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道路施工材料道路施工材料泛指用于道路和桥梁工程及其附属造物所用的各类建筑材料，主要包括土、砂石、沥青、水泥、石灰、工业废料、钢铁、工程聚合物、木材等材料及它们组成的混合料。
道路工程材料是道路工程建设于养护的物质基础，其性能直接决定了道路工程质量和服务寿命。
1.砂石材料砂石材料是石料和集料的统称，石料和集料是道路与桥梁工程结构及其附属物中用量最大的一类才材料，石料制品课直接用于砌筑结构物或用于道路铺面，集料也可直接用于铺筑道路路面基层或垫层，但更多的是制备成沥青混合料、水泥混凝土和基层混合料，用于铺筑沥青路面面层或路面基层。
岩石质量主要取决于其造岩矿物和成岩条件，在道路工程中常用岩石品种为石灰岩、花岗岩，玄武岩，辉绿岩等；岩石的主要理学指标为单轴无侧限抗压强度，物理常数为密度，含水率和吸水率，在季节性冰冻地区应考虑所用岩石的抗冻性。
集料是不同粒径矿物组成的混合物，集料的密度对其物理理学性能有这重要的影响，而且是混合料组成设计的重要参数。
用于道路路面结构的粗集料应具备足够的抗压碎性，抗磨耗性和抗冲击性，用于表层的粗集料还应具有足够的抗磨光性，集料的理学性能分别用压碎性磨耗性，磨耗值，冲击值和磨光值等指标表示。
集料的颗粒组成用级配表示，集料级配与集料的密实度和内摩擦阻力有着直接的关系，也是进行矿质混合料组成设计的主要依据。
矿物混合料是由两种或两种以上的集料按一定比例组成的，确定这个比例关系的过程称为配合比设计。
矿质混合料的配合比的计算方法有数解法（计算法，规划求解法）和图解法。
用于建造基础的水泥混凝土拌合料制备用碎石或le石颗粒的最大尺寸不应大于70mm，而用于路面铺筑不能大于40mm。
用于水泥混凝土拌合料制备的碎石或le石不应含有多于25%的板状与针状粒料，二粉状及粘土粒料也不应超过1%。
2.水泥和石灰水泥和石灰石是道路工程建筑中使用较为广泛的无机胶凝材料。
该类材料经物理化学过程能产生强度和胶凝能力，将砂石等散装材料胶凝成整体，或将构件结合成整体。
道路工程材料期末重点总结一、介绍道路工程材料是指在道路建设或维护过程中使用的各种物质，包括路基材料、沥青混合料、水泥混合料和辅助材料等。
这些材料不仅对道路的结构和性能起着关键作用，还直接影响道路的使用寿命和行车安全。
因此，对道路工程材料的研究和选用至关重要。
二、道路工程材料的分类根据其用途和性质，道路工程材料可以分为以下几类：1. 路基材料：主要由天然土壤或矿物颗粒组成，用于构建道路的路基层和基底层，具有承载能力和排水性能；2. 沥青混合料：由沥青、矿料和填料按一定配合比混合而成，用于制造柔性路面层，具有较好的弯曲性能和抗水性能；3. 水泥混合料：由水泥、矿料和填料按一定配合比混合而成，用于制造刚性路面层，具有较高的强度和耐久性；4. 辅助材料：包括黏合剂、增稠剂、防腐剂等，用于改善道路工程材料的特性和性能。
三、路基材料1. 路基材料的性质要求：路基材料的主要性能要求是承载能力、抗冻性和排水性。
承载能力是指路基材料能够承受的荷载；抗冻性是指路基材料在低温环境下的抗冻破坏能力；排水性是指路基材料能够有效排水，防止路基内水分的积聚。
2. 常用的路基材料：(1) 天然土壤：天然土壤是指未经改良的现场土壤，包括黏土、砂土和砾石等。
天然土壤可以根据其塑性指数和颗粒分布曲线等指标来进行分类和评价。
(2) 工程填土：工程填土是指通过填筑方式得到的土壤，包括回填土、垫层土、坚实填料和悬浮填料等。
工程填土可以通过加水密实和加冻融循环试验等来评价其稳定性和抗冻性。
3. 路基材料的改良和加固：为了改善路基材料的性能，常常采用物理改良和化学改良的方法。
物理改良包括加固和加水密实，可以通过夯实、振动和加荷方法来实施。
化学改良包括雪融剂和土壤改良剂的使用，可以改变土壤的结构和性质，提高其稳定性和抗冻性。
四、沥青混合料1. 沥青混合料的组成和性能：沥青混合料由沥青、矿料和填料组成，通过混合而成。
沥青是一种黑色的胶状物质，具有粘接性和弹性；矿料是指石子和矿石等坚硬颗粒；填料是指填充物料，可以提高沥青混合料的体积稳定性和耐久性。
第1篇一、路基材料1. 土石材料：用于路基填筑，提高路基稳定性。
包括黏土、砂土、砾石等。
2. 水泥：用于路基稳定、加固，提高路基抗冻性能。
常用于水泥稳定碎石基层。
3. 沥青：用于路面铺设，提高路面抗滑、耐磨性能。
常用于沥青混凝土路面。
二、路面材料1. 沥青混凝土：由沥青、矿料、填料等组成，具有良好的抗滑、耐磨、抗老化性能。
2. 水泥混凝土：由水泥、砂、石子、水等组成，具有高强度、耐久性。
3. 沥青碎石混合料：由沥青、粗碎石、细碎石、矿粉等组成，具有良好的抗滑、耐磨性能。
4. 沥青稳定碎石：由沥青、粗碎石、细碎石、矿粉等组成，具有良好的抗滑、耐磨、抗裂性能。
5. 水泥稳定碎石：由水泥、砂、石子等组成，具有良好的抗滑、耐磨、抗裂性能。
三、排水材料1. 沥青排水板：具有良好的排水、隔水、防渗性能，用于路面排水。
2. 水泥排水板：由水泥、砂、石子等组成，具有良好的排水、隔水、防渗性能，用于路面排水。
3. 沥青碎石排水层：由沥青、粗碎石、细碎石等组成，具有良好的排水、隔水、防渗性能，用于路面排水。
四、防护材料1. 钢筋：用于提高路面、路基、桥梁等结构的抗裂、抗弯性能。
2. 钢筋混凝土：由水泥、砂、石子、钢筋等组成，具有良好的抗裂、抗弯、耐久性能。
3. 防水材料：如沥青防水卷材、橡胶防水材料等，用于防止路面、路基等结构渗水。
五、施工辅助材料1. 水泥：用于路基、路面、桥梁等结构的浇筑。
2. 砂、石子：用于路基、路面、桥梁等结构的填筑。
3. 沥青：用于路面铺设、防水等。
4. 水泥稳定碎石：用于路基稳定、加固。
5. 沥青稳定碎石：用于路面铺设、防水等。
6. 沥青碎石混合料：用于路面铺设、防水等。
总之，道路工程施工材料种类繁多，质量要求严格。
施工过程中，应严格按照设计要求、规范标准选用合适的材料，确保道路工程的质量和安全。
第2篇一、路基材料1. 土壤：路基工程的基础材料，需根据土壤性质进行分类，如砂性土、黏性土等。
道路工程材料慕课-回复道路工程材料慕课是一门介绍与道路建设相关的材料知识的在线课程。
在这门课程中，学生将学习到与道路工程材料有关的各种概念、材料特性、性能测试方法以及选择与设计准则等相关内容。
下面，我们将逐步回答与道路工程材料慕课主题相关的问题。
1. 什么是道路工程材料？道路工程材料是指用于建设和维护公路、街道、高速公路等交通基础设施的各种材料，包括但不限于沥青、混凝土、碎石、水泥等。
这些材料必须具备一定的强度、耐久性和耐候性能，以确保道路的安全、舒适和可靠性。
2. 道路工程材料的特性有哪些？道路工程材料的特性涵盖许多方面，包括物理特性、力学特性和化学特性等。
