This article presents research on the behavior of cement-bonded particleboards under mechanical stress caused by the electrostatic cargo. The composition of the boards was modified using alternate raw materials–dust ( DU ) forming during the serve of cement-fibre boards and particle mix ( PM ) generated in the production of cement-bonded particleboards. The particleboards ( 1-year-old ) were subjected to an adverse environment ( 100 to 250 freeze cycles ). mechanical parameters were tested, and the development of defects during static load of the boards by bending was analyzed using acoustic emission. Particleboards with modify compositions are slenderly more immune to adverse environments. The results of the acoustic emission showed the different types of defects occurring under stress by bending. Standard-composition particleboards showed defects located chiefly under the cylindrical stress-test head. The limited boards showed larger placement distribution of the occurring defects that were besides concentrated further away from the cylindrical stress head.
The energy during the occurrence of defects was higher in the limited boards in the localization of weight application than in the address boards. thus, the localization of function of the defects in the cement-bonded particleboards within this sketch was analyzed in detail through a combination of physical, mechanical, microstructural and acoustic techniques. Boards aged one year were subjected to testing and analysis upon reaching 100 to 250 frost/defrost cycles. During the stress test of the bend load, it was potential to describe processes of formation and build up of active defects in the structure of the cement-bonded particleboards thanks to the synchronize lotion of acoustic emission and an electro-hydraulic device ( with the possibility to monitor and record datum on a personal computer ). cute is the description of differences in the behavior of boards of different compositions, arsenic well as the comparison of the effects of the adverse environment. furthermore, besides essential was the supplement of other techniques, such as ocular microscopy. It was found that the submit of long-run lastingness of boards with modify writing was not sufficiently covered by other authors. inquiry of adept publications besides showed the absence of findings regarding the localization of the defects in cement-bonded particleboards with a modified composition. Some authors focus on using the acoustic emission method acting for the analysis of a wide assortment of construction materials, for model [ 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43 ]. however, the presently available publications offered no citation of evaluating the behavior of cement-bonded particleboards using the acoustic discharge method acting during their mechanical stress by static deflect. A more celebrated degradation occurs in materials on the basis of a cement matrix and an organic filler ( chiefly wood ) due to temperature and humidity changes ( see, for model, findings of studies [ 12, 13 ] ) than in the font of inorganic construction materials ( concrete, mortar, and so forth ). The key standard for the serviceability of board materials in constructions is their flex lastingness and modulus of elasticity in bending. frankincense, it may be assumed that boards are largely stressed by the bending load. The behavior is, consequently, essential of cement-bonded particleboards ( exposed to adverse environment ) over the course of static flexural ( bending ) load. The key is a net designation, localization and description of occurring defects, ultimately leading to the definitive weakness of the material.

