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This paper represents and analyses the experimental data for investigation of freezing and associated temperature and moisture variations in subgrade of “Almaty-Bishkek” highway (2013–2016). Experimental data regarding temperature and moisture have been obtained by special sensors which were installed in different depths of a vertical hole, drilled in a multilayer pavement and subgrade of the highway. Measuring of temperature has been performed according to the principle of thermal resistance variation, and measuring of moisture has been performed in accordance with the principle of dielectric permeability. It was stated that temperature in points of subgrade is varied only in an annual cycle in south-eastern region of Kazakhstan, daily cycles are not available. Amplitude temperature values are decreased with the depth increase and lag in time is increased for the graphs of temperature variation with the depth increase. The character of variation and maximal value of freezing depth can be different depending on the character of air temperature variation and possible interchanging of cold and warm periods in winter. The temperature can be decreased lower than 0 ℃ in the top part of subgrade in winter periods. In such a case, sharp decrease for quantity of liquid moisture occurs, i.e. part of moisture transforms into a solid condition (ice). Quantity of moisture becomes more after thawing than it was before freezing. The value of this accumulated moisture content is connected with the duration of frozen condition for the top part of subgrade and maximal freezing depth of a highway.

This paper gives the results of experimental research of temperature variation and its effect on distribution of moisture in pavement and subgrade of a highway located in the eastern region of Kazakhstan. The sensors consisting of two elements have been used to measure temperature and moisture. The first of them is designed for measurement of temperature and based on the effect of thermal resistance, and the second one based on diamagnetic penetration allows measuring of moisture. Peculiarities of temperature variation in time in pavement layers and points of subgrade, temperature distribution in the depth at different time moments have been described. Important characteristics have been determined – duration of a frozen condition and freezing, average rates of freezing and defreezing in points of pavement and subgrade located in various depths. Quantity of unfrozen water in subgrade soil depends on negative temperature and initial moisture and it is satisfactorily approximated by semi-logarithmic function. Keywords: Pavement, Subgrade, Sensors, Temperature, Moisture, Unfrozen water

The paper investigates experimentally the distribution, variation in time of a temperature and moisture in a pavement and subgrade of a highway located in the south of Kazakhstan. Sensors designed in the form of a metal capsule containing the element for temperature measurement through thermal resistance and the element for moisture measurement on diamagnetic permeability have been used for measuring. Peculiarities have been described for daily, quasi-seasonal and annual cyclic variation of temperature and moisture in the pavement and subgrade. Quantitative characteristics have been determined and statistically evaluated for cyclic freezing and thawing (number of freezing and thawing cycles, a minimal temperature in cycles, frozen condition duration) in the pavement points. Data have been shown for freezing and thawing processes of the pavement. Unfrozen water content has been quantitatively described in the base layer of the pavement depending on a negative temperature.

The matters of investigation for water thermal regime of pavement and subgrade structures of the highways are especially important as the moisture and temperature distribution in pavement and subgrade layers impact greatly on their deformation and strength indicators. Experimental results, which can be obtained by special measurement devices, are primary ones for establishing of peculiarities and regularities for distribution and migration of heat and moisture in the mentioned structural elements of the highways. Special measurement devices are required to obtain such experimental data. The paper shows the results for analysis of temperature and moisture variation in points of pavement and subgrade of “Almaty-Bishkek” highway. Temperature measurement has been performed by set of special sensors. Regular temperature and moisture measurement have been performed for the period from September 18, 2015 to June 2, 2016. Regularities for temperature regime variation in points of pavement for 24 hours are coordinated with air temperature variations. Amplitude of vibration for temperature is decreased with the depth increase. Moisture in subgrade points is gradually decreased with the reduction of daily average air temperature.