Use Of Pumice Research Articles

Effect of Recycled Concrete Aggregate Utilization Ratio on Thermal Properties of Self-Cleaning Lightweight Concrete Facades

In today’s environment, where energy is desired to be used more efficiently, it has been understood that the interest in the use of lightweight concrete with superior performance in terms of thermal insulation properties has increased. On the other hand, it has been stated that construction waste increases rapidly, especially after severe earthquakes. In this context, encouraging the use of recycled concrete waste and efficient disposal of construction and demolition waste is of great importance for the European Green Deal. It is also known that pollutants such as COx and NOx stick to facades over time, causing environmental pollution and visual deterioration. It has been reported that materials with photocatalytic properties are used in lightweight concrete facade elements to prevent such problems. This study examines the effect of using recycled concrete aggregates on the thermal properties of self-cleaning lightweight concrete mixtures (SCLWC). For this purpose, an SCLWC containing 1% TiO2 and 100% pumice aggregate was prepared. By replacing pumice aggregate with recycled concrete aggregate at the rates of 15%, 25%, 35%, 45% and 50%, four different SCLWCs with self-cleaning properties were produced. High-temperature resistance, thermal conductivity performance, microstructure analysis and photocatalytic properties of the produced mixtures were examined. It has been understood that the unit volume weight loss of SCLWC mixtures exposed to high temperatures generally decreases due to the increase in the recycled concrete-aggregate substitution rate. However, it was determined that the loss of compressive strength increased with the increase in the amount of recycled concrete-aggregate replacement. Additionally, it was determined that the thermal-conductivity coefficient values of the mixtures decreased with the use of pumice. After SCLWC mixtures were exposed to 900 °C, small round-shaped crystals formed instead of C–S–H crystals.

Strength and elevated temperature resistance properties of the geopolymer paste produced with ground granulated blast furnace slag and pumice powder

The production of cement results in large amounts of CO2 emissions. In order to reduce the energy consumption and gas emissions associated with cement production, a new technology called geopolymerisation has been developed to produce concrete without the use of cement by using aluminosilicate materials as raw materials. The purpose of this study is to evaluate the effect of various parameters on the geopolymer based slag/pumice paste. Slag (GGBFS) and pumice powder were used as binders in different slag/pumice ratios (100:0, 90:10, 80:20, 70:30 and 60:40) and activated with sodium hydroxide (NaOH) at 12 and 14 M concentration and cured for 3 and 7 days at 65 °C temperature. The effect of these parameters on compressive strength and resistance to elevated temperatures was investigated. Microstructural (SEM, EDX) and chemical (FT-IR, XRD) analyses were also carried out to determine the effect of slag/pumice ratio, NaOH concentration and curing time on the properties of the geopolymer pastes. The results showed that the use of slag significantly increased the compressive strength, while the use of pumice with slag increased the resistance of geopolymer pastes to elevated temperatures. For the geopolymer paste produced with slag, high compressive strength can be obtained by a long period of oven curing, whereas for pumice a short period of oven curing and a long period at low temperature can be used. In conclusion, the most effective of the different parameters was the percentage of slag/pumice in the first degree and then the molarities of NaOH, while the least effective parameter was the curing time.

Lightweight pumice mortars for repair of historic buildings –Assessment of physical parameters, engineering properties and durability

The subject of the presented research was an experimental analysis of physical, engineering and durability parameters of lightweight mortars intended for the repair of historical buildings. Compatibility criteria, the requirements of technical standards and guidelines, and last but not least, previously published research results dealing with the development of mortars for repair delicate historic structures were taken into account in the design of mortar composition. Crushed pumice of a similar grain size was used to lighten the reference lime-based mortar and natural hydraulic lime mortar with quartz filler. Replacement of quartz sand with pumice was 25, 50, 75 and 100% by volume. The use of pumice allowed the fundamental physical, mechanical, hygric, thermal and durability parameters of the lightweight mortars to be such that they met the standard requirements for repair mortars and the heritage conservation requirements for compatibility with the original materials of historic masonry. The main finding was the fact that by replacing sand with pumice, a significant increase in the porosity of the mortars was achieved, while maintaining sufficient mechanical strength due to the pozzolanic reaction of the pumice. Mortars based on natural hydraulic lime have become more resistant to frost and salt crystallization. The advantage of the developed mortars was their low thermal conductivity and high water vapor permeability, which made them suitable for use on damp masonry, which is a substantial scientific contribution of the manuscript.

