Water Absorption Values Research Articles

Characterization of Mixtures Based on High-Density Polyethylene and Plasticized Starch.

This paper presents the obtaining and characterization of blends based on high-density polyethylene (HDPE) and plasticized starch. In addition to plasticized starch (28.8% w/w), the compositions made also contained other ingredients, such as polyethylene-graft-maleic anhydride as a compatibilizer, ethylene propylene terpolymer elastomer, cross-linking agents, and nanoclay. Plasticized starch contains 68.6% w/w potato starch, 29.4% w/w glycerin, and 2% w/w anhydrous citric acid. Blends based on HDPE and plasticized starch were made in a Brabender Plasti-Corder internal mixer at 160 °C, and plates for testing were obtained using the compression method. Thermal analyses indicate an increase in the crystallization degree of the HDPE after the addition of plasticized starch. SEM micrographs indicate that blends are compatibilized, with the plasticized starch being well dispersed as droplets in the HDPE matrix. Samples show high hardness values (62-65° ShD), good tensile strength values (14.88-17.02 N/mm2), and Charpy impact strength values (1.08-2.27 kJ/m2 on notched samples, and 7.96-20.29 kJ/m2 on unnotched samples). After 72 h of water immersion at room temperature, mixtures containing a compatibilizer had a mass variation below 1% and water absorption values below 1.7%. Upon increasing the water immersion temperature to 80 °C, the sample without the compatibilizer showed a mass reduction of -2.23%, indicating the dissolution of the plasticized starch in the water. The samples containing the compatibilizer had a mass variation of max 8.33% and a water absorption of max 5.02%. After toluene immersion for 72 h at room temperature, mass variation was below 8%.

Introducing new wheat milling passages to manage the ultra-fine flours of primary streams: Roles of granulation in starchy content

The size distribution of ultra-fine flours (UFF) is crucial for determining the physicochemical properties of the final wheat milling product. To optimize the milling process, new passages with a stack of fine mesh sieves are used. The UFF extracted from both break and reduction passages exhibits a wide range of functionality and physicochemical characteristics, were incorporated into five reconstituted flour blends. By splitting of UFF fraction isolated from primary passages, the quality of baked bread can be modified manually without using any enzymes or chemical improvers. Substituting the default milling stream with 60% of primary UFF increases the availability of starch for gelatinization by shifting the peak temperature to a higher number. This creates stronger starch-gluten network exhibiting increased elasticity. Raised viscoelasticity and hence water absorption value result in higher loaf volume. The infrared spectroscopy analysis revealed a specific peak at 1659 cm−1, associated with water absorption in the amorphous region of starches, which was recorded as the highest intensity for UFF reduction samples. These results were in agreement with imposing a higher starch damage. Furthermore, structural amorphization was also observed based on a broader shallow XRD curve for samples incorporated with UFF of reduction passages due to higher grinding strength generated through the smooth rolls. The lowest polydispersity index content was calculated for break UFF samples and more uniformity in particle size distribution was found. This finding highlighted the effective role of corrugated rolls for producing the certain range of flour granulation.

A case study of crushed stone for road construction application: amphibolite and basalt varieties from Croatia

Crushed stone is one of the most exploited and important mineral raw material. Emphasis is given to determination of mineralogical and petrographic properties, of two genetically different rocks of silicate composition, commonly used as crushed stone for road constructions, as their physical properties depend on them. First is amphibolite from Vetovo, and second is basalt from Vratnik locality, both sourced from Croatia. Tests conducted according to European and Croatian norms evaluated the real and apparent density, open and total porosity, and water absorption of stones. The relationship between mineralogical and physical properties led to the following conclusions: the open porosity values of amphibolite samples are low, which is a consequence of the medium to high degree of metamorphism, (plagioclase and hornblenda), sosiritization, and undisturbed rock features. The total water saturation was achieved in a brief time, confirming this statement. The basalts have different porosity and water absorption values, which are consequences of differences their textural-structural properties (glassy, intersertal or intergranular groundmass), amount of amygdules, presence or absence of chlorite/volcanic glass. Furthermore, the percentage of plagioclase in the modal composition differs, and the plagioclase itself has been altered, and the amount of clay, sericite and calcite vary in two different varieties of basalt. Compared to amphibolites, basalts have notably higher water absorption values as well. Accordingly, the studied amphibolite has water absorption less than 0.5% and is suitable for use in a road construction application for wearing course in the asphalt pavement, and studied basalt is not.