具体来说，它们需要具备良好的抗压强度、抗拉强度、抗冻融性、耐磨损性、抗滑移性等特性，以应对不同的道路使用环境和负荷条件。
3. 如何测试道路工程材料的性能？对道路工程材料的性能进行测试是确保其质量和性能达到设计要求的重要一环。
常用的测试方法包括试验室试验和现场试验。
试验室试验可以测定材料的物理和力学性质，如强度、模量、耐久性等；而现场试验则能够模拟实际使用环境，检测材料的实际性能，包括抗滑移性、附着性、声波反射等。
4. 材料选择和设计准则有哪些？在道路工程中，材料的选择至关重要，它将直接影响到道路的使用寿命和性能。
常见的材料选择和设计准则包括：- 耐久性：选择能够在不同气候条件下保持稳定性能的材料；- 可回收性：考虑可持续发展，选择能够进行再利用或回收的材料；- 成本效益：选择经济实用的材料，同时考虑其使用寿命和维护成本；- 环保性：选择对环境影响较小的材料，如低碳排放材料。
尽管面对不同的道路用途和工程要求，材料选择和设计准则会有所不同，但以上几点是考虑材料选择的基本准则。
总结起来，在道路工程材料慕课中，学生将学习到道路工程材料的定义、特性、性能测试方法以及选择和设计准则。
这些知识将帮助他们在实际道路工程中做出准确的材料选择和设计决策，从而提高道路的质量和可靠性。
道路工程材料
道路工程材料是指用于建设和维护道路的材料。
道路工程材料包括沥青混合料、碎石、水泥、沙子等。
首先，沥青混合料是道路工程中常用的材料。
它由沥青和矿物铺料组成，具有良好的抗水、耐久性和耐磨性。
沥青混合料适用于各种道路，如高速公路、城市道路和乡村道路。
使用沥青混合料可以提高道路的承载能力和耐久性，延长道路的使用寿命。
其次，碎石也是道路工程材料中重要的一种。
碎石由大小不等的石块组成，被广泛用于道路的基础层和面层。
碎石可以提供良好的承载能力和排水性能，能够使道路更加坚固，不易坍塌。
此外，碎石还可以用于修建路堤和排水沟，起到加固和排水的作用。
再次，水泥也是道路工程中常用的材料之一。
水泥用于混凝土路面的建设，具有良好的强度和耐久性。
水泥混凝土路面可以承受重载交通的压力，不易出现裂缝和坑洼，提高道路的整体平整度和舒适性。
此外，沙子也是道路工程材料中不可或缺的一种。
沙子广泛应用于道路基层的填充和路面的铺设。
沙子可以提供稳定的路基和良好的排水性能，使道路更加平整和稳定。
同时，沙子还可以用于路基的加固和施工过程中的辅助材料。
综上所述，道路工程材料是建设和维护道路所必需的材料。
沥
青混合料、碎石、水泥和沙子等材料在道路工程中发挥不同的作用，使道路具有良好的承载能力、耐久性和排水性能。
选择合适的道路工程材料是确保道路质量和使用寿命的重要环节。
道路建设工程施工材料随着我国经济的快速发展，交通运输业作为国民经济的重要支柱，其基础设施的建设尤为重要。
道路建设工程作为交通运输业的重要组成部分，对于促进地区经济发展、提高人民生活水平具有举足轻重的作用。
而在道路建设工程中，施工材料的选择和使用是确保工程质量、安全和进度的重要因素。
本文将从道路建设工程施工材料的角度，探讨其种类、要求及选择和使用方法。
一、道路建设工程施工材料的种类道路建设工程施工材料主要包括沥青混凝土、水泥、钢材、砂石、木材、塑料等。
其中，沥青混凝土是道路面层的主要材料，水泥是道路基层和桥梁等结构物的主要建筑材料，钢材用于道路桥梁的结构加固和施工设备，砂石用于道路基层和混凝土的制作，木材和塑料主要用于施工临时设施和支架等。
二、道路建设工程施工材料的要求1. 质量要求：道路建设工程施工材料必须符合国家相关标准和规范，具备良好的力学性能、耐久性能和环保性能。
例如，沥青混凝土应具备较高的抗剪强度、抗车辙性能和耐候性；水泥应具备较高的强度、耐久性和收缩性能；钢材应具备较高的强度、韧性和焊接性能。
2. 性能要求：道路建设工程施工材料应具备良好的施工性能，如易于搅拌、铺设和压实等。
同时，材料在运输和存储过程中应保持稳定，不易流失、损坏和变质。
3. 环保要求：道路建设工程施工材料应符合国家环保要求，尽量选用低碳、环保、可持续发展的材料。
例如，选用废弃物作为部分原材料，减少对环境的污染。
4. 经济要求：道路建设工程施工材料在满足质量、性能和环保要求的基础上，应具有较高的经济性。
在选用材料时，要综合考虑材料的价格、运输成本、施工难度等因素，力求降低工程成本。
三、道路建设工程施工材料的选择和使用1. 沥青混凝土的选择和使用：沥青混凝土的选择应根据道路等级、气候条件、交通状况等因素进行。
一般情况下，高速公路和城市主干道应选用高强度、耐久性好的沥青混凝土；次干道和支路可选用中强度、耐久性较好的沥青混凝土。
Assignment for Road Engineering MaterialsChapter 1 & Chapter 2Name：Class ：NO. ：SCHOOL OF HIGHW AY COLLEGECHANG’AN UNIVERSITYOCTOBER 31, 2013Chapter one Aggregate1.Here are two kinds of stone, and the test results are shown in following table.Which kind of stone has better performance?Solution:Step 1, the porosity of these two stone can be calculated as the following formula:n=(1−ρdρt)×100%And the n A=0.07> n B=0.Step 2, the value saturation-water coefficient of A stone is 0.75, which is higher than theB stone’s, 0.65.Step 3, the higher porosity of stone is, the better water absorption gets and the worse frost resistance is. So is the saturation-water coefficient. From what has been mentioned above, the stone A apparently gets a higher porosity of stone and saturation-water coefficient, so the stone A is worse at frost resistance.Conclusion: stone B has better performance.2.Please describe the difference between strength indexes of stone and aggregate,and the