Insight on the Properties of Pumice Mineral for the Combined Adsorption Distillation of Membrane Reject Water

The current study evaluated the use of pumice, a volcanic mineral and common sand, in treating reverse osmosis membrane reject water (ROR) using a novel combined adsorption distillation (CAD) method. The CAD method is developed to separate the dissolved solids through adsorption distillation, i.e., leaving the vaporized distillate as freshwater and concentrated brine. The adsorption potential of pumice and sand was investigated at different adsorbent doses, i.e., 2, 5, and 10 g, and consecutive CAD adsorbent backwashing cycles. The improved results were achieved at a 10 g pumice dose. However, its adsorption efficiency declined in longer CAD cycles, i.e., due to the separated deposition of solids. After backwashing, the adsorbed and accumulated salts were slightly removed, and pumice adsorption capacity was maintained for up to 20 cycles of CAD. The properties of the pumice, i.e., before and after five CAD cycles and after backwashing, were characterized with scanning electron microscopic (SEM), elemental disruptive spectroscopy (EDS), and X-ray diffraction (XRD), which revealed that the porous structure of the pumice was completely accumulated with deposits of ionic salts, which were slightly washed away after backwashing, but accumulation remained continued in post-CAD cycles. The explored method revealed a high potential of pumice in water filtration.

Recycling Nutrient-Rich Municipal Wastes into Ready-to-Use Potting Soil: An Approach for the Sustainable Resource Circularity with Inorganic Porous Materials

Using waste products is a promising and sustainable alternative to conventional non-renewable peat and nutrient-rich renewable materials. Their products are gaining importance for closing the loop in the ornamental plant industry. Porous inorganic materials have recently become potential bulking agents (BA) for sewage sludge (SS) owing to their high porosity, surface area, passivation capacity, high recycling potential, and potting soil components. The main purpose of the present work was to investigate the feasibility of pumice (PU) and expanded perlite (EP) on composting parameters, nutrient bioavailability and suitability of SS to serve as an ornamental substrate. The addition of PU and EP at 50% (v/v) resulted in higher porosity, optimal initial moisture content, higher temperature rise (56.24 ± 0.13 °C, 56.21 ± 0.11 °C, respectively), and higher CO2 evolution (39.41 ± 0.17%, 41.70 ± 0.22% daily peaks). Composting with inorganic BA at EP-50 and PU-50 mixtures was beneficial owing to high nitrogen content (3.82 and 3.70%, respectively) and readily bioavailable nutrients (270 mg kg−1 phosphates and 1835 mg kg−1 potassium). The use of PU and EP was found helpful in improving the slow-release nutrient properties of the compost. The overall results indicated that composting SS with PU and EP is a viable approach to achieve good composting properties and a good nutrient-providing profile if the compost is used as a component for potting soil components or garden soil amendments.

Avaliação do esmalte dentário de cão por microscopia eletrônica de varredura após diferentes tipos de polimento

Abstract Polishing is an important procedure which takes part in the periodontal disease treatment, being commonly performed with the help of prophylactic paste and provides smoothing of the tooth surface, hindering the adhesion of new plaque. With this study we aimed to evaluate by means of scanning electron microscopy (SEM), the effects of dental polishing observing, qualitatively, the effectiveness and the damage, in three distinct treatments after calculus removal. Twenty (20) teeth were used (four of each dog), from which were obtained three samples each. The sixty samples were distributed into three groups (G0= tooth segmentation submitted to prophylaxis without polishing; G1= vestibular surface prophylaxis followed by polishing with the use of Defengy OC® and G2= vestibular surface prophylaxis followed by polishing with the use of pumice and fluorine gel). The samples were prepared and sent to images execution via SEM. These images, with enlargement of 100x and 500x, were evaluated and the classification averages were obtained. The statistical analysis of these averages was made through the Friedman nonparametric test using the software R. Statistical differences were observed (P<0,05) between groups 0 and 1 in the 100x magnification, whereas in the 500x magnification there was no difference (P>0,05) between the groups. The evaluation based on SEM images at two magnifications was essential, as it allowed the visualization of grooves and remaining calculi in a comprehensive way at 100x magnification and in more detail at 500x.

