Search results for: coarse aggregate

Authors: Brahim Safi, Djamila Aboutaleb, Mohammed Saidi, Abdelbaki Benmounah, Fahima Benbrahim

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The inorganic wastes are currently used in the manufacture of concretes as mineral additions by cement substitution or as fine/coarse aggregates by replacing traditional aggregates. In this respect, this study aims to valorize the mineral wastes in particular glass wastes to produce granulated foam glass (as fine aggregates). Granulated foam glasses (GFG) were prepared from the glass powder (glass cullet) and foaming agent (limestone) according to applied manufacturing of GFG (at a heat treatment 850 ° C for 20min). After, self-compacting mortars were elaborated with fine aggregate (sand) and other variant mortars with granulated foam glass at volume ratio (0, 30, 50 and 100 %). Rheological characterization tests (fluidity) and physic-mechanical (density, porosity /absorption of water and mechanical tests) were carried out on studied mortars. The results obtained show that a slightly decreasing of compressive strength of mortars having lightness very important for building construction.

Keywords: glass wastes, lightweight aggregate, mortar, fluidity, density, mechanical strength

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Authors: M. Parvez Alam, M. Bilal Khan

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Concrete is the material of choice where strength, performance, durability, impermeability, fire resistance, and abrasion resistance are required. The hunger for the higher strength leads to other materials to achieve the desired results and thus, emerged the contribution of cementitious material for the strength of concrete In present day constructions, concrete is chosen as one of the best choices by civil engineers in construction materials. The concept of sustainability is touching new heights and many pozzolonic materials are tried and tested as partial replacement for the cement. In this paper, comprehensive review of available literatures are studied to evaluate the performance of pozzolonic materials such as ceramic waste powder, copper slag, silica fume on the strength of concrete by the partial replacement of ordinary materials such as cement, fine aggregate and coarse aggregate at different percentage of composition. From the study, we conclude that ceramic wastes are suitable to be used in the construction industry, and more significantly on the making of concrete. Ceramic wastes are found to be suitable for usage as substitution for fine and coarse aggregates and partial substitution in cement production. They were found to be performing better than normal concrete, in properties such as density, durability, permeability, and compressive strength. Copper slag is the waste material of matte smelting and refining of copper such that each ton of copper generates approximately 2.5 tons of copper slag. Copper slag is one of the materials that is considered as a waste which could have a promising future in construction Industry as partial or full substitute of aggregates. Silica fume, also known as micro silica or condensed silica fume, is a relatively new material compared to fly ash, It is another material that is used as an artificial pozzolonic admixture. High strength concrete made with silica fume provides high abrasion/corrosion resistance.

Keywords: concrete, pozzolonic materials, ceramic waste powder, copper slag

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Authors: O. M. Omar, G. D. Abd Elhameed, A. M. Heniegal, H. A. Mohamadien

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Green concrete are generally composed of recycling materials as hundred or partial percent substitutes for aggregate, cement, and admixture in concrete. To reduce greenhouse gas emissions, efforts are needed to develop environmentally friendly construction materials. Using of fly ash based geopolymer as an alternative binder can help reduce CO2 emission of concrete. The binder of geopolymer concrete is different from the ordinary Portland cement concrete. Geopolymer Concrete specimens were prepared with different concentration of NaOH solution M10, M14, and, M16 and cured at 60 ºC in duration of 24 hours and 8 hours, in addition to the curing in direct sunlight. Thus, it is necessary to study the effects of the geopolymer binder on the behavior of concrete. Concrete is made by using geopolymer technology is environmental friendly and could be considered as part of the sustainable development. In this study the Local Alkaline Activator in Egypt and dolomite as coarse aggregate in fly ash based-geopolymer concrete was investigated. This paper illustrates the development of mechanical properties. Since the gained compressive strength for geopolymer concrete at 28 days was in the range of 22.5MPa – 43.9MPa.