frankincense, in the discipline presented hera, chief components of the matrix and makeweight of the cement-bonded particleboards were substituted with by-products [ 24, 25, 26, 27 ], specifically those from the cement-bonded particleboard production ( produced by CIDEM Hranice, a.s. ). The display panel composing was modified by dust ( DU ) and particle mix ( PM ) from the cement-bonded particleboard production. however, no research was conducted regarding the re-use of by-products created by the production of cement-bonded particleboards in their further production. only Ezerskiy et alabama. [ 23 ] focused on the use of lay waste to from cement-bonded particleboard production in fine-grain concrete. however, the Ezerskiy report chiefly regards the proportion of recipe depending on the majority weight and strength characteristics of the designed concrete. thus, there was no emphasis on the survey of links from the material perspective of the proposed mixtures. rather, the focus remained on calculating mathematical models evaluating the achieve characteristics of the designed materials with modify composition. Another crucial fact is that Ezerskiy et aluminum. used pine away produced by a ship’s company named TAMAK. considerable differences are apparent from the comparison of the weight writing of the cement-bonded particleboards of those produced by CIDEM ( cement—50 %, wood—18 %, water—30 %, hydration additives—2 % ) and TAMAK ( cement—65 %, wood—24 %, water—8.5 %, hydration additives—2.5 % ). The current environmental situation strengthens efforts leading to the growth of waste-free technologies. In the case of existing output technologies, the producers make efforts toward maximizing the use of whatever barren they produce. therefore, two modified mixtures of cement-bonded particleboards were designed and developed in collaboration with the Czech producer CIDEM Hranice, a.s. Among other sources, the musical composition of these formula reflects the existing findings of the authors [ 1 ]. Findings exist from a number of studies focused on the practice of versatile alternate materials in cement-bonded particleboards, for exercise [ 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22 ]. Cement-bonded particleboards are a frequently used construction element. This material combines the characteristics of the cement matrix and spruce chips. Over 55,000 thousand 3 of these boards are produced annually in the Czech Republic. The boards are used in many construction units—façades, floors, partitions and railings, etc. per annum, approximately 12,000 t of by-products are created during the processing of these boards without foster habit, ending in landfills. specifically, approx. 7000 t/year of dust is produced ( from sanding and cutting the boards ), and approx. 5000 t/year of edgings ( from formatting the boards ). All primary coil materials were batched into the blend ( directly in the CIDEM Hranice, a.s. product facility ) mechanically. This is the standard method of dosing and mixing compounds in the industrial production of cement-bonded particleboards. alone the option compounds were manually added directly to the mixer in a defined come. Boards covering 4 mixing devices were produced for each formula ( a full of approximately 11 thousand 3 of concoction for dining table production ). Test specimens were then prepared from the second and third mixer load to ensure sufficient homogeneity of the ask convention, specifically the concoction. Due to the length of the production line, a transitional alteration of the composing of the cement-bonded particleboards may occur prior to achieving the needed consistent constitution of the mix. furthermore, the structure, specifically the microstructure of PM and DU, was analyzed in detail. First, analyses using the ocular microscope were executed ( see ), followed by a scanning electron microscope ( see ). Both the alternative components are cases of particulate matter where the size of particles corresponds to the results establishing coarseness ( see ). therefore, DU contains a larger phone number of smaller particles, a well as more wood matter. PM has larger clusters of particles ( larger grain ) formed during the age of the mix during outdoor storage. Both PM and DU contain a very mature cement matrix. The considerable amount of chips is covered by a ticket layer of the matrix, on which the hydration products of cement are besides visible. additionally, the absorption pace was established in the case of option DU and PM components. It was found that PM shows an absorption rate of 38.6 % and DU an assimilation pace of 50.8 %. This corresponds with the identify content of forest matter and coarseness. The DU and PM materials were used for the production of the cement-bonded particleboards in a raw state, meaning without far mechanical or early alteration. On the contrary, Ezerskiy et aluminum. [ 23 ] focused on the possible function of CBPB waste in a modify musical composition, specifically, grinding in a ball factory for 30 minute. The chemical typography in terms of the presence of the individual compounds corresponds to cement-bonded particleboards ( see ). The fact that DU contains a higher total of wood material is meaning. The forest contentedness is established using the TOC method ( entire organic carbon content—a calculation with comparative samples of cement and primary chips ). The deviation in the amount of early chemical compounds in comparison with the DU and PM are not importantly celebrated, with the exception of the SiO 2 content. With respect to the mineralogical constitution, it may be stated that in both these cases of alternative materials, the substances are on the basis of a silicate matrix. consequently, the be mineralogical phases were identified : portlandite, quartz, calcite, traces of cement clinker minerals ( peculiarly belite ), a well as ettringite and a slightly increased background ( characterizing the presence of the amorphous phase—in this case hydrating admixtures, possibly the amorphous share of cellulose ). Detailed analysis results for the by-products from march and production of cement-bonded particleboards ( produced by CIDEM Hranice, a.s. ) are covered by Melichar et alabama. in [ 24, 25, 26, 27 ]. The DU and PM option components have notably different grain ( see ), where these materials show a granulate compass from 125 µm to 2 millimeter. The DU material features a higher ratio of smaller particles. This fact would be expected given the origin of the individual components ( DU—particles from cutting, PM—a fresh concoction for the production of cement-bonded particleboards ). The adopt images show the DU and PM by-products used as alternative components of cement-bonded particleboards. additionally, particle assortment PM remaining after the output of cement-bonded particleboards was used. This by-product is formed, for example, during the change of product conditions ( allowance of board thickness, concoction, etc. ; experience ). PM is not stored in towers but in a cover space along with cuttings ( from cutting cement-bonded particleboards ). From the position of collecting by-products, the cement-bonded particleboard production line has a total of four silo ( Towers 1, 2, 4 and 5 ; watch ). These towers capture and temporarily store atom by-products. The modification of the formula musical composition was created using the scatter from grinding DU formed as a by-product of processing these boards. DU is collected as the by-product in Tower 2. The dust-removal Tower 2 is designed to collect dust from the format watch. The debris from the format attend is extracted via cyclone device, where larger particles are collected, while the debris continues to the fabric trickle of the dust-removal column. The unevenness of the properties ( frankincense besides the composition ) of DU is lowest among all the by-products ( see other dust-removing towers ), practically about constant. consequently, DU could be considered a potentially identical concern intersection for further consumption. The particleboards are based on spruce wood ( see ). The calculate below shows the distribution and size of chips along with alternative compounds ( screen analysis ; see ). additionally, body of water and hydration compounds were used in the production of these boards. Portland-slag cement CEM II/A-S 42,5 R whose specific surface area of 458 m 2 /kg ( for size and distribution of particles–see ) and concentration of 3124 kg/m 3 was used for the production. The initial fructify clock ranges between 215–250 min. Standardized compressive persuasiveness after 28 days reaches values of approx. 59 MPa. The chemical writing of the cement is shown along with the by-products DU and PM in the watch board ( see ). Measurement methods used to determine the chemical composition were as follows : hydrometric, photometric, flame atomic absorption spectrophotometry, complexometric titration and mercurymetry ( in an external testing ground ). The typography of change recipe is based on findings and existing results of research by the authors in collaboration with CIDEM Hranice, a.s., see for exercise [ 1, 26, 27 ]. These results, therefore the fabric for the composition of the modify formula, were obtained within long-run cooperation of the authors with the Institute of Technology of Building Materials and Components, Faculty of Civil Engineering, BUT and CIDEM Hranice, a.s. The amounts of modifying components besides reflect the stream production of by-products at the CIDEM Hranice, a.s. production line. The cement-bonded particleboards for these tests were produced in collaboration with CIDEM Hranice, a.s. The default convention of their boards consists of cement, spruce chips, sodium silicate and aluminum sulfate. The composition of the cement-bonded particleboards is shown in the follow table ( see ). A Keyence VHX-950F ocular microscope ( Keyence, Japan ) was used to supplement outputs of acoustic emission. This enabled focusing on areas where defects were identified in higher amounts or energy. Localities where the increased occurrence of defects was identified, however, where the concluding damage of the test specimen did not occur, were chiefly