Pumice Aggregate Research Articles

Development of high strength light weight concrete for RC beams by using optimum replacement level of pumice aggregate

Development of high strength light weight concrete for RC beams by using optimum replacement level of pumice aggregate

Importance of pumice amount in the design of self-compacting lightweight concrete

Although concrete has high compressive strength values, it has a heavy unit volume and low tensile strength. In this study, the normal-weight aggregate, which takes up the most space in concrete by volume and mass, was partially replaced with pumice aggregate, and macro steel fiber (30 mm) was also added to the mixtures. This experimental work aims to investigate the effect of pumice aggregate amount on the fresh and hardened properties, as well as the flexural performance of the self-compacting lightweight concrete (SCLC). The replacement proportions of pumice aggregate with crushed sand were arranged as 45%, 50%, and 55% of the entire aggregate by weight. Three mixtures, each with 1% macro steel fiber reinforcement and without fiber, were prepared for each mixture scenario. The mix design of these six mixtures was arranged to achieve the self-compacting ability and the workability tests recommended by EFNARC (slump-flow, T50, J-ring) were taken into account. To investigate the mechanical properties (compressive, splitting tensile, and flexural strengths) and flexural toughness of the samples, the specimens were cured in water at 23±2 °C for 28 days. As a result, the unit volume weights of the specimens produced from pumice-substituted mixtures decreased with the increase in the pumice dosage, while the compressive, splitting tensile, and flexural strengths decreased. However, it has been determined that all SCLC mixtures including pumice aggregate provided workability properties in general and had enough compressive strength to be used in the production of structural bearing elements, regardless of fiber content. As a result, the optimum pumice aggregate replacement percentage with crushed sand was found to be 45% and the best flexural performance values of the specimens having macro steel fiber were observed in the ones having 45% pumice aggregate substitution.

Understanding and predicting micro-characteristics of ultra-high performance concrete (UHPC) with green porous lightweight aggregates: Insights from machine learning techniques

Ultra-high performance concrete (UHPC) is an advanced material in construction. Porous lightweight aggregates (PLWA) could reduce the self-shrinkage risk of UHPC by maintaining internal relative humidity. However, understanding and predicting the water migration processes influenced by PLWA are still challenging. Given that machine learning (ML) has shown promise in modeling complex relationships, this study aims to create a reliable ML model to predict and analyze the micro-properties of UHPC with different green PLWAs (pumice and phosphogypsum aggregates). Furthermore, it aims to enhance our understanding of how PLWA influences the microstructure development within the UHPC. The research results demonstrated that convolutional neural network (CNN) algorithm with an R2 value exceeding 0.95 in both the test and training data. Meanwhile, the CNN was employed to predict time-dependent water content and hydration degree of UHPC containing various types of PLWA and multiple-aggregates, aiding in the exploration of how different PLWA impact the water migration of UHPC. Based on the ML analysis results, pumice aggregates and multiple-aggregates both contributed to reducing the rate of water migration, subsequently reducing UHPC shrinkage. Finally, some insights on the use of ML techniques for predicting and understanding the micro properties of UHPC were discussed. ML was employed for micro-performance prediction and in-depth analysis, thereby advancing the intelligent evolution of green UHPC products.

An Experimental Investigation of Light Weight Concrete Using Pumice Aggregate for Short Wall Panel Under the Application of Axial Load

The project study with the special concrete such as light weight concrete by using pumice aggregate (Natural aggregate). One of the disadvantages of conventional concrete is having high self weight. This heavy self-weight will make it to some extent an uneconomical structural material. Light weight concrete having low density reduces dead load and increase the thermal insulation. The reduction in density is produced by using it as a replacement of coarse aggregate partially in concrete. In this Study an attempt has been made to find the compressive strength of light weight aggregate concrete using mix M25 with poly carboxyl ether admixture under the application of axial load on short wall panel. Light weight concrete is made by replacement of Coarse Aggregate of Pumice aggregates.

