Wyniki wyszukiwania - BazTech

1

Enhancement of tensile performance of concrete by using synthetic polypropylene fibers

Jienmaneechotchai Thunyawee, Foytong Piyawat, Khunkitti Pirat, Sata Vanchai, Chindaprasirt Prinya

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

|

2023

|

Vol. 32, No. 4

320--337

EN

The research attempted to investigate the effect of polypropylene fibers (PP fibers) on the mechanical characteristics of concrete. According to ASTM C39/C39M and ASTM C 1609/C1609M, standard testing methods were used to examine the concrete compressive and flexural strength, post-cracking behavior, and toughness. The mechanical properties were evaluated at different ages of concrete curing, namely 1 day, 7 days, and 28 days, and for different quantities of fiber volume portions, specifically 0.0%, 0.5%, and 1.0%. The results demonstrate that a fiber volume of 0.5% is the most effective in obtaining the highest compressive strength. The recorded values at the related testing ages were 31.07 MPa, 41.51 MPa, and 46.68 MPa. Additionally, the utilization of 0.5% and 1.0% volume of PP fiber in concrete resulted in improved flexural strength and post-cracking performance. The toughness values for these mixes were 2.0 and 2.6 times higher than those for the plain concrete. Upon analyzing the fracture surface, there was a homogeneous distribution of fibers, which played a significant role in enhancing the overall functionality of the concrete. The research validated that the inclusion of polypropylene fibers substantially enhanced the mechanical characteristics of concrete, emphasizing the potential of fiber reinforcement in concrete-based implementations.

2

Enhancement of mechanical properties of concrete using microwave cured bamboo composites

Adeniyi Ajayi Joseph, Gana James, Adanikin Ariyo, Ogedengbe Kola, Idowu Abundance

Archives of Civil Engineering

|

2022

|

Vol. 68, nr 3

553--567

EN

Microwave curing of bamboo fiber increases the physical and mechanical qualities of cement concrete, according to previous studies. However, there are limited research on their endurance when used as an additive in concrete manufacturing to increase strength. The impact of bamboo fiber and Styrene Butadiene Rubber (SBR) on the mechanical and microstructure of the resulting concrete is investigated in this study. With the inclusion of bamboo fiber ranging from 0-1.5%, a mix ratio of 1:1.5:3 was used. To make the samples, 10% SBR by weight of cement was dissolved in the mixing water. The batching was done by weight, with a water cement ratio of 0.6. Compressive strength, water absorption, swelling, modulus of elasticity, and modulus of rupture were all studied as mechanical properties. Various characterization tests such as SEM, EDS, FTIR, XRD, and TGA were performed on the microstructure, crystalline nature, and mineral composition of certain samples. According to the FTIR study’s findings, peak levels were detected in the O-H stretching, C-H fiber and CH2 functional groups, carbonyl group, C-O and C-C functional groups. As the temperature climbed, TGA measurements showed a drop in weight. The XRD test revealed peak levels of 6.611, 4.255, and 3.855 for sanidine, quartz, and calcite, respectively. After 28 days, the inclusion of bamboo fibers as an additive in concrete shows some promising outcomes in compressive strength, with samples containing 1% and 1.5% bamboo fiber cured at 80°C having a higher compressive strength value.

3

Density and mechanical properties of Scots Pine (Pinus sylvestris L.) wood from a seedling seed orchard

Mederski P. S., Bembenek M., Karaszewski Z., Giefing D. F., Sulima-Olejniczak E., Rosińska M., Łacka A.

Drewno : prace naukowe, doniesienia, komunikaty

|

2015

|

vol. 58, nr 195

117--124

EN

Seedling seed orchard (SSO) growing conditions are different to those in the forest. Trees grow in wide spacing with more access to sunlight and competition between trees is less intense causing larger annual rings and limited height growth. The objective of this research was to: 1) determine the density and mechanical properties of Scots pine (Pinus sylvestris L.) wood grown in an SSO and 2) suggest the most suitable use of this wood. Five trees (25-year-old) were selected using the Urich II method. Final samples (from the height of dbh) were cut from pith to bark, in the four cardinal directions. From all five trees, 159 samples were used to determine: 1) the wood density, 2) the compressive strength parallel to the grain, 3) the modulus of rupture, and 4) the strength quality coefficient. For each property the following mean values were obtained: 327 kg m-3, 32 MPa, 59 MPa and 0.10, respectively. The density did not depend on the dbh or mean width of annual ring. At the same time, the mechanical properties depended strongly on the wood density. In all cases, the wood property values of the Scots pine from the SSO were lower in comparison with those published for Scots pine grown in regular stand conditions. Therefore, pine wood from SSOs should be used in the paper industry.

4

Mechanical properties of investment casting moulds reinforced with ceramic fibre

Nadolski M., Konopka Z., Łągiewka M., Zyska A.

Archives of Foundry Engineering

|

2008

|

Vol. 8, iss. 4

149-152

EN

This work deals with mechanical properties of thin-walled ceramic moulds for investment casting at the dewaxing stage. The main purpose of this work has been increasing their bending strength, expressed by the modulus of rupture (MOR), and determining their corresponding work of fracture, characterised by the fracture index (FI). An essence of the concept is applying aluminosilicate materials in the fibrous form along with grain silica materials as the reinforcing material for the thin-walled mould matrix.

