Slump Value Research Articles

New strategy for closing the plastic loop: Lightweight concrete by the waste of recycled synthetic fibers

Environmental protection related to the mismanagement of plastic waste and rational consumption of natural raw materials is an essential goal of the building materials industry and the production of structural lightweight concrete. Plastic waste is not a degradable polymer and increases severe environmental burdens each moment due to its significant quantity. In addition, the recycling of plastic materials is lower than that of other materials. It is usually described as an inefficient and complex process. The textile industry offers an eco-green, effective part of the recycling loop of plastics. Therefore, many textile mills consider recycled plastics as synthetic fiber raw material, particularly for household applications. Unfortunately, such a process results again in another waste known as popcorn. This study aims to introduce an end-of-life management option for the waste of synthetic textile fibers manufactured from recycled plastic materials in construction. Furthermore, the study presents a novel approach to develop an eco-green lightweight structural concrete by incorporating a unique type of lightweight aggregate (popcorn aggregate) as a 100% environmentally friendly product. To achieve that, fourteen mixes of fine and coarse popcorn aggregate contents (25%, 50%, and 100%) are considered to replace the fine and coarse natural aggregate by volume. In addition, the workability, compressive, splitting tensile, flexural strength, microstructure analysis, and Energy Dispersive X-ray Spectrometry are assessed. The results revealed that the higher the substitution ratio of ordinary aggregates by popcorn aggregates, the higher the slump value. Meanwhile, the unit weight of hardened concrete exhibited a tangible decrease at a 100% replacement ratio of fine and coarse natural aggregates; a 56% reduction achieved a dry density of 1059 kg/m³. Moreover, the compressive strength results indicated a decrease of 32% for mixing 25% fine e popcorn aggregate with 100% coarse popcorn aggregate, resulting in a compressive strength of 45 MPa. Fine ally, no evidence of chemical interactions between the popcorn aggregate and the cementitious element during hydration is found.

Effectiveness of Limestone Powder as a Partial Replacement of Cement on the Punching Shear Behavior of Normal- and High-Strength Concrete Flat Slabs

The objective of this study is to investigate the performance of normal- and high-strength concretes including limestone powder (LP) through their mechanical properties. Moreover, sustainable flat plates made of these concretes were investigated through their punching strength. For this purpose, two different types of concrete (normal- and high-strength) with various limestone replacement ratios of 0%, 5%, 15%, and 20% by weight were designed. The fresh and hardened characteristics of the mixtures were investigated at various ages. By this means, the experimental behavior of reinforced concrete (RC) flat plate slabs made with limestone powder subjected to punching shear failure was studied. Slump value increased up to a 5% replacement of LP; after that, there was a tendency for the slump value to decrease as the replacement of limestone in normal-strength LP concrete increased. However, slump values for high-strength LP concrete increased as the LP replacement amount increased. There was a steady decrease in the compressive strength and splitting tensile strength values with the increase in LP content in normal concrete. However, in the high-strength LP concrete, with more than 10% of replacement LP, a decrease in the compressive strength values and splitting tensile strength values occurred. Compared to the control slab specimen without LP, in normal strength, the slab specimens with LP exhibit a larger ultimate shear load for slab specimens containing 5% and 10% of LP. The maximum increment for RC slabs containing 10% limestone powder was 3.8%. However, in high-strength concrete, the slab specimens with LP remained at the same ultimate shear load as control slabs, up to 10% of LP. high-strength concrete slabs with 5–20% LP showed an overall increase of (17.2%) in punching strength over the corresponding LP normal-strength concrete slabs. The corresponding increase for control slabs was 18.8%. It can be concluded that introducing LP improves the slab punching strength in a similar way that is found in non-sustainable slabs when using either normal- or high-strength concrete.