test methods.Solution:a)The major strength index for stone is uniaxial compressive strength. The result ofmeasuring uniaxial compressive strength test is represented as resilient modulus R=PA with triaxial chamber with external LVDT’s and load cell. And the prepare sample can be cube (in road engineering) or cylinder (in bridge engineering).b)The major strength index for aggregate is crushing value. And the test method is in thebelow.Procedure to determine Aggregate Crushing Valuei)The aggregates passing through 12.5mm and retained on 10mm IS Sieve are oven-driedat a temperature of 100 to 110o C for 3 to 4hrs.ii) The cylinder of the apparatus is filled in 3 layers, each layer tamped with 25 strokes ofa tamping rod.iii) The weight of aggregates is measured (Weight ‘A’).iv) The surface of the aggregates is then leveled and the plunger inserted. The apparatus is then placed in the compression testing machine and loaded at a uniform rate so as to achieve 40t load in 10 minutes. After this, the load is released.v) The sample is then sieved through a 2.36mm IS Sieve and the fraction passing through the sieve is weighed (Weight ‘B’).vi) Two tests should be conducted.Aggregate crushing value = (B/A) x 100%.3.Please describe the classification of aggregate from deferent perspectivesSolution：Solution:Notification: There is some other types of aggregate by different standards●Crashed gravel●Crushed sand●Stone chip●Filler●Slag4.There are two kinds of aggregate, and the test results are shown in followingtable. Please describe the difference of the performance of these two kinds of aggregate.Solution:The lower crushing value is, the better anti-crushing performance aggregate gets. And so is the Los Angeles abrasion ration. So, the aggregate B has a better anti-crushing and anti-crushing and abrasiveness performance.The higher polishing value is, the better anti-slip performance aggregate gets. So, the aggregate A has a better anti-slip performance.5. Please describe the definition, the test and the calculation methods of densitiesof aggregate, and give the rank of different densities.Solution:a) True density:Definition: the mass of a unit volume of the impermeable portion of material, including the solid and impermeable pore.. Test: Le Chatelier flask methodCalculation method: ρs=m s v sb) Apparent density:Definition: the mass of a unit volume of the impermeable portion of material, including the solid and impermeable pore. Test: Wire basket methods Calculation method: ρa=m s v s +v nc) Bulk density:Definition: the mass of a unit volume of material under natural status, including solid, permeable and impermeable pores. Test: Wire basket methods for coarse aggregate Flask method for fine aggregate Calculation method: ρb=m s v s +v n +v id) Stacking density ：Definition: dry mass per unit volume of aggregate under some stacking methods.including ：Loose density, Tamping density, Compaction