Abstract Phenol–formaldehyde resin-bonded particle- board (PF board) and isocyanate resin-bonded particle- board (MDI board) were soaked in water at 40, 70 and 100 °C, and the relationships between soaking conditions and board properties were analyzed. The relationships between the deterioration of board properties resulting from water soaking and those arising from outdoor expo- sure were also analyzed. At 100 °C, the modulus of rupture (MOR) and internal bond strength (IB) of the PF board decreased significantly within the first hour, and subse- quently constant values were shown with increasing soaking time. This low constant value was defined as the lower limit. At 70 °C, both the MOR and IB decreased with increasing soaking time, and reached the lower limit. At 40 °C, however, neither decreased significantly with increasing soaking time and neither reached the lower limit. The MOR of the MDI board showed the same trend as the PF board. However, the IB of the MDI board showed a different trend to the PF board, that is, the lower limit of IB required extensive soaking, even at 100 °C. The MOR and IB of both the PF and MDI boards reached the lower limit when thickness change peaked. On the other hand, the MOR and IB for outdoor exposure were lower than those for water soaking, even at the same thickness change. The
Flexural strength provides two useful parameters, namely; the first crack strength which is primarily controlled by matrix and the ultimate flexural strength or modulus of rupture which is determined by the maximum load that can be attained by the tested sample. In China, the flexural properties of cement- stabilized with macadam or pozzolans reinforced with polypropylene fibre have been studied by Zhang, (Sumrerng Rukzon et al., 2009). Flexural properties of concrete are important to the design engineers to serve as a guide to the selection of appropriate construction materials. Ukpata, (Ramarao and Seshagiri Rao, 2003), studied the flexural properties of lateritic sand and quarry dust as fine aggregate. Their results compared favourably with normal concrete at 25- 50 % replacements. The quality and strength desired in concrete is fundamentally related to its compressive strength. Compressive strength is the most convenient way of measuring and assessing the quality of hardened concrete using the equation (1)
Ten samples of both materials; opaque dental porcelain and commercial opaque dental porcelain were used. The test applied by Instron 3366. This test was conducted by placing a sample of known width and thickness onto two parallel bars with the bottom of the sample in contact with the bars. By slowly lowering two additional parallel bars with a force gauge attached, the bar was deflected until it breaks. By multiplying factors for the width and thickness of the sample as well as the force load at the point of breakage, then modulus of rupture can be calculated using equation 2.
Four types of specimens made from the above four mixtures were fabricated in this testing program. The Φ15 x 30 cm cylinders were used to determine the physical properties of concrete including modulus of elasticity and wave velocity. The Φ10x 20 cm cylinders were mainly tested for compressive strength and tensile strength. The cubic specimens of 15 x 15 x 15cm in dimension with an additional No. 6 steel bar being planted into the specimens, which also follows the ASTM, was used for pullout test in order to determine the pullout strength of concrete. Three-point bending beam specimen of 10 x 10 x 35cm in dimension was employed for flexural test. This was used to determine the modulus of rupture and flexural
2) M.S.Alam et al. (1980) performed experiment to present effect on modulus of rupture due to factors such as Duration of Infiltration, Cement/aggregate ratio, Size of aggregate, Rate of cooling, Water/cement ratio, Period of curingon SIC. He found that as the sulphur content increases infiltration in the first 100 minutes increases and it completes at 540 minutes. Longer the duration of infiltration longer will be the infiltrated portion of specimen and hence modulus of rupture increases.Tensile strength of sulphur concrete (without cement) is not more than 6.8744MN/m2 whereas SIC has much higher tensile strength. At cement/aggregate ratio of 0.65 maximum modulus of rupture will occur. With sand as only aggregate the modulus of rupture of SIC is over 13.755MN/m2. When above part is replaced by ¾” size aggregate the modulus of rupture reduces to 8.9407MN/m 2 .At w/c ratio of 0.2 to 0.4 modulus of rupture increases and modulus of rupture becomes independent above w/c ratio of 0.7. Up to w/c ratio of 0.4, percentage of sulphur decreases and then it increases. The percentage of sulphur infiltration is minimum at w/c ratio of 0.43. At w/c ratio of 0.42 the porosity becomes minimum. There is no increase in strength when w/c ratio is increased above 0.7.longer the period of curing lesser will be the sulphur infiltration.The optimum period for curing is 3 days.  When specimen were cooled at following temperature following changes occurred in modulus of rupture.