Keywords: geopolymer, molarity, sodium hydroxide, sodium silicate

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Authors: Robert Bušić, Ivana Miličević, Larisa Šargač

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The construction industry generates a large amount of waste, which poses a challenge for disposal and often requires significant areas for landfill. Therefore, recycling construction waste has become imperative. This study focuses on investigating the use of locally available recycled concrete as a substitute for traditional aggregates and analyzing the impact of this change on the mechanical and durability properties of concrete. The research begins with the crushing of locally available waste concrete, followed by sieving and sorting the aggregate into different fractions. Four concrete mix designs were created, with one serving as a reference mixture without recycled aggregate, while the remaining three mixes included recycled aggregate in varying proportions. The experimental part includes testing the key properties of concrete in both fresh and hardened states, including slump and flow tests, compressive strength, static modulus of elasticity, and shrinkage of the concrete, with the aim of assessing the impact of locally available recycled aggregate on concrete properties. By using experimental testing methods, the results were compared with conventional concrete, providing deeper insights into the potential advantages and disadvantages of using locally available recycled concrete in various construction projects.

Keywords: concrete, durability, recycled aggregate, sustainability

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Authors: T. D. Gunneswara Rao, Mudimby Andal

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Research on the utilization of fly ash will no longer refer the fly ash as a waste material of thermal power plants. Use of fly ash in concrete making, makes the concrete economical as well as durable. The fly ash is being added to the concrete in three ways namely, as partial replacement to cement, partial replacement to fine aggregates and admixture. Addition of fly ash to the concrete in each one of the form mentioned above, makes the concrete more workable and durable than the conventional concrete. Studies on fly ash as partial replacement to cement gained momentum as such replacement makes the concrete economical. In the present study, an attempt has been made to understand the effects of fly ash on the workability characteristics and strength aspects of fly ash concretes. In India, major number of thermal power plants are producing low calcium fly ash. Hence, in the present investigation, low calcium fly ash has been used. Fly ash in concrete was considered for the partial replacement of cement. The percentage replacement of cement by fly ash varied from 0% to 40% at regular intervals of 10%. Moreover the fine aggregate to coarse aggregate ratio also has been varied as 1:1, 1:2, and 1:3. The workability tests revealed that up to 30% replacement of cement by fly ash in concrete mixes water demand for reduces and beyond 30% replacement of cement by fly ash demanded more water content for constant workability.

Keywords: cementing efficiency, compressive strength, low calcium fly ash, workability

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Authors: A. Sivakumar, K. Srinivasan

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The main objective of the study is focused in producing slag based geopolymer concrete obtained with the addition of alkali activator. Test results indicated that the reaction of silicates in slag is based on the reaction potential of sodium hydroxide and the formation of alumino-silicates. The study also comprises on the evaluation of the efficiency of polymer reaction in terms of the strength gain properties for different geopolymer mixtures. Geopolymer mixture proportions were designed for different binder to total aggregate ratio (0.3 & 0.45) and fine to coarse aggregate ratio (0.4 & 0.8). Geopolymer concrete specimens casted with normal curing conditions reported a maximum 28 days compressive strength of 54.75 MPa. The addition of glued steel fibres at 1.0% Vf in geopolymer concrete showed reasonable improvements on the compressive strength, split tensile strength and flexural properties of different geopolymer mixtures. Further, comparative assessment was made for different geopolymer mixtures and the reinforcing effects of steel fibres were investigated in different concrete matrix.