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.

Examining the Workability, Mechanical, and Thermal Characteristics of Eco-Friendly, Structural Self-Compacting Lightweight Concrete Enhanced with Fly Ash and Silica Fume.

This study compares the workability, mechanical, and thermal characteristics of structural self-compacting lightweight concrete (SCLWC) formulations using pumice aggregate (PA), expanded perlite aggregate (EPA), fly ash (FA), and silica fume (SF). FA and SF were used as partial substitutes for cement at a 10% ratio in various mixes, impacting different aspects: According to the obtained results, FA enhanced the workability but SF reduced it, while SF improved the compressive and splitting tensile strengths more than FA. EPA, used as a fine aggregate alongside PA, decreased the workability, compressive strength, and splitting tensile strength compared to the control mix (K0). The thermal properties were altered by FA and SF similarly, while EPA notably reduced the thermal conductivity coefficients. The thermal conductivity coefficients (TCCs) of the K0-K4 SCLWC mixtures ranged from 0.275 to 0.364 W/mK. K0 had a TCC of 0.364 W/mK. With 10% FA, K1 achieved 0.305 W/mK; K2 with 10% SF reached 0.325 W/mK. K3 and K4, using EPA instead of PA, showed significantly lower TCC values: 0.275 W/mK and 0.289 W/mK, respectively. FA and SF improved the thermal conductivity compared to K0, while EPA further reduced the TCC values in K3 and K4 compared to K1 and K2. The compressive strength (CS) values of the K0-K4 SCLWC mixtures at 7 and 28 days reveal notable trends. Using 10% FA in K1 decreased the CS at both 7 days (12.16 MPa) and 28 days (22.36 MPa), attributed to FA's gradual pozzolanic activity. Conversely, K2 with SF showed increased CS at 7 days (17.88 MPa) and 28 days (29.89 MPa) due to SF's rapid pozzolanic activity. Incorporating EPA into K3 and K4 reduced the CS values compared to PA, indicating EPA's lower strength contribution due to its porous structure.

Effect of Fly Ash and Metakaolin Substituted Forms on Structural Properties in Light Mortar with Pumice Aggregate

In this study, experimental tests were conducted on composite mortars in different forms prepared using lime, pumice, fly ash, and metakaolin. This research aims to recycle fly ash produced as industrial waste and produce a building material that is durable, lightweight, and provides good insulation. In the composite structure mortar mixture designs prepared for the experiments, CEN standard sand was replaced with Nevşehir pumice (0.5-4 mm) at the rates of 10%, 20%, and 30%, respectively, and fly ash-metakaolin was replaced with the cement at the rates of 10%, 20%, and 30%, respectively. A total of 13 different mixtures were prepared. Unit volume mass test, Ultrasonic test, water absorption test, compressive strength test, bending test, thermal conductivity coefficient test, scanning electron microscope (SEM) analysis, and thermogravimetric - differential thermal (TGA/DTA) analysis were performed on the prepared samples. ) analyses were made. As a result of the research, it was determined that T30 (All: Pumice + Fly Ash + Metakaolin) mortar mixture provided the highest compressive strength and thermal conductivity coefficient and the lowest dry unit volume weight compared to other mortar mixtures.

Synergistic Effects of Corn Stalk Ash and Fly Ash on the Properties of Lightweight Concrete Using Pumice Aggregate

Synergistic Effects of Corn Stalk Ash and Fly Ash on the Properties of Lightweight Concrete Using Pumice Aggregate

Experimental Analysis of Mechanical Properties of Fiber Reinforced Cenosphere Lightweight Concrete with Higher Temperature Effect

