首页
登录
职称英语
What materials were not used for road surfaces during the last century? [br] [o
What materials were not used for road surfaces during the last century? [br] [o
游客
2023-12-14
54
管理
问题
What materials were not used for road surfaces during the last century? [br]
Mr. Jones: What materials were used for road surfaces during the last century?
Engineer: Usually they were gravel and macadam. Tars and asphalt were originally used only as coverings, but later they were used as binders and finally as hot mixtures.
Mr. Jones: Concrete is a modem material as far as road - building goes, isn’ t it?
Engineer: Relatively speaking. But you might be surprised to know that a concrete road was built as early as 1893 in Ohio. But it was only 5 miles long. More extensive projects were not undertaken until much later, around 1912 or 1913.
Mr. Jones: This was because of the increase in traffic?
Engineer: That’ s right. Especially in the use of heavy tracks. More rigid pavements, such as concrete and brick, became a necessity. For light traffic, though, water-bound macadam, gravel, sand clay, and bituminous mixtures were still used.
Mr. Jones: What are turnpikes usually made of?
Engineer: Turnpikes are usually made of reinforced concrete about 8 to 10 inches thick, placed on a granular sub-base, which in turn is placed on a well - tacked earth subgrade. Of course, the construction depends a lot on the local climate, rainfall, soils, and so on.
Mr. Jones: How do you mean--climate?
Engineer: Frost is one of the main problems. For example, in Maine, where frost is quite frequent, the typical turnpike construction is a thin top layer of asphaltic concrete on a base layer of sand and gravel placed on a 36 - inch, frost - free, granular subgrade.
Mr. Jones: What is the width of these roads?
Engineer: The early two - lane roads were about 20 feet wide. But with higher automobile speeds, the width requirements increased greatly. To give you an example, the Pennsylvania Turnpike has two 12 - foot lanes in each direction, separated by a median 10 feet wide. On each side there is a 10 -foot stabilized shoulder, marking a total width of 78 feet. The New Jersey Turnpike averages 100 feet in width, with three lanes in each direction.
Mr.Jones: I guess wider roads are being built every day.
Engineer: That’ s right. Sometimes you think that, no matter how good a road you build, the speed and weight of vehicles will always be one step ahead.
选项
A、the increase in traffic
B、the cost of other materials
C、the change of the climate
D、the construction of the roads
答案
A
解析
concrete为"a constraction material consisting of sand, conglomerate gravel, broken stone, or slag in a mortar or cement matrix"混凝土。
转载请注明原文地址:https://tihaiku.com/zcyy/3272330.html
相关试题推荐
Thefamous______GoldRushbeganintheU.S.inthemid-nineteencentury.A、New
Almostacenturyafterhisdeath,thewell-knownFrenchauthorJulesVerneha
Almostacenturyafterhisdeath,thewell-knownFrenchauthorJulesVerneha
Almostacenturyafterhisdeath,thewell-knownFrenchauthorJulesVerneha
______isthecapitalofScotlandsincethe15thcentury.A、ManchesterB、Edinburg
The18thcenturywitnessedanewliteraryform-themodernEnglishnovel,whichc
YouaregoingtograduatefromUniversity,andduringtheresttimeyouare
Duringthefirst70yearsofthe20thcentury,inequalitydeclinedandAmericans
Duringthefirst70yearsofthe20thcentury,inequalitydeclinedandAmericans
Inthe19thcentury,inEngland,thereappearedaliterarytrend______.A、Romant
随机试题
Inthesecondhalfofeachyear,manypowerfulstormsareborninthetropic
Althoughitmighthavehappenedanywhere,myencounterwiththegreenbananas
中国经济发展潜力大、优势足、空间广,前景光明。【T1】我们有9亿多劳动力,其中1.7亿多受过高等教育或有专业技能。(非限制性定语从句)每年大学毕业生7
由于历史的演变,传统的沿袭,地理位置与气候条件的差异及饭店用途、功能、设施的不同
幼儿思考问题总是借助具体事物或具体事物的表象,对具体的语言容易理解,对抽象的语言
共用题干 某业主向甲保险公司担保50万元的财产保险,又同时就同一标的向乙保险公
赵老师是四(1)班的班主任,她对待工作认真负责、勤奋严谨,每天都会关注班级微信群
地下连续墙开挖,对确定单元槽段长度因素说法正确的有( )。A.土层不稳定时,应增
孕妇,30岁。主诉乏力,易倦,检查血红蛋白低于正常。应该补充的物质是( )。A
在月经周期中,形成雌激素分泌第二个高峰的直接原因是A.卵泡刺激素分泌增加 B.
最新回复
(
0
)