Green materials for construction industry from Italian volcanic quarry scraps

Italian volcanic quarry scraps, with fine particle size and of little market interest, have been considered for the manufacturing of lightweight geopolymers and highly porous foams. Both powders have been alkali activated with NaOH solution at 8 M and 3 M, respectively.Geopolymers were characterized in terms of density, porosity, humidity absorption/desorption, mechanical strength and microstructure. All samples (with a bulk density of 1.5–1.6 g/cm3) exhibited a porosity of approximatively 35 vol% but featured a quite variable compressive strength (3–7 MPa), depending on the use of pumice or lapillus. The same quarry scraps were easily converted into highly porous foams (porosity of 75 vol%), by intensive mechanical stirring of alkali-activated suspensions, with the help of a surfactant.

Reaction, structure and properties of eco-friendly geopolymer cement derived from mechanically activated pumice

The suitability of pumice, an altered volcanic rock, for the synthesis of geopolymer cement has been investigated. The reactivity of pumice was improved by mechanical activation (MA) in a stirred media mill for various rotor speeds (3 and 5 m/s) and residence times (ranging from 1 to 10 min), respectively. MA resulted into increase in specific surface area (SSA). The effect of SSA of pumice on reactivity is evident from the increase in lime adsorption capacity, which increased from 70.7 mg CaO/g solid material to 234.7 mg CaO/g solid material and the area under the calorimetric peak which increased from 4 mJ to 16.6 mJ and from 9.3 to 27.2 mJ at 27 and 60 °C aging temperatures, respectively. X-ray powder diffraction (XRD) revealed that amorphization increased up to 7% as a result of MA on the particles. Amorphous content has further increased by another 2% after geopolymerization, which can be attributed to consumption of quartz which formed reaction products. A positive correlation has been found between milling time, area under calorimetric peak and compressive strength. Geopolymer with the highest strength (13.8 MPa) was made using pumice with the highest SSA (3838 cm2/g). These results are encouraging and point to the significant potential of the use of pumice as an alternative material to develop an eco-friendly geopolymer cement that contributes toward reducing the carbon dioxide emission associated with the cement production.

POMZA AGREGANIN ÇİMENTO ESASLI TİKSOTROPİK RÖTRESİZ İNCE TAMİR HARCININ PERFORMANSINA ETKİSİ

In this experimental study, a detailed investigation was carried out on the physical, mechanical, and especially the shrinkage characteristics of cementitious repair mortars with the use of ground pumice in with 0/100 μm and 0/2 mm grain sizes. In the experimental analysis, the effects of the use of pumice aggregate in fine and coarse sizes on the density, porosity, compressive strength, flexural strength, elasticity properties and drying shrinkage values of the repair mortar were analyzed in detail. In mixtures with pumice component, the ratio of fine:coarse pumice, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30 and 80:20 by weight were used in mixtures, respectively. Although the drying shrinkage rates of test specimens were determined at a relatively higher value than the control mortar, the shrinkage values of all pumice aggregate repair mortar specimens were within the value range stipulated by the relevant standards. It was determined that the shrinkage amount of the specimens in which coarse size pumice aggregate was used more in mortar mixtures was lower than the shrinkage amount of the specimens with fine size pumice aggregate. This situation was associated with the porosity rate of the mortar, and the shrinkage of the mortars with higher porosity was determined to be lower.