densityCalculation method: ρ=m sv s +v n +v i +v fRank: ρs >ρa>ρb>ρ6. The gradation curves of three kinds of aggregate are show in right Fig. Pleasejudge the gradation categories, and the structure of asphalt mixture consisted of these aggregate Solution:Gradation A is the gap gradation. One or more intermediate particle sizes aggregates are missing.Gradation B is the continuous gradation. The particles distribute on each sieve size from the large to small.Gradation C is the open gradation. The particles distribute on larger sieve size.7.Discuss the differences between gradation and fineness modulus of fineaggregate Have sand A and sand B, which have the same fineness modulus, the same gradation?Solution:Gradation, the particle sizes and size distribution, refers to the proportion by mass or weight of aggregate particles distributed in special particle-size ranges, not only to individual fine and coarse aggregate , but also to the combined or mixed aggregateFineness modulus, a value which statistically represents the coarse or fine condition of fine aggregate, is statistically determined by the percentage of coarse aggregateSo, the different gradation can have the same fine modulus, and the same fine modulus may not represent the same gradation.Sand A and sand B can have the same the same fineness modulus but not the same gradation.8.Sieving test results of 500g sand are shown in table. Please fill the blank, andcalculate the fineness modulus.=2.052μf=(A2.36+A1.18+A0.6+A0.3+A0.15)−5A4.75100−A4.759.The passing percentages of four aggregates are listed in the Tab.9.1 and thegradation limit are shown in Tab.9.2. Please use the graphic method and linear programming method to determine the proportions in mixed aggregate according to the mid-value of gradation limits, and calculate the composite gradation.Table 9.1Table 9.2Solution:Linear programming methodThe gradation can be designed by the Excel macro, linear programming, as long as some constraints are correctly set.Here is the gradation design sheet.Designed values of gradation are the numbers with the blue background. They are proportions of different components which are simulated by linear programming.With the assumed amount of four aggregates, the composite values can be calculated and they are displayed in the sheet.And next is the gradation curveThere are four lines in this illustration. From the legend, it can be known that the purple one, composite gradation, is always between the upper limit of gradation and lower limit of gradation and approaching the middle value of gradation. So, the design of composition gradation is qualified.Graphic method：The gradation is illustrated in the attached graph.10.The shape and surface texture of aggregate particles are important for bothcement concrete and hot mix asphalt.(1)For preparing PCC, would you prefer round and smooth aggregate orrough and angular aggregate? Briefly explain why.