Beam samples with 450 mm x 100 mm x 100 mm size were made in the lab to determine the modulus of rupture as per ASTM C78 standards 4 . All the beam specimens were cast and cured in accordance with ASTM C192 specifications 5 . Beams specimens, tested using universal testing machine (UTM), were supported on both sides. 75 mm length of beam from each face of the support was supported on thick steel plates as shown in Figure 2. The remaining 300 mm length was divided in three equal portions to accomplish the ASTM C78 requirements that the intermediate distance between points should be equal to depth of the beam. Circular rods, with an overlying thick steel plate, were used to equally transfer the point load applied through UTM as shown in Figure 2.
The effects of SMC application on the soil modulus of rup- ture are shown in Fig. 3. All the SMC applications resulted in a significantly lower soil modulus of rupture after the 21st and 42nd days compared to the 62-day incubation. In gen- eral, the soil modulus of rupture decreased as the applica- tion rates of SMC increased. These effects can be explained by the high organic matter contents of SMC that improved soil structure mechanically (Gümüs and ¸Seker, 2015; ¸Seker, 2003), as the SMC used in the study contains significant amounts of organic substances. The modulus of rupture can also be related to the inhibitory effects of SMC on the tight unity formation of soil particles. The structural stabilization is related to organic matter inputs (Caravaca et al., 2002; Fer- reras et al., 2006), and thus a significant decrease in the mod- ulus of rupture was possibly attained with the application of SMC. Organic amendments are known to decrease bulk den- sity and particle density in soil (Moreno et al., 2016). The absence of such effects after 62 days can be related to the decrease in aggregate stability and organic substances. This most probably resulted from the breakdown of soil aggre- gation and the aggregates of soil organic matter by mixing pot contents to simulate repeated cultivation (Carrizo et al., 2015; ¸Seker, 2003).
The modulus of rupture of MDF(MDI), which was 36.1 MPa before exposure, decreased for 2 years, and then subsequently stabilized at around 30 MPa (Fig. 4d). In contrast, the modulus of rupture in MDF(MUF) was 45.4 MPa before exposure, and then decreased to 28.2 MPa after 5 years (Fig. 4e). MDF(MDI) retained 77.1 % of the initial modulus of rupture after 5 years, but retention of MDF(MUF) reduced to 62.0 % (Table 3). In MDF(MDI), the coefficient of variation did not increase due to exposure but remained constant. Conversely, the coefficient of variation in MDF(MUF) increased from 6.47 % before exposure to 9.44 and 14.0 % after 4 and 5 years, respectively. These increases were smaller, however, than those in PB(PF) and OSB(aspen). Therefore, 95TL in MDF(MUF) lowered to a lesser extent, with 48.8 % of the initial level being retained after 5 years.