Kapasitas Lentur Balok Beton Ringan Dengan Penambahan Serat Ijuk

Lightweight concrete is concrete that has a specific gravity that is lighter than ordinary concrete. Lightweight concrete can be interpreted as concrete that has a volume weight between 1400-1850 kg/m 3 . The use of materials that have a light density in the concrete mix will reduce the overall weight of the concrete, thereby reducing the dimensions of the structure and can reduce structural loads, especially dead loads. Pumice or pumice is an aggregate that is classified as light aggregate. This type of stone is widely spread in the North Maluku region. In this study, pumice stone was used as a coarse aggregate for making concrete, the use of pumice as a coarse aggregate tends to reduce the compressive strength, so fiber fibers were used as an added material to the concrete mixture so that fiber concrete was obtained. . This study uses experimental methods, cylindrical specimens with 15 cm and height 30 cm for compressive strength testing, beam test specimens with a size of 15 cm x 20 cm x 120 cm for flexural strength testing. The reinforcement in the concrete beam is varied with variations of 2 reinforcement, 3 reinforcement and 4 reinforcement. The test results show that the use of palm fiber as an added material for the manufacture of lightweight concrete can increase the compressive strength of concrete by 11.70% against lightweight concrete without fibers. The addition of 4 reinforcement at the bottom of the beam tends to increase the capacity of the lightweight concrete beam by 3.28%.

REVIEW OF THE FLEXURAL STRENGTH OF LIGHTWEIGHT CONCRETE BEAM USING PUMICE STONE AS OF SUBSTITUTION PARTIAL COARSE AGGREGATE

This research was conducted to analyze the flexural behavior of unreinforced concrete beams produced by substituting coarse aggregate with pumice stones in order to reduce the weight. The specimens used were designed to be 15x15x70 cm in dimension while the coarse aggregate was replaced by the pumice stone at 25%, 50%, 75%, and 100%. Test object without pumice stone (0%) as control beams.The test was conducted at a two-point load with the beam loaded up to the period it failed. The results showed the partial substitution of a higher percentage of the coarse aggregate with pumice produced lower flexural capacity and the beams become lighter with the weight recorded to have reduced by 20.05%. This means the partial replacement of more coarse aggregate with pumice stone has the ability to reduce the weight of the beam and its flexural strength.The use of pumice as a substitute for coarse aggregate in unreinforced concrete beams against tensile strength is good because the tensile strength tends to be higher than the tensile strength of concrete in general.

The use of pumice amended with sand media for domestic wastewater treatment in vertical flow constructed wetlands planted with lemongrass (Cymbopogon citratus)

The performance efficiency in constructed wetlands (CWs) technology is primarily affected by the media material and the types of plants used. Recently, investigations into the usage of local materials and plants in CWs has increased. Pumice is a material which is potential used as a media. However, research on amendment of pumice with other media in CWs is still limited. Therefore, this study aims to evaluate the potential of pumice amended with sand media and planted with lemongrass (Cymbopogon citratus) in CWs to remove organic matter, suspended solids, nutrients, and coliform. The adsorbents were characterized using X-ray diffraction, FTIR and XRF followed by adsorption experiments for PO4–P. Furthermore, Six vertical flow (VF) mesocosms with a diameter of 10.2cm and 55cm depth were established over six months. The treatments were based on percentage of sand media amended with pumice and planted with lemongrass. Furthermore, the barren media were applied to investigate the effect of lemongrass. The loading rate of domestic wastewater into the VF mesocosms was 2 L/day while inflows and outflows were determined for nutrients, organic matter, suspended solids and coliform. The adsorption of PO4–P followed the Langmuir model with adsorption capacity was 0.089 and 0.067 mol/g for pumice and sand, respectively. The results also showed that the removal efficiency of TSS, COD, NO3–N, NO2–N, PO4–P and total coliforms were in the range of 93.7–97.3 %, 52–83 %, 63–86 %, 51–74%, 81–88 % and 92–97 %, respectively. Based on the results, the highest removal efficiency was observed in the sand media amended with 50 % pumice and planted with lemongrass, while the lowest was found in the barren sand media.

Bromide Transport through Soil Columns in the Presence of Pumice

Solute transport parameters, similar to soil physical and chemical properties, can be affected by the presence of organic and mineral soil conditioners. In this study, the effect of different levels (0, 3, and 6 weight percent) of the inexpensive and easily accessible pumice conditioner on the parameters of bromide transport in sandy loam soil columns (diameter and height of 10 cm) was investigated. The transport parameters were estimated based on the breakthrough curves (BTCs) by the inverse modelling of the convection-dispersion equation (CDE) and the mobile-immobile model (MIM) using the CXTFIT software. The BTCs showed that bromide transport in the sandy loam soil columns, regardless of the presence of pumice, was mainly equilibrium, and the CDE was more efficient than the MIM, which is based on non-Fickian and non-equilibrium transport. The peak of the BTCs (maximum relative concentration) was lower in the treatments containing pumice and belonged to more pore volume than the controlled treatment did. This indicates a lack of preferential flow and thus, a reduction in the amount of bromide consumed in the treatments containing pumice. The increase of pumice content did not have a significant effect on the parameters of mobile water fraction (β) and mass transfer coefficient (ω) in the MIM, confirming the equilibrium transport of bromide. A 3% increase in the pumice content in the soil caused an increase and a decrease of 47% in dispersivity (λ) and Peclet number (Pe), respectively. In general, it can be concluded that the use of pumice in field conditions can prevent water loss and nutrients and reduce groundwater contamination by reducing the preferential paths.