(2)For preparing HMA, would you prefer round and smooth aggregate orrough and angular aggregate? Briefly explain why.Solution:(1)For PCC, the round and smooth aggregate particles are desirable to improveworkability. Because the angular aggregate will be more difficult to work in place and easier to be fractured. Besides, aggregate with a rough texture are more difficult to compact into a dense configuration than smooth aggregate.(2)For asphalt mixture, angular and rough aggregate Particles are desirable to improveworkability. Because angular aggregate produce bulk materials with higher stability than round aggregate and the roughness of aggregate surface plays an important role in the way of aggregate compacts and bonds with binder materials.11.A sample of coarse aggregate from a stockpile has the following properties:Mass of wet aggregate=5298gMass of oven dry aggregate=5216gMass of aggregate in water=3295gMass of SSD aggregate=5227Determine:(a)The bulk & apparent specific density(b)The moisture content and absorption of stockpile aggregateSolution：Known: m a=5216g,m f=5227g,m w=3295g,m1=5298ga)The apparent specific densityγa=m am a−m w=2.72The bulk specific densityγf=m am f−m w=2.70b)The absorption contentw x=m f−m am a×100%=0.21% The moisture contentw x=m1−m am a×100%=1.57%Chapter two Portland Cement1.Briefly describe the hardening process of lime.Solution:The hardening process of lime comprises two parts, recrystallization and carbonification.Part 1: RecrystallizationCa(OH)2 + nH2O =Ca(OH)2∙nH2OThe reaction product has some strength by the crystal and shows some cementing properties.Part 2: CarbonificationCa(OH)2 + CO2=CaCO3The reaction product is insoluble, showing better water stability. And it makes material denser and higher strength.2.Discuss the reason of the generation of under-burnt lime and over-burnt lime.Explain the harms of over-burnt lime to concrete structure, and how to eliminate the harm.Solution:a) Under-burnt limeGeneration reason:When fire heat in limekiln is not even or raw material size is over large, some product may become “under-burnt lim e” which is considered as residue. It will reduce actual content of active ingredient.b) Over-burnt limeGeneration reason: If firing process is over heat or over time, some product may become“burned lime”.Harms:Because some expansion from “burned lime”in volume will still take place during application process and in service stage, it will result in cracking and plaster flaking.Elimination:Immersing the burnt lime in the slaking pool for several weeks so that those unslaked grain can get totally slaked. (陈伏)3.What ingredients are used for the production of Portland cement? What is therole of gypsum？