Study of hydrophobic cemented paste backfill (H-CPB) to prevent sulphate attack

One of the challenges encountered in mining is acid mine drainage (AMD) in sulphurous ores in response to rainfall and groundwater. CPB one of the most prevalent waste management systems addresses this issue today. Nevertheless, in the long term, the concretion in CPB may become ineffective because of external factors, such as groundwater and rainfall. The relevant sources in the literature have no mention of AMD problems that may occur in the long term with CPB, particularly in metallic ores. Most studies indicate that the issue which can be prevented by using cement. However, due to the destructive effects of nature, cement alone would be insufficient. Consequently, the research's principal aim is to form CPB hydrophobic, thereby reducing the interaction between CPB and water. In the study, stearic acid was chosen as the hydrophobic agent and application method to the CPB and the changes in load-bearing capacity were studied. Specimens were tested by ion chromatography, X-ray diffraction (XRD), elemental analysis by combustion, water absorption, uniaxial compressive strength (UCS), and scanning electron microscopy (SEM). There was a decrease in the load-bearing capacity while gaining the hydrophobic properties of the material. The results confirm the validity of the selected agent and method and reveal that the effect of sulphate decreases with increasing hydrophobicity yet, there is no significant decrease in the 7, 14, and 28-day UCS tests. The optimal results were achieved when Stearic Acid (SA) was used at a concentration of 1.25 % for 7 % Portland cement and 0.75 % for 11 % Portland cement, with a UCS strength of 1.223 and 2.008 MPa, respectively. The expected benefit of stearic acid was realized as the water absorption value of the reference sample was 2.50 times higher in 7 % cement and 4.25 times higher in 11 % cement than the same value in Hydrophobic Cemented Paste Backfill (H-CPB). These results indicate that AMD formation can be prevented in the future with H-CPB. The results demonstrate that stearic acid, with the new methodology, forms the CPB hydrophobic, while only an acceptable strength loss was observed. Additionally, the outcomes point out that the methodology adopted does not consider a significantly adverse impact on hydration phase of concretation and can be utilized as an environmentally friendly backfilling method, thereby being evaluated as the cleaner backfilling for further CPB applications.

Impact of thermomechanical pretreatment by twin-screw extrusion on the properties of bio-based materials from sugarcane bagasse obtained by thermocompression

The aim of this study was to produce binderless materials by thermocompression from lignocellulosic biomass pretreated using twin-screw extrusion. The impact of twin-screw extrusion pretreatment on sugarcane bagasse (SCB) was evaluated, along with the effects of two associated parameters: the liquid-to-solid (L/S) ratio and the screw profile, using three different mechanical shear rates. It was shown that twin-screw extrusion pretreatment resulted in materials with improved properties as compared to those obtained with untreated SCB. The mechanical properties and water resistance of materials obtained after pretreatment were mainly impacted by the screw profile. The flexural modulus increased from 5.3 to 6.1GPa and the flexural strength from 39.0 to 55.5 MPa. Water absorption (WA) from the thermocompressed materials ranged from 25 to 62 %, and thickness swelling (TS) from 24 to 67 %. Materials obtained with a 0.4 L/S ratio had lower flexural strength but the best water resistance. For the same L/S ratio, the use of a more shearing screw profile improved the material properties, especially the water resistance. The best material was produced with pretreated SCB using a 1.25 L/S ratio with the most restrictive screw profile, resulting in materials with a 5.6GPa flexural modulus, 55.5 MPa flexural strength, and WA and TS values of 44 % and 42 %, respectively.

