INFLUENCE OF FORMING PRESSURE OF SAMPLES MADE OF THE MIXTURE OF

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1 INFLUENCE OF FORMING PRESSURE OF SAMPLES MADE OF THE MIXTURE OF UNBURNT CLAY AND SAPROPEL ON THERMOPHYSICAL PROPERTIES JUOZAS NAVICKAS, DALIA KASPERIUNAITE Aleksandras Stulginskis University, Lithuania Abstract: The article deals with the dependencies of density of samples made of pure clayey soil, sapropel and clayey soil mixture on formation pressure; it also deals with the dependency of heat conductivity and absorption capacity of samples made of clayey soil with 20% additives of sapropel on formation pressure and absolute humidity of samples. It has been established that density of dry samples increases when formation pressure is enhanced. Density of samples made of pure clayey soil increases more than of samples made of clayey soil and sapropel mixture. The dependence of heat conductivity in samples, formed at MPa on absolute humidity, is linear, whereas, in samples, formed at less than 26 MPa, is nonlinear. The dependence of absorptive power on formation pressure belongs on the duration of samples keeping over water. Linear regressive analysis of investigation data has been fulfilled using a packet of statistical programmes SPSS-15. It is established that absolute humidity of samples and formation pressure are statistically significant (Sig.>0,001), and humidity of samples during measurements is more important to heat conductivity than formation pressure (Beta values are equal to 0,781 and -0,528 respectively). Keywords:Clay, sapropel, heat conductivity, density, absorption Introduction The mixture of sapropel and clayey soil is perspective substance in producing building materials (Brakš, 1971; Biriasov et al., 1987; Garliauskas et al., 2004; Katkevičius et al., 1998; Lopotko et al., 1985; Mandeikytė, 1997; Žvironaitė, 1997; Kurzo, 2005). Building materials made from these mixtures have unique properties dependable on the conditions of production and percentage composition of mixture. Lots of authors investigated the properties of sapropel mixtures with various additives (Gurklienė et al., 2004; Gurskis et al., 1996, 1998, 1999, 2000, 2004; Iljins et al., 2005; Navickas et al., 2005). The purpose of the work is to investigate the dependencies of density, heat conductivity and absorption capacity on formation pressure in samples made of sapropel and clayey soil mixture. The samples were formed from easily melting clayey soil found in Kaunas Šatijai clay quarry. The clay was remilled additionally before making. It had particles: if their measurements were from 2 mm to 0,063 mm, they made 0,3 %, 63 2 μm 32,3%, less than 2 μm 67,4%. The samples were formed from 22 % absolute humidity mass, which was made of 20 % sapropel and 80% clayey soil. The ph of used sapropel was 5,7, and its dry mass was only 6,46 %. Organic substances in a dry mass made 91,03%. The samples were pressed by hydraulic press ПГ-100 (Kasperiūnaitė et al., 2010). The samples were formed using 7 40 MPa pressure in an indoor temperature. The samples, after taking them from forms, were dried at indoor temperature till constant mass appears. The process of desiccation was continued in a thermostat at 105ºC also to a constant mass. Further, the samples were cooled in a hermetic vessel to a constant thickness. The density and volume of samples was established applying Archimedes s principle; heat conductivity was measured up by conductivity gauge FOX200, and absorptive power was established according the methods that were described above (Kasperiūnaitė et al., 2009). Results of research The dependence of density of samples made of dry clayey soil and samples made of clayey soil and sapropel mixture on formation pressure is given in Fig.1 below. It can be observed, that density, enhancing formation pressure, increases both in dry samples made of pure clayey soil and in samples made of mixture of clayey soil and sapropel. However, true to form, density values of samples made of pure clayey soil are larger than of samples made of sapropel and clayey soil mixture. The dependence of density of samples made of pure clayey soil on formation pressure is more expressed than of samples made of sapropel and clayey soil. Besides, the samples made of pure clayey soil were formed of formation mass having 9% of absolute humidity. Absolute humidity of formation mass determines the density of a sample (Iljins et al., 2005), therefore, it is impossible to compare the above mentioned dependences, however, it is obviously seen that the additive of sapropel lessens density. Sapropel as an additive enhances scattering of experimental points as it is calculated using trend lines and the coefficients of their determination. The dependence of the samples formed using 7-40 MPa pressures on absolute humidity of samples is presented in Fig.2. It can be observed from the above mentioned results that heat conductivity of samples increases when formation pressure enhances. Absolute humidity of samples also increases heat conductivity, however, as it can be seen, 254