5

Badanie właściwości mechanicznych cienkościennych form powłokowych

Nadolski M.

Archiwum Odlewnictwa

|

2006

|

R. 6, nr 18/2

261--266

PL

W pracy zaprezentowano metody badań właściwości mechanicznych cienkościennych form powłokowych wykonanych w metodzie wytapianych modeli. W celu oznaczenia wytrzymałości na zginanie zastosowano metodę pomiaru zbliżoną do testu MOR (Modulus of Rupture), uzupełnioną o pomiar ugięcia próbki przy obciążeniu krytycznym. Materiał badawczy pobrano z dwóch różnych odlewni precyzyjnych.

EN

The methods of investigation of mechanical properties of shell molds for investment casting are described in the paper. Measuring method similar to the MOR test completed with the measurement of deflection at the critical load has been applied in order to determine the bending strength.

6

Właściwości kompozytów cementowo-włóknistych z dodatkiem mikrosfer

Pichór W., Petri M.

Kompozyty

|

2004

|

R. 4, nr 11

319-325

PL

Przedstawiono wyniki badań kompozytów cementowo-włóknistych z dodatkiem wypełniacza w postaci mikrosfer pozyskiwanych jako uboczny produkt spalania paliw stałych. Mikrosfery są frakcją popiołu lotnego, o formie kulistej, w większości wypadków wypełnionej wewnątrz gazami spalinowymi, powstającą podczas spalania węgla kamiennego w elektrowniach. Ścianki mikrosfer zbudowane są z amorficznej fazy glinokrzemianowej, o dobrej przyczepności do matrycy cementowej. Dzięki właściwościom izolacyjnym i niskiej gęstości objętościowej mikrosfery mogą stanowić atrakcyjny lekki wypełniacz, pozwalający uzyskać kompozyty o zredukowanej gęstości przy zadowalających właściwościach wytrzymałościowych. Zbadano wpływ zawartości mikrosfer przy zmiennej ilości włókien polimerowych na podstawowe cechy użytkowe kompozytów, przede wszystkim właściwości mechaniczne, w tym moduł zniszczenia i wskaźniki odporności na pękanie. Wykonano również obserwacje mikroskopowe SEM ze szczególnym uwzględnieniem strefy kontaktowej mikrosfera-matryca cementowa oraz włókno-matryca cementowa.

EN

The results of investigation the fibers reinforced cement composites with cenospheres as fillers are presented in this paper. Cenospheres are lightweight, thin-walled hollow spheres consisting mainly of silica and alumina filled with air and gasses, and are by-products of the combustion of pulverized coal at the thermal power plants. Some properties of used cenospheres are shown in Table 3. Usually, cenospheres are polluted by ash particles and before application they should be cleaned. Figure 1 shows the difference between cenospheres before and after wet dust separation. They are potentially interesting filler due to their properties and may be used to lightweight cement based composites production. Several series of composites with different amount of fibers and different volume of cenospheres have been prepared in this experiment. But in each case the fibers' volume has been set as proportion to cement matrix content. Mix proportions and properties of fiber used have been presented in Tables 1 and 2, respectively. The influence of cenospheres content on the relative density of composites and the influence on the total open porosity are shown in Figure 2. Relative density of composites linearly drops due to increase of cenospheres volume. Open porosity of such composites may be connected only with cement paste. The effect of cenospheres content on this property may be explained closely by decreasing of cement paste volume in composites. Load-deflection curve for two different series of composites subjected to third-point bending and the method of calculation the toughness indexes I5 and I10 are shown in Figure 3. Figure 4 shows result of mechanical properties investigation of composites. The flexural strength mainly depends on cenospheres content but influence of fiber volume is rather small. However, in the modulus of rupture case his level depends on the cenospheres volume (similar to effect on the flexural strength) and on the fibers content. The role of fibers in fracture process is significant when the brittle cement matrix is broken. According to results obtained in bending test the toughness indexes are calculated, too. A value of each of them mainly depends on fiber type and volume and on properties of matrix. In this case the level of toughness indexes are quite high. The SEM observations of interfacial zone between cenosphere-cement matrix and fiber-cement matrix are presented, too. Figure 6 presents specimen's surface after cracking where broken fibers are visible. Those pictures and SEM observation presented in Figure 7 show the good bonding between fiber and cement matrix and cenospheres and cement matrix, too. The interfacial region between components with porous structure and crystals of portlandite didn't observed. The results show that use of the cenospheres as lightweight filler may be a way to obtain the low or moderate density fiber reinforced cement composites with good mechanical properties.

7

Niektóre problemy wytrzymałości cienkościennych form odlewniczych

Piłkowski Z., Nadolski M.

Archiwum Odlewnictwa

|

2004

|

R. 4, nr 14

413-419

PL

Przedstawiono aktualne problemy ulepszania ceramiki cienkościennych form dla technologii wytapianego modelu celem wyeliminowania pęknięć podczas dewaksacji.

EN

The paper presents advances in shell molding for investment casting, some problems of the water based binder systems and fiber reinforced ceramic shell molds.