EFFECT OF TEMPERATURE ON ADHESION OF CLAY SOIL TO STEEL

Cercetări Agronomice în Moldov Vol. XLV, No. 2 (150) / 2012 EFFECT OF TEMPERATURE ON ADHESION OF CLAY SOIL TO STEEL B. AZADEGAN 1, J. MASSAH 2 * *E-mil: jmssh@ut.c.ir Received April 14, 2012 ABSTRACT. Soil dhesion is one of the importnt fctors in mesuring the mount of energy consumption. In this pper, the effect of temperture on the mount of cly soil dhesion ws investigted. The soil used in this reserch ws sturted cly mud. In order to mesure dhesion, specific instrument ws designed. The dimensions of the metl plte were 210 70 20 mm nd its weight ws 2.5 kgf. The metl plte lloy ws st37. The dhesion ws clculted from the difference between weight of wter used for clering the metl plte of the soil nd the weight of the metl plte. Six levels of temperture from 5 to 30 c were pplied. A refrigertor nd n oven were used for getting the required temperture. The test ws performed three times for ech level. Results showed tht n increse in temperture from 5 to 30 c decreses the soil dhesion. Three equtions such s liner polynomil, exponentil nd qudrtic polynomil correlted with the experimentl dt nd the result showed tht the qudrtic polynomil model hd the best correltion with experimentl dt. Key words: Soil dhesion; Energy consumption; Cly soil; Correltion. INTRODUCTION Adhesive soils which cnnot be self-unloded occupy 1/2 to 1/3 of the whole truck cpcity during dump truck trnsporting soil (Tong, 1992). It is sid tht the energy consumption to overcome the sliding resistnce of soil to the ploughshre surfce is bout 30-50 of the whole energy consumption during cultivtion (Hendrick nd Biley, 1982). Humn beings cn obtin gret benefit if such dhesion nd friction re reduced even slightly. Norml dhesive force t the soil tool interfce depends on vrious fctors including soil properties, tool mteril nd tool surfce, soil wter content nd interfcil conditions. Zeng (1995) climed tht the soil dhesion to soilengging tool incresed with norml 1 Irrigtion nd Drining Deprtment, College of Abourihn, University of Tehrn, Tehrn, Irn 2 Deprtment of Agrotechnology, College of Abourihn, University of Tehrn, Tehrn, Irn 21

B. AZADEGAN, J. MASSAH stress on it. The norml dhesion cn be treted s hving ction similr to tht of norml lod t the interfce (Fountine, 1954; Gill nd Vnden Berg, 1968; Zeng, 1995; Shi-qio, 2004) described such interfce t four wter content levels. Mny reserches were crried out on the physicl nd engineering properties of soil. Rjrm nd Erbch (1999) studied the effect of wetting nd drying on soil physicl properties. In nother reserch, Zheng Pn et l. (1998) compred the reltionship between pddy soil dhesion to steel nd to rubber. Pesonen-Leinonen et l. (2006) determined soil dhesion to plstic surfce using rdioctive trcer. There re vrious mechnisms through which two prticles in the nture exert force on ech other; the force of ttrction between them is usul nturl phenomenon. Depending on the prticle type, it cn be cohesion-if the two prticles re from the sme prent mteril, or cn be dhesion-if the two re from different prent mteril. Cohesion nd dhesion re the moleculr phenomen occurring t the interfce of liquid nd gs, resulting from the electricl interctions of solid microscopic prticles. The mximum distnce up to which the force of cohesion between molecules cn ct is known s their moleculr-rnge ( 10-7 cm) (Oswl, 1994). An imginry sphere drwn round molecule with its rdius equl to the moleculr rnge nd its center coinciding with the center of the molecule is clled the sphere of influence of the molecule. My it be frm implements, construction mchinery or ny other soil-engging tools, their lrger force requirement increses the input energy nd hence lesser work is resulted per unit effort supplied, which is especilly significnt in sticky soils. In griculturl pplictions, soil-tool dhesion is of greter importnce especilly when previling soil is rich in cly content nd hence sticky by nture. Vrious investigtions hve been crried out to study dhesion mechnism, to quntify soil dhesion properties, to determine their contributing fctors, nd to develop mens of reducing soil-dhesion (Gill nd Vnden Berg, 1968; Chncellor, 1994; Ren et l., 2001). The present study ws conducted to determine cly soil dhesion in vrious tempertures to control energy consumption. Nomenclture A Are of plte, mm 2 W p Weight of plte, kgf 1,, 7 Dimensionless coefficient in models R 2 Coefficient of determintion P Adhesion, Mp RMSE Men squre error g Grvity ccelertion, m/s 2 SSE Some of squre error W w Weight of wter, kgf T Temperture, c 22