emphasized. Furthermore, cracks in the area of the definitive price of the test specimen were analyzed. The trace dividing the area into tensile and clash defects is set up experimentally ( in the lab ), and publications submit versatile ratios from 1:7000 to 1:100,000 [ 56, 57 ]. The value in the standard differed for versatile materials and must be established experimentally [ 58 ]. In this case, the value of 1:100,000 A f : RA was set upon the evaluation of all thus-far perform measurements. The x-axis is expressed in a logarithmic scale for clearness. The size of the individual points mutually differentiates by the solution entail square ( RMS ) of the given signal that could be seen as the weight of the discharge. The Kaiser effect documents the collection of damage in the evaluate structure upon cyclic tension. It is therefore closely related to the mechanical integrity of the evaluate structure [ 53, 54, 55, 56, 57 ]. When we express the measurements of acoustic emissions using the RA and F a values, the leave is the addiction depicted in. Thus, should we apply tension upon an element that is thinly built without damage ( caused by cyclic tension ), the person emissions will fall into the left-bottom and right-upper area of the diagram. On the contrary, should the emission read high values of F a and relatively broken values of the stress proportion RA, these are significant defects that Ohtsu et alabama. relate primarily to tensile defects. On the other pass, defects falling below the shown specify line left bottom are largely assigned as friction-type damage, therefore closer to fatigue defects. In evaluating the simple test of deflection, bending military capability and elasticity modulus are among the main receive parameters. The acoustic emission documents the increasing arm of the working diagram up to the moment of damage and the subsequent decrease branch. Each individual modern defect created by the effect of the load potency is documented through a recorded sign. To interpret the end product measurements, the Kaiser impression [ 31 ], designed in 2007 by Grosse and Ohtsu, may be used for the purpose of monitoring cyclically stressed reinforced iron-and-concrete elements by AE. Two ratios may be used for this interpretation that can be expressed as follows : acoustic discharge signals from both sensors used were recorded over the course of the measurement. An model of one individual signal is shown in previous graph ( see ), indicating the main parameters evaluated within this publication. Almost twenty dollar bill unlike parameters are typically recorded according to exchangeable procedures [ 37 ]. subsequently, the dependencies of the individual analyze properties enabled the localization of the geological formation of defects upon static stress of the cement-bonded particleboards using flexural bending load. The sum increase of the signal was 64 dubnium ( 34 dubnium pre-repeater + 30 dubnium software amplification on the measuring tease ), the brink value for the person hits was 31.482 µV ( 30.0 dBAE ), the sampling of the hits was set to 10 MHz. The data from the electro-hydraulic device connected to a personal computer were exported, providing dependencies time/strength, bend/strength. The acoustic discharge bodily process was monitored using the DAKEL-ZEDO system [ 36 ]. A stereophonic ZEDO-AE unit intended for processing acoustic emission signals was used for the actual quantify. The monitor of the acoustic emission bodily process took place along with establishing the flex properties. frankincense, the identical specimens were used. The attachment during the three-point load bending test and location of the AE sensors is apparent in. The localization of the defects was analyzed during the stress of tested specimens using three-point deflect. Two acoustic discharge sensors of type IDK09 ( Dakel company, Prague, Czech Republic ) were placed on the examination specimens ( see boron ). subsequently, the screen specimen was subjected to stress by bending using the Testometric M350-20CT electro-hydraulic device ( see and ). The electrostatic load application was synchronized with the acoustic discharge, meaning both devices were turned on simultaneously. According to technical standard EN 310, the flex stress was applied with the rate of 3 mm/min of moving the cross load. The specific acoustic discharge sources may be used for deducing the initiation and distribution of cracks [ 32, 33 ]. a lot feat is devoted to the cogitation of the accurate identification of the sources of acoustic emissions, and many algorithms were designed to define the sources of acoustic emissions. These algorithms could be divided into two groups. The first is a non-iterative group ( these algorithm assume the lapp speed for all stations, thus being relatively uncompromising in dealing with variable star speed models ). The second group is iterative algorithm ( the derivative method, the consecutive search method acting, the familial algorithm and the simplex method acting ) [ 34, 35 ]. These algorithms are based on the assumption that the acoustic waves spread immediately from their source along a occupation to the detector. therefore, they assume the environment in which the waves spread is sufficiently homogeneous for generating acoustic waves. such types of algorithm lose their preciseness in the case of two different environments or the case of deflection of the beget waves [ 35 ]. The acoustic discharge occurs in the AE informant upon the let go of of energy due to stimulation by inner or external tension. The AE event is emitted through irreversible dislocation and abasement processes in the microstructure and macrostructure of the material. The release energy is transformed into a mechanical try pulsation diffuse through the substantial as a longitudinal or cross wave. ampere soon as the wave hits the come on of the material, it is detected by a piezoelectric detector. The signal detected by the AE detector and transposed to an electric form is referred to as an AE bespeak [ 31 ]. Unlike most other approaches to non-destructive examination, the AE method detects lone active defects occurring inside the monitor structure. These defects may occur only during stress ( mechanical, temperature or chemical stress ) within the monitor structure. passive voice defects or the form of the social organization do not significantly affect the localization of the AE [ 30 ]. The acoustic emission ( AE ) bodily process was monitored throughout the three-point bending test. acoustic discharge is among the most modern methods for evaluating materials in engineering and fatigue duty applications. The source of AE may arise from multiple phenomena depending on the character of material. Most sources of acoustic emissions are related to damage [ 28 ]. The detection of these emissions is normally used for predictions of material defects. The disadvantage is that AE depends on the used load [ 29 ]. This means that come disconnections may not generate a detectable acoustic emission. To enable their attachment into the testing electro-hydraulic device, blocks are glued onto the specimens. Steel targets fixed by an adhesive on the basis of a two-component epoxy resin ( the glue solidifies approximately 24 h ) were used for this purpose. As in the case of flex, the rate of the load of the specimens must be established to achieve damage within ( 60 ± 30 ) s. The rate for establishing the ductile force was 3 mm/min, frankincense reaching damage in all tested specimens between 30 to 40 s. The test specimens for this test have the form of a public square with the side of ( 50 ± 1 ) millimeter. The specimens must be cut precisely, with a 90° fish, and their edges must be neat and clean. The ductile forte vertical to the plane of the board was established according to the technical EN 319 standard [ 52 ]. According to the provisions of this average, the characteristic is established upon ductile burden affecting the test specimen to the point of its damage in the management vertical to the flat of the specimen ( identical to the plane of the field ). tensile persuasiveness perpendicular to the airplane is determined from the maximum strength affecting the surface for the screen specimen. where : fifty 1 is the distance between the centers of the supports in millimeter ; b is the width of the examination specimen in millimeter ; t is the thickness of the test specimen in millimeter ; F 2 − F 1 the addition in the load in the linear contribution of the load bend in N ; F 1 is approximately 10 % and F 2 approximately 40 % of the utmost load F soap ; a 2 − a 1 the increase in bend in the center of the length of the testing specimen ( corresponding to F 2 − F 1 ). In this specific font, the thickness of the boards was 12 millimeter, and the distance between the supports was 240 millimeter. With obedience to the analysis of the localization of defects, the duration of the screen specimen was determined to be 380 millimeter. Thus, an extra 45 millimeter were left on each slope of the specimens for the placement of the acoustic emission sensors. The rate of establishing the flex load was 3 mm/min, frankincense resulting in the damage of all tested specimens within 35 to 50 s. The distance between the centers of the supports is established with the preciseness of 1 millimeter 20 times the nominal thickness of the board. The load is established at a constant rate to achieve the utmost, meaning the wrong of the specimen, within ( 60 ± 30 ) s. The testing scheme arrangement is shown in and. Strength and modulus of elasticity in bending were established in accordance with the relevant technical EN 310 standard [ 51 ]. Bending characteristics are established by applying a cargo into the center of the test specimen. The specimen is placed on two cylindrical supports, and the load is applied using a cylindrical weight headway located parallel with the supports between them, thus creating a three-point crouch. The elasticity module is established using the linear character of the load bend. The bending military capability of each specimen is calculated by stipulating the proportion of the deflect moment M at maximum lode F soap to the moment of its stallion cross-section.

