Effect of dynamic load impact of missile on mechanical behavior of ferrocement

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Effect of dynamic load impact of missile on mechanical behavior of ferrocement

  1. 1. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME295EFFECT OF DYNAMIC LOAD: IMPACT OF MISSILE ONMECHANICAL BEHAVIOR OF FERROCEMENT –INFRASTRUCTURE APPLICATIONMohammed Mansour KadhumPhD, Assistant Professor,College of Engineering, Babylon University,Iraq / Babylon / 40 StreetABSTRACTAn investigation into the behavior of ferrocement barriers subjected to impactload testing and missile impact is reported. This impact test was used to evaluate themechanical behavior of cement mortar panels reinforced with one or more of the followingreinforcement types: square steel chicken wire meshes, hexagonal steel chicken wire meshes,steel fibers and polypropylene fibers randomly distributed in plane. One missile impactvelocity, size and weight was used to investigate the results of the influence of variousmechanical parameters on impact effects due to projectile impact.This paper describes the first part of a study, which aims to apply of ferrocementpanel in road as a base course to treatments and investigate the wider issues with itsapplication to road pavements.The test results showed that the depth of penetration of projectiles decreasedfrom 23mm for the plain cement mortar panel to 8.7mm for the ferrocement panels withsquare steel wire mesh reinforced cement mortar Panels. Whereas, the cement mortar panelswhich are reinforced with randomly distributed polypropylene fibers showed no enhancementto impact resistance when measured by the depth of penetration caused by the projectiles.Also, the drop load depth can be a reasonable indicator of cumulative damage in the case ofdrop impact testKeywords: Ferrocement; Missile impact; Projectiles; Depth of penetration; barriersINTERNATIONAL JOURNAL OF CIVIL ENGINEERING ANDTECHNOLOGY (IJCIET)ISSN 0976 – 6308 (Print)ISSN 0976 – 6316(Online)Volume 4, Issue 2, March - April (2013), pp. 295-305© IAEME: www.iaeme.com/ijciet.aspJournal Impact Factor (2013): 5.3277 (Calculated by GISI)www.jifactor.comIJCIET© IAEME
  2. 2. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME2961. INTRODUCTIONFiber and mesh reinforced concrete was found to be adequate in sustainingimpact, blast, explosion and other forms of dynamic loads. Although, the tougheningmechanism was well understood in this composite material under statically applied loads,unfortunately in case of impact and other dynamic loads, our understanding is inadequate(Banthia et al., 1998).Several studies such as (Mansur et al.,2000) on punching shear strength offerrocement have shown that due to its reinforcement characteristics it has an incrediblemechanical characteristics. However, they used a thin-walled composite comprising closelyspaced layers of fine wire mesh encapsulated in a cement mortar matrix.Generally, researchers (Ramakrishnan et al., 1980; Swamy and Jojagha 1982)were used the drop weight test developed by (Schrader, 1981) and published by the (ACIcommittee 544-1988) to measure the impact resistance of fiber reinforced cement composites.The economical and environmental advantages of using reinforcement toprovide thinner road structures, longer life cycles and reduction in maintenance costs and ofcourse savings in natural resources due to prolonged service intervals.On the other hand, the projectile impact feature could be more representative. Ingeneral, the projectile impact mass leads to two types of responses which are: Firstly, the loadcollision local effects such as surface indentation and local crushing suffered by the target orpenetration of the projectiles. Secondly, the overall dynamic responses of the target whichconsist mainly of wave propagation and scabbing.The depth of penetration is a function of the velocity and mass of the projectileas well as the stiffness of the targets material. For concrete the latter parameter is normallyrelated to the compressive strength (Gao 2007).In the present work, the first type of responses has been investigated which depends on thefollowing parameters:- Projectile properties: weight, caliber, shape and strength.- Target properties: strength, ductility and density.- Striking velocity: impact velocity and angle of incidence.2. EXPERIMENTAL PROGRAM2.1 Testing procedure and instrumentationThe ferrocement specimens which are subjected to test should be cast in rigiddismountable moulds made of metal. The spacing of steel mesh wires and fiber reinforcementin the moulds should correspond to the regular reinforcement ratios. The identical spacingbetween particular layers of wire mesh in specimens and structure was attained. The detailsof the test specimens are shown in Figure 1.