The modulus of rupture followed a similar trend to the compressive strength and showed a slight decrease for the mortar incorporated with rice husk from 3.13 MPa to 2.20 MPa. However, the modulus of rupture distinctly decreased compared with the mortar containing rice husk, showing 0.98 MPa for H5 down to 0.53 MPa for H8. The visual inspections on the broken specimens revealed that in spite of the rupture the broken specimens were not fully split as the leaves of date palm still held to the pieces together, hence protecting the samples from totally splitting. A similar trend was observed by Kriker et al . The relationships between the modulus of rupture and the bulk compositions of rice husk and date palm leaves are shown in Fig. (4). It demonstrated that adding rice husk into the mortar gave better mechanical properties than incorporating date palm leaves. However, the properties of the mortar containing rice husk could be enhanced by treating rice husk in alkaline solutions like Ca (OH) 2 and removing hemicellulose lignin or
The testing apparatus is calibrated before commencing the testing procedures. The test is carried out on the machine by a punch and two supports. These two components are the sources for three point bending test. It will be tested until the specimen fail or break off and the Modulus of Rupture (MOR) value is calculated by taking the average result from all the samples that already being tested. The software that is used to obtain the data is Trapezium2 which is similar with the tensile test. The specimens is tested by using the Universal Testing Machine (UTM), as shown in Figure 2.
Excessive deflection of concrete floor slabs is a recurring serviceability problem (Gilbert 2012, Stivaros 2012). Others have investigated contributing factors including: construction methods and associated loading (Kaminetzky & Stivaros 1994), cracking due to restrained shrinkage, creep and flexure (Bischoff 2007, Scanlon & Bischoff 2008), and early-age concrete properties (ACI 435 1995, Khan 1995). Provisions in current building codes, CSA A23.3-14 in Canada (CSA 2014) and ACI 318-14 in the United States (ACI 2014), account for some but not all of these effects. The effect of loading concrete members at very young ages (three days is not uncommon given current construction practices) on the associated deflections remains uncertain. Construction loads may subject young concrete to large bending moments causing flexural cracking. Accurate predictions of the modulus of rupture, the elastic modulus, and the cracked moment of inertia are necessary because computed deflections are sensitive to these properties.
Abstract We investigated the properties of composite board formed using base sheets of aluminum foil-laminated and polyethylene (PE) plastic-laminated liquid packaging paperboard (LP) as an alternative to recycling these items in wastepaper stream. Boards of different specific gravities ranging from 0.55 to 0.75 were made by pressing shredded LP blended with urea resin having resin content of 6%– 10% at 180°C. Subsequently, we also prepared mixed particleboard [wood (WD) particles and LP mixed], three- layered particleboard (LP as the middle layer, WD in the upper and lower layers), and wood particleboard all having resin content of 10% and various specific gravities. Static bending and internal bonding strengths and thickness swell- ing of the specimens were determined to examine their properties. At the same specific gravity, the properties of LP particleboards were affected by their resin content. The modulus of rupture (MOR), modulus of elasticity (MOE), and internal bond strength of the LP particleboards increased with increasing specific gravity of the boards at the same resin content, but thickness swelling of the LP particleboards showed the reverse trend. The average MOR of the LP particleboards approximated that of the mixed particleboards and was greater than those of the three-layered particleboards and wood particleboards. Internal bond strength and thickness swelling of the LP particleboards were smaller than those of the other particleboards. Based on the above observations, we deemed that LP can be made into composite boards with adequate properties either alone or mixed with wood particles.
For the preparation of test specimens, cement, M-sand, coarse aggregate admixture and water were used. Firstly mixing of dry materials was done in a drum type mixer. Super plasticizer was mixed with water and was then added to the dry materials. The required quantities of steel and polyester fibers were taken according to the volume fraction and these fibers were added during mixing. Workability of fresh concrete was checked using a standard slump cone. The freshly mixed concrete was poured layer by layer, into standard cubes of size 150mm for compressive strength test, 150 × 300 mm cylinders for splitting tensile test and modulus of elasticity and into 100 × 100 × 500 mm prisms for finding modulus of rupture. Total number of layers was three. Each layer was compacted by giving 35 strokes per layer with standard tamping bar. The top surface was levelled using a smooth trowel after compaction. For each mix cubes, cylinders and prism were caste. Each specimen was tested after 28 days of curing period.