Experimental Study on Workability of Natural Aggregate Concrete Incorporated with Crumb Rubber

This study investigated the effect of crumb rubber on the workability of fresh concrete. Crumb rubber was used to replace fine aggregate at 0%, 5%, 10%, 15% and 25%. Physical properties (particle size gradation, specific gravity, bulk density and aggregate impact value) of the aggregates: sharp sand, Bida natural stone and crumb rubber were determined. Furthermore, the sharp sand and Bida natural stone used for this research were characterized as normal weight aggregates while the crumb rubber was characterized as a light weight aggregate. Workability of the concrete in its fresh state was extensively studied. Generally, the workability of fresh concrete reduced as the crumb rubber increased from 0% to 25%. The reduction in slump values was adduced to the absorbent nature of the crumb rubber. Hence, the research recommended a water-to-cement ratio of 0.55 – 0.60 for use in the production of concrete containing crumb rubber. It was concluded that crumb rubber can be used to produce low workability concrete for use in mass concrete foundations, lightly reinforced concrete elements and roads.

Efek Molaritas Aktivator (NaOH) pada Beton Geopolymer dengan Bahan Pengikat Limbah Fly Ash PLTU Lontar

The average temperature of the earth's surface has increased by 0.74 ± 0.18°C over the past hundred years, caused by 65% carbon dioxide (CO2) emissions. Of the total CO2 emissions, around 6% come from the cement industry. Geopolymer concrete can be a solution to the problem because it does not use cement as a binder, but uses fly ash and activator materials. This activator material is to activate fly ash to become a binder. The aim of this study was to determine the effect of variations in the molarity of the NaOH activator on the workability, setting time, and compressive strength of geopolymer concrete. This study used fly ash from PLTU Lontar with a ratio of NaOH:NNa2SiO3 of 1:1.5, then the NaOH was varied with concentration levels of 5 Molar, 8 Molar, 11 Molar, and 14 Molar. From this research, it is known that the molarity level of the activator (NaOH) affects the workability (slump value), setting time, and compressive strength of concrete. The higher the molarity level of the activator (NaOH), the lower the workability of the concrete (the slump value decreases), the slower the setting time of the concrete, and the higher the compressive strength of the concrete. The most optimal variation is 14 Molar NaOH geopolymer with a slump value of 15 cm, initial setting time of 90 minutes, final setting time of 203 minutes, and compressive strength at 28 days of 54.60 MPa.

Inovasi Teknologi Beton Self Compacting Concrete Terhadap Panjang Pengaliran (L-Flow) Dengan Variasi Umur Perawatan Beton

The aim of this research is to analyze the effect of adding hyperplasticizer and retarder on the compressive strength of self-compacting concrete. Fine aggregate and coarse aggregate from the Jenneberang River, Kab. Gowa. The concrete mix design uses a trial and error mix design for self-compacting concrete by making visual observations, so that the physical conditions of the mixture appear to be sufficient to produce a good mix. The stages of this research, by finding a comparison of the slump flow values ​​of the self-compacting Concrete concrete, then making test objects, after that curing the test objects using the water curing method for 28 days, then testing the compressive strength of the self-compacting Concrete concrete to produce comparison to the compressive strength of normal(conventional) concrete. The results of this research show that self-compacting concrete has a compressive strength value of 46.25 Mpa compared to normal concrete of 45.02 Mpa, an increase of 2.73% compared to normal concrete. And the slump value of normal concrete is 8 - 13 cm, while the slump flow of self-compacting concrete is 63 - 84.9 cm, with a time range between 2.53 - 3.46 seconds, able to reach a diameter of 500 mm on the segregation board.

Comparative Analysis of Two Different Combinations of Pretreatment Methods for Treating Recycled Concrete Aggregates