  3. 3. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME297Figure 1. Dimension and detail of the specimenThe mould is supplied by separating combs that stabilize the horizontal position of wiremesh and distance sheets that determine the stable vertical position of the wire mesh layers. The stripsof particular wire mesh layers passing through the separating combs and separated by distance sheetsare rigidly fixed in each opposite two ends of the mould.In this experimental investigation, a spherical head of non-deformable type projectilewith a mass of about 0.2kg and diameter of 25mm was used. The small balls projectile were shootfrom a shooting gun as shown in Figure 2. The head and body of the projectiles were made from steeland aluminum respectively. These projectiles were ejected by air pressure at velocity of about 218m/sec; this speed is sufficient to model collision by an aircraft. Also, a high speed camera, whichcapable of recording about 5350 frames per second was poisoned beside the specimen to recordcollision behavior when the missile projectile approach to the tested panel specimen.The panel specimen was suspended vertically in front of the gun by two steel slings toallow free movement after impact. Also, the impact direction of the steel ball projectiles was mountednormally to the ferrocement panel as can seen in Figure 2. After being impacted by the projectilemissiles, the panel specimens were examined visually. Various measurements, such as penetrationdepth, dimension of damage area of both front and rear faces and weight of flying concrete weredetermined. The shooting distance of the gun was kept at 5.0 meters away from the panel target.Point of collisiongunSteel and aluminum ball projectilesFerrocement panel barrierSpecimenStopperFigure 2. Dimension of the missile projectile an schematic impact test apparatus arrangementB) Test SetupA) Missile ProjectileHeadBody45 20 1045400mm400mmThickness of panel= 50mmSteel wire mesh fixedin place by rivets
  4. 4. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME298For the ferrocement panel specimens which were subjected under impact load,the conducted impact test was the drop-weight test. In this work, a testing apparatusmanufactured locally is presented. The details of this apparatus were presented by earlierwork of (Barr and Baghli 1989). The impact apparatus consists of three main components:i. The supporting frame,ii. The drop weight guide system, andiii. The impact masses or strikers.A special supporting frame was manufactured and used. This supporting framewas made using four steel beams of the type W-shape (W4×13) welded and arranged to form asquare shape. Steel bars of (25mm) diameter welded on top faces of each four steel beams toprovide a simply support for the ferrocement panel specimen edge as shown in Figure 3.The specimens simply supported and the impacting mass was dropped freely through theguiding system at the center of the specimen by a line contact between the impacting massand the specimen surface. The front end of the impact masses has a rounded surface in orderto create a line contact between the impact mass and the test specimens. The numbers ofblows which cause ferrocement fracture were calculated as impact resistance. The energyproduced by each blow is given by the product of the drop height and weight of the striker,and then the total impact energy is determined by multiplying the energy per blow by thenumber of blows.2.2 Casting and curing the panel specimensAfter the mould preparation, cement mortar mixture was mixed using a smallrotating mixer. Then the mixture is casted in the prepared mould in layers each of 5mm. Forthe ferrocement panels a layer of chicken wire mesh was fixed in place each 10mm of depth;i.e. 4 layers for each panel. While for the fiber reinforced cement mortar plates, the specifiedFigure 3. Schematic diagram showing impact apparatus
