Differentiated Drying of the Mixtures Colloidal Components Used in the Construction of Underground Infrastructure Procedia Engineering 165 ( 2016 ) 806 – 816 1877 7058 © 2016 The Authors Published by[.]
Available online at www.sciencedirect.com ScienceDirect Procedia Engineering 165 (2016) 806 – 816 15th International scientific conference “Underground Urbanisation as a Prerequisite for Sustainable Development” Differentiated drying of the mixtures colloidal components used in the construction of underground infrastructure Anatoly Kizurov a,*, Igor Lapshin a, Sergey Kokoshin a a Northern Trans-Ural State Agricultural University, Respubliki str 7, Tyumen, 625003, Russia Abstract Differentiated method of drying of the mixtures colloidal components used in the construction of underground infrastructure is proposed The theoretical analysis of the drying process of the colloidal components in the processes of heating and cooling at natural convection is completed 2016The TheAuthors Authors Published by Elsevier Ltd is an open access article under the CC BY-NC-ND license © 2016 © Published by Elsevier Ltd This (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of the 15th International scientific conference “Underground Peer-review under scientific committee of the 15th International scientific conference “Underground Urbanisation as a Urbanisation as aresponsibility PrerequisiteoffortheSustainable Development Prerequisite for Sustainable Development Keywords: colloid body, building mixtures, drying of building mixtures, differentiated drying Introduction Stricter requirements apply to mixes used on underground infrastructure objects that are related to aggressive influence of moisture, salts and acids contained in the soil [11] The end product will depend on the requirements of the technological standards for the preparation of solutions for the construction of underground infrastructure To meet the technical standards of the solutions preparation it is necessary to use mixtures of a certain faction, humidity and so on Changes in humidity component of the building mixes, depending on humid-temperature environmental parameters impede the compliance with technological standards of solutions preparation of mixes [10] * Corresponding author Tel.: +7-3452-29-01-57 E-mail address: Impossible_@mail.ru 1877-7058 © 2016 The Authors Published by Elsevier Ltd This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of the 15th International scientific conference “Underground Urbanisation as a Prerequisite for Sustainable Development doi:10.1016/j.proeng.2016.11.779 807 Anatoly Kizurov et al / Procedia Engineering 165 (2016) 806 – 816 The most common and most sensitive to humid-temperature parameters of the environment component of mixes is sand, as it applies to colloidal systems or colloids [14, 15] Sand, like colloid body, has equilibrium humidity, which depends on the temperature and humidity of the environment [6, 12] Requirements for sand, as a component of mixes, [4, 5] regulate to use sand with a moisture content of not more than 2% for the preparation of acid solutions used in the construction of underground infrastructure The equilibrium moisture content of sand ranges from to 20% depending on the temperature and humidity of the environment, therefore, before the preparation of mortars, the sand is dried [13] The issue of maintaining the moisture content of the colloidal component mixes at the time of the solutions preparation, such as sand, is relevant in the construction of underground infrastructure Subjects and Methods The sand was chosen to study as a colloidal component mixes for the construction of underground infrastructure The main physical characteristics are taken from the standard documentation for carrying out of theoretical researches of differentiated sand drying process [5] In the first approximation the grains of sand represent a sphere with diameter d The process of sand drying (moisture transfer) as a colloid body in general is described by Lykov (1) [10, 12]: qm a m U (u G 4) (1) where am – the coefficient of moisture internal diffusion m4/%; ρ – density of matter, kg/m3; u – the gradient of moisture content, %/m; δ – the coefficient of thermal diffusion, %/K; Θ – the gradient of temperature, K/m The direction of the temperature and humidity gradients for the processes of heating and cooling is presented in figure a) b) Fig.1 The gradient of temperature and humidity in the grain of sand, a – heating; b – cooling 808 Anatoly Kizurov et al / Procedia Engineering 165 (2016) 806 – 816 The formula (1) shows the relationship of the moisture transfer process depending on the distribution of humidity and temperature on colloid body During convective heating (drying) of the body, a temperature gradient opposite to the gradient of moisture content on the sign and is directed from the center of the body to the surface, which leads to lower moisture transfer According Filonenko G K the temperature gradient Θ = 1°C creates the intensity of moisture transfer that is comparable to the humidity gradient u in the range % Colloid body has the ambient temperature In the stationary state (if Θ→0, dqm/dt→const) In the case of heating a temperature gradient directed towards the center of the body (towards the gradient of humidity), that reduces the speed of drying (if Θ>0, dqm/dt→min) In the case of cooling, the temperature gradient directed from the center of the body (coinciding in direction with the gradient of humidity), that increases the speed of drying (if Θ