The concentration of the boards was established in accord with the requirements of the technical standard EN 323 [ 50 ]. Density is determined as the proportion of the slant of the test specimen to its book. Determining both the bulk and slant were executed at the same humidity of the screen specimens. The trial specimen for this test has the shape of a square with a minimal side length of 50 millimeter. additionally, specimens used for testing bending characteristics were used for establishing the density of analyze boards. Density is stated in kg/m 3. The requirements for the properties of cement-bonded particleboards are stipulated in standards [ 46, 47, 48, 49 ]. This standard besides establishes the requirements for extra properties, such as size changes, resistance against puncture and frost resistance. Before testing, the quiz specimens were always stored in the define conditions, mean at the relative humidity of ( 65 ± 5 ) % and temperature of ( 20 ± 2 ) °C. All measurements and tests were performed upon the specimens reaching a ceaseless weight in this environment. In this case, the ceaseless weight is defined by the deviation in two consecutive weight tests in the interval of 24 hydrogen, where this deviation is ≤ 0.1 %. consequently, it is apparent that from the perspective of unifying the long time of testing, the specimens exposed to 250 frost/defrost cycles had to be removed from the storage of 75 % humidity approximately after 10 months of maturing. The command number of cycles of exposure to the adverse environment was executed over the course of approximately two months. At the historic period of 1 class, the specimens were fix for evaluation of their properties, including the analysis of the localization of defects resulting from flexural bending load. The EN 1328 standard requires a minimum of 50 of the above-described frost/defrost cycles. The evaluation of freeze resistance that characterizes lastingness was executed within the image of 100 to 250 cycles. The reason was the reliable tell of changes in properties of the change boards in a more long-run horizon. consequently, the following sets of test specimens were produced and exposed to the adverse environment : For both the Czech Republic and most of Europe, a distinctive example of an adverse environment is the cyclic frost/defrost effect. frankincense, the focus was aimed at monitoring the effect specifically from this environment. The testing of frost resistance of cement-bonded particleboards is covered by the technical standard EN 1328 [ 45 ]. Before testing, test specimens are submerged in a water bath at the temperature of 20 °C for 48 h. Subsequently, fluctuating frost/defrost takes position with the presence of water. The run of temperature cycles in relation to time is shown in the pursuit graph ( see ). On the other handwriting, the possible storage of boards in an environment with depleted humidity would not provide sufficient hydration of the cement matrix. The relative humidity in the place in the repositing of these boards was monitored once every two months. The fluctuation in humidity and temperature over the class of their ripen did not exceed ±4 % and ±3 °C. The specimens were left in these conditions for a period of one year in order to evaluate their parameters in a more long-run scene. The specimens exposed to adverse conditions anterior to testing were removed from the memory conditions earlier. The time was planned to ensure that all specimens ( both reference specimens and those exposed to frost ) were tested at the same age, meaning one year. The screen specimens were stored in the laboratories of the Institute of Technology of Building Materials in an environment with a proportional humidity of 75 % at a temperature of approximately 22 °C. The relevant technical foul regulations set no conditions for storing cement-bonded particleboards for long-run suppurate of the screen specimens. The reason for establishing the above conditions was the fact that these boards contain a relatively senior high school share of forest matter ( approximately 63 % ). Despite being mineralized, this wood topic changes its percentage in response to changes in humidity which could have ( in the case of excessive humidity—for example, submergence in water system ) a negative impression on the class of maturing. The production of quiz specimens took place immediately at the CIDEM Hranice, a.s. production tune. This company is a leading producer of cement-bonded particleboards in the Czech Republic with a significant flat of export afield. The test specimens were cut from the boards approximately ten days after production. The specimens were transported to the laboratories of the Institute of Technology of Building Materials and Components, Faculty of Civil Engineering, BUT, where they were prepared for all planned tests and analyses .