  5. 5. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME299quantity of (crimped steel or polypropylene) fibers was randomly dispersed in plane each5mm depth layer.The fresh panels with the mould were covered with polyethylene sheetsimmediately after casting to prevent dryness and plastic shrinkage cracks. Two days later themould was dismantled carefully and the panels were moist cured by immersing in a watercuring basin for 28 days. After this period of curing the panels were taken off the curingbasin, dried for about two hours before conducting the experimental tests.2.3 MaterialsOrdinary Portland cement and natural sand passing through sieve 2.38mm wereused in the ratio of (cement : fine aggregate was 1:1) by weight. The water-cement ratio usedkept was 0.5. To improve workability, a superplastisizers was added at 0.065% by weight ofcement. Galvanized welded wire meshes were used throughout the test program.2.4 Types of ferrocement panel specimensThe ferrocement panel specimens were reinforced with the following types ofreinforcement:1- Steel chicken wire meshes.2- Steel fibers.3- Polypropylene fibers.4- Steel chicken wire meshes and steel fibers.5- Steel chicken wire meshes and polypropylene fibers.In the present study, the impact resistance of these five types of ferrocementpanel specimens was determined. The panel designation, mix proportions and reinforcementdetails are given in Table 1. The properties of crimped steel fibers and polypropylene fiberswhich were used as reinforcing fibers are given in Table 2. Also, the properties of the squaresteel wire meshes and hexagonal steel wire meshes which were used as reinforcing wiremeshes are given in Table 3.Table 1. Specimens designation and reinforcement details.SpecimensType of ReinforcementFibersVolumeFraction %Steel Wire meshes% by VolumeRP Plain cement mortar ---- ----FS1 Steel fibers 0.9 -----FS2 Steel fibers 0.8 -----FP1 Polypropylene fibers 0.9 -----FP2 Polypropylene fibers 0.8 ----FM Square steel wire mesh ---- 0.9FH Hexagonal steel wire mesh ---- 0.8FMS Square steel wire mesh + steel fibers 0.45 0.45FMPSquare steel wire mesh + polypropylenefibers0.45 0.45FHS Hexagonal steel wire mesh + steel fibers 0.4 0.4FHPHexagonal steel wire mesh + polypropylenefibers0.4 0.4
  6. 6. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME300Table 2. Properties of the reinforcing fibersFiber TypeDensitykg/m3TensileStrength (MPa)Equivalent Diameter(mm)Length(mm)Aspect RatioCrimped steel 7700 1080 0.4 40 100Polypropylene 925 330 0.42 50 119.05Table 3. Properties of the steel chicken wire meshes.2.5 Compressive strength testThe specimens which will be tested finally for compressive strength wereobtained by cutting six cubes of dimensions 50mm × 50mm × 50mm from each plain mortar,fiber reinforced mortar and ferrocement panel.Practically, the best direction of cutting the cubes is obtained by putting thepanel in the same position at which it was cast with mortar; as the upper surface is weakerthan the molded surfaces. Such method of cutting ensures that the strength of concrete isjustifiable because there is no significant amount of splinters and fragmentation and hence thequality of planes and dimensional tolerances are attained to be in the best manner.3. TEST RESULTS AND DISCUSSION3.1 GeneralAll panels were conducted with identical projectile velocities of 218 m/sec. Theresults of the projectile penetration test, the compressive strength, impact resistance test; anddensity tests are given in Table 5. Additionally, Figure 4 and 5 demonstrate the values ofprojectile penetration into each type of panel with the designated reinforcement.From Figure 4 and 5, the effect of the type of reinforcement on the depth ofpenetration can be clearly detected. However, it can be seen obviously from Figure 4 that theferrocement panel which was reinforced with square steel chicken wire mesh (FM) with(0.9%) volume fraction of steel reinforcement has shown the lowest value of depth ofpenetration (8.7mm). This proves that it has superior characteristic in impact resistance thanthe other panels. Whereas, the panel which was reinforced with the polypropylene fiber (FP1)has the highest value of depth of penetration (23.3mm), which means that it acquires thelowest impact resistance compared with the other panels even the non reinforced one(23.0mm). Also, it can be seen that the cement mortar panel which was reinforced with(0.9%) volume fraction of crimped steel fibers randomly distributed in plane possessed a lowvalue of projectile penetration (9.0mm) which indicates remarkable impact resistance.On the other hand, the ferrocement panel which was reinforced with (0.8%)volume fraction of hexagonal steel chicken wire mesh (FH) has shown a low value of depthof penetration (8.9mm). While, the panel which was reinforced with the polypropylene fiberWire MeshesWireDiameter(mm)Densitykg /m3 Tensile Strength (MPa)Weight per UnitAreakg /m2Square Meshes 0.20 7720 980 0.2765HexagonalMeshes0.29 7680 938 0.2474