Abstract: This study concentrates in determining the optimum fiber content in the Hybrid fiber reinforced concrete with glass and polypropylene fibers. Specimens for five mixes with varying total volume of fiber were casted. The percentages of fibers used are 0, 0.5, 1, 1.5, 2 by weight of cement using Glass fiber of 60% and Polypropylene fiber of 40% in the total fiber volume. The specimens were tested in compression, modulus of elasticity and modulus of rupture. The M1.0G60P40 showed increase in strength about 24.2%, 33.7% and 13.1% in compression, modulus of elasticity and modulus of rupture.
This research work is aimed to investigate the effects of partially replacing fine aggregate with our local additive quarry dust with steel powder in concrete at optimum replacement percentage which will help to reduce the cost of structure. Common river sand is expensive due to excessive cost of transportation from natural sources. Also large-scale depletion of these sources creates environmental problems. As environmental transportation and other constraints make the availability and use of river sand less attractive, a substitute or replacement product for concrete industry needs to be found. River sand is most commonly used fine aggregate in the production of concrete poses the problem of acute shortage in many areas. In such a situation the Quarry rock dust can be an economic alternative to the river sand. This paper presents the feasibility of the usage of Quarry Rock Dust as hundred percent substitutes for Natural Sand in concrete. Mix design has been developed for M20 grade using design an approach IS. Also the proposed work is aimed to analyse whether the strength of concrete will increase or not while adding the steel powder with concrete. Six different replacement levels namely 10%, 20%, 30%, 40%, 50% and 60% are chosen for the study concern to replacement method with 1% steel powder. A range of curing periods started from 7 days, 14 days and 28 days are considered. Tests were conducted on cubes, cylinders and beams to study the strength of concrete made of Quarry Rock Dust with steel powder and the results were compared with the Natural Sand Concrete. It is found that the compressive, flexural strength and tensile strength Studies of concrete made of Quarry Rock Dust are more than the conventional concrete. It was reported that significant increase in compressive strength, modulus of rupture and split tensile strength when 40 percent of sand is replaced by Quarry Rock Dust in concrete with 1% steel powder.
width in beech is not expected to be inverse (e.g. Bouriaud et al. 2004), the actual rule disregards the measurements of the ring width because this param- eter is overcome by the direct density determination. The principal mechanical properties of the speci- mens, namely local modulus of elasticity in bending (modulus of elasticity – MOE) and bending strength (modulus of rupture – MOR), were determined ac- cording to the European standard EN 408:2010. The tests were carried out by means of a universal testing machine (METRO COM Engineering s.p.a., Gar- bagna Novarese, Italy; 200 kN), using some linear variable displacement transducers (Monitran Ltd., Penn, United Kingdom) for measuring the defor- mations under loading conditions. For each sample, two small clear woods were cut as close as possible to the point of rupture for the physical character- ization. In addition, the strength determining defect and the failure mode were recorded. The density and the moisture content of specimens were determined as indicated by the standards ISO 3131:1985 and EN 13183-1:2003, respectively. Edgewise bending tests were performed on the beams graded as S (struc- tural) in accordance with the Italian grading rule “Hardwood”. The characteristic values of the bend- ing strength, modulus of elasticity and density were calculated for the beams selected in the S grade, ac- cording to the European guideline EN 384:2010. The factor for adjusting the characteristic value of the MOR to the size of the sample and to the number of samples (k s ) was not applied. This choice was justi- fied by the necessity to check the feasibility of this species for structural uses, considering this test only as the first attempt needed to set a program on fu- ture tests and a suitable extended sampling. For these reasons, the strength classes successively assigned have to be considered as provisional allocations.
and modulus of rupture of sintered products. Apparent porosity, bulk density, and water absorption of the sin- tered products were determined following ASTM C 373 standard procedure. Phases present in the sintered speci- mens were identified using X-ray Diffractormeter (XRD), while the microstructural examination was conducted using Scanning Electron Microscopy (SEM). The ele- ments present in the sintered products were identified using Energy Dispersive X-ray (EDX).