2 the run of the growth depends on sample formation pressure. From pointed trend lines we see that when there are similar coefficients R 2, samples formed at MPa pressure, the dependence of heat conductivity on absolute humidity of samples W can be describes using linear function, and samples formed aw b aw 2 bw c using pressure less than 26 MPa have the dependence described by a polynomial. After calculating trend lines and choosing only such trend lines that have coefficients R 2 larger than 0,99, we can explain the above mentioned experimental dependencies in a following way: the larger sample formation pressure, the closer particles of substance are and they form capillaries of less diameter. When sample formation pressure is equal to the range from 40 MPa to 26 MPa, humidity existing in the capillaries of samples moves towards surface according to additional pressure and heat conductivity decreases in a linear way. Heat transport from particle to particle, diffusions together with secret heat transport and radiation mechanism function here. Capillaries having unequal diameters are usually formed in samples formed using pressure less than 26 MPa ρ = 9,048pf ,5 R2 = 0, ρ = 4,3563pf R2 = 0,9313 The density of the sample r kgm clay 20% of sapropel Linear (clay) Linear (20% of sapropel) Forming preasure p f MPa Fig.1. The dependence of density of samples on sample formation pressure Experimental points and trend lines of samples made of pure clayey soil Experimental points and trend lines of samples made of clayey soil with 20% sapropel additives. Capillary water fills them not fully; air water vapour plugs are formed and they impede water vapour diffusion as well as prevent capillary water to move towards surface. Therefore, heat transfer decreases according to diffusion and secret heat transfers in samples that have been formed using pressure less than 26 MPa. Comparing dry samples and samples having 8% of absolute humidity formed using 7 and 40 MPa pressure, the difference of heat conductivity between humid and dry samples shows that heat conductivity in humid samples is larger in 36% than id dry samples. After processing the dependencies of heat conductivity by programme SPSS15, it is established that absolute humidity of samples in a process of measurements and formation pressure are statistically significant (Sig.>0,001), and humidity of samples to the average of heat conductivity is more important than sample formation pressure (Table 1, Beta values are equal to 0,781 and -0,528 respectively)

3 Model Results of linear regressive analysis Unstandardized Standardized Coefficients Coefficients t Sig. Table 1. B Std. Error Beta 1 (Constant) 0,504 0,007 74,631 0,000 W, % 0,015 0,001 0,781 28,495 0,000 p f, MPa -0,008 0,000-0,528-19,246 0,000 Applying unstandardized coefficients, we get a linear equation of regression to prognose the average of heat conductivity λ in samples:, (1) 0,504 0,015W 0, 008 p f here W humidity of samples during measurements in %; p f sample formation pressure MPa. The dependence of sample absorption capability on sample formation pressure is presented in Fig.3. It can be seen that absorption capability ambiguously depends on sample formation pressure. In the beginning of the process (in a period of two days) absorption capability is inversely proportional to sample formation pressure. After three days of experiments absolute humidity in samples, formed using 7 and 40 MPa, becomes equal. 0,55 0,5 λ = -0,0021W 2 + 0,0259W + 0,2758 λ = -0,0013W 2 + 0,0207W + 0,3201 R 2 = 0,9567 R 2 = 0,9823 λ = -0,0011W 2 + 0,0188W + 0,3434 λ = -0,0007W 2 + 0,017W + 0,3507 R 2 = 0,9916 R 2 = 0,984 λ = 0,0114W + 0,3675 λ = 0,0132W+ 0,3812 R 2 = 0,996 R 2 = 0,9925 The heat conductivity λ Wm -1 K -1 0,45 0,4 0,35 0,3 0,25 λ = 0,0135W + 0,3845 R 2 = 0,9913 λ = 0,013W + 0,3922 R 2 = 0, The humidity of a sample W % Poly. (7) Poly. (12) Poly. (16) Poly. (21) Linear (26) Linear (31) Linear (35) Linear (40) Fig.2. The dependence of heat conductivity on absolute humidity of samples formed at 7 40 MPa formation pressure. Ratings at points and trend lines show formation pressure MPa of samples After keeping samples over water for 9 days, it was established that absorption capability in samples, formed using 7 25 MPa, does not almost depend, and maximum absorption can be noticed in samples, which are formed using MPa. The fact can be explained in the same way as in heat conductivity case. When 256

4 The humidity of a sample W % sample formation pressure increases, the diameter of capillaries enhances too. Therefore, in the beginning of absorption on account of diffusion water vapour transfer is quicker in samples formed using less pressure. The thinner a capillary is, the earlier water column forms in it, because the smaller the diameter of a capillary is, the larger concentration of nucleus forms. Scilicet, absorption of water vapour takes place in the samples in two modes: water vapour diffusion in capillaries and moving of formed water column in a capillary Formation pressure p f MPa Fig.3. The dependence of sample absorption capability on sample formation pressure in various terms of keeping samples over water. Ratings at experimental points correspond to sample keeping term in hours Conclusions 1. The density of samples made of clayey soil and of clayey soil with 20% of sapropel additives has linear dependence on sample formation pressure (coefficients of determination are 0,9811 and 0,9813 respectively). 2. Linear dependence (formation pressure is MPa) and nonlinear dependence (formation pressure is less than 26 MPa) are observed in the dependencies of heat conductivity on sample formation pressure. 3. Humidity of samples while measuring is more important to the average of heat conductivity than sample formation pressure (standardized coefficients 0,781 and -0,528 respectively). 4. During two primary days the capacity of absorption was larger in samples made using small formation pressure, and later the capacity of absorption is larger in samples made using the largest pressure (30 40 MPa). References Braksh, N.A., Sapropelevije otlozhenjija i puti ih izspolzovanjija. Riga Zinatne, pp Dalia Kasperiūnaitė, Feliksas Mikuckis, Juozas Navickas. Nedegto molio bandinių su sapropelio priedu termofizikinių savybių tyrimas. ISSN X LŽŪU MOKSLO DARBAI Nr. 86(39), TECHNOLOGIJOS MOKSLAI. Garliauskas, T.; Kasperiūnaitė, D.; Navickas, J., Presavimo slėgio įtaka nedegto molio bandinių savybėms. Chemijos ir fizikos mokslų vaidmuo žemės ūkio technologijų plėtrai : tarptautinė mokslinė konferencija skirta LŽŪU, Chemijos ir Fizikos katedrų įkūrimo 80-mečiui. Kaunas, ISBN pp Gurklienė, A.; Iljins, U.; Navickas, J.; Šaferis, V.; Ziemelis, I., Tiesinės regresijos taikymas nedegto molio bandinių šilumos laidžio prognozei. Chemijos ir fizikos mokslų vaidmuo žemės ūkio technologijų plėtrai : tarptautinė mokslinė konferencija skirta LŽŪU, Chemijos ir Fizikos katedrų įkūrimo 80-mečiui. Kaunas, ISBN pp

