Библиографический список
Coste, D., North, B., Sheils, J., Trim, J. Common European Framework of Reference for Languages: Learning, teaching, assessment. Cambridge: Cambridge University Press, 2001.
Gallager R. M., Ingram P. Complete Chemistry. Oxford: Oxford University Press, 2000.
Graves M., August D., Mancilla-Martinez J. Teaching Vocabulary to English Language Learners. New York: Teachers College Press, 2013.
Harmer J. How to Teach English. Harlow: Pearson Education, 2007.
Komorowska H. Metodyka nauczania języków obcych. Warszawa: Fraszka Edukacyjna, 2011.
Oakhill J., Cain K., Elbro C. Understanding and Teaching Reading Comprehension. New York: Routledge, 2015.
Ur P. A Course In Language Teaching. Trainee Book. Cambridge: Cambridge University Press, 1999.
УДК 625.72
магистрант Абросимов М.С.
Сибирская государственная автомобильно-дорожная академия (СибАДИ), Омск
Abstract. This article focuses on the process of formation of thermal cracks in asphalt pavements. We consider two conditions for the formation of these cracks and the analysis of these conditions and offer a method of the solution of this problem by using materials with a low coefficient of thermal expansion in the construction of asphalt pavement.
Аннотация. В статье рассматривается формирование термических трещин в асфальтных покрытиях. Анализируются условия возникновения трещин и способы предотвращения их формирования. Предлагается использование материалов с низким коэффициентом теплового расширения при строительстве асфальтных покрытий.
Key words: сracking; thermal expansion; thermal contraction; coefficient of thermal expansion; modulus of elasticity; mechanical stress.
Ключевые слова: термическая трещина; коэффициент теплового расширения; тепловое расширение; тепловое сжатие; модуль упругости; механическое напряжение.
USING OF ROCK MATERIALS WITH LOW COEFFICIENT OF LINEAR THERMAL EXPANSION IN ASPHALT PAVEMENT
Cracking in asphalt pavement is one of the main problems of the road sector. During the entire life cycle asphalt pavement is exposed daily to various adverse influences. Aging, freezing and thawing, movement of road transport, atmospheric precipitation is reducing the quality of asphalt regularly.
Mesh of cracks formed over time adversely affects surface smoothness and strength of pavement and consequently transport and operational performance of the road.
This article touches upon the occurrence of cracks in asphalt pavement under thermal expansion and thermal contraction.
Asphalt is a material which characteristics depend on temperature. At positive temperatures it increases in volume and becomes plastic. At lower temperatures it shrinks and becomes brittle.
After the construction of road pavements in winter thermal cracks are formed on the surface, which divide pavement into separate plates. The strength of the pavement becomes significantly lower.
We assume the fact that the cracking occurs under the influence of thermal loads, due to changes in linear size while cooling of the asphalt pavement. We define the distance between the cracks in the pavement. The solution of this problem is possible under the conditions of temperature change:
1) temperature in the layer thickness is the same;
2) temperature in the layer thickness varies linearly.
For the calculation of the first condition the following scheme is applied:
Fig. 1 – Scheme of the calculation of the distance between the cracks according to the first condition
As a result of calculations the formula for determining the distance between the cracks was obtained:
,
(1)
– the strength limit of asphalt in tension, MPa;
– the modulus of elasticity of asphalt, MPa;
– coefficient of linear expansion of the asphalt;
– the range of temperature change at cooling of pavement;
– the density of the asphalt layer, kg/m3;
– free fall acceleration, m/s2;
– the coefficient of the friction between the asphalt layer and
base.
For the calculation of the second condition the following scheme is applied:
Fig. 2 – Scheme of the calculation of the distance between the cracks according to the second condition
As a result of calculations the formula for determining the distance between the cracks was obtained:
(2)
In most cases, the source rocks for crushed stone are the alkaline rock – limestone, because it has good bounding with bitumen. The coefficient of linear expansion of limestone is α = 8×10-6.
To increase the crack resistance of asphalt pavement, rock material with a coefficient of linear thermal expansion that is equal to zero or close to it should be used. Such materials having a linear coefficient of thermal expansion of 5.4×10-6 are basalts, gabbros and diorites.
In accordance with the requirements of the asphalt pavement construction technology, asphalt layers can be constructed in autumn when the air temperature is not below + 10 °C.
The standards regulate the requirements of the granulometric composition of the rock material; strength; frost resistance; determine the content of silt and clay particles; the presence of adverse components and impurities; however they do not regulate rock materials by their thermal characteristics, such as the coefficient of linear thermal expansion.
The use of stone materials with low coefficient of linear thermal expansion will significantly reduce the formation of the thermal cracks and extend life of asphalt pavements.
Научный руководитель – М.А. Ращупкина, канд. тех. наук, СибАДИ; Т.Г. Галкина, канд. филолог. наук, доцент кафедры «Иностранные языки» СибАДИ, Омск