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

JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(4), 16-21 ISSN:2325–4513(PRINT) ISSN 2325 - 453X (ONLINE)RESEARCH ARTICLE 16Suitability of Prosopis Chilensis (Mesquite) Wood forCement Bonded AggregatesAshraf Mohamed Ahmed Abdalla 1 * and Hamdoun Ali Abdelrahman 21 Department of forest products and Industries, Faculty of Forestry University of Khartoum2 Department of Forestry and range science, Faculty of Natural resources and environmental studies, University ofKordofan(Received April 19, 2013; Accepted June 30, 2013)Abstract— The objective of this work is to study the compatibilityof mesquite wood (Prosopis chilensis) with ordinary Portlandcement and its suitability for the production of wood-cementaggregates. Determination of extractive content of mesquite woodusing cold water, hot water and mild alkali extraction methodsfollowing ASTM standard, (D 1110-56) was conducted underlaboratory condition using completely randomized design.Mesquite wood compatibility with ordinary Portland cement wasstudied by soaking in water and soaking in sodium hydroxidesolution also addition of calcium chloride and addition of gypsumwas investigated. The Effect of cement/wood ratios of 2:1, 3:1, 4:1and 5:1) on the properties of mesquite wood cement aggregateswas studied. The results showed that mesquite wood extractivescan successfully be removed or minimized by soaking in cold water.Also the results indicated that mesquite wood can combine wellwith cement even without treatment. However addition of gypsum(20% based on cement weight) increased the compressive strengthmore than 100% when compared with the other treatments.Index Terms— Prosopis chilensis, wood-cement aggregates,Portland cement, Extractives, Binder.PI. INTRODUCTIONortland cement is an inorganic binder that can be used forthe production of composite panels. Many studies havefocused on understanding the complex behavior of awood-cement-water mixture [1-7]. At present time,wood-cement panels are experiencing renewed interestsbecause of their potential application in the building industry [8].They have specific advantages over conventional resin-bondedparticleboard that includes resistance to fire, insects and rots.Also they have advantages of light weight over normal concrete.But cement-wood bonded products cannot pass withoutproblems; one of these problems is the poisoning effect of woodextractive on cement setting process [2, 5, 6, 7, 9, 10, 11]. Theextractives are more abundant in hardwoods than in softwoods[12]. Many Sudanese hardwood species contain a verity ofextractive that are expected to cause problems in cement setting[2, 5, 6, 7]. The knowledge of*Corresponding author E-mail: amahmed@uofk.eduAddress: Department of forest products and Industries, Faculty of ForestryUniversity of Khartoumextractive content of these species will help to predict to acertain extend the suitability of various species for productionof cement bonded products. Abdelgadir and Ibrahim [2]concluded that compressive strength of wood-cement mixtureis considerably reduced as cement/wood ratios were decreasedfor the five Sudanese hardwood species studied.Mesquite Prosopis chilensis is one of these species. It colonizedmany habitats in different part of Sudan and is utilized only forfire wood. Several efforts were undertaken to control mesquitebut they were not sustainable due to strong coppicing power ofthis species, one way of controlling the fast growth and spreadof mesquite is to manage it for production of round wood forbuilding, wood based composite and processed fodder fromfruit to prevent dispersion of seeds by animal. This study is anattempt to find another way of utilizing mesquite wood (sap andheart wood) for production of cement bonded aggregates.The overall objective of this work is to study the compatibilityof mesquite wood (Prosopis chilensis) wood with ordinaryPortland cement and its suitability for the production ofwood-cement aggregates. While specific objectives are: Tostudy the effect of extraction methods on the amount ofextractives of mesquite wood (sapwood and heartwood), toinvestigate the effect of different pretreatments on mesquitewood-cement compatibility, to investigate the effect ofcement-wood ratios on the performance of mesquitewood-cement aggregates and to study the effect of partialreplacement of cement by gypsum using a fixed cement-woodratio.II. MATERIALS AND METHODSWoodThe wood material used in this investigation was obtained fromProsopis chilensis (mesquite) collected from Bara area,Northern Kordofan state. This wood is characterized its darkbrown color, frequently with a purple hue; it is very hard and thegrain is irregular, but easy to work. It has applications incarpentry, floors, and as poles and fuel.The wood manually was cut into chips, milled using hammermill and then screened using a set of standard meshes. Theportion which passed through mesh 0.5 mm was used for woodsolubility and that passed through mesh 2 and 4 mm was usedfor preparation of the test specimens because it constitutes thebulk of the prepared wood material (about 80%).