Objectives: This research is aimed at comparing the performance of two sets of treatments. The first set of treatments tests the performance of heated, abrasioned, and fly ash-treated recycled concrete aggregates (RCA), while the other set of treatments examines the performance of heated, abrasioned, and silica fume-treated aggregates. Though previous research has examined the performance of the standalone treatment methods for enhancing RCA properties, there is a research gap that attempts to study the performance of the combinations of various treatments and their merits. To bridge the gap in the literature, this study compares the combination of two sets of treatment methods to investigate the relative effectiveness of the combination of the treatment methods that can improve RCA properties. Methods: The study was conducted using the concrete mix design procedure outlined in IS 10262-2019 in the laboratory. As part of the experimentation program, a total of 24 sample cubes were casted and tested. Findings: A 14.5% reduction in water absorption was observed for 10mm heated, abrasioned, and fly ash-treated aggregates, whereas a 15.2% reduction in water absorption was observed for 20mm heat-treated, abrasioned, and fly ash-treated aggregates compared to untreated aggregates. Similarly, for heat-treated, abrasioned, and silica fume-treated aggregates, a 41.7% reduction in water absorption was observed for 10mm aggregates, and a 45% reduction was observed for 20mm aggregates over untreated aggregates. A 133% increase in slump value was observed for heated, abrasioned, and fly ash-treated aggregates, whereas a 150% increase in slump value was observed in the case of heated, abrasioned, and silica fume-treated aggregates. Further, a 150 % increase in compressive strength was observed for heated, abrasioned, and fly ash-treated aggregates, and a 165% increase in compressive strength was observed for heated, abrasioned, and silica fume-treated aggregates over untreated aggregates. Novelty: This research addresses the ninth United Nations Sustainability Development Goal, i.e., Industry, Innovation, and Infrastructure, as it promotes the use of eco-friendly construction practices. Moreover, the present research offers a manifold contribution to the state-of-the-art literature on construction management and offers numerous implications for the construction industry. Keywords: Recycled concrete aggregates, Silica fume treatment, Fly ash treatment, Water absorption, Workability, Compressive strength

Transforming waste into sustainable building materials: Properties and environmental impacts of Geopolymer concrete with recycled concrete aggregates

<p>Industrial by-products such as cementitious materials or aggregates have the potential to mitigate the adverse environmental effects associated with traditional cement manufacture. Geopolymer Concrete (GPC) is more eco-friendly than conventional concrete because it does not require cement. GPC with Recycled concrete aggregates (RCA), Ground granulated blast furnace slag (GGBS), and Fly Ash (FA) reduce raw material use and create sustainable infrastructure. GPC compounds increase workability, slump value above standard concrete, and reduce the amount of water usage. The study examines GPC mechanical properties, durability, and environmental properties with different RCA content. The M30 concrete mix design is established by trial and error utilizing a 0.45 water/binder ratio. GPC with 0%, 10%, 20%, 30%, 40%, and 50% recycled coarse aggregate replaced natural aggregate(NA) by mass. GPC with 50% GGBS provides an early strength of 96% of normal compressive strength on day seven. The compressive, split tension, and flexural strengths exhibit significant improvement with up to a 40% substitution of NA with RA. These results highlight GPC's potential as a sustainable alternative in the construction sector.</p>

Mechanical characterization of fiber-reinforced rubberized recycled concrete

Dumping non-biodegradable wastes, such as construction and demolition waste (CDW) and scrap tires, is causing significant environmental problems. Thus, this study used recycled coarse aggregate (RCA) and crumb rubber (CR) procured from CDW and scrap tires as a partial replacement of natural aggregates. 30% natural coarse aggregate (NCA) was replaced by RCA, and 0, 5, 10 and 15% natural fine aggregate (NFA) was replaced by CR. Besides these, 0.5% polypropylene (PP) fiber was incorporated into the concrete mixtures. Different physical and mechanical properties of rubberized recycled concrete (R2C) and fiber-reinforced rubberized recycled concrete (FR2C) were investigated. Microstructural analysis, chemical analysis, failure modes, and cost-effectiveness were also evaluated. Simplified regression equations have been proposed to predict various mechanical properties of R2C and FR2C mixtures. The inclusion of RCA, CR, and fiber decreased the slump value of the fresh concrete up to 69.7%. The compressive strength decreased with an increase in CR percentage, but it increased by including fiber content. Though all the R2C and FR2C specimens exhibited lower tensile and flexural strength, a marginal reduction was found in FR2C specimens containing up to 5% CR content, which was only 3.3% and 6.8% lesser compared to the control samples. The surface resistivity test revealed that the chloride ion penetrability may be very low for all the combinations of R2C and FR2C specimens. By raising the percentage of CR, the UPV decreased, but the addition of PP fiber slightly increased the value. The cost analysis results pointed out that both the R2C and FR2C combinations saved more energy (up to 2.22 times) and decreased fuel consumption (up to 20.2%). Finally, the present study will aid in advancing sustainable fiber-reinforced rubberized recycled concrete.

