(L) Seeds on Germination of Striga Hermonthica (Del.) Benth Seeds

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JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(4), 16-21 ISSN:2325–4513(PRINT) ISSN 2325 - 453X (ONLINE)17Cement and other materialsPortland cement produced by Atbra cement Corporation, Sudanwas used as binding material for all experiments. Other materialused includes, calcium chloride CaCl 2 used as cement settingaccelerator. Sodium hydroxide NaOH used as pretreatmentsolvent and gypsum CaSO 4 .2H 2 O used as chemical additives.Methodsvsome of the promising results obtained in the first threeexperiments will be used in the latter one. These experimentsare, determination of extractive content of mesquite wood(extractives solubility) using cold water, hot water and mildalkali extraction methods following ASTM standard, 1981 (D1110-56)[13], selection of the best pretreatment/s to be appliedto mesquite wood to improve its compatibility with ordinaryPortland cement (soaking in water, soaking in sodiumhydroxide solution, addition of calcium chloride and addition ofgypsum); investigation of the effect of cement/wood ratios (2:1,3:1, 4:1 and 5:1) on the properties of mesquite wood cementaggregates and studying the effect of cement partial replacementby gypsum when low cement wood ratio (3:1) was used.The effect of Extraction methods on mesquite wood extractivecontentCold water extractionTwo grams of milled oven dry wood were soaked into 300 ml ofdistilled water and left for 48 hours at room temperature, thesoluble portion was filtered, and then the residues were washedwith distilled water and dried into an oven at 105ºC. Dryingprocess was continued until constant weight was obtained, thenthe extractive content was calculated based on the initial sampleweight.Hot water extractionTwo grams of (oven dry) milled sieved wood were soaked into100 ml of hot distilled water and maintained at 70ºC in waterbath for three hours, then the sample was treated as in cold waterextraction.Mild alkali extractionsTwo concentrations of Sodium hydroxide solution wereprepared, (namely 0.5% and 1%) and used as extraction agent.Two grams of milled sieved wood were soaked in 100 ml of0.5% sodium hydroxide solution and maintained in a water bathat 97-100ºC for one hour, and then the sample was treated as incold water treatment.Effect of pretreatments applied to mesquite woodThe pretreatments used for mesquite wood to improve itscompatibility with Portland cement were, soaking in cold water,addition of calcium chloride, soaking in 1% sodium hydroxideand addition of gypsum.Soaking in cold waterFor cold water treatment wood particles were soaked in tapwater for two weeks. Every two days, water was replaced byclean water to remove water soluble extractive that dissolved,and then the wood particles were air dried for one week. Using afixed cement wood ratio of 2:1 and the appropriate amount ofwater, a mixture of wood, cement and water was prepared fromwhich five experimental specimens were produced. Theappropriate amount of water was calculated according to thefollowing equation:[6]W= 0.35C+ (0.3-MC) ×W oWhereW: water/LC: Cement weighs KgW o : Oven dry weigh of wood KgMC: Moisture content of woodThe specimens were prepared using metallic mould of 7×7×7cm.Then the specimens were left for 24 hours for cement setting,and the metallic mould was removed from the specimens afterwhich the specimens were soaked in water for 28 days in orderto allow complete curing of cement.Soaking in sodium hydroxide solutionThe wood particles were soaked in 1% sodium hydroxidesolution for 24 hours, and then the particles were washed severaltimes with tap water to remove the sodium hydroxide andextractive. They were left to air dry after that five specimenswere prepared using the same method described in the previoussection.Addition of Calcium chloride (CaCl 2 )Based on cement weight 3% of calcium chloride was added tothe wood, cement and water mixture. Five specimens wereprepared from this mixture in the same way as in the precedingsections.Addition of GypsumBased on cement weight 20% of commercial gypsum was addedto the mesquite wood cement mixture and then the experimentproceeded as in the cold water treatment to produce fiveexperimental units.ControlUntreated wood from Prosopis chillensis (mesquite) was mixedwith cement using the same ratio as control to compare theabove mentioned pretreatments. Five specimens were producedusing the same method as that used for cold water treatment.The effect of cement/wood ratios on the properties ofmesquite wood cement aggregatesUsing Completely Randomized Design (CRD) with fivereplicates. Four cement wood ratios namely 2:1, 3:1, 4:1 and 5:1were used. Wood particles were mixed with Portland cementwithout any treatment or additives, the required amount of waterwas added, then the mixture was molded into testing metallicmold of (7×7×7 cm) and left for 24 hours for setting. Then theresulting cubes were soaked in water for four weeks forcomplete cement curing.
JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(4), 16-21 ISSN:2325–4513(PRINT) ISSN 2325 - 453X (ONLINE)18The effect of cement partial replacement by gypsum on theproperties of Mesquite wood cement aggregatesUnder completely randomized design with five replicates usinga fixed cement wood ratio of 3:1, four levels of cementreplacement by gypsum were done. The selected levels ofreplacement were 10, 20, 30 and 50% based on cement weight.Wood particles were mixed with Portland cement, and thegypsum according to each level of replacement, and thenproceeded as in the effect of cement wood ratio experiment.Another replicate was molded without any gypsum to serve ascontrol.Property measurementAll the specimens were tested for water absorption for 2 and 24hour, density and compressive strength according to ASTMStandard (D-1039).Statistical AnalysisThe data collected from the above mentioned experiments wasanalyzed using (SAS) software [14]. Analysis of variance andmean separation test using Duncan’s multiple range tests.III. RESULTS AND DISCUSSIONSEffect of extraction methodsTable 1 shows the result of the mean separation test for theeffect of different extraction methods used to determine theextractives content of mesquite wood. One percent mild alkaliextraction method gave the highest content and wassignificantly different from cold and hot water extractionmethods, while no significant differences was observed between1 and 0.5% mild alkali extraction method. Also no significantdifferences was found between 0.5% mild alkali extraction andcold water method, which was not significantly different fromhot water extraction. Generally as the severity of extractionmethod increase the percentage of extractive content increased.These conclusion not agreed with the findings of Mohammed[15] when he concluded that, the extractive contents of thestudied species (Acacia nilotica, Calotropis Procera,Cupressus lusitanica and Eucalyptus microtheca) variedbetween 5.9% and 11.2% when extracted with cold water,between 19.5% and 25.65 when extracted with hot water andbetween 23% and 39.6% when extracted with NaOH 1% andincreased by increasing the severity of extraction method. Theseresults indicated that mesquite wood extractive can successfullybe removed or minimized by soaking in cold water.Table 1The effect of extraction methods on mesquite wood extractivecontentExtraction methodExtractive content (%)NaOH 1%NaOH 0.5%Cold waterHot water31.07a28.60ab20.19bc12.60cIn the same column, means with the same letter/s are notsignificantly different at P =0.05Effect of wood pretreatment on some properties of mesquitewood cement bonded aggregatesThe results of the mean separation test for the effect of woodpretreatment on the air dry density, compressive strength andwater absorption percentage (2 and 24 hours) of the mesquitewood cement bonded aggregate is presented in Table 2.Regarding air dry density significant difference was foundbetween addition of gypsum and other pretreatments, theaddition of gypsum rank first, while no differences wereobserved between addition of calcium chloride and untreatedwood (control) which were significantly different from eithersoaking in cold water or 1% sodium hydroxide solution. Asexpected, addition of gypsum increases the air dry density andthis obviously due to high density of gypsum itself. Also thisfinding was not in line with the finding of Ahn and Moslemi [16]who observed that CaCl 2 tends to improve the bond betweenwood and cement and rank first, while in this study addition ofcalcium chloride ranks second and share the same ranks withuntreated wood. From the above discussed results it can beconcluded that mesquite wood can combine well with cementeven without treatment.Table 2Effect of wood pretreatments on mesquite wood cementbonded aggregate some propertiesTreatment Density Compressive Water absorption (%)(g/cm 3 )strength(kgf/cm 2 )2 hours 24 hoursGypsum 1.126 a 51.318 a 45.423 a 50.286 aCalcium1.009 b 24.799 b 32.491 b 37.582 bchlorideControl 0.9972 b 24.675 b 24.688 c 28.126 cCold water 0.9176 c 23.223 b 22.708 c 26.489 cdNaOH 1% 0.8338 d 09.123 c 18.796 c 22.736 dIn the same columns, means with the same letter/s were notsignificantly different at 0.05
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(L) Seeds on Germination of Striga Hermonthica (Del.) Benth Seeds

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