Tensile strength and durability performances-based evaluation of 3D-printed and mold-cast fibrous geopolymer composites produced at various alkaline activator combinations

This study aimed to investigate the effects of the sodium silicate-to-sodium hydroxide ratio, SH molarity, and carbon fiber volume fraction on the tensile strength and durability properties of mold-cast and 3D-printed geopolymer composites, including flexural and splitting tensile strengths, ultrasonic pulse velocity, water absorption, sorptivity index, and chloride penetration properties. For that purpose, the ground-granulated blast furnace slag and fly ash were employed as alumino-silicate-rich raw material. In order to activate the alumino-silicate-rich raw material, two sodium silicate/sodium hydroxide ratios of 1 and 2 and three sodium hydroxide molarities of 8M, 10M, and 12M were designated. Furthermore, carbon fiber was incorporated into the geopolymer composites at three volume fractions: 0 %, 0.3 %, and 0.6 %. In total, 18 nonfibrous and fibrous geopolymer composites were manufactured in two different ways: mold-cast and 3D-printed. The findings demonstrated that the strength and durability characteristics of 3D-printed specimens were inferior to those of mold-cast specimens, attributed to the presence of weak interfacial bonds between layers. It has been observed that the incorporation of carbon fiber has the effect of improving tensile strength performance. Nevertheless, the addition of carbon fiber led to a slight decrease in UPV values, and an increase in water absorption and sorptivity index values. Also, it adversely influenced the chloride penetration of geopolymer composites. The findings of the study also indicated that increasing the sodium hydroxide molarity had a positive impact on the strength and durability properties of the composites. Nevertheless, it was observed that increasing the sodium silicate-to-sodium hydroxide ratio led to a decrease in both tensile strength and durability performances. Additionally, the microstructure of the geopolymer composites was analyzed using scanning electron microscope (SEM) images.

Wood-fiber insulation boards (WFIB) produced with hardwood and softwoods species and polylactic acid (PLA) fibers as a binder

ABSTRACT Wood fiber insulation boards (WFIB) produced with natural binders have been gaining recognition as an eco-friendly material, however there is limited information on the effect of different wood fiber and sustainable binders on WFIB production. This study investigates the impact of density, wood fiber origin, and pertinency of polylactic acid (PLA) as a binder. Flexible WFIB with densities of 80, 100 and 120 kg/m3 were produced by hot-press method with fibers of pine and spruce as softwoods, and beech and birch as hardwoods. Bicomponent fibers, composed by two concentrical layers of polylactic acid (PLA) were utilized as a renewable-origin binder at a proportion of 10%. Technological properties such as short-term water absorption, compression test and thermal tests properties were assessed. The density of the WFIB significantly influences the water absorption, compression strength, and thermal conductivity, with all these values increasing as the density rises. Insulation boards made from hardwood fibers showed greater water absorption and compression values compared than their softwood counterparts. Softwood-WFIB single-samples with a density of 80 kg/m3 reported lower thermal conductivities than hardwoods ones. The present study shows the promising feasibility of producing flexible wood fiber insulation boards from natural fibers and polylactic acid as a renewable binder.

Improvement in Taste Quality of Rice Porridge Using Konjac Glucomannan.

Improving the taste quality of rice porridge in a scientific way is essential to guiding residential and commercial production. This study aimed to determine the impact of konjac glucomannan (KGM) on the taste quality of rice porridge. The obtained results showed that the optimal concentration of KGM added to rice porridge is 1%. This was primarily observed via the reduction in water absorption, swelling power, and iodine blue value, thus increasing the hardness of rice porridge. At the same time, KGM also reduced the free water content and improved the water-holding capacity of rice porridge. Nevertheless, the pasting properties showed that the high viscosity of KGM raised the pasting viscosity of rice flour, thereby enhancing the stickiness of rice porridge with the increase in the KGM concentration. In addition, KGM gave the rice porridge a stronger aroma. Sensory evaluations further confirmed significant improvements in the color, odor, palatability, and overall acceptability of KGM-supplemented rice porridge (p < 0.05). To summarize, adding an appropriate amount of KGM was beneficial in forming a richer flavor and improving the taste quality of rice porridge. The findings offer valuable insights into the scientific processing of rice porridge products.