4. Results and Discussion

4.1. Physical and Mechanical Parameters

A Density is one of the monitor and measure parameters of cement-bonded particleboards. According to EN 634-2, the minimal required density value is 1000 kg/m3. The achieve results, including their graphic depicting, are shown in the follow table ( see ) and graph ( see ). It is apparent that not all tested types of boards achieve density > 1000 kg/m3 flush after 250 frost/defrost cycles .An external file that holds a picture, illustration, etc.
Object name is materials-14-06788-g012.jpgOpen in a separate window

Table 3

Mixture Density
[kg/m3]
Average Density
[kg/m3]
Absolute Error
[kg/m3]
Relative Error
[%]
Ce-Ref 1245–1317 1287 14.4 1.12
Ce-M10 1252–1285 1272 6.8 0.53
Ce-M15 1254–1305 1272 11.1 0.87
Ce-M20 1274–1319 1298 8.7 0.67
Ce-M25 1172–1303 1245 25.7 2.07
Du-Ref 1292–1318 1309 5.5 0.42
Du-M10 1288–1328 1313 8.5 0.65
Du-M15 1297–1305 1301 1.5 0.12
Du-M20 1302–1385 1348 16.3 1.21
Du-M25 1211–1288 1245 15.1 1.21
Pm-Ref 1274–1412 1336 27.0 2.02
Pm-M10 1321–1389 1364 14.4 1.06
Pm-M15 1331–1411 1372 15.4 1.12
Pm-M20 1297–1392 1314 26.1 1.99
Pm-M25 1259–1331 1299 14.1 1.09