The aim of this research is to explore the impact of polypropylene fibers and glass fibers on the mechanical characteristics of lightweight concrete when subjected to elevated temperatures. Different fiber ratios ranging from 0.25% & 0.50% by volume of concrete were tested to evaluate their impact on various concrete mixtures. Cenosphere is lightweight material as used with cement as bonding material. Pumice aggregate, which is known for its lightweight properties, was utilized as the coarse aggregate. The study aimed to explore various characteristics of lightweight concrete such as slump value, unit weight, and compressive, tensile, and flexural strength. The concrete samples were subjected to different temperatures ranging from 200°C to 400°C for two hours. The findings revealed that the addition of glass fibers improved the tensile strength of the concrete and enhanced the compressive and flexural strength of the lightweight concrete. However, the incorporation of polypropylene fibers resulted in more cracks and pore formation in the concrete. Additionally, the compressive and flexural strength of the concrete decreased with an increase in temperature up to 400°C.

Improving the Performance of Porous Concrete by Utilizing the Pumice Aggregate

The performance of porous concrete, widely used for storm-water management, can be compromised due to the limitations of conventional aggregates. This research investigates the potential of pumice aggregate, a lightweight volcanic material, to enhance the mechanical strength, durability, and permeability of porous concrete. A series of experimental tests were conducted to evaluate the effects of varying pumice aggregate content on the properties of porous concrete. The results demonstrate that the inclusion of pumice aggregate significantly improves the compressive strength, flexural strength, and freeze-thaw resistance of porous concrete. Moreover, the permeability of the concrete mixtures is enhanced, allowing for better storm-water infiltration. The favorable porous characteristics of pumice aggregate contribute to increased void content within the concrete, enhancing its water storage capacity and reducing runoff. These findings suggest that utilizing pumice aggregate can lead to the development of more sustainable and efficient porous concrete systems for storm-water management. The incorporation of pumice aggregate not only improves the mechanical and hydraulic performance of porous concrete but also offers environmental benefits by utilizing a lightweight and natural material. The findings of this research have significant implications for sustainable construction practices and the effective management of storm-water runoff.

Impact of thermal loads on silica fume-modified lightweight concrete: Machine learning approach to assess compressive strength evolution

Fire resistance of concrete is complex to comprehend as it is a composite material with ingredients of varied thermal properties. As the behaviour of concrete subjected to thermal loads is complex and required exhaustive experimentation, the use of soft computing techniques can be beneficial for predicting the residual compressive strength of concrete. Leveraging the power of machine learning (ML), specifically Artificial Neural Network (ANN), Random Forest (RF), and AdaBoost (AdB) models, this study aims to overcome the limitations of conventional prediction methods. Models were developed for the prediction of residual compressive strength of light weight concrete with silica fume (SF) exposed to thermal loads. Cement, silica fume, lightweight pumice aggregate, water-to-cement ratio, superplasticizer, and temperature were taken as input attributes while residual compressive strength was taken as output. Firstly, the data were subjected to extensive statistical analysis before the models were created. Additionally, hyperparameter tuning using grid search was done to increase the models' efficiency. The coefficient of determination (R2), root mean squared error (RMSE), and mean absolute error (MAE) as model evaluation parameters were used to evaluate the performance of various developed ML models. When the performance of models was compared, it was found that the AdaBoost (AdB) model outperformed all other ML models. Hence, this study highlights the significance of ML techniques in addressing complex engineering challenges and underscore the practical implications for optimizing structural design and performance.

Enhancing the Compressive Strength of M30 Grade of Concrete Using Pumice With 50% GGBS and Metakaolin Comparing with Conventional Concrete

