THE ANALYSIS AND MECHANICAL ACTIVATION OF WASTE DUST FROM PROCESSING OF CEMENT-BONDED PARTICLEBOARDS

Exploring enhanced high-temperature resistance: Analyzing the combined impact of fibers and nanoparticles in mortars

This study measured the physical properties in bending of the rat femur and compression of the rat first tail vertebra subjected to deep freezing at -80 degrees C for 2 weeks, 6 weeks, 12 weeks and freeze drying. This study also measured the mechanical changes after in vivo allograft of fresh bone, deep freezing(2, 6, 12 weeks) and freeze drying. Analysis for deep freezing groups showed a mean 7.2% decrease in bending strength and 11.0% decrease in compressive strength when compared with the control group, but there was no statistical difference in the duration of deep freezing. The groups of in vivo graft after deep freezing showed 23.1% and 22.2% decrease in bending and compressive strength. There was no statistical difference in the duration of deep freezing. The freeze drying group showed a 9.7% decrease in bending strength and no significant difference in compressive strength. The group of in vivo graft after freeze drying showed a 30.1% and a 41.3% decrease in bending and compressive strength. The above results suggested that there would be some mechanical limitation in using freeze dried graft for supporting implants.

The advancement of reactive powder concrete (RPC) technology primarily focuses on modifications to its conventional composition. This involves substituting Portland cement (CEM I) with alternative cement types and finely ground mineral additives, as well as replacing quartz aggregate with another type of aggregate. The paper presents an analysis of the properties of RPC obtaining using waste sand and powder generated during the processing of aggregates from migmatite-amphibolite rock. Research into RPC mixtures revealed that in one scenario, replacing quartz powder with waste powder resulted in a significant increase in flexural strength by 23%, although there was a slight decrease in compressive strength by 7%. However, when both quartz powder and quartz sand were substituted with waste powder and waste sand, there was a 14% reduction in compressive strength, while flexural strength increased, albeit to a much lesser extent. The analysis of mineral composition and microstructure of migmatite-amphibolite waste powder and sand revealed that the primary factor contributing to the increase in flexural strength is the presence of biotite in a flake shape form. The microscopy images clearly show hydration products gathering mainly at the rims of biotite flakes and not on their smooth surfaces. The reason could be better availability for hydration products attachment and lower steric hindrance to the rims of single biotite flakes instead of its large packets. Conversely, the reduction in RPC compressive strength, resulting from the substitution of quartz sand with migmatite-amphibolite waste sand, can be attributed mainly to the lower compressive strength of the waste sand itself. Test results indicate that the waste powder generated during the production of migmatite-amphibolite aggregates, which contains fine flakes of biotite, can be utilised as a mineral admixture in concrete, thereby enhancing its flexural strength.

Physicochemical properties of hydroxyapatite/montmorillonite nanocomposite prepared by powder sintering

Biopolymers based on proteins are applied in the building materials technology to modify and improve their selected properties. These polymers are designed as natural admixtures that improve the workability of materials. Casein is an example of a protein-based organic polymer. It is a protein obtained from cow’s milk. The paper aimed at investigating the prospects of enhancing the strength properties of a binder prepared on a basis of metakaolin and hydrated lime. The mix was modified with powdered technical casein at 0.5%, 1%, 3%, and 5% as a partial replacement for the binder mix by mass. The study involved investigating the effect of the applied natural admixture on the flexural and compressive strengths, as well as pore size distribution. The average pore diameter decreased in the recipes with casein in the amount of 0.5% and 1%, while it increased when the amount of casein equaled 3% and 5%. Only the 0.5% casein admixture caused a decrease in the total porosity. The results show a clear dependence of the strength parameters on porosity. The admixture of casein significantly increased the flexural strength of the pastes, and decreased the compressive strength. The highest increase in flexural strength (by 205.7%) was caused by the admixture of 0.5% casein, while the greatest decrease in compressive strength (by 28%) was caused by the 3% casein admixture. The flexural strength was enhanced, i.a., due to the improved adhesion and mutual bonding of lime particles, resulting from the application of a sticky admixture. No notable difference was indicated during carbonation by the phenolphthalein test. The lime binder is characterized by a slow setting process and low mechanical strength. The results of the research showed the possibility of improving the flexural strength using small amounts of natural admixture, which may broaden the scope of application of this binder.