Open in a separate window The above concentration values fail to enable the recording of a clear colony of the assortment compositions and the conditions of their adverse exposure. A more noteworthy decrease in density, approximately 3–5 %, is luminary entirely in the case of a higher issue of frost/defrost cycles ( specimen sets M20 ). An interest find is a fact that in the case of some sets, an increase in density. however, this increase ranged under 3 %. With deference to the reached density values, these are rather negligent differences. No clear dependencies could besides be concluded through the evaluation of absolute errors ( graph in shown as error pipeline segments ) of densities established for each tested located. The absolute errors reach values in the interval from 1.5 kg/m3 to 27 kg/m3, which corresponds to the relative error range of 0.12 % to 2.02 %. very like concentration values without apparent dependence on the composition of the test boards types could be attributed to the lower dose of substitution components. additionally, the senior high school compatibility of the alternate substituents DU and PM with the cement-bonded boards plays a function. Bending military capability is one of the most crucial custom properties in the sheath of cement-bonded particleboards. The achieve results of this lastingness, including their graphic depiction, are shown in the comply table ( see ) and graph ( see ). According to EN 634-2, the minimal required value of bending potency is 9 N/mm2. All tested cement-bonded particleboards reach the average flex force > 9 N/mm2 and this is besides after 250 frost/defrost cycles. This line up is very utilitarian from the perspective of modified boards which thus proved identical good lastingness .An external file that holds a picture, illustration, etc.
Object name is materials-14-06788-g013.jpgOpen in a separate window

Table 4

Mixture Bending Strength
[N/mm2]
Average Bending Strength
[N/mm2]
Absolute Error
[N/mm2]
Relative Error
[%]
Ce-Ref 11.2–12.5 12.0 0.3 2.30
Ce-M10 11.1–12.2 11.7 0.2 1.92
Ce-M15 10.3–10.9 10.6 0.1 1.11
Ce-M20 8.9–10.4 9.8 0.3 3.12
Ce-M25 8.6–10.9 9.7 0.4 4.51
Du-Ref 11.2–12.2 11.7 0.2 1.73
Du-M10 9.8–13.1 11.4 0.6 5.63
Du-M15 10.5–11.5 10.9 0.2 1.83
Du-M20 9.3–11.4 10.4 0.4 3.95
Du-M25 8.9–11.6 10.3 0.5 5.10
Pm-Ref 9.9–12.4 11.6 0.5 4.33
Pm-M10 10.9–11.7 11.3 0.2 2.06
Pm-M15 10.6–12.2 11.4 0.3 2.51
Pm-M20 9.6–11.0 10.3 0.2 2.25
Pm-M25 8.9–12.1 10.5 0.6 5.91

Open in a separate window The results of all screen types of cement-bonded particleboard prove the negative effect of adverse environment on bending potency. The proportion of potency before and after the stipulate number of frost/defrost cycles R ( according to EN 1328 ) ranges between 0.98 and 0.81 ( which corresponds to the decrease of bending persuasiveness from 2.3 to 18.6 % ). Boards Ce-Ref reached the highest potency ( without exposure to frost conditions ), while the deviation in comparison with change boards Du-Ref and Pm-Ref are not identical significant ( 0.3 to 0.4 N/mm2 ). The decrease in lastingness, due to the effect of a lower dose of cementum in the boards, corresponds with outputs presented by Zhou et aluminum. [ 21 ]. Zhou focused on the possibility of using waste wood treated with chromate copper arsenate ( CCA ) in particleboards. Boards with vary ratios of wood and cement were tested, specifically from 1.0 to 4.0 ( cement/wood ). In the area of cement/wood proportion = 2.0 to 3.0, bending strength ranged from 8.44 to 9.52 N/mm2. The change boards Du and Pm show a lower decrease in bending lastingness due to an adverse environment, as apparent from 150 frost/defrost cycles. This determine is particularly interest because in both cases, the cementum was replaced with inert filler. however, in the case of the Pm boards, this fact could be attributed to the substitution of 4 % of dapper chips with an alternative material. aside from the chips, PM besides contains the cement matrix that is besides present on the chips. additionally, the chips contained in the PM are already once mineralized ( both by ions of sodium silicate and birdlime ions from cement ). In the case of the Du boards, the lower decrease in strength ascribable to the frost consequence could be attributed to the option part used. The DU alternate crude material contains many more fine components compared to PM. DU is besides an inert makeweight, but thanks to the particle size, there is a better adhere and common effect with the matrix in the cement-bonded particleboards. The different proportion of cement and woodwind chips could besides have a beneficial effect on frost resistance, which is in part supported by the results of a study conducted by Soroushian et aluminum. [ 13 ] Among early findings, he concluded that the ratio of cement and wood matter positively affects the frost resistance of cement-bonded particleboards. specifically, Soroushian found that in the case of the wood/cement proportion = 0.28, higher bending strengths were achieved upon exposure to 25 frost/defrost cycles, compared to the wood/cement proportion = 0.35. however, it must be taken into report that the course of the frost/defrost cycles presented in [ 13 ] was unlike from the course of cycles described in chapter 3.2. According to [ 13 ], the bicycle lasted a entire of 24 hydrogen, where 12 planck’s constant were freezing and 12 hydrogen thaw. however, absolute errors and relative errors ( diversions from averages ) are besides all-important from the position of the achieved bend potency values. Boards with modified writing are characterized by a higher degree of results unevenness. This finding refers to values established upon exposure to frost/defrost cycles. The Pm boards show the most variable results. therefore, in this respect, a certain relation between the modification of the board writing with an alternative material ( inert makeweight ) at the expense of primary coil composites with a bending intensity may be observed. Results presented by Wang et aluminum. [ 8 ] besides confirm the effect of the identify unevenness of the bending force of PM ( in comparison with Ce ). According to Wang et al., the decreased dose of cement at the expense of the alternative filler ( construction waste forest ) causes the increase of the divergence from the median prize of bending military capability. however, when comparing the absolute error with the findings of Fuwape et alabama. [ 14 ], it may be concluded that the Du and Pm mixtures are overall characterized by very low unevenness of the individual measurement. Fuwape et aluminum. found that the cement-bonded particleboards density of 1175 kg/m3 achieved a deflect forte of 8.11 N/mm2 with an absolute error of 2.04 N/mm2 ( approx. 25.2 % ). however, Fuwape et alabama. analyze properties with the subject of the waste-paper and waste-wood filings. In this deference, the option components DU and PM could be seen as more compatible and frankincense better mutually reactive with the cement-bonded particleboard matrix. By stressing the boards by bending, it was possible to identify both bend persuasiveness and the modulus of elasticity in bending. This property is essential from the perspective of evaluating the behavior of boards with modified convention under burden. The achieve results are shown in the pursuit table ( see ) and graph ( see ). According to EN 634-2, the minimum compulsory value for the modulus of elasticity in bending is 4500 N/mm2 ( Class 1 ), 4000 N/mm2 ( Class 2 ), respectively. All tested cement-bonded particleboards reach average values of the modulus of elasticity in bending > 4500 N/mm2, and this is besides after 250 frost/defrost cycles .An external file that holds a picture, illustration, etc.
Object name is materials-14-06788-g014.jpgOpen in a separate window