Solution:Production of Portland cement starts with two basic raw ingredients: a calcareous material and an argillaceous material.The calcareous material is a calcium oxide, such as limestone, chalk or oyster shells.The argillaceous material is a combination of silica and alumina that can be obtained from clay, shale, and blast furnace slag.Besides, there are some other adjustable materials such as diatomite (SiO2),magnetite (Fe2O3), alumina (Al2O3), etc and gypsum and activity mixtures.Gypsum plays a role as a retarder to regulate the setting time of the cement in the concrete and a control amount of gypsum can prevent some side-effect.4.What are P.I, P.II, P.O, P.S, P.P, P.F shorted for?Solution:P.P means Portland-pozzolana cement;P.F means Fly-ash Portland cement;P.I. and P.II. mean Portland cement;P.O. means Ordinary Portland cement;P.S. means Portland slag cement.Notation: In America, the P.I. stands for normal type Portland cement while P. II.means moderate sulfate resistance type Portland cement. And they two type are inseparable in China.5.What are the four mineral compounds in Portland cement? How do thechemical compounds contribute to the hydration, strength and other properties?Solution:The four mineral compounds in Portland cement are tricalcium silicate (3CaO·SiO2), dicalcium silicate (2CaO·SiO2), tricalcium aluminate (3CaO·Al2O3), tetracalcium aluminoferrite (4CaO·Al2O3·Fe2O3).The chemical components’ contribution of hydration can be summarized in the following table.More specifically, the relationship can be reflected by inequalities.Hydration speed:C3A>C3S>C4AF>C2SHydration heat:C3A>C3S>C4AF>C2SEarly strength:C3S>C3A>C4AF>C2SPost strength:C3S~C2S>C3A ~ C4AF6. What are the primary chemical reactions during the hydration of Portlandcement?Solution:C 3S hydration:C 2S hydration:C 3A hydration:In water without gypsumIn water with gypsum➢ After the gypsum exhaustedC 4AF hydration:It’s similar to C 3A.7. Describe the corrosion and prevention of cement stone?Solution:1) The corrosion of cement stone includes:Calcium hydroxide dissolved lost in fresh water;Erosion of sulfate;Erosion of magnesium salt;Erosion of carbonate.2) The ways to prevent cement from corrosion includes:a) Choosing right type cement which produces less amount calciumhydroxide [Ca(OH)2] during process of hydration, such as Portland slagcement;b) Selecting cement with less content of C3A;c) Improving construction technology and denseness of cement;d) Painting of waterproof coating on cement surface.8. Why should we determine the water requirement of normal consistency ofcement?Solution:There are two reasons about that:Setting time or soundness is measured only under the condition ofnormal consistencyNormal consistency expresses a state that cement pastes shows the sameconsistency.222223(3)()CaO SiO nH O xCaO SiO yH O x Ca OH ⋅+→⋅⋅+-22222)()2(2OH Ca x O yH SiO xCaO O nH SiO CaO -+⋅⋅→+⋅O H O Al CaO O H O Al CaO O H O Al CaO 2322322328219427)3(2⋅⋅+⋅⋅→+⋅322413()12C A Ca OH H O C AH ++→4134222342233332C AH CaSO H O H O CaO Al O CaSO H O++→41323423312C AH AFt CaO Al O CaSO H O +→9.Define the initial and final