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

JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(4), 16-21 ISSN:2325–4513(PRINT) ISSN 2325 - 453X (ONLINE)19The results of the mean separation test for the effect of differentwood pretreatments on compressive strength (Kg/cm 2 ) showedthat addition of gypsum gave the highest value and wassignificantly different from all other treatments followed bycontrol, addition of calcium chloride and soaking in cold water,between which no differences were found. Extraction by NaOH1% was ranked last, and this may be attributed to the adverseeffect of the sodium in lowering the air dry density, in this studyincreasing density associated with better properties and this isgoes in total agreement with the finding of abdalgadir andIbrahim [2] who stated that the compressive strength is highlycorrelated with the density of wood cement mixture. Previousworks of Hassan [17] and Ibrahim [18] concluded that, additionof calcium Chloride help in improving the compressive strengthand ranked first, while in this study addition of calcium chlorideranked secondly. Addition of gypsum (20% -based on cementweight) increased the compressive strength more than 100%compared with the others treatments and displaced calciumchloride from the top rank. This may possibly be due toincreased air dry density. An exciting result was that soakingmesquite wood in cold water as well as control shared the samerank with addition of calcium chloride, which indicated thatmesquite wood can safely be used to produce cement bondedproducts without any sort of treatment. This may be attributed tothe fact that the extractives present in mesquite wood did nothave an inhibitory effect on cement setting.As shown in Table 2 the results of the mean separation test forthe effect of wood pretreatment on the water absorptionpercentage of mesquite wood – cement bonded aggregates.,addition of gypsum, addition of calcium chloride and controlsgave the best result when soaked for two hours and were notsignificantly different from each other, but were significantlydifferent from soaking in cold water and soaking in 1% sodiumhydroxide solution (Table 2). But when soaking was extendedto 24 hours, addition of gypsum and addition of calciumchloride significantly improved water absorption, while controlranked third, but not significantly different from addition ofcalcium chloride. Soaking in 1% sodium hydroxide solutionopposite was true. The results of mean separation test for theeffect of cement/ wood ratio on water absorption are shown in 7revealed that, significant differences between the ratios wereobserved when the specimens were soaked for 2 hours, with thetrend that as cement wood ratio increased water absorptiondecreased. This result goes in total agreement with the findingof Elten [21] who found that the water absorption tended todecrease as the amount of cement was increased from 50:50 to30:70. Obviously, a higher wood content (lower cement: wood:ratio), would result in greater water absorption due the nature ofwood which will be less surrounded by cement, but increasingthe cement ratio results in better coating of wood particles. Thisprevents them from absorbing water. There were alsosignificant differences between ratios when specimens weresoaked for 24 hours, which indicate that the aggregatesshowed the highest percentage of water absorption. Generallypretreating any hardwood improves water absorptionpercentage due to improvement of cement setting conditions.Previous work by Hassan [17] and Ashraf and abdalazim [5]concluded that the addition of calcium chloride significantlyimproved water absorption percentage. However addition ofgypsum in this study showed better aggregate performance thanaddition of calcium chloride.Effect of cement/wood ratios on the density of mesquitewood/cement bonded aggregatesMean separation test results for the effect of cement wood ratioon mesquite wood-cement bonded aggregates air dry density,compressive strength and water absorption percentage (2 and 24hours) were presented in Table 3. Regarding air dry density, nosignificant differences were observed between ratios 4:1 and5:1which gave the highest value. But there were significantdifferences between the other ratios. As expected increasingcement/wood ratio results in increased aggregate air dry densitysince addition of more cement means increasing the specimenweight. The same conclusion was found by Zhou and Kamdem[19] who stated that, cement-bonded particleboard that utilizelarge amounts of cement in comparison to wood (cement: woodratio higher than 3:1), result in final product with high density(>1300 kg/m 3 ), because cement is denser than wood. AlsoOyagade et al., [20] reported that veneer laminatedcement-bonded particleboard were stronger and stiffer withincreased cement/wood ratio due to increased density.As shown in Table 3 significant differences were foundbetween the four studied ratios regarding compressive strength.As observed from the Table 3 increasing cement: wood ratioresulted in increasing compressive strength. This can beattributed to the increased air dry density. This goes in totalagreement with the finding of Abdelgadir and Ibrahim [2] whoconcluded that compressive strength of cement- wood mixturefor five Sudanese hardwood species is considerably reduced ascement/wood ratios were decreased and theabsorbed huge amount of water during the first hours of soaking,while increasing the soaking time result in only a fewpercentages of increase (3-6%). which agreed well with theconclusion of Hassan [17] who concluded that soaking in waterfor 24 hours increased the amount of water absorption by anaverage of 6% compared to soaking for 2 hours. From all abovementioned results, it may be concluded that aggregates with lowcement wood ratio absorb more water and possesses lowercompressive strength. However, aggregates with highercement/wood ratio (4:1 and 5:1) absorb small amount of water,possesses higher compressive strength and heavy weight (highdensity). The aggregate produced with cement wood ratio of 3:1had reasonable weight, good strength and reliable density. Theoverall conclusion is that 3:1 cement wood ratio is the suitableand recommended ratio to be used for untreated mesquite wood.

JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(4), 16-21 ISSN:2325–4513(PRINT) ISSN 2325 - 453X (ONLINE)20Table 3Effect of cement/wood ratios on some properties of mesquite wood/cement bonded aggregatesCement/wood ratio Density Compressive strength Water absorption (%)(g/cm 3 )(kgf/cm 2 )2 hours 24 hours5:1 1.475 a 110.72 a 19.38 d 25.9 c4:1 1.394 a 90.90 b 23.64 c 27.9 c3:1 1.148 b 37.94 c 31.55 b 34.9 b2:1 0.822 c 16.59 d 44.66 a 50.8 aIn the same columns, means with the same letter/s were not significantly different at P= 0.05Table 4Effect of cement partial substitute by gypsum on some properties of mesquite wood/cement bonded aggregatesGypsum replacement Density Compressive strength Water absorption (%)percentage (%) (g/cm 3 )(kgf/cm 2 )2 hours 24 hoursControl (0) 1.148 a 37.94 b 31.55 a 34.90 a10 1.097 b 56.89 a 26.45 b 29.85 b20 1.057 b 39.37 b 30.85 ab 33.84 ab30 1.034 b 25.74 c 33.90 a 37.76 a50 1.014 b 24.88 c 34.06 a 36.94 aIn the same columns, means with the same letter/s were not significantly different at P= 0.05Effect of cement partial substitute by gypsum on the density ofmesquite wood/cement bonded aggregatesThe results of the mean separation test for the effect of cementpartial replacement by gypsum on mesquite wood-cementbonded aggregates air dry density, compressive strength andwater absorption percentage (2 and 24 hours) were presented inTable 4. The mean separation test for air dry density shows that,no significant differences were found between the differentpercentages of the substitute (10, 20, 30 and 50%, based oncement weight). But there is a trend of reducing density byincreasing the gypsum replacement percentage and statisticallyappear to be significant. In general the pure cement density isapproximately twice the density of the gypsum. This fact mayexplain the reduction caused in specimens air dry density asgypsum replacement percentage increase.For the compressive strength the mean separation test showedsignificant differences between all levels of replacement (10, 20,30 and 50%). The highest compressive strength was associatedwith 10% substitute which was significant differences from allother substitute levels. This was followed by 20%. However nosignificant differences were observed between 30 and 50%substitute. When comparing this result with control, the controlcompressive strength showed no significant difference from thatof 20% replacement, while 10% replacement improved thecompressive strength significantly over that of the control. Thegypsum partial replacement of 10% increased the compressivestrength more than 100 percent when compared with thepercentage 30 and 50. This indicated that the partialreplacement of cement by gypsum in fewer amount is sufficientto improve the aggregates compressive strength. Whileincreasing the percentage more than 20% causes reduction oncompressive strength of the aggregate. This may be attributed tothe fact that increasing the amount of gypsum affected thesetting and curing process of cement through absorbing morewater, rendering insufficient amount of water for cement setting.Also a possible explanation may be due to the decrease whichoccurred in the aggregate density. According to SudaneseStandard, the minimum requirement of compressive strength forburnt clay bricks should not be less than 20 Kg/cm 2 . Referringto the result of this experiment, the worst mesquite wood cementaggregates showed compressive strength of 24.8 Kg/cm 2 whichexceeds the required compressive strength by the standard.Lower percentages of substitute significantly improve waterabsorption of the aggregate when soaked for both 2 and 24hours as shown in Table 4. Increasing replacement percentagesignificantly increases water absorption for both periods ofsoaking. A possible explanation may be that increasing gypsumpercentage takes more water during the molding, so negatively

JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(4), 16-21 ISSN:2325–4513(PRINT) ISSN 2325 - 453X (ONLINE)21affect the process of cement setting. Which result in poorcoating of wood particles with cement, so when subjected tomoisture, they absorbed large quantity of water.IV. CONCLUSIONSBased on the findings and results of this study, the followingconclusions can be drawn:-- Mesquite (Prosopis chilensis) wood extractives cansuccessfully be removed or minimized by soaking incold water.- Mesquite wood can combine well with cement evenwithout treatment.- Addition of gypsum (10% based on cement weight)increased the compressive strength more than 100%when compared with the other treatments.- The addition of gypsum resulted in better performancethan the addition of Calcium chloride.- Increasing cement portion resulted in increasedaggregates density, increased compressive strengthand lower percentage of water absorption.- The gypsum partial substitute of 10% increased thecompressive strength more than hundred percent whencompared with the percentage 30 and 50, thisexpressed that the partial substitute of cement bygypsum in fewer amount is sufficient to improve theaggregates compressive strength.REFERNCES[1] Sandermann, H.J. Preusser, and W. Shweers. 1960. The effect of woodextractives on the setting of cement-bonded wood materials.Holzforschung 14(3):70-77.[2] Simatupang, M.H. 1979. The water requirement of manufacturedcement-bonded particleboard. Holz Roh-Werkst 37:379-382.[3] Miller, D. P. 1987: Wood-cement composite: interactions of woodcomponents with Portland cement Ph.D. Dissertation, University of Idaho,and Moscow, Idaho, USA.[4] Abdelgadir, A.Y. and M.F.S. Ibrahim 2003. Effect of pretreatments andcement/wood ratio on compatibility of wood with Portland cement. SudanSilva 9(2): 77-85.[5] Ashraf M.A. Abdalla and A.Y. Abdelgadir. 2006. Effect of particle size andcement/wood ratio on some properties of Acacia nilotica wood-cementaggregates. Sudan Silva 12(1): 41-52[6] Bashir, Amel, A; Abdelazim Y. A. and Osman T. Elzaki 2007. Effect ofCement/Wood Ratio, Calcium Chloride Content and Pressure oncompressive Strength of Acacia seyal Wood-Cement Aggregates. SudanSilva 13 (1): 25-35.[7] Ashraf Mohamed Ahmed Abdalla; Tarig Tag Elsir Hassan; Abdelazim YassinAbdelgadir and Abdael Lateif El Tayeb Mahoumd. 2010. Effect of coldwater duration extraction and calcium chloride treatment on physicalproperties of Acacia nilotica wood-cement aggregates. Sudan Silva 14(1):1-9[8] Dinwoodie, J. M.; Paxon, B. M. 1983: wood cement particleboard- Atechnical assessment. Building Research Establishment informationpaper. IP 4/83:1-4.[9] Paramenwaran, V. N.; Broker, F. W.and Simatupang, M. H. 1977: Micromorphological studies on mineral-bonded wood composite. Interactionbetween binders and wood. Holzforschung 31: 173-178.[10] Parameswaran, V. N.; Broker, F. W. 1979; Micro morphologicalinvestigation on wood- cement composite after long –term use.Holzforchung 33:97-102.[11] Abdelazim Yassin Abdelgadir and Ashraf M. Ahmed Abdalla. 2005.Effect of wood pretreatments on the modulus of rupture of Acacia niloticawood-cement aggregate. Sudan Silva 11(1): 79-84[12] Gnannaharan, R, and T. K. Dhamodaran, 1985. Suitability of sometropical hard wood for cement-bonded wood-wool board manufacturesHolzforschung 39(6):337-340.[13] American Society of Testing and Materials 1956 (ASTM). Annual Bookof ASTM Standards, Vol. 04-02. C39-83b.[14] SAS Institute Inc. 1990. SAS/STAT Guide for Personal computers. Version6 Ed. SAS Institute Inc., Carry, NC.[15] Mohammed, A.A 1999.The effect of wood extractives of someSudanese tree species on Portland cement setting M.Scthesis submitted tothe University Khartoum.[16] Ahn, W. Y.; Moslemi,A.A. 1980. SEM examination of Portland cementbonds. Wood Sciences and Technology. 13: 17-82.[17] Hassan, T.T.E. 1999. Effect of Some Physical and Chemical additives onthe mechanical and physical properties of Acacia nilotica wood cementmixture. M.Sc. Thesis submitted to the University of Khartoum.[18] Ibrahim. M. F. 1995. Effect of Species Treatment and Cement woodRatios on the Compressive Strength of Wood-Cement Mixture. M.Sc.Thesis, Faculty of Forestry, University of Khartoum-Sudan.[19] Zhou, Y.; Kamdem, D.P. 2002. Effect of cement/wood ratio on theproperties of cement-bonded particleboard using CCA-treated woodremoved from service. Forest Products Journal 52 (2): 73-81.[20] Oyagade, A.O.; S.O.O. Badejo, and O. A. Omole 1995. A preliminaryevaluation of flexural properties of wood-veneer laminatedcement-bonded particleboard from tropical hardwood species. Journal oftropical forestry and wood technology of the timber Developmentassociation of India 41 (3): 25-29.[21] Elten, G.V. 2000. Production, Properties and application of various woodscement products. Especially wood Journal. September/October2000:18-24.