Effect of pumice powder and nano-clay on the strength and permeability of fiber-reinforced pervious concrete incorporating recycled concrete aggregate

Pervious concrete (PC) has been widely used to construct concrete pavements and to increase the permeable surfaces all over the world. With the boost in the use of PC, it is necessary to make it more environmental-friendly and cost efficient. This study investigates employing recycled concrete aggregate (RCA) and pozzolanic additives as a partial replacement (PR) of natural coarse aggregate (NCA) and Portland cement, respectively. For this purpose, the NCA was replaced with 10%, 25%, 50% and 100% RCA and the Portland cement was replaced with 10%, 25% and 50% pumice used in combination with 1–3% nano-clay (NC). The compressive and flexural strengths, void content, density, and permeability of concrete were evaluated. Moreover, the effect of adding three different types of fibers including steel fiber (STF), macro-fiber (MF), and waste plastic fiber (WPF) at volume fractions of 1% and 2% on the properties of concrete was studied. A total number of 7791 specimens from 371 mixtures were cast and tested. Using RCA decreased density, compressive strength (CS) (up to 58%) and flexural strength (FS) (up to 64%) and increased the void content and permeability (up to 15%) of concrete. The use of pumice generally reduced the early-age strength of concrete; however, using 10–25% pumice increased the mechanical strength at 90 days. Incorporating 1–3% NC also had positive effects on the strength properties and led to a minor reduction in permeability. STF performed better than MF and WPF, and adding 1% STF, MF, and WPF increased the 180-day FS of RC25 by 78.9%, 67.4% and 37.1%, respectively. The effectiveness of fibers declined with the increase in RCA content, which could be related to the poor compaction of concrete. According to the test results, the 90-day CS of mix RC50Pu25 with 2% STF and mix RC100Pu10NC1 was equal to the control mix. Therefore, it sounds that it is a feasible approach to significantly reduce the consumption of NCA and cement by using specific dosages of the other materials used in this study.

Surface roughness of enamel and root surface after scaling, root planning and polishing procedures: An in-vitro study

ObjectivesThe aim of this study was to evaluate enamel and root surface roughness on exracted human teeth by using different tecniques (ultrasonic scaler, hand instruments, polishing paste, pumice and air powder system). Materials and methodsA total of 200 samples were divided into two groups (enamel and root) randomly with 100 samples for each enamel and root groups. The groups were divided into 5 subgroups: Group I: ultrasonic scaler, group II: hand instruments, group III: polishing paste, group IV: pumice, group V: air-powder. Surface roughness (Ra) was assessed with Mitutoyo SJ-410 device. The one-way analysis of variance (ANOVA) test along with the Tukey test was used for statistical analysis. P values less than 0.05 were considered statistically significant. ResultsThe use of ultrasonic scalers caused the highest roughness increase on the enamel surface (0.935 ​± ​0.010), whereas the use of pumice was the least (0.896 ​± ​0.018) (p ​< ​0.05). There was a significant difference between ultrasonic scalers and all the groups (hand instruments, polishing paste, pumice and air powder system) on enamel surface (p ​< ​0.05). Maximum surface roughness increase was observed in the ultrasonic scalers on root surface. There was a significant difference between ultrasonic scalers and polishing paste, pumice and air powder on root surface, respectively (p ​< ​0.05). ConclusionThe use of ultrasonic scalers cause more rough enamel and root surfaces than hand instrumentation and polishing tecniques. Clinical relevanceUneven surfaces adversely affect the intended periodontal healing by creating a retention area of microbial dental plaque.