MATERIALS AND METHODS Soil description The present investigtion ws crried out t the College of Abourihn of the University of Tehrn. Sturted cly mud ws used in the entire of this study. Cly soil ws obtined from n griculturl field in Vrmin City. The soil type used in this study, ccording to the USA soil clssifiction, ws cly soil with 50 to 80% cly (prticle dimeter less thn 0.01 mm). Experimentl procedure A plstic continer with 25 cm length, 12 cm width nd 7 cm height ws used in experiments. This plstic continer ws used for prepring cly mud with uniform qulifiction. For prepring the cly mud, 1.5 liter wter ws dded to 4 kgf of cly soil until sturted cly mud ws obtined. A blde ws used to chieve uniform mixture. After prepring uniform mixture, blde ws used to smooth the mud surfce. Smple product ws pcked into refrigertor nd oven in order to get different tempertures. A refrigertor (HY108, Emerson, Irn) ws used for controlling the smple temperture rnge from 5 C to 15 C. For ech chnge in the temperture of refrigertor, the smple ws kept into the refrigertor for seven hours until temperture ws uniform ll over the smple. The continer nd smple were covered with plstic sheet to reduce moisture loss by evportion. The room temperture ws 20 C. In order for the smple to rech 25 C nd 30 C of temperture n oven ws used (E.O.155, Cmos, Irn) nd the smple ws kept in the oven for 3 hours to rech uniform temperture. Three thermometers were put into different positions of the smple. The smple ws kept into the refrigertor. The temperture of ll the three thermometers ws red every one hour. After seven hours, the tempertures of the three thermometers were close to the temperture needed for the experiment. This process ws repeted for the smple lying in the oven nd the time needed to rech uniform temperture throughout the smple ws three hours. In order to mke up for the wter loss which occurs s result of evportion the smple ws weighed before nd fter being plced in oven nd of the decresed weight ws replced by dding of wter. Mesurement of dhesion In order to mesure soil dhesion, specific instrument ws designed. This instrument includes pulley, rope, two continers, vlve nd smooth metl plte with 210 mm length, 70 mm width, 20 mm thickness nd 2.5 kgf weight. The metl plte lloy ws st37 (Fig.1). For mesuring the dhesion, the metl plte ws first set on the smple surfce slowly. The metl plte ws set on the smple surfce for 30s then the rope ws set on the pulley nd one end of the rope ws ttched to the metl plte by hook nd the other end ws ttched to n empty continer. The wter ws dded to the empty continer slowly nd stedily in order to prevent dmping effect when pouring wter into the continer. Adding wter continues until the plte detches from the smple surfce. After seprting the plte from the smple, the mount of the wter inside the continer ws mesured by n electronic precision blnce hving n ccurcy of 0.001 kgf. The dhesion ws clculted s the difference between the weight of the dded wter nd the weight of the plte. 23

B. AZADEGAN, J. MASSAH Ech experiment ws crried out three times in ech temperture rnge. (Ww W p) 9.81 P = (1) A where P is the dhesion of soil in Mp, W w is the weight of wter in kgf, W p is the weight of plte in kgf nd A is the re of plte in mm 2. Figure 1 - Schemtic view of pprtus for mesurement The experimentl dt ws fitted to the equtions proposed in the literture for dhesion s shown in Tble 1. The coefficient of dhesion ws estimted from the experimentl dt using the regression nlysis (spss 13) which minimizes residul sum of squres. The models were fitted by mens of numericl curve-fitting in MATLAB computer progrm. Three criteri were used to verify the models coefficient of determintion (R 2 ), sum of squre error (SSE) nd men squre error (RMSE). Tble 1 - Empiricl equtions describing the dhesion Nme of the eqution Eqution Eq. No. Liner polynomil P = 1T+ 2 (2) Qudrtic polynomil P 2 = T + T+ (3) 3 4 5 Exponentil P = 6exp(7T) (4) RESULT AND DISCUSSION The results of the vrince nlysis of cly soil dhesion re given in Tble 2. The results indicted tht there ws significnt difference mong ll tempertures in 1 % of probbility. Men vlues of dhesion for sturted cly soil s function of temperture re shown in Fig. 2. As cn be seen from Fig. 2, one of the 24