Impact of manufactured sand and sintered fly ash aggregate on the mechanical and durability characteristics of normal-strength soncrete

This study examined the impact of substituting Natural Coarse Aggregate (NCA) with varying quantities of sintered fly ash aggregate (SFA) in concrete. To ensure sustainability, manufactured sand (M-Sand) was consistently substituted for river sand in all mixtures. Slump values increased as the SFA content increased, which positively impacted workability. The results suggest that a complete replacement of the coarse aggregates can achieve substantial weight reduction potential. Even though compressive strength, split tensile strength, flexural strength, and Young's modulus decreased as the SFA content increased, all compositions (SFA0, SFA50, and SFA100) surpassed the minimum field requirement of 20 MPa compressive strength. Impact testing adversely affected the impact strength of the SFA50 mix, while SFA0 and SFA100 demonstrated comparable failure modes. It is important to note that replacing 50% NCA with SFA resulted in an increase in concrete durability, as demonstrated by a lower average sorptivity value. The results of this study indicate that SFA is a potential partial replacement for NCA. It provides advantages in terms of workability, weight reduction, and potential enhanced durability, while still maintaining adequate strength for field applications.

The Exploration of the Characteristics of Concrete Incorporating Ultrafine Coal Bottom Ash and Spent Garnet

The building sector is a significant contributor to global carbon emissions, primarily due to the production of cement, a crucial construction material. The need for sustainable building practices has spurred research into alternative materials to traditional cement and sand. Two such materials, ultrafine coal bottom ash (uCBA) and spent garnet (SG), have shown potential as substitutes for cement and fine aggregate, respectively. This research examines the effectiveness of uCBA as a partial replacement for cement and SG as a partial replacement for fine aggregate in concrete, at varying levels of 3%, 6%, and 9% for uCBA and 10%, 20%, and 30% for SG. Initially, the chemical composition analysis was conducted using an X-ray fluorescence spectrometer (XRF), and the particle morphology of uCBA, OPC, and SG was examined through field emission scanning electron microscopy (FE-SEM). Then, the study evaluates the performance of these materials based on slump value, compressive strength, and splitting tensile strength, with specimens undergoing 28, 56, and 90-day curing periods. Results indicate that integrating uCBA and SG in concrete at levels of 3% and 10%, respectively, enhances compressive and splitting tensile strength while decreasing environmental impact. Moreover, workability improves with higher substitution levels. Overall, this research indicates that uCBA and SG hold great potential as replacements for cement and fine aggregate in concrete, providing a means to mitigate the environmental impact of construction.

Aloe Vera-Based Concrete Superplasticizer for Enhanced Consolidation with Limestone Calcined Clay Cement

Self-consolidating concrete (SCC) is renowned for its outstanding workability and ability to seamlessly flow into intricate structures with minimal vibrations, achieved through the incorporation of chemical admixtures. This study pioneers an innovative approach by exploring the use of the cost-effective and readily available plant extract aloe vera mucilage (AVM) as a bio-admixture for SCC. The primary objective is to assess the impact of AVM on SCC formulations, including those comprising ordinary Portland cement (OPC) and blended cement LC3 (clinker 50%, calcined waste clay 30%, limestone 15%, gypsum 5%). AVM is applied at varying dosages at up to 10%. Findings reveal that LC3 exhibits lower consistency, reduced slump values, and extended initial and final setting times compared to OPC. With increasing plasticizer dosage, V-funnel and L-box values decrease. Notably, OPC samples with both plasticizers outperform LC3 in compressive strength at 7, 14, and 28 days. Significantly, a 2.5% AVM dosage demonstrates enhanced compressive strength in both OPC and LC3 samples. In summary, this research positions AVM as an innovative and comparable alternative to commercial plasticizers, contributing to reduced yield stress and increased slump flow in SCC.