The aim is to compare the conventional concrete by employing a mix of M30 grade concrete, a novel pumice aggregate is used to partially replace the coarse aggregate to create lightweight concrete. All groups were prepared at the composition of 40% Cement and replacing 50% GGBS, 10% Metakaolin is kept constant in our concrete. Coarse aggregate replaced by novel pumice stone and M-sand as Fine aggregate. The group of 6 cubes was formed according to the curing dates of 28 days. Metakaolin and GGBS are procured from Scientific Company and Novel Pumice Aggregate are arranged from online traders. Cement and M sand were arranged from the local shop. The group of 18 cubes was formed according to the Curing date for 28 days. To determine the compressive strength, two groups and a total of 36 cubes were constructed. The average compressive strength test result for conventional concrete of grade M30 at 28 days is 30.28 N/mm2. The average result for Group I and for 18 cubes for the M30 grade of concrete @ 28 days Compressive Strength test result of Concrete with Novel Pumice Aggregate stone and Partial Replacement of GGBS and Metakaolin by the weight of cement is 35.19 N/mm2. From the independent t-test analysis p=0.000, i.e., smaller than p=0.05(p<0.05) which indicates that there is a noteworthy statistical distinction between the two groups. The compressive strength of concrete of M30 grade at 28 days of compressive strength test results of concrete with new pumice aggregate stone and partial replacement of GGBS and Metakaolin by the weight of cement is increased.

Damage and Deterioration Mechanism of Coal Gangue Mixed Pumice Aggregate Concrete Under Freeze–Thaw Cycles

The world is facing the problem of depletion of natural sand and gravel resources, and a large amount of coal gangue solid waste is produced in Inner Mongolia, China, which has low utilization rate and causes ecological pollution. In order to improve the gangue in the mining infrastructure construction of a wide range of application prospects, the use of coal gangue as the coarse aggregate of pumice concrete is of great significance. Inner Mongolia is a cold region, and gangue mixed aggregate concrete (MFC) will certainly face the damage caused by freeze–thaw cycles. Therefore, design gangue by different volume replacement rate (0%, 20%, 40%, 60%, 80%,100%) to replace pumice coarse aggregate. The results show that with the increase of gangue substitution rate, the mass loss rate, relative dynamic elastic modulus, and peak stress of MFC decrease, but the trend of peak strain increases. It is mainly attributed to the less Al2O3 and SiO2 content of gangue, which makes the MFC hydration products decrease with the increase of substitution rate and more original microcracks and pores in the specimens. In addition, the damage model of MFC was established by using Weibull statistical distribution theory and the principle of LEMAITRE equivalent effect variation assumption, and the damage evolution characteristics were explored by combining the experimental results. It can provide the theoretical basis for the application of MFC in cold regions.

MECHANICAL PROPERTIES OF SUSTAINABLE FIBER-REINFORCED LIGHTWEIGHT AGGREGATE CONCRET

With the rapid growth of high-rise buildings and large-scale structures, there is a need to preserve natural resources and reduce loads on buildings by using lightweight concrete to achieve better performance for structures. In the study, four groups were prepared; the first group included one mix containing natural aggregate, and the second mix replaced all the natural aggregates with lightweight pumice aggregates. These mixes are reinforced with carbon fiber with a 0.5% volume fraction. In the second group, a variable volume fraction of carbon fiber of (0.0 and 1%) of mixes. In the third group, the mixes have different lengths of carbon fiber (20mm, 30mm) and a volume fraction of carbon fibers 0.5%. Finally, the fourth group partially replaces sand as a variable with a percentage of lightweight fine aggregates (10% and 30%) reinforced with fibers. Adding carbon fibers to the concrete specimens by 0.5% and 1% improved splitting tensile strength and flexural strength compared to the specimens containing carbon fibers with a length of 5mm. Also, enhanced samples containing fibers by 0.5% and lengths of 20 mm or 30 mm, compared to the sample containing carbon fibers with a length of 5 mm. Also, the specimens containing lightweight fine aggregates as a replacement with a percentage of sand have a lower splitting tensile strength and flexural strength than the reference mix.