The effects of high temperature on mechanical properties of cementitious composites reinforced with polymeric fibers

The influences of fibres originating from different waste materials on the fresh and hardened properties of self-compacting concrete (SCC) were investigated in this study. For this purpose, a total number of 13 mixes of wood (WF), polyvinyl chloride (PF), aluminium (AF), and iron filing (IF) fibres, with volume fractions (Vf) of 0.5%, 1.0%, and 1.5% were prepared. The investigated fresh properties of the prepared mixes were slump flow, T500, V-funnel as well as L-box tests, while the hardened properties were compressive strength, flexural strength, and ultrasonic pulse velocity (UPV). The findings indicated that although the majority of the prepared SCC mixes met the required self-compacting criteria, the inclusion of the waste fibres negatively affected the mix workability, particularly when Vf of 1.5% was used. Regarding the hardened properties, SCC mixes-containing IF exhibited a slight increase in both compressive and flexural strength compared with the reference mix without fibres, whereas mixes with AF fibres demonstrated a noticeable decrease in compressive strength, but with a comparable level of flexural strength. However, the flexural strength of WF and PF decreased as their Vf increased in the SCC mixes, although a slight increase in compressive strength was noted in the mixes with PF. Furthermore, there was no reliable relationship to be constructed between the compressive strength and UPV tests for all fibres used.

Investigation of the effect of different grading on the mechanical properties of reactive powder concrete

This paper presents the results of an experimental investigation to study recycling-methods of Fiber-Reinforced Polymers (FRP), extracted from Wind-Turbines Blades into concrete. Chemical composition (non-organic), mineralogical analysis, organic content, pozzolanic activity were examined. The effects of adding waste wind-turbine blade FRP-material (WTB-FRP) into concrete as a partial replacement of cement and fiber reinforcement were studied under the uniaxial compression and 3-point bending load. According to the test results, the high wooden content caused significant increase in the setting time of cement paste (up to 4 days for 40% of cement replaced) and significant drop in compressive and flexural strength if added as powder due to the retardant properties of wood powder and its high water absorption. The concrete mixture tests for the fibers showed slight decrease in compressive strength (up to 4% for 1,25% of fibers by weight) and increase in flexural strength up to 15%. No deterioration of E-glass by high alkalinity of hydrated cement was observed due to the protective layer of polymer formed around the fibers.

This study discusses the effect of the addition of resin fibers (Dicranopteris linearis) on the characteristics of concrete. The purpose of fibers to the characteristics of concrete. horns, anti-termite, not easily broken and resistant to humid air and is a plant that grows a lot in Pagar Alam City area. Therefore, the researchers decided to examine the effect of adding resin rod fibers to the characteristics of concrete. characteristics of this concrete is an experimental method that is tested, namely the physical material test, slump test, compressive and flexural strength of concrete. Experiments with the addition of resin rod fibers to the concrete mix of 0.5% of the weight of normal concrete cement. All samples were tested at the age of 3,7,14,21 and 28 days. Based on the test results, 3 cm and 5 cm long resin fibers were used. At 3 cm compressive strength of 28 day old concrete decreased by 0.36% from normal concrete with flexural strength increased by 0.02% of normal concrete while at 5 cm compressive strength of 28 day old concrete decreased by 0.66% of concrete normal while the flexural increase as much as 0.04% of normal concrete. The decrease in compressive strength is due to the addition of impregnated fibers into the concrete which will create more voids or voids in the concrete, the reduced density of concrete and disruption of the bond between cement and other concrete aggregates and the increase in flexural strength is caused because the resin fibers play a role in resisting cracks due to the pressure exerted by them. occurs in the concrete so as to increase the flexural strength of the concrete.

Active silica containing materials in the sub-micrometer size range are commonly used for modification of strength parameters and durability of cement based composites. In addition, these materials also assist to accelerate cement hydration. In this paper, two types of diatomaceous earths are used as partial cement replacement in composition of cement paste mixtures. For raw binders, basic physical and chemical properties are studied. The chemical composition of tested materials is determined using classical chemical analysis combined with XRD method that allowed assessment of SiO2 amorphous phase content. For all tested mixtures, initial and final setting times are measured. Basic physical and mechanical properties are measured on hardened paste samples cured 28 days in water. Here, bulk density, matrix density, total open porosity, compressive and flexural strength, are measured. Relationship between compressive strength and total open porosity is studied using several empirical models. The obtained results give evidence of high pozzolanic activity of tested diatomite earths. Their application leads to the increase of both initial and final setting times, decrease of compressive strength, and increase of flexural strength.