  7. 7. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME301randomly distributed in plane (FP2) has a depth of penetration of (22.9mm). Actually it isequal to that of the non reinforced panel as can be seen in Figure 5.However, the preceded experimental results clearly indicate that the ferrocementpanels reinforced with steel wire meshes or the steel fibers are possess appreciable impactresistance and can successfully used as barriers against impact loads.Effect of volume fraction and different types of fibers (steel and polypropylene)on the characteristics of impact test is presented in Figures 6 and 7. From the results, it isclear that the impact resistance of the ferrocement was improved with higher ratio of volumefraction and type of fiber. Also, it can be seen from these results that the energy inputrequired to initiate first crack and to produce failure in fiber reinforced panel specimens isvery much greater than that for plain cement mortar.Table 5. Results of the conducted tests.SpecimenFailure ModeWeightofFlyingConcrete (kg)Densitykg/m3CompressiveStrength(MPa)No. ofBlowsTotalAbsorbedEnergy(N.m)MeanDepth ofPenetration (mm)PerforationScabbingatFirstCrackatFailureRP 2.60 2120.00 40.0 3 19 745.6 23.0F S1 2.15 2160.00 46.4 6 77 3021.5 9.0FS2 2.05 2159.50 45.0 5 68 2668.3 9.1FP1 3.10 2104.24 37.0 4 23 902.5 23.3FP2 2.92 2105.46 39.0 3 21 824.0 22.9FM 1.95 2166.20 49.0 6 73 2864.5 8.7FH 2.18 2165.06 47.0 5 71 2786.0 8.9FMS 1.90 2165.70 48.0 9 93 3649.3 8.8FMP 1.74 2134.50 40.4 5 52 2040.5 9.2FHS 1.90 2160.03 46.2 8 86 3374.6 9.0FHP 2.00 2132.46 40.2 5 48 1883.5 9.3Figure 4. Effect type of fiber and square steel wiremeshreinforcement on depth of projectile penetrationFigure 5. Effect type of fiber and hexagonal steelwire meshreinforcement on depth of projectile penetrationSpecimens Designation81012141618202224DepthofPentration(mm)FP1 RP FMP FS1 FMS FMSpecimens Designation81012141618202224DepthofPentration(mm)RP FHP FS2 FHS FHFP2
  8. 8. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME302In addition and depending on the obtained results of both projectile penetration depthand the compressive strength of the panels, it was found that there is a negative relationshipbetween the mean depth of projectile penetration on one side and the compressive strength onthe other side as shown in Figure 8.Furthermore, it was found that while the non reinforced (plain) cement mortar panelpossessed 23.0mm depth of projectile penetration with 40MPa compressive strength, theferrocement panel which was reinforced with square steel wire mesh possessed 8.7mm depthof projectile penetration with 49MPa compressive strength. However, from the precededresults it can be concluded that the inclusion of steel wire mesh reinforcement which isdecrease the depth of projectile penetration by about (37.8%) can correspondingly result anincrease in the compressive strength by about (22.5%).Figure 8. Depth of projectile penetration versus compressive strength of the ferrocement panels36 38 40 42 44 46 48 50Compressive Strength (MPa)81012141618202224DepthofPentration(mm)Figure 6. Absorbed energy by different typesof specimensFigure 7. Impact resistance of variousspecimens
  9. 9. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME3033.2 Modes of failureAfter a carefully examination of the type of cracking and crushing of concrete, twomodes of damages were identified for the specimens in the present test program. As shown inFigure 9, and also indicated in Table 5, these two modes of failure are: perforation andscabbing. It can be observed from the said figure that the depth of crater depends on the typeof reinforcement.As expected and regardless of the type and amount of reinforcement employed, it wasobserved that the panel specimens (RP, FS1, FS2 and FH) failed in perforation mode.Meanwhile, the panel specimens (FP1, FP2, FM, FMS, FMP and FHP) failed in scabbing.Results found from impact resistance tests that all specimens broke into pieces once the no. ofimpact blows causes the first crack, which indicate their brittle nature. The fractures of thespecimens are clean with little debris, thus emphasizing the tensile nature of the actual failureprocess, as shown in Figure 10.The economical and environmental advantages of using reinforcement to providethinner road structures, longer life cycles and reduction in maintenance costs and of coursesavings in natural resources due to prolonged service intervals.B) Rear Face DamageB) Rear Face DamageB) Rear Face DamageB) Rear Face DamageFHPFHPFHPFHPFMPFMPFMPFMPA) Typical Front Face DaA) Typical Front Face DaA) Typical Front Face DaA) Typical Front Face DamagemagemagemageFMSFMSFMSFMSRPRPRPRPFigure 9. Mode of failure of the tested specimensFS1FS1FS1FS1 FHFHFHFH