Thermal and mechanical performance of lightweight geopolymer concrete with pumice aggregate

AbstractThis study aims to prepare and assess the mechanical characteristics of fly ash (FA)‐based lightweight geopolymer concrete (LWGPC) utilizing pumice as a coarse aggregate. A comprehensive set of 16 LWGPC mixtures were synthesized. The first twelve mixtures produced with varying alkaline to FA ratio and varying proportions of coarse aggregates. The mixture proportion that has given the highest compressive strength (CS), was selected to create four other LWGPC mixes with water‐to‐solid ratios (w/s) ranging from 0.17 to 0.23. Fresh and mechanical properties as well as thermal conductivity (TC) of the LWGPC samples were examined. The experimental findings indicate an inverse relationship between the w/s ratio and mechanical properties of LWGPC samples. Notably, the mechanical properties attain their highest values at the lowest w/s ratio, primarily attributed to reduced porosity and higher concentration of alkali solution in the mixtures with lesser water content. The LWGPC achieved highest CS of 13 MPa, modulus of elasticity (ME) of 8.8 GPa, flexural strength (FS) of 2.2 MPa, and tensile splitting strength (TSS) of 1.64 MPa. The oven dry density (ODD) and TC values ranged from 1746 to 1815 kg/m3 and 0.119 to 0.131 W/m K, respectively. A low‐cost and eco‐friendly novel lightweight concrete composition with low TC was developed.

Evolution of the pore structure of pumice aggregate concrete and the effect on compressive strength

Abstract China possesses abundant pumice resources and thereby makes the utilization of pumice in the preparation of pumice aggregate concrete (PAC) a significant strategy for environmental protection and resource conservation. To obtain the effect of pumice pore structure variation on the compressive strength of PAC, PACs with strength classes LC20, LC30, and LC40 were prepared. Moreover, the pore structure of PAC was characterized using nuclear magnetic resonance to investigate the effect of pore structure variation on the compressive strength of PAC. Results showed that the higher the coarse aggregate content of PAC, the higher the percentage of large capillary and non-capillary pore sizes of PAC, corresponding to higher porosity and lower compressive strength. The hydration products in PAC continuously fill in the pore structure, the proportion of large capillary pores and non-capillary pore size gradually decreases, the proportion of small capillary pores and medium capillary pore size gradually increases, the pumice concrete matrix gradually becomes dense, and the compressive strength increases. The prediction model of the pore structure and compressive strength is established based on gray theory, and the relative error between predicted and tested values is not significant, which can effectively predict its compressive strength. It provides effective guidance for the engineering practical application of PAC.

Çimento Hamuruyla Kaplanmış Pomza Agregalarının Su Emme ve Darbe Dayanımı Performanslarının İncelenmesi

Pumice aggregate, which has high reserves in our country, is used in the production of lightweight concrete, however, it is not preferred as a structural lightweight concrete since its low mechanical properties. The mechanical properties of pumice aggregates can be improved by coating their surfaces. In this way, the coated pumice aggregates can be used to produce lightweight concrete. This study investigated the coating potential of Kayseri and Ahlat pumice aggregates with cement paste. The flow diameter, marsh funnel, and 28-day flexural and compressive strength values of the cement paste 0.55-0.50 w/b ratio and 0.35-0.30 w/b ratio with 1.5% plasticizer admixture were determined. At the end of 28-day curing, the Coating effectiveness of the produced samples was investigated via optical microscope, aggregate impact value, water absorption, and unit weights, and comparisons were made with uncoated aggregates. After coating, it was determined that Ahlat and Kayseri pumice aggregates were crushed by 11% and 18%, considering the impact strength result, moreover a decrease in water absorption was obtained by 50.49% and 78.32%, respectively. As a result, the water absorption values of the coated pumice aggregates decreased, and the aggregate impact values increased compared to the uncoated pumice aggregates.