5 Gurskis, V.; Kasperiūnaitė, D.; Navickas, J., Sapropelio įtaka nedegto molio bandinių savybėms. Tarptautinės mokslinės konferencijos Vandens telkinių apsauga ir valdymas straipsnių rinkinys. Kaunas, 2004, pp Gurskis, V.; Navickas, J.; Iljins, U.; Ziemelis, I., Research on the heat conductivity of building materials made of unburnt clay with various additional elements. Proceedings of the Latvia university of agriculture. B-technical sciences, Jelgava, 1998, pp Gurskis, V.; Navickas, J.; Ramukevičius, D., Organinio sapropelio panaudojimas nedegto molio statybinėms medžiagoms gaminti. Tarptautinės konferencijos,,melioracija ir kraštotvarka medžiaga, Kaunas, 2000, pp Gurskis, V.; Navickas, J.; Ramukevičius, D.; Ciūnys, A., Kalkinio sapropelio panaudojimas nedegto molio statybinėms medžiagoms gaminti. Aplinkotyra 99, Kaunas, 1999, pp Gurskis, V.; Navickas, J.; Vaišvila, K.A., The influence of aditional elements on the building materials characteristics of unburned clay. Proceedings of international scientific conference hydraulic engineering and land management, Kaunas, 1996, pp Iljins, U.; Navickas, J.; Ziemelis, I., Application of Linear Regression While Investigating the Influence of Lime and Organic Sapropel on the Properties of Unburnt Clay Samples. Inženierproblēmas lauksaimniecībā : starptautiskā zinātniskā konference. Jelgava, pp Kasperiūnaitė, D.; Mikuckis, F.; Navickas, J., Nedegto molio bandinių termofizikinės savybės. ISSN X LŽŪU mokslo darbai Nr. 82(35). Kasperiūnaitė, D.; Navickas, J.; Garliauskas, T., Influence of formation conditions of unburned clay samples on their properties. Rural development 2005: Globalisation and integration challenges to the rural of East and Central Europe: the second international scientific conference: proceedings. Akademija, ISSN Vol. 2, b. 2: Biomedicine and Technological Sciences. pp Kasperiūnaitė, D.; Navickas, J.; Garliauskas, T., Properties of unburned clay samples. Engineering for rural development: 5 th international scientific conference: proceedings, may 18-19, Jelgava, ISSN pp Kasperiūnaitė, D., Navickas, J., Thermophysical properties of samples made of the mixture of sawdust and sapropel // Applied information and communication technologies [elektroninis išteklius]: proceedings of the 4-th international scientific conference Jelgava Latvia, April 22-23, 2010 Jelgava, ISBN pp [ISI proceedings]. Katkevičius, L.; Ciūnys, A.; Bakšienė, E., Ežerų sapropelis žemės ūkiui. Vilnius, 1998, 92 p. Kurzo, B.V., Zakonomernosti formirovanjija I probljemi izspoljzovanjija sapropolja. Minsk, pp.224 Lopotko, M.Z., Pekom, L.P. i dru., Primennjenjije sapropeljej v proizvodstve stroiteljnih materialov. Torfanaja promishljenostj, 12, pp Mandeikytė, N., Keramika su sapropelio priedais. Tarptautinė konferencija. Vandens telkinių būklė ir gerinimo metodai. LŽŪU, 1997, pp Navickas, J.; Gurskis, V., Kalkinio ir organinio sapropelio įtaka nedegto molio bandinių savybėms. Vagos. ISSN X. Nr. 67(20) (2005), pp (CAB Abstracts). Virjasov, G.P., Ivanova, L.A., Fedotov, A.I., Osnovnije napravljenjija izspoljzovanjija sapropeljej. International scientific conference Improvement of natural lakes and artificial water reservoirs. Kaunas,, pp Žvironaitė, J., Sapropelio panaudojimo statybinių medžiagų pramonėje galimybės. Tarptautinė konferencija. Vandens telkinių būklė ir gerinimo metodai. LŽŪU, 1997, pp