Table 5

Mixture Modulus of Elasticity in Bending
[N/mm2]
Average Modulus of Elasticity in Bending
[N/mm2]
Absolute Error
[N/mm2]
Relative Error
[%]
Ce-Ref 7054–7881 7496 160.3 2.14
Ce-M10 5987–6774 6356 152.3 2.40
Ce-M15 6080–6382 6231 58.2 0.93
Ce-M20 5036–6174 5487 232.7 4.24
Ce-M25 3757–5847 4710 406.9 8.64
Du-Ref 7960–8250 8105 55.9 0.69
Du-M10 6119–7265 6692 220.5 3.30
Du-M15 5389–6874 6111 286.2 4.68
Du-M20 5032–7388 6374 466.3 7.32
Du-M25 3694–5653 4578 382.4 8.35
Pm-Ref 7730–8413 8160 139.9 1.71
Pm-M10 6870–7569 7220 134.5 1.86
Pm-M15 6715–7776 7246 204.2 2.82
Pm-M20 6045–6752 6399 136.0 2.13
Pm-M25 4021–5981 4965 377.9 7.61

Open in a separate window The decreasing swerve in the modulus of elasticity in bending in the individual rule, due to the effect of the frost/defrost cycles, approximately copies bending military capability. Nonetheless, some fundamental differences may be observed here in comparisons of the modulus of elasticity, specifically in boards Ce-Ref, Du-Ref and Pm-Ref. The boards with modify compositions, meaning Du-Ref and Pm-Ref, achieve higher levels in modulus of elasticity in bending than in the case of the address Ce-Ref boards. The lone exception are values of the modulus of elasticity in bending established after the photograph to 250 frost/defrost cycles, meaning Du-M25 and Pm-M25. Fuwape et aluminum. [ 14 ] besides reports the different class of intensity and the modulus of flexibility in bend of cement-bonded particleboards with change composition. The contradictory vogue in forte and modulus of elasticity in bend is besides confirmed in the results presented by Savastano et alabama. [ 19 ]. In this sketch, Savastano focuses on cement and pine chip boards. The pine chips are substituted by up to 12 % by kraft pulp from sisal and banana thriftlessness and from Eucalyptus grandis pulp mill residues. however, an essential fact is that the above studies do not cover the effect of frost/defrost cycles on the board properties. The authors [ 14, 19 ] only analyzed the consequence of the change on the composition of cement-bonded particleboards and this, specifically, by substitution of wood chips. Upon closer examination of the obtained values ( witness ), specifically the deflect in the elastic sphere ( meaning between 10 and 40 % of maximum forte ) in comparison with the crouch persuasiveness, it was found that the Du and Pm boards are less elastic. This refers to boards that are not exposed to the adverse conditions of freeze, meaning Du-Ref and Pm-Ref. however, these differences are not very meaning in comparison with the reference Ce-Ref boards. The bend ( distortion ) of all types of boards upon reaching the bending force is similar. This fact is related to the modification of the typography of chips. The primary chips were replaced by chips from alternate materials ( DU—1 % and PM—4 % ). The spruce up chips contained in the DU and PM are already mineralized and of much smaller size in the case of DU. additionally, the modification of the matrix of the boards must be considered ( DU—6 % and PM—4 % ). however, the demeanor from the position of elasticity of the limited boards upon reaching 250 frost/defrost cycles is different. Du-M25 boards peculiarly show the greatest decrease in the modulus of elasticity. Another interesting find is that while the modulus of elasticity drops more notably in all board types after 100 frost/defrost cycles, after 150 cycles, it does not appear to be significant ( compared to the 100 cycles ). This phenomenon was observed in all three dining table types : Ce, Du, a well as Pm. As in the character of bending potency, the proportional errors increased with the increasing number of frost/defrost cycles. however, upon comparing the proportional errors of bending lastingness and the modulus of elasticity in bending, it is apparent that the individual values of the modulus prove larger variances. The comparison of relative errors merely confirmed the increased variability of results in the case of Du boards, compared to Ce. therefore, it can not be clearly stated that the change of the compositions of boards with alternative materials would have any effect on the increased variability of the individual values of the modulus of elasticity in deflection ( the comparison of Ce and Pm ). The proportion of bending lastingness to the modulus of elasticity in crouch ( fm/Em ) approximately corresponds with the results presented by Okino et alabama. [ 20 ]. This is an interest receive, as it refers to a basically different composition of the cement-bonded particleboards in comparison with the study [ 20 ] and the inquiry presented here. The cross tensile force perpendicular to the plane of the dining table characterizes the cohesiveness of the cement-bonded particleboard in the direction of its press process. This feature is significant for the boards, as most particles are oriented along the plane of the board during the compaction. therefore, the cement-bonded particleboard shows different properties in the cross commission, including lastingness. The results of establishing the ductile force perpendicular to the plane of the board are shown in the be table ( see ) graph ( see ). According to EN 634-2, the minimum required tensile intensity perpendicular to the plane of the board is 0.5 N/mm2. All tested cement-bonded particleboards reach modal tensile persuasiveness ≥ 0.5 N/mm2, and this even upon 250 frost/defrost cycles.

