to be heated while the aggregates are mixed in while cold and damp (no need for drying). Environmental side-effects resulting from the evaporation of volatiles from the mix are avoided since curing does not result in the release of volatile Foamed asphalt can be stockpiled with no risk of binder runoff or leeching. Since foamed asphalt remains workable for very extended periods, the usual time constraints for achieving compaction, shaping and finishing of the layer are avoided. Foamed asphalt layers can be constructed in adverse weather conditions, such as in cold weather or light rain, without affecting the workability or the quality of the finished layer.3 DESIGN CONSIDERATIONS3.1 GeneralLaboratory tests conducted on foamed asphalt should evaluate resistance to deformation, as well as variations in cohesion and strength with moisture and temperature. As the strength of foamed asphalt mixes is extremely sensitive to moisture conditions, these should be taken into account in the test methods. Because foamed asphalt mixes can take on characteristics ranging from granular materials to those of high quality asphalt materials, the test method selected should be able to handle a wide range of material types. It is advisable to correlate field performance with laboratory test results in order to develop suitable target values (criteria) for the laboratory- measured properties.3.2 Bitumen PropertiesFoamed bitumen, also referred to as expanded bitumen, is a hot bituminous binder which has been temporarily converted from a liquid to a foam state by the addition of a small percentage of water (typically 2 per cent). The foamed bitumen is characterized in terms of expansion ratio and half-life. The expansion ratio of the foam is defined as the ratio between the maximum volume achieved in the foam state and the final volume of the binder once the foam has dissipated. The half-life is the time, in seconds, between the moment the foam achieves maximum volume and the time it dissipates to half of the maximum volume3.2.1 Foaming PotentialThe foaming characteristics of bitumen play an important role during the mixing stage of foamed asphalt production. It can be expected that maximized expansion ratios and half-lives will promote binder dispersion within the mix. Castedo Franco and Wood (1983) found that any bitumen, irrespective of grade or origin, could be foamed with an appropriate combination of nozzle type, water, air and bitumen injection pressure. However, Abel (1978) found that:bitumen which contained silicones could have reduced foaming abilities;bitumens with lower viscosities foamed more readily and had higher foam ratios and half-lives than bitumens with higher viscosities, but the use of high viscosity bitumens resulted in superior aggregate coating; anti-stripping agents intensified the foaming ability of bitumens, and acceptable foaming was only achieved at temperatures above 149 C.3.2.2Foamed Bitumen Content (BC)In foamed-asphalt mixes the optimum bitumen content often cannot be clearly determined as it can in the case of hot-mix asphalt. The range of binder contents (BC) that can be used is limited by the loss in stability of the mix at the upper end of the range and by water susceptibility at the lower end. It appears that one significant parameter is the ratio of binder content to fines content, i.e. the viscosity of the binder-fines mortar plays a significant role in mix stability (see section 3.3). Table 3.1 may be used as a guide to select the appropriate binder content based on the fines content of the mix. Akeroyd and Hicks (1988) also proposed the use of a proportional binder-fines relationship to select the binder content, ranging from a binder content of 3,5 per cent binder for 5 per cent fines content to a binder content of 5 per cent for 20 percent fines content. However this approach may not be applicable for all types of material, because of the varying binder absorption characteristics of fines which, in turn, depend on the source (parent) material.3.3 Aggregate PropertiesResearch has shown that a wide range of aggregates may be used with foamed-bitumen, ranging from crushed stone to silty sands and even to ore tailings, as shown in Table 3.2. Certain types of soil may require lime treatment and grading adjustments to enable them to perform satisfactorily. Figure 3.1 shows the Mobil foam stabilization grading chart (Akeroyd and Hicks, 1988). Materials conforming to Zone A of the chart have been found to be suitable for foam treatment for heavily trafficked roads. Materials conforming to Zone B are suitable for lightly trafficked roads, but could be adjusted to Zone A materials by the addition of coarse fractions. Materials in Zone C are deficient in fines and are not appropriate for foam stabilization unless fines are added.3.4 Moisture ConditionsThe moisture content during mixing and compaction is considered by many researchers to be the most important mix design criteria for foamed asphalt mixes. Moisture is required to soften and breakdown agglomerations in the aggregates, to aid in bitumen dispersion during mixing and for field compaction. Ruckel et al (1982) recommend that the moisture-density relationship be considered in the formulation of trial mixes. Insufficient water reduces the workability of the mix and results in inadequate dispersion of the binder, while too much water lengthens the curing time, reduces the strength and density of the compacted mix and may reduce the coating of the aggregates. The optimum moisture content (OMC) varies, depending on the mix property that is being optimized (strength, density, water absorption, swelling). However, since moisture is critical for mixing and compaction, these operations should be considered when optimizing the moisture content.3.5 Curing ConditionsStudies have shown that foamed asphalt mixes do not develop their full strength after compaction until a large percentage of the mixing moisture is lost. This process is termed curing. Curing is the process whereby the foamed asphalt gradually gains strength over time accompanied by a reduction in the moisture content. Ruckel et al (1982) concluded that the moisture content during the curing period had a major effect on the ultimate strength of the mix.However, Lee (1980) provided experimental evidence which suggested that moisture loss wasnot a prerequisite for strength gain in foamed asphalt mixes. Whichever the case, a laboratory mix design procedure would need to simulate the field curing process in order to correlate the properties of laboratory- prepared mixes with those of field mixes. Since the curing of foamed asphalt mixes in the field occurs over several months, it is impractical to reproduce actual field curing conditions in the laboratory. An accelerated laboratory curing procedure is required, in which the strength gain characteristics can be correlated with field behaviour, especially with the early, intermediate and ultimate strengths attained. This characterization is especially important when structural capacity analysis, based on laboratory-measured strength values, is required. Most of the previous investigations have adopted the laboratory curing procedure proposed by Bowering (1970), i.e. 3 days oven curing at a temperature of 60 C. This procedure results in the moisture content stabilizing at about 0 to 4 per cent, which represents the driest state achievable in the field. The strength characteristics of samples cured in this manner are representative of the in-service state app

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