Keywords: accelerators, alkali activators, geopolymer, hot air oven curing, polypropylene fibres, slag, steam curing, steel fibres

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Authors: Shams Ul Khaliq, Mushtaq Zeb, Fawad Bilal, Faizan Akbar, Syed Aamir Abbas

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Self Compacting Concrete as the name implies--is the concrete requiring a very little or no vibration to fill the form homogeneously. Self Compacting Concrete (SCC) is defined by two primary properties: Ability to flow or deform under its own weight (with or without obstructions) and the ability to remain homogeneous while doing so. Flow ability is achieved by utilizing high range water reducing admixtures and segregation resistance is ensured by introducing a chemical viscosity modifying admixture (VMA) or increasing the amount of fines in the concrete. The study explores the use waste marble dust (WMD) to increase the amount of fines and hence achieve self-compatibility in an economical way, suitable for Pakistani construction industry. The study focuses on comparison of fresh properties of SCC containing varying amounts of waste marble dust (WMD) with that containing commercially available viscosity modifying admixture. The comparison is done at different dosages of super plasticizer keeping cement, water, coarse aggregate, and fine aggregate contents constant.

Keywords: self compacting concrete, waste marble dust (WMD), flow ability, segregation resistance

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Authors: Z. Funda Türkmenoğlu, Mehmet Türkmenoglu, Demet Yavuz,

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In this study, the effects of waste marbles as aggregate material on workability and hardened concrete characteristics of self compacting lightweight concrete are investigated. For this purpose, self compacting light weight concrete are produced by waste marble aggregates are replaced with fine aggregate at 5%, 7.5%, and 10% ratios. Fresh concrete properties, slump flow, T₅₀ time, V funnel, compressive strength and ultrasonic pulse velocity of self compacting lightweight concrete are determined. It is concluded from the test results that using waste marbles as aggregate material by replacement with fine aggregate slightly affects fresh and hardened concrete characteristics of self compacting lightweight concretes.

Keywords: hardened concrete characteristics, self compacting lightweight concrete, waste marble, workability

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Authors: H. Gonen, M. Dogan

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Meerschaum, which is found in the earth’s crust, is a white and clay like hydrous magnesium silicate. It has a wide area of use from production of carious ornaments to chemical industry. It has a white and irregular crystalline structure. It is wet and moist when extracted, which is a good form for processing. At drying phase, it gradually loses its moisture and becomes lighter and harder. In through-dry state, meerschaum is durable and floats on the water. After processing of meerschaum, A ratio between %15 to %40 of the amount becomes waste. This waste is usually kept in a dry-atmosphere which is isolated from environmental effects so that to be used right away when needed. In this study, use of meerschaum waste as aggregate in lightweight concrete is studied. Stress-strain diagrams for concrete with meerschaum aggregate are obtained. Then, stress-strain diagrams of lightweight concrete and concrete with regular aggregate are compared. It is concluded that meerschaum waste can be used in production of lightweight concrete.

Keywords: lightweight concrete, meerschaum, aggregate, sepiolite, stress-strain diagram

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Authors: Nadine Ali Hassan, Ngoc Son Nguyen, Didier Marot, Fateh Bendahmane

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This paper aims at presenting a study of the effect of scalping methods on the mechanical properties of coarse soils by resorting to numerical simulations based on the discrete element method (DEM) and experimental triaxial tests. Two reconstitution methods are used, designated as scalping method and substitution method. Triaxial compression tests are first simulated on a granular materials with a grap graded particle size distribution by using the DEM. We study the effect of these reconstitution methods on the stress-strain behavior of coarse soils with different fine contents and with different ways to control the densities of the scalped and substituted materials. Experimental triaxial tests are performed on original mixtures of sands and gravels with different fine contents and on their corresponding scalped and substituted samples. Numerical results are qualitatively compared to experimental ones. Agreements and discrepancies between these results are also discussed.