An external file that holds a picture, illustration, etc.
Object name is materials-14-06788-g015.jpgOpen in a separate window

Table 6

Mixture Transverse Tensile Strength
[N/mm2]
Average Transverse Tensile Strength
[N/mm2]
Absolute Error
[N/mm2]
Relative Error
[%]
Ce-Ref 0.96–1.01 0.99 0.01 0.95
Ce-M10 0.67–0.79 0.75 0.03 3.39
Ce-M15 0.69–0.83 0.75 0.03 3.71
Ce-M20 0.62–0.78 0.72 0.03 4.66
Ce-M25 0.59–0.78 0.68 0.04 5.40
Du-Ref 0.86–0.89 0.88 0.01 0.73
Du-M10 0.76–0.92 0.83 0.03 3.80
Du-M15 0.61–0.81 0.71 0.04 5.42
Du-M20 0.44–0.64 0.54 0.04 7.13
Du-M25 0.35–0.57 0.49 0.05 9.56
Pm-Ref 0.84–0.97 0.91 0.02 2.63
Pm-M10 0.77–0.85 0.82 0.02 2.05
Pm-M15 0.65–0.81 0.74 0.03 4.26
Pm-M20 0.55–0.81 0.66 0.05 7.85
Pm-M25 0.38–0.71 0.57 0.07 11.52

Open in a separate window The results of testing ductile intensity vertical to the plane of the board confirm the necessity of establishing all all-important properties of the given material, as the frost/defrost effect was most luminary here. The Ce boards, meaning the reference assortment, are shown as the best in the evaluation. however, the course of the curves characterizing the share in a decrease of ductile forte is interest ( see —dashed curves ). In the event of Ce, a sharp decrease may be observed upon the effect of ampere short as 100 frost/defrost cycles. The DU and PM alternative crude materials do show a sharply but rather gradual decrease of tensile potency due to the effects of the adverse environment. The most abrupt decrease of ductile strength, perpendicular to the plane of the board, is shown in the shell of boards made from the Du-M25 materials, specifically 44 %. The necessity of the relevant technical average [ 48 ] is at least 0.5 N/mm2. therefore, it is discernible that, upon reaching 250 frost/defrost cycles, tensile military capability is clearly very significantly affected. This phenomenon is most probable related to the fact that in the event of the Du boards, a larger sum of cement was replaced by the alternative component, specifically by 7 % of the dust from control panel processing ( where DU reaches approx. 25 % of the wood topic ). The proportional error ( divergence from the average value ) increases with the count of frost/defrost cycles. This phenomenon is most luminary in the case of DU and PM alternative raw materials ( see ). As is apparent from the comparison of achieve average values of ductile persuasiveness perpendicular to the plane of the board with the results presented by Okino et alabama. [ 20 ], the Du and Pm boards achieved notably higher values ( and this flush upon 250 frost/defrost cycles ). The research presented by Okino et aluminum. shows the results of this characteristic ( IB—internal alliance ) within the range of 0.19 to 0.40 N/mm2 .

Leave a Reply

Your email address will not be published.