Most of the construction uses concrete as the main building material because concrete has many advantages compared to other materials. Concrete has a high enough weight, various attempts were made to reduce the weight of the concrete for example using lightweight aggregates or concrete made without sand or concrete made hollow Innovations in the development of precast lightweight concrete are urgently needed at this time to support the development of development that is being carried out by the government. From the studies that have been carried out on lightweight concrete and fiber concrete, this research will develop the results of previous studies, namely by combining lightweight concrete and fiber concrete to obtain precast lightweight concrete. This research was conducted to find out how much influence the use of pumice and and fiber on compressive strength and flexural strength of precast lightweight concrete. Variations in the addition of a mixture of pumice with aggregate are divided into 4 comparisons, namely 0: 100, 20: 80, 40: 60, 60: 40, where each mixture is added 0.1% fiber from the volume of concrete, then printed in cube and beam molds. Compressive tests were carried out on the cube and flexural tests were carried out on beams. From the test results was obtained that the addition of pumice to the concrete mixture can cause a decrease in compressive strength of the concrete from 202 kg/cm2 to 129 kg/cm2 whereas with the addition of fiber there is an increase in flexural strength is 24.48 kg/cm2. The specific gravity obtained is 1.664 gr/cm3 so this concrete can be classified into lightweight concrete.

A study on the effects of high temperature on mechanical properties of fiber reinforced cementitious composites

The effects of Mg and Si additions into the matrix on the tensile, bending and compressive strengths of the carbon fiber reinforced aluminium alloys (CFRM: PAN based high modulus CF, Vf=70%) fabricated by a pressure infiltration method have been studied.The main results obtained are as follows.(1) Mg addition up to 10 mass% to the Al matrix increases the bending strength up to 1250 MPa at about 8%Mg, but decreases the compressive strength to 600 MPa. The FRM with the matrix of Al-7.8%Mg alloy having a high bending strength of 1250 MPa and a low compressive strength of 600 MPa shows pull-out of the fibers on the fracture surface by SEM observation. No precipitates are observed by high resolution TEM in the interface between the fibers and matrix.(2) Si addition of about 3% to the Al-Mg matrix makes a significant decrease in bending strength to 900 MPa and a small decrease in compressive strength to 500 MPa.(3) Si addition up to 12 mass% to Al matrix makes a small increase in bending strength to 600 MPa and a significant decrease in compressive strength to a level lower than 500 MPa.(4) Mg addition of about 1% to the Al-Si alloy matrix makes a significant increase in compressive strength up to 1000 MPa at about 7%Si, without changing of the bending strength. The FRM with the matrix of Al-7.1%Si-0.36%Mg alloy having a low bending strength of 600 MPa and a high compressive strength of 1000 MPa exhibits flat fracture like shear mode for bending test. High resolution TEM work identifies the Al4C3 precipitates on the interface.(5) Tensile strength and bending strength have a relationship based on our results using thin bending specimen. Therefore, we regarded the bending strength as the substitute of the tensile strength.

This research investigates the durability of waste banana fiber (BF) reinforced Earth of Datça (ED)-based geopolymer (EDBG) mortar under consecutive cycles of freeze-thaw, wetting-drying, and sulfate attack tests. ED is the volcanic tuff of the Datça Peninsula in Türkiye and was utilized as an aluminosilicate source, while sodium silicate (SS) and potassium hydroxide (KOH) solutions were used for alkaline activation. BF with a 20-mm length was added to the geopolymer mortar in the contents of 0.5, 1.0, and 1.5%. Mortars were cured at 70°C and 95±5% RH for 24h, followed by ambient air curing at 20 °C and 55±5% RH for 28 days. In parallel with the increase in the fiber content added to the geopolymer (EDG) mortar, there was a slight decrease in compressive strengths but a significant increase in flexural strengths, as expected. This trend was also observed after all aging tests except after the sodium sulfate (Na2SO4) attack. With the 1.5% BF inclusion, the gain in compressive strength, flexural strength and weight was 27.31%, 12.79%, and 1.58% respectively, which might be due to the crystallization of the absorbed salts inside the structure. Among the aging tests, although freeze-thaw has the most deteriorating effect on both EDG and EDBG mortars, the utilization of fiber decreased the damage to the material, and the integrity of the material was maintained. The behavior of the material under the effect of wetting-drying can be defined as “0-specimen intact.” Therefore, it was proven that the use of banana fiber enhanced the durability of EDBG mortars under the aforementioned aging tests, and the building material produced within this experimental study can be used safely.