Mechanical and thermal properties of lightweight concrete produced with polyester-coated pumice aggregate

With the technological advances in the field of building materials, there has been an increasing focus on the research of lightweight concrete made with coated aggregates for improving the durability of concrete. In this study, pumice aggregates were coated with cast-based polyester to obtain polymer-coated pumice aggregates (PCPA). Lightweight concretes were produced with different cement dosages (200, 250 and 300) and PCPAs at different ratios (0%, 50% and 100%). Physical properties, mechanical strength, thermal properties and internal structure analysis (SEM-EDS) of the produced concrete samples were performed. According to the RILEM functional classification of lightweight concrete, the test results showed that REF D300 and REF D250 dosage series are in the semi-load-bearing lightweight concrete class, and the other all series are in the insulation concrete class, and the produced concretes can be classified as lightweight insulation materials. It can also be used in non-load-bearing walls or as an alternative lightweight insulation material.

Bushfire Resistance of Lightweight Masonry Blocks Made with Diatomite Aggregate

‘Diatomite’ is a naturally occurring soft material that contains fossilized skeletal remains of diatoms. It is lightweight, and the porous structure of the aggregate possesses low thermal conductivity. This study was aimed at developing masonry (i.e., cement) blocks using diatomite aggregate and assessing their suitability for use in bushfire shelters and external walls of buildings in bushfire-prone areas. First, the chemical and physical properties of mix components (i.e., cement, sand, and diatomite aggregate) were determined. Then masonry block cement mixes including a cement-sand (i.e., standard) and three different cement-diatomite (i.e., diatomite) mixes were developed by absolute volume method. The properties of fresh mixes; slump and fresh density and properties of hardened mixes; density, compressive strength, and water absorption were investigated, while bushfire and building fire resistance of developed masonry blocks were examined by exposing them to the standard fire curve for 30 min and three hours, respectively. The obtained results from this experimental study showed that diatomite mixes have a negative correlation between the amount of diatomite aggregate and the density and compressive strength, while a positive correlation for water absorption and bushfire and building fire resistance. All the developed diatomite blocks are ultralightweight, loadbearing, and have three hours of building fire resistance. Further, the obtained results were compared with those of the standard and two other previously developed lightweight masonry blocks/mixes using expanded perlite and pumice aggregates. In comparison to the standard and other diatomite, expanded perlite, and pumice blocks, blocks made with 60% of diatomite aggregate are recommended for use in bushfire shelters and other buildings in bushfire-prone areas.

Dual use of pumice in lime mortars

The use of natural pumice as pozzolanic materials in lime mortars has been known since ancient times. Current professional works are more concerned with the effects of coarse natural pumice used as an aggregate in cement mortars or self-compacting concrete, than with replacing the binder with ground pumice. The use of a combination of finely ground natural pumice as a binder substitute and at the same time the lightening of lime or cement mortars with coarse natural pumice has not yet been the subject of any research. For this reason, the aim of this paper is to describe the effects of the partial replacement of lime with finely ground natural pumice on the mechanical, microstructural and durability properties of air-lime mortars lightweight with coarse natural pumice, which meet the functional and technical criteria imposed on repair mortars. Pumice is lightweight amorphous volcanic material with porous structure created by entrapment of gasses during the rapid cooling of lava. It shows similar pozzolanic activity to trass or natural zeolite predicting an improvement in mechanical properties and durability of lime-pumice mortars. The fine pumice addition to lime mortars led to decrease in amount of kneading water required for the preparation of the mortars with the same workability. The use of lightweight pumice aggregate in the composition of mortars led to their higher porosity, lower density, improved capillary transmission capability and water absorption, and increased salt crystallization resistance, while the replacement of lime with fine pumice resulted in an increase in the strengths and frost resistance of the prepared mortars. The resistance of the mortars to the salt crystallization of NH4NO3, Na2SO4, and NaCl was improved, although the mortars had relatively low resistance to the reaction of NH4NO3 and Na2SO4, where nitrocalcite, cesanite, and calcium sulfoaluminates were formed, breaking the structure of the mortars. Considering the compatibility, functional and technical criteria, lime-pumice lightweight mortars could be classified as repair mortars.