INFLUENCE OF MIX PROPORTION ON WORKABILITY OF LATERIZED CONCRETE

The increase in infrastructural development in the tropic has led to high demand for concrete production. Consequently, its constituents became very scarce and costly, especially the naturally occurring constituents. Laterite as an abundant naturally occurring material in the tropics is only put in use as filling material or in road construction. This study presents the determination of influence of nominal mix proportion (1:2:4, 1:1.5:3 and 1:1:2) at a constant water cement ratio of 0.5 with laterite fully replacing sand (fine aggregate). 72 numbers of cubes of size 100 mm were prepared for the different concretes, while 12 numbers were cast for each mix proportion and cured in the curing tank at 3, 7, 14, 28 days. Though the laterite was found to be a normal weight aggregate, it was also identified as A – 7 – 6, medium plastic clayey and porous material, with a specific gravity of 2.59. For the fresh concrete, the slump value and degree of workability were obtained using the Vee-bee consistometer and slump tests in both laterite and conventional concrete in all the three mix proportions (1:2:4 : 0.5, 1 : 1.5 : 3 : 0.5, 1 : 1 : 2 : 0.5). The Vee bee second for the mix proportions (1:2:4 , 1:1.5:3 and 1:1:2 ) are 13:18 , 09:44 and 6.0 for the conventional concrete while 14:47 , 12: 41 and 9:30 for Laterized concrete.

Effect of enhanced pozzolanic activity in nickel slag modified with Al2O3 on mechanical properties of cemented fine tailings backfill

Cemented tailings backfill has gained widespread acceptance in mining industries due to its stable performance and environmental advantages. However, Ordinary Portland cement (OPC), based on engineering experience, falls short in meeting the requirements of cost-effectiveness and environmental protection criteria for cemented fine tailings (median size d50 <20 µm) backfill. Nickel slag (NS), an industrial solid waste with potential reactivity derived from nickel manufacturing processes, is currently employed as a concrete additive at a low rate. In this work, a modification was conducted by melting-quenching the NS-Al2O3 mixtures, followed by a physicochemical analysis of the resulting granulated samples (GAN) using BET and X-ray fluorescence. The mineralogy and structural properties were examined for the GAN samples using X-ray diffraction and Fourier transform infrared spectroscopy. Each of the T-CGAN pastes was formulated by replacing 40 wt% of OPC with the GAN, and then blended with fine tailings at 1:4. The flowability and compressive strength were measured for the T-CGAN pastes, while the hydration products and microstructures of the paste samples were analyzed by derivative thermogravimetry and scanning electron microscope, respectively. The results indicate that the addition of Al2O3 not only provides abundant network formers to GAN glass, but also facilitates the conversion of [SiO4] tetrahedrons from Q4 with strong bond energy to Q3 and Q2 with lower ones, thereby significantly enhancing the pozzolanic activity of the original NS. The T-CGAN slurries exhibit slight decreases in slump values from 228.8 to 224.9 mm compared to T-OPC slurry (236.5 mm), attributed mainly to the strong water absorption of GAN. T-CGAN pastes with higher Al2O3 addition acquired greater compressive strengths during the whole curing ages. After 90 days of curing, T-CGAN20 paste achieves the maximum compressive strength (5.14 MPa), higher than that of the T-OPC by 1.03 MPa. The T-CGAN pastes richer in Al2O3 release more reactive Si and Al to participate in the pozzolanic reaction with calcium hydroxide, contributing to additional formations of C-S-H gel and C-A-H, with SEM micrographs showing a compact microstructure with elevated ratios of Ca/Si, Al/Si, and Fe/Si. This study suggests an effective and environmental way to enhance the pozzolanic activity of the original NS by incorporating Al2O3. The modified NS can then be utilized as a high-performance cement substitute for cemented fine tailings backfill, which also significantly enhances the sustainability for both mining and building industries.