importnt fctors influencing the dhesion is temperture. Adhesion ws decresed with n increse in the temperture of the smple. With n increse in temperture from 5 ºc to 30 ºc, dhesion of cly soil ws decresed from 8.53 10-4 to 1.57 10-4 Mp. The curve fitting procedure ws performed for three semi-empiricl models. The sttisticl results of the three semi-empiricl models tht re determintion coefficient R 2, sum of squre error SSE nd men squre error RMSE re given in Tble 3. Tble 2 - Anlysis of vrince for dhesion of soil t different tempertures Source df Sum of squres Men of squres F Tretment 5 1.163 10-6 2.327 21.19 ** Error 12 1.318 10-7 1.098 Totl 17 1.295 10-6 CV% 22.72 ** Corresponding to 1% probbility Figure 2 - Experimentl nd predicted dhesion for sturted cly mud using qudrtic polynomil s function of temperture Tble 3 - Result of sttisticl nlysis of the modeling of dhesion Model nme R 2 Adhesion RMSE SSE Liner polynomil 0.9674 0.5622 1.264 Qudrtic polynomil 0.9902 0.3556 0.3793 Exponentil 0.9787 0.4548 0.8275 25

B. AZADEGAN, J. MASSAH The coefficient vlues of liner polynomil, qudrtic polynomil nd exponentil models for determining the dhesion of sturted cly soil re represented in Tble 4. The results indicted tht the highest vlue of R 2 nd the lowest vlues of SSE nd RMSE could be obtined by qudrtic polynomil model. A comprison of the experimentl nd predicted dhesion vlues using qudrtic polynomil model is illustrted in Fig. 2. Tble 4 - The coefficient vlues of liner polynomil, qudrtic polynomil nd exponentil model Model nme Liner polynomil Qudrtic polynomil Exponentil coefficient 1-0.2928 2 9.737 3 0.006159 4-0.05084 5 11.17 6 12.34 7-0.06417 CONCLUSIONS The temperture ws effective on the dhesion of cly soil. With n increse in temperture from 5 ºc to 30 ºc, the dhesion of cly soil ws decresed bout 82%. The results showed tht the qudrtic polynomil model hd the strongest correltion with the experimentl dt. REFERENCES Chncellor W.J., 1994 - Friction between soil nd equipments-review. ASAE Pper, No. 94-1034. Fountine, E.R.,1954 - Investigtions into the mechnism of soil dhesion. Journl of soil science, 5(2):251-263. Gill W.R., Vnden Berg G.E., 1968 - Soil dynmics in trction. Agriculturl Hndbook, No. 316. Agriculturl Reserch Service. US Deprtment of Agriculture. Hendrick J.G, Biley A.C., 1982 - Determining components of soilmetl sliding resistnce, Trns. ASAE, 25 (4) (1982) 845-849. Oswl M.C., 1994 - Soil physics. Oxford & IBH Publishing Co. Pvt.Ltd. New Delhi. Pesonen-Leinonen E., Redsven I., Neuvonen P., Hurme K.R., Pääkkö M., Koponen H.K., Pkknen T.T., Uusi-Ruv A., Hutl M., Sjöberg A.M., 2006 - Determintion of soil dhesion to plstic surfce using rdioctive trcer. Applied Rdition nd Isotopes 64, 163-169. Rjrm G, Erbch D.C., 1998 - Effect of wetting nd drying on soil physicl properties. Journl of Terrmechnics 36 (1999) 39-49. 26

Ren L.Q., Tong J., Li J. Q., Chen B.C., 2001 - Soil dhesion nd biomimetics of soil-engging components. Journl of Agriculturl Engineering Reserch, 79, 239-263 Shi-qio D., 2004 - The mechnism of reducing soil dhesion nd the design of bionic plow. Ph.D. Thesis, Jilin University (unpublished) (In Chinese). Tong J., 1993 - Study on reducing dhesion nd resistnce of soil to soil engging components of mchinery for lnd locomotion by bionics, Ph.D. Thesis, Jilin University of Technology, Chngchun, Chin (In Chinese). Zeng D., 1995 - The dynmics of mechnicl-edphic system. Agriculturl Hndbook Beijing Science nd Technology Press, Beijing, Chin (In Chinese). Zheng Pn J., Xiong Lu Z., 1998 - Reltionship between pddy soil dhesion to steel nd to rubber. Journl of Terrmechnics 35 (1998) 155-158. 27