Inovasi Desain Roster Beton dengan Mengutamakan Unsur Privacy dan Estetika

A roster is a nonstructural construction that plays a role in regulating the temperature and humidity of the air in the room; not only that, a roster is also often used as a room divider. The number of roster product designs on the market allows roster manufacturers to make products whose designs tend to prioritize less privacy and only prioritize aesthetic factors in the design of the roster structure. This research was conducted to create changes in roster design to improve the function of the roster, where the roster itself must have optimal air circulation and an element of privacy that is maintained. This research uses an experimental method by making its concrete roster design innovation and comparing it with existing products on the market; as a comparison, 2 product design samples were taken from the market and tested. Tests are carried out in the form of air circulation testing, facade testing, compressive strength testing, and water absorption testing. AutoDesk CFD software is used as a means for testing air circulation and as a success parameter for testing compressive strength and water absorption per SNI 03-1570-1989. The value of the air circulation test is 866343.0 cm3/s = 866.343 Liter/s for the 1st design, 842725.0 cm3/s = 842.725 Liter/s in the 2nd design, 7964661.0 cm3/s = 796.4661 Liter/s in the 3rd design. The compressive strength result obtained is 1.25 N/mm2. The results of the test values of compressive strength and water absorption show that they can meet the specified requirements. This concrete roster design innovation can make the right solution for consumers when choosing a more optimal concrete roster.

Synthesis Of Biofoam Based On Glucomannan Porang And Polyvinyl Alcohol (PVA) With The Addition of Seaweed Dregs

Biofoam (Biodegradable foam) is an alternative packaging to Styrofoam made from natural raw materials that can be biodegraded in the soil. Biofoam is generally made from 3 constituent materials in the form of main ingredients in the form of starch or other similar materials, plasticizers such as PVA and also fillers in the form of fibers containing cellulose. The purpose of this study was to determine the effect of the combination of porang glucomannan, PVA and seaweed pulp on biofoam and to determine the best formulation and characteristics of the biofoam samples made.. The technique of making biofoam was done using baking technique with 9 different treatments. Each treatment was repeated 3x and observations were made on biofoam structure, mechanical properties testing (tensile strength, elongation and young modulus), water absorption test, and biodegradation test. The results showed that Polyvinyl Alcohol plays a role in the formation of a hollow biofoam structure. The thickness parameter value for each treatment was 0.628-1.939 mm. The tensile strength value of each treatment has a value ranging from 15.989-35.265 N/mm². The elongation value for each treatment ranged from 25.719-76.427%. The young modulus value for each treatment ranged from 0.343-0.896 N/mm². The water absorption value of each treatment obtained values ranging from 35.81-77.12%. And the value of testing biodegradation parameters obtained values ranging from 8.68-32.18%. So that the best treatment obtained using the multiple attribute method is the A3B1 treatment (PVA 15% and the ratio of seaweed pulp concentration to glucomannan 1: 2).

AN ANALYSIS ON THE USE OF MODIFIED EXPANDED PERLITE AND PUMICE IN INORGANIC BONDED FIBROUS COMPOSITE BOARDS

It is often stated that there is an energy efficiency difference between optimum energy use and actual energy use in the world. In the construction industry, various building materials are produced and used to optimize energy efficiency in buildings. Among these building materials, inorganic bonded fibrous composite boards, whose energy efficiency criteria have begun to be improved, are widely used both in Türkiye and in the world. This article presents an experimental analysis of the utilization of modified expanded perlite and pumice as key constituents in the development of inorganic bonded fibrous composite boards. The study investigates the influence of these modified porous materials on the physical, mechanical, and thermal properties of the composite boards. For this purpose; composite mortars were produced using micronized quartz sand, a hybrid fiber consisting of cellulose and glass fiber, modified expanded perlite (MEP) with stearic acid (1, 2, 3, 4, 5, 6, 7, 8, 9 wt.%) and modified pumice (MPU) with stearic acid (1, 2, 3, 4, 5, 6, 7, 8, 9 wt.%). In order to make a comparison, a control mortar that did not contain modified expanded perlite and modified pumice was produced. Through a series of experiments, it is concluded that the density values of all other mixture designs with MEP and MPU aggregate additives under equivalent conditions are lower than the control sample. The water absorption values of the samples always remained below the control sample, and with the increase in the MPU ratio and decrease in the MEP ratio, the water absorption values of the samples also decreased. The average modulus of rupture (MOR) value of control sample in the analysis made after 14 days of curing under ambient conditions is 3.73 MPa. The highest MOR value of the test samples is 3.51 MPa, which is the mixture using the highest MPU. The thermal conductivity value of the control mixture is 0.352 W/mK. The thermal conductivity value of test mixtures with MEP and MPU aggregates varies between 0.175 W/mK and 0.287 W/mK.