PENGARUH NILAI SLUMP PADA KUAT TEKAN BETON DENGAN CAMPURAN AIR PAYAU

Concrete is a combination of constituent materials which consists of hydraulic cement (portland cement), coarse aggregate, fine aggregate, water, and additives. Generally, the use of concrete starts from the bottom construction to the top construction. In use in under construction, concrete will be in a variety of environments, one of which is an aggressive environment such as brackish water. This study aims to determine the ratio of the compressive strength of concrete and the split tensile strength of concrete in a mixture of brackish water and the concrete's compressive strength at various slump values (25–50 mm), 75–100 mm), 150–175 mm), and (&gt; 175 mm). This research method uses an experimental research method at the Civil Engineering Laboratory, Faculty of Engineering, Muhammadiyah Parepare, in June–August 2022. The research results obtained show that the brackish water mixture in concrete results in a 10% decrease in the material's compressive strength compared to normal concrete and split tensile strength. The compressive strength of brackish water-mixed concrete with slump variation (75–100) is an average of 2.67 MPa, which is 10.68% of the normal concrete compressive strength value of 25 MPa. The compressive strength of brackish water mixed concrete with slump variation (75–100) is the result of the highest concrete compressive strength compared to other slump variations, and the compressive strength of brackish water mixed concrete with slump variation (&gt; 175) is the lowest in concrete compressive strength results compared to other slump variations.

PENGARUH UKURAN BUTIR AGREGAT KASAR TERHADAP KAPASITAS KUAT TEKAN DAN NILAI SLUMP BETON POROUS

Porous concrete is an innovation and development solution for parking areas, yards and pedestrian areas, as a way to avoid standing water or even flooding. The purpose of this study was to determine the proportion of the optimum coarse aggregate mixture for porous concrete in terms of compressive strength and slump value. The research method used was experimental research conducted at the Laboratory of Structures and Materials, Muhammadiyah Parepare University. The results of this study can indicate that the optimum mixture proportions were obtained at aggregate variations of 0.5-1 cm. The compressive strength with an aggregate size of 0.5-1 cm is 6.13 MPa, an aggregate size of 1-2 cm is 5.47 MPa, while an aggregate size of 2-3 cm is 5.00 MPa. The slump value with an aggregate size of 0.5-1 cm is 196 mm, an aggregate size of 1-2 cm is 192 mm, while an aggregate size of 2-3 cm is 178 mm.

A Study on the Substitution of Rice Husk Ash with Natural Sand of Cement Concrete

Researchers from all around the world are currently investigating the feasibility of utilizing agricultural and/or industrial wastes as a resource for the building sector. In addition to saving money, recycling these materials could aid in making the planet a cleaner, greener place to live. Fibrous waste products such as sugar cane bagasse and ethanol vapour are produced during the sugar refining process.. In this study, fine aggregate in concrete was replaced with rice husk ash at the volumetric percentages of 0%, 10%, 20%, 30%, and 40%. Testing was done on both fresh concrete, using methods like the slump cone test, and on hardened concrete, using methods like the compressive strength, split tensile strength, and flexural test. The slump value of the samples was found to decrease when the rice husk ash level enhanced. Up to 20% substitution of rice husk ash with fine aggregates resulted in an improvement in mechanical characteristics.

EFFECT OF COMPRESSIVE STRENGTH AND SLUMP VALUE OF CONCRETE USING LIME POWDER (CaCO3) AS A PARTIAL REPLACEMENT OF CEMENT

Lime powder is the result of burning with a temperature of  900-1500 °C from limestone and then immediately splashed with air when conditions are hot. Limestone is a material derived from white and fine sedimentary rock which is mainly composed of the mineral calcium. This study aims to determine the effect of strong compressive strength and slump value on the partial replacement of cement with lime powder. This study used an experimental method by comparing the compressive strength and slump value of concrete mixed with lime powder. This research was conducted for 2 months. The results showed that variations of 0%, 1% and 5% lime powder met the desired slump requirements, which were between 50 – 125 mm, while the 10% variation did not meet the requirements. Testing the compressive strength of concrete at 28 days with a 0% variation of 25.29 MPa, a 1% variation of 25.38 MPa, a 5% variation of 25.57 MPa and a 10% variation of 20.67 MPa. So it can be concluded that lime powder can be used as a partial replacement for cement with variations of 1% and 5% because the slump value meets the requirements and the resulting compressive strength has increased from normal concrete.