Pengaruh Populasi Ikan Lele Dan Jenis Media Tanam Terhadap Pertumbuhan Dan Hasil Tanaman Bayam (Amaranthus Sp.) Pada Sistem Akuaponik

This study aims to study the interaction between catfish populations and the type of growing media on the growth and yield of spinach (Amaranthus sp.) Cultivated by the aquaponics system. This research was conducted using an experimental method (experiment), from July to August 2020 in the experimental area of the PUSKOPAD complex, Tanjungsari District, Sumedang Regency. at an altitude of 850 m above sea level. The experimental design used was the Split Plot Design with the basic design of the RAK. Which consists of 2 factors with 2 repetitions. The first factor or mainplot is the catfish population (i) which consists of 4 levels, namely: (i1) = 0 tails, (i2) = 10 tails, (i3) = 20 tails, (i4) = 30 tails. The second factor or subplot is the type of planting medium (m) which consists of 4 types, namely: (m1) = Rockwool, (m2) = Oyster mushroom waste, (m3) = husk charcoal, (m4) = Pumice stone. Based on the results of experiments regarding the influence of catfish populations and the type of growing media on the growth and yield of spinach grown in the aquaponic system. That there was an interaction between the treatment of catfish populations and the type of planting medium on the parameters of the observation of plant height at 20 days after planting (DAS) and 30 DAS and leaf number at 10 DAS and 35 DAS. The use of pumice growing media is best used for the cultivation of spinach in an aquaponic system and a population of 20 catfish is sufficient to provide the nutrient needs needed by spinach plants.

Varnish technology during the 16th–18th century: The use of pumice and bone ash as solid driers

Abstract The historical varnish technology is of interest to various fields in cultural heritage. To understand the material properties of these historic surface coatings it is important to get insight in the technological background, i.e. the relationship between the material and the processing method. This study has specifically focused on the use of pumice stone and bone ash often mentioned in historical sources as driers for oil-based coating systems. For this purpose lute and Italian violins from the period between the 16th to the mid 18th century were examined. Both, the main organic composition of the varnish and the addition of mineral additives were considered. Based on the analytical data and the corresponding information from historical written sources, the siccativation of oil-based varnishes with pumice stone and bone ash was simulated experimentally. The results of these reconstructions confirm that the technological know-how behind these varnishes is far more complex than it may appear at first glance and that the organic and inorganic components must be regarded as a balanced technological system where each of the various components has a specific function. In this context, these inorganic additives effectively induced accelerated drying, improved the mechanical film properties of young films and showed a stabilizing effect on the long-term degradation during aging.

Analysis of The Mechanical Properties of Concrete Beams That Use Pumice as a Partial Substitution of Concrete Mixtures

One of the most common inhibiting factors in the archipelago is the lack of availability of material resources and human resources. One of the options is the use of lightweight concrete precast using materials around the islands. The local material which is widely distributed in North Maluku is pumice but it has not been used maximally because so far it has only been used as pile material. This study aims to analyze the effect of partial substitution of pumice on fine aggregate in a concrete mixture. This research was carried out experimentally in a laboratory using UTM and divided into 2 stages. Stage 1, designing and analyzing concrete mix using pumice compared without using pumice, Phase 2 testing using concrete beam dimensions of 600x150x100 mm with an inter load of 150 mm. Beam test results show that the limited use of pumice in a concrete mixture does not greatly affect the strength of normal concrete beams, as indicated by the deflection value and strength of concrete blocks that are almost as large.

The Effect of Addition on Pumice and Fiber on Compressive and Fluxural Strength Precast Lightweight Concrete

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.

The potential use of pumice in mine backfill

AbstractThe use of natural pozzolans in concrete applications is gaining more attention because of the associated environmental, economic, and technical benefits. In this study, reference cemented mine backfill samples were prepared using Portland cement, and experimental samples were prepared by partially replacing Portland cement with 10 or 20 wt.% fly ash as a byproduct (artificial) pozzolan or pumice as a natural pozzolan. Samples were cured for 7, 14, and 28 days to investigate uniaxial compressive strength development. Backfill samples containing 10 wt.% pumice had almost a similar compressive strength as reference samples. There is strong potential for pumice to be used in cemented backfill to minimize costs, improve backfill properties, and promote the sustainability of the mining industry.