  10. 10. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME3044. CONCLUSIONSFrom the results of the experimental investigations reported herein, the following conclusionscan be drawn:1- The advantages of employing steel wire mesh or steel fiber reinforcement appreciablydecreases depth of projectile penetration and correspondingly increases thecompressive strength of the cement mortar panels.2- In this study, it is observed that the value of compressive strength decrease withaddition of polypropylene fiber.3- Another objective of this study was that will provide recommendations as to bestpractice use of ferrocement panel in road as a base course and improvements thatcould be made to the specification.4- Within the scope of this experimental investigation reported two mode of failure areobserved: perforation, and scabbing.5- The drop load depth can be a reasonable indicator of cumulative damage in the caseof drop impact test.6- The impact resistance of the ferrocement was improved with higher ratio of volumefraction and type of fibers.7- It was found that the ferrocement panel which was reinforced with square steel wiremeshes has the lowest depth of projectile penetration (8.7 mm) i.e. possessed superiorimpact resistance, while the ferrocement panel which was reinforced with hexagonalsteel wire meshes comes next with a depth of projectile penetration (8.9 mm).8- The cement mortar panel which was reinforced with crimped steel fibers (FS1)reveals a low depth of projectile penetration close to that of the ferrocement panels(9.0 mm) i.e. comparable impact resistance.9- The cement mortar panel which was reinforced with polypropylene fibers (FP1) hasthe highest depth of penetration (23.3mm) which indicates that such polymeric fiberreinforcement does not enhance impact resistance if measured by the presentprojectile penetration depth method.Figure 10. Damages of specimens under impact loadFHSFHSFHSFHSRPRPRPRP
  11. 11. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME305REFERENCES1. ACI Committee 544, 1988, "Measurement of Properties of Fiber Reinforced Concrete",ACI Materials Journal, Vol.85, No.6, Nov.-Dec., pp.583-593.2. Banthia, N.; Yan, C. and Sakai, K., 1998, "Impact Resistance of Fiber Reinforced Concreteat Subnormal Temperatures", Cement and Concrete Composites, Vol.20, pp.393-404.3. Barr, B. and Baghli, A., 1989, "A repeated Drop-weight Impact Testing Apparatus forConcrete", Magazine of Concrete Research, Vol.40, No.144.4. Mansur, M. A., Ahmed, I., and Paramasivam, P., 2000, "Punching Shear Behavior ofReinforced Ferrocement Slabs", ACI Structural Journal, Vol.97, No.5, Sep.-Oct.5. Ramakrishnan, V.; Brand Shaug, T.; Coyle, W.V. and Schrader, E.K., 1980, "AComparative Evaluation of Concrete Reinforced with Straight Steel Fibers and Fibers withDeformed Ends Glued Together into Bundles", ACI Journal, Vol.77, No.3, May-June,pp.135-143.6. Schrader, E.K., 1981, "Impact Resistance and Test Procedure for Concrete", ACI Journal,Vol.78, No.2, March-April, pp.141-146.7. Swamy, R.N. and Jojagha, A.H., 1982, "Impact Resistance of Steel Fiber ReinforcedLightweight Concrete", Journal of Cement Composites and Lightweight Concrete, Vol.4,No.4, November, pp.209-220.8. Gao, X. 2007, "Mix Design and Impact Response of Fibre Reinforced and Plain ReactivePowder Concrete", M.Sc. Thesis, RMIT University, Melbourne, Australia.9. K. Sasiekalaa and R. Malathy, “Flexural Performance of Ferrocement LaminatesContaining Silicafume and Fly Ash Reinforced with Chicken Mesh”, International Journal ofCivil Engineering & Technology (IJCIET), Volume 3, Issue 2, 2012, pp. 130 - 143, ISSNPrint: 0976 – 6308, ISSN Online: 0976 – 6316.10. Dr. Prahallada. M.C, Dr. Prakash. K.B and Dr. Shanthappa B.C, “Effect of Redmud onthe Properties of Waste Plastic Fibre Reinforced Concrete an Experimental Investigation”,International Journal of Civil Engineering & Technology (IJCIET), Volume 2, Issue 1, 2011,pp. 25 - 34, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.11. P.A. Ganeshwaran, Suji and S. Deepashri, “Evaluation of Mechanical Properties of SelfCompacting Concrete with Manufactured Sand and Fly Ash”, International Journal of CivilEngineering & Technology (IJCIET), Volume 3, Issue 2, 2012, pp. 60 - 69, ISSN Print:0976 – 6308, ISSN Online: 0976 – 6316.

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