Pemanfaatan Limbah Keramik Sebagai Bahan Alternatif Campuran Agregat Kasar Pada Beton

In every construction and renovation project, there is often waste that is rarely reused. The utilization of ceramic waste as a coarse aggregate in concrete can be an interesting alternative because ceramic waste shares characteristics and properties similar to coarse aggregate materials, such as hardness, and has the potential to reduce negative environmental impacts and the depletion of raw materials. Therefore, this research adopts an experimental method at the laboratory of the National Education University in Denpasar by creating five different variations of cylindrical specimens, each with three samples. The ceramic waste variations used are 0%, 10%, 15%, 20%, and 40%. By using an FAS value of 0.6, the slump value was obtained, where the larger the ceramic waste mixture value, the smaller the slump value, as this occurs due to the water absorption value in the ceramic waste being 10.51%. However, despite this, the slump value still falls within the planned range of 5.0 cm to 12.0 cm, and for the planned compressive strength value, which is 175 kg/m2, the highest average concrete strength value is found in the 0% variation, which is 16.01 MPa or equivalent to 192.83 kg/cm2. The concrete with a 10% variation has a compressive strength of 15.21 MPa or 183.25 kg/cm2, the concrete with a 15% variation has a compressive strength of 15.01 MPa or 180.82 kg/cm2, the concrete with a 20% variation has a compressive strength of 13.64 MPa or 164.38 kg/cm2, and the concrete with a 40% variation has a compressive strength of 9.87 MPa or 118.96 kg/cm2. This research can be used as additional literature or as an evaluation material for further research.

Real-time laser scanning for conditioned coarse-grained soil monitoring on conveyor belt in earth pressure balance shield

To address the hysteresis in assessing the workability of conditioned soils and the inefficiency in estimating the soil volume flow rate in tunnelling practice, a novel real-time assessment and monitoring approach was proposed. Based on laser scanning technology and point cloud data analysis, the approach can monitor the workability and the volume flow rate of conditioned soils on the horizontal conveyor belt of an earth pressure balance (EPB) shield in real-time. Firstly, the accuracy of laser scanning measurements was verified by comparing manually measured slump and spread values with laser scanning results. Then, a series of model tests for scanning the coarse-grained soils with different conditioning parameters and belt speeds on the horizontal conveyor belt were performed. The appropriate ranges of secant angle and unevenness of soil cross-sectional profile were obtained for assessing the workability of conditioned soils. The volume flow rate was calculated by integrating the cross-sectional areas of conditioned soils. Finally, the proposed approach was successfully applied in identifying the workability of conditioned soil and its discharge rate in the EPB shield tunnelling project. This study contributes to the real-time monitoring of conditioned soils on the horizontal conveyor belt and provides practical insights for the optimal management of EPB shield tunnelling.

Technical Properties of Normal Concrete with Alum Additive

Concrete is a widely used construction material due to its numerous advantages in terms of structural performance, cost-effectiveness, implementation, and maintenance. Compressive strength is a critical property that must be considered for concrete used as a structural component. This property can be influenced by various factors, including the addition of chemical substances to the concrete mix. Alum is commonly employed as a water clarifying agent. In concrete mixtures, alum decomposes into aluminium and trioxide sulfate compounds found in cement. Incorporating alum into concrete is expected to enhance the aluminium and cement content. This research aims to investigate the technical properties of normal concrete when supplemented with alum. The technical properties under consideration include slump value and compressive strength, with a fixed mix proportion of cement: sand: gravel = 1:2:3. Alum is added in proportions of 2%, 4%, 6%, and 8% by weight of cement in the concrete mix. The findings of this present study indicate that the highest compressive strength is achieved in concrete specimens with 2% alum addition by weight of cement, reaching 35.629 MPa, while the corresponding slump value is 7.75 cm