Biochar-enabled carbon negative aggregate designed by core-shell structure: A novel biochar utilizing method in concrete

Using carbon-negative biochar is promising for the carbon footprints reduction of construction materials; however, directly utilizing biochar in concrete would negatively influence its mechanical properties, particularly when the utilizing volume exceeds a certain threshold. By designing as a core-shell structure through cold-bonding method, a novel carbon-negative core-shell aggregate (CSA) with a biochar core and a cementitious shell was developed in this study. The aggregate was characterized by strength, density, and water absorption measurements, meanwhile, analyzed by hydration heat, XRD, TGA, SEM/BSE, and X-CT. The results showed that the developed MG80 biochar-CSA attained a loose bulk density of 789 kg/m3. It exhibited a crushing strength of 6.84 MPa, a water absorption value of 19.4 %, and a significantly superior strength efficiency of 8669 Pa·m3/kg compared to commercially sintered artificial lightweight aggregates and other cold-bonded aggregates documented in literature. The carbon emission assessment indicated that producing one ton of MG80 biochar-CSA emitted −69 kg CO2, which was much lower than the commercial sintered aggregates. Concrete developed by replacing natural aggregate with 90 % MG80 biochar-CSA exhibited a compressive strength of 42.2 MPa while maintaining lightweight with density of 1866 kg/m3, which conforms to the standard-classified structural lightweight aggregate concrete.

INVESTIGATION OF PHYSICAL, MECHANICAL AND THERMAL PROPERTIES OF MINERAL ADMIXED AUTOCLAVED FOAM CONCRETE

In this study, the aim was to develop a non-combustible, economical, and entirely domestically sourced and technology-based autoclaved foam concrete thermal insulation material. In autoclaved foam concrete (AFC) with a density of 300 kg/m3, which meets thermal insulation material standards, the density, capillary water absorption coefficient, compressive and flexural strengths, ultrasonic pulse velocity, dynamic modulus of elasticity, thermal conductivity, and the mineralogical properties of hydration products based on XRD of some silica-based mineral additives (fly ash, amorphous silica, and metakaolin) substituted at different ratios (5%, 10%, and 15%) for cement were investigated. Autoclaving improved the physico-mechanical properties of mineral-added foam concrete. Among the mineral additives, the highest strength values were obtained in the foam concrete with 5% metakaolin, while the lowest thermal conductivity and capillary water absorption values were obtained in the foam concrete with 5% fly ash. The study concluded that autoclaving is highly effective in producing a sustainable thermal insulation material in foam concrete.

Use of Various Industrial and Eggshell Wastes for the Sustainable Construction Sector