setting time, and briefly describe the test methods.Solution:Definition➢Initial setting timeThe initial setting time is the interval between the mixing of the cement with water and the time when the mix begins to lose plasticity,stiffening to a certain degree.It marks roughly the end of the period when the wet mix can be molded into shape➢Final setting timeThe final setting time is the interval between the mixing of the cement with water and the time when the mix completely lose plasticity.It represents the point at which the set cement has acquired a sufficient firmness to resist a certain defined pressure.Test method➢ A sample of cement paste is prepared with water required for normal consistency➢Maintained in 30min➢Penetration is repeated in every 5s near the initial setting➢The initial setting time is when the distance between the test needle and the bottom is 4mm±1mm➢Penetration is repeated in every 15min near the final setting➢The final setting time is when the distance between the test needle and the surface is 0.5-1mm10.What is the strength grade of Portland cement, and how to determine thestrength grade of a given Portland cement?Solution:Strength grade of Portland cement is classified by the compressive strength and flexural strength of the required curing day. The “MPa” is used to represent the strength grade. Portland cement has three strength grade and six types, i.e. 42.5,42.5R, 52.5, 52.5R, 62.5, 62.5R.The measuring method of strength grade of a given Portland cement is ISO method. The process are preparing the 40mm×40mm×160mm standardspecimen with cementstandard sand =13and waterscement=0.5and then measuring theflexural strength and compressive strength with enough curing days (3 days or 28 days) at the standard curing requirements.11.Please analyze the volume unsoundness of Portland cement. What effects doesvolume unsoundness bring to structures?Solution:The volume unsoundness of Portland cement means the ability to retain volume of cement paste after setting.Lack of soundness (unsoundness) is attributed to excessive amount of free lime or magnesia (ƒ-CaO, ƒ-MgO) and extra-gypsum.12.There are two batches of Portland cement from Plant A and Plant B, and theirmineral compounds are given in the following table. Please compare their differences about strength development and hydration heat features, and discuss the reasons.Solution:The Portland cement from plant B may have a higher hydration heat and lower strength development. By contrast, The Portland cement from plant A may have a lower hydration heat and higher strength development.The amount of C3A plays a dominate role in the hydration heat. And there is more C3A in the Portland cement of plant B. So, it may have a higher hydration heat.The mount of C3S plays a dominate role in the strength development. And there is more C3S in the Portland cement of plant A. So, it may have a higher hydration heat.。