The alternative composites’ production alleviates the serious problem generated by global warming. Methods to reduce the amount of cement used in concrete production, for example, are being investigated to determine how to reduce carbon dioxide emissions in many applications. Egg shells and various industrial wastes, which are recommended to use in the construction sector at an appropriately high rate, also cause serious environmental damage. Bottom ash (BA) and marble powder (MP) wastes are used today in civil engineering applications. In addition, it is important to increase the use of eggshells due to their rich calcium carbonate content. In this work, BA and MP wastes were blended with eggshells to produce cement paste composites. Two different sets of composites were prepared during this study. The composites were prepared with cement (80%), BA (20%), and MP (20%) wastes by weight with 0.3%, 0.75%, 1.5%, and 2.5% eggshell waste. The fresh (flow table), physical (dry unit mass, apparent specific gravity, and porosity), mechanical (unconfined compressive strength and flexural strength), and durability (water absorption, seawater resistance) tests were conducted. According to the experimental results, the composites can be classified as lightweight construction materials. The test results showed that 0.75% eggshell by weight of cement in bottom ash and marble powder can be used as an optimum value for better performance. The bottom ash mixtures groups are higher water absorption and porosity values when referring to the marble powder mixture groups. The highest compressive strength value was found at 56.03 MPa in the MP mixture group and 52.79 MPa in the BA mixture groups with these optimum eggshell combinations at 56 days. The MP mixture group showed better resistance to seawater when referring to the bottom ash blended mixtures. Laboratory-produced composites are possible candidates for cost-effective and environmentally friendly building materials. The eggshells have a promising alternative binder for concrete in the near future and they are utilized together with industrial wastes such as BA and MP in sustainable concrete construction.

Improvement of Physical and Mechanical properties of High-performance Sand Concrete with different Silica Fume content

Silica fume (SF) is widely used for the improvement of several properties of cementitious materials. For this purpose, this study investigated the effect of SF content on the mechanical and durability properties of high-performance sand concrete (HPSC). The experiment work consists of the preparation of HPSC by adding different amounts of SF (0 %, 4 %, 6 %, and 8 %) as a replacement for ordinary Portland cement at a constant water-to-cement ratio of 0,35. The compressive and flexural strengths were performed on the HPSC samples with two standardised sizes of 40 mm × 40 mm × 40 mm and 40 × 40 × 160 mm, which cured during 3, 7, and 28 d. In contrast, both water absorption and water capillary absorption analyses were conducted under a prismatic size of 40 × 40 × 160 mm and cured for 28 d. Based on the test results, the optimal amount of SF was obtained using mechanical strength analysis (6 %). The results showed that at this content of SF, the compressive strength and flexural strength increased by 6,19 and 10,03 %, respectively. In contrast, the addition of SF above this concentration slightly increased the mechanical properties. However, the lowest value of water absorption was obtained for the sample with 6 % SF content. Indeed, at this concentration of SF, the water absorption and the capillarity values of HPSC samples decreased by 8,80 and 8,57 %, respectively.

Recyclable fully biobased high-performance epoxy thermosets

Thermosetting polymeric materials play a pivotal role in numerous sectors due to their versatility in tailoring physicochemical and mechanical properties and their exceptional performances. The aim of this study is to design 100 % bio-based high performant and recyclable thermosets. To achieve this goal, a natural and renewable-based epoxy monomer, triglycidyl ether of phloroglucinol (TGPh), was crosslinked with biobased anhydrides to create novel polymeric resins. Through detailed investigations, it was found that the designed materials have storage moduli values at room temperature ranging from 2.1 to 3.4 GPa, with damping factors spanning from 86 °C to 163 °C depending on the nature of the anhydride. Tensile tests corroborated the performant mechanical properties of the designed bio-resins, showing Young's modulus values ranging from 1.2 to 1.5 GPa. Furthermore, the water absorption values are very low, ranging from 0.25 % to 0.35 %. Besides, the designed bio-resins exhibited rapid dissolution in TBD/EG solution, as well as thermo-mechanical reprocessability.

The evaluation of the effects of different curing methods on concrete

This research explores the impact of various curing methods on the water absorption and compressive strength of concrete. To evaluate these properties, 45 cubes of mix ratio 1:2:4 were tested under different curing methods namely water ponding, sand, polythene sheet coverage, sawdust and water sprinkling. All the cubes were cured at an average laboratory temperature. Water absorption, compressive strength and SEM-EDX tests were conducted on the concrete cubes after curing for 7, 14 and 28 days. The study found that the water absorption and compressive strength values at 7, 14, and 28 curing days ranged from 1.53 to -1.12% and 21.30 to 31.40 N/mm2, respectively and varied depending on the curing method used. All the cementitious compositions of the concrete cubes of all the curing methods showed an increase with the increase in curing age and ranged between 0.01 and 81.67, while their SEM images revealed heterogeneous microstructures consisting of aggregates, cement paste, and voids.Sand and sawdust curing produced the highest and lowest compressive strength values, respectively. Based on these findings, sand curing was identified as the most favourablemethod. Further investigation should be carried out.

Assessment of Changes in Selected Features of Pine and Birch Wood after Impregnation with Graphene Oxide.

In this work, pine and birch wood were modified by graphene oxide using a single vacuum impregnation method. The research results indicate that the impregnation of wood with graphene oxide increases the crystallinity of cellulose in both pine and birch wood, and the increase in crystallinity observed in the case of birch was more significant than in the case of pine. FT-IR analyses of pine samples impregnated with graphene oxide showed changes in intensity in the absorption bands of 400-600, 700-1500 cm-1, and 3200-3500 cm-1 and a peak separation of 1102 cm-1, which may indicate new C-O-C connections. In the case of birch, only some differences were noticed related to the vibrations of the OH group. The proposed modification also affects changes in the color of the wood surface, with earlywood containing more graphene oxide than latewood. Analysis of scanning electron microscope images revealed that graphene oxide adheres flat to the cell wall. Considering the differences in the anatomical structure of both wood species, the research showed a statistically significant difference in water absorption and retention of graphene oxide in wood cells. Graphene oxide does not block the flow of water in the wood, as evidenced by the absorbability of the working liquid at the level of 580-602 kg/m3, which corresponds to the value of pure water absorption by wood in the impregnation method using a single negative pressure. In this case, higher graphene oxide retention values were obtained for pine wood.

Experimental investigation of metakaolin ingredients on bonding of steel fibers to cement in paste of steel fiber concrete under sulfate and sulfate–chloride attack

The present study aimed to produce specimens made from steel fibers/metakaolin (SFs/MK) composite concrete that would achieve superior strength characteristics and controlled cracking behavior under aggressive media (i.e. sodium sulfate and sodium chloride). The composite of SF and concrete is full of porosity, creating weak zone in the specimens. Therefore, the use of clay materials is required to reduce the porosity. In this context, the general physical and chemical properties of clay, including structure and the percentage of alumina and quartz, play a significant role in forming composites with suitable mechanical properties. The changes in weight of SFs, effects of the aging period in terms of strength, and effect of aggressive solution are investigated and compared with SF reinforced concrete. The findings from N2 adsorption-desorption, field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), X-ray fluorescence (XRF) and compressive strength tests indicate that MK with disordered stacking and higher percentage of alumina, and lower quartz content provides better bonding in the concrete composite. According to the experiments conducted in this study, a 15.0 % MK and 2.0 % SF replacement of cement increased the sulfate and chloride resistance due to porosity, and water absorption values, respectively.

Utilisation Of Clamshells As Aggregate Substitute In Paving Blocks

Paving blocks are becoming more popular among consumers because they are environmentally friendly, can save groundwater, are easy to install and maintain, and have many shapes that add aesthetic value. This study aims to determine the difference of shells on the water absorption capacity of paving blocks and the strength of paving blocks. Experiments were conducted at the structure and materials laboratory of Muhammadiyah University of Parepare from August to October 2023 for this research method. The results showed that the water absorption of paving blocks was influenced by the addition of seashells. The water absorption values of the 0%, 5%, 10%, and 25% variations were 1.4 percent, 2 percent, 3.4 percent, and 3.7 percent for the 7-day treatment period; 0.6 percent, 1.7 percent, 2.4 percent, and 3.3 percent for the 14-day treatment period; and 1.3%, 2.8 percent, 3.0 percent, and 4.6 percent for the 28- day treatment period. According to the above results, the more clamshells added, the greater the water absorption. The compressive strength shows that the addition of clamshells affects the compressive strength of block paving. The compressive strength values were 23.841 Mpa, 9.365 Mpa, 21.587 Mpa, and 11.429 Mpa at the 28-day curing age, respectively. The more clamshells added, the lower the compressive strength.