Keywords: coarse soils, mechanical behavior, scalping, replacement, triaxial devices

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Authors: Selvam M., Vadthya Poornachandar, Surender Singh

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These Reclaimed Asphalt Pavement (RAP) aggregates are generally dumped in the open area after the demolition of Asphalt Pavements. The utilization of RAP aggregates in cement concrete pavements may provide several socio-economic-environmental benefits and could embrace the circular economy. The cross recycling of RAP aggregates in the concrete pavement could reduce the consumption of virgin aggregates and saves the fertile land. However, the structural, as well as functional properties of RAP-concrete could be significantly lower than the conventional Pavement Quality Control (PQC) pavements. This warrants judicious selection of RAP fraction (coarse and fine aggregates) along with the accurate proportion of the same for PQC highways. Also, the selection of the RAP fraction and its proportion shall not be solely based on the mechanical properties of RAP-concrete specimens but also governed by the structural and functional behavior of the pavement system. In this study, an effort has been made to predict the optimum RAP fraction and its corresponding proportion for cement concrete pavements by considering the low-volume and high-volume roads. Initially, the effect of inclusions of RAP on the fresh and mechanical properties of concrete pavement mixes is mapped through an extensive literature survey. Almost all the studies available to date are considered for this study. Generally, Indian Roads Congress (IRC) methods are the most widely used design method in India for the analysis of concrete pavements, and the same has been considered for this study. Subsequently, fatigue damage analysis is performed to evaluate the required safe thickness of pavement slab for different fractions of RAP (coarse RAP). Consequently, the performance of RAP-concrete is predicted by employing the AASHTO-1993 model for the following distresses conditions: faulting, cracking, and smoothness. The performance prediction and total cost analysis of RAP aggregates depict that the optimum proportions of coarse RAP aggregates in the PQC mix are 35% and 50% for high volume and low volume roads, respectively.

Keywords: concrete pavement, RAP aggregate, performance prediction, pavement design

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Authors: M. Eckert, M. Oliveira

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The intensive use of natural aggregates, near cities and towns, associated to the increase of the global population, leads to its depletion and increases the transport distances. The uncontrolled deposition of construction and demolition waste in landfills and city outskirts, causes pollution and takes up space. The use of recycled aggregates in concrete preparation would contribute to mitigate the problem. However, it arises the problem that the high water absorption of recycled aggregate decreases the bleeding rate of concrete, and when this gets lower than the evaporation rate, plastic shrinkage cracking occurs. This phenomenon can be particularly problematic in hot and windy curing environments. Cracking facilitates the flow of liquid and gas into concrete which attacks the reinforcement and degrades the concrete. These factors reduce the durability of concrete structures and consequently the lifetime of buildings. A ring test was used, cured in a wind tunnel, to evaluate the plastic shrinkage cracking sensitivity of recycled aggregate concrete, in order to implement preventive means to control this phenomenon. The role of several aggregate properties on the concrete segregation and cracking mechanisms were also discussed.

Keywords: recycled aggregate, plastic shrinkage cracking, wind tunnel, durability

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Authors: Ji Wenzhan, Zhang Tao, Li Guoyou

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Concrete is the most widely used building material in the world. At the same time, the world produces a large amount of construction waste each year. Waste concrete is processed and treated, and the recycled aggregate is used to make pervious concrete, which enables the construction waste to be recycled. Pervious concrete has many advantages such as permeability to water, protection of water resources, and so on. This paper tests the recycled aggregate obtained by crushing high-strength waste concrete (TOU) and low-strength waste concrete (PU), and analyzes the effect of porosity, amount of cement, mineral admixture and recycled aggregate on the strength of permeable concrete. The porosity is inversely proportional to the strength, and the amount of cement used is proportional to the strength. The mineral admixture can effectively improve the workability of the mixture. The quality of recycled aggregates had a significant effect on strength. Compared with concrete using "PU" aggregates, the strength of 7d and 28d concrete using "TOU" aggregates increased by 69.0% and 73.3%, respectively. Therefore, the quality of recycled aggregates should be strictly controlled during production, and the mix ratio should be designed according to different use environments and usage requirements. This test prepared a recycled aggregate permeable concrete with a compressive strength of 35.8 MPa, which can be used for light load roads and provides a reference for engineering applications.

Keywords: recycled aggregate, permeable concrete, compressive strength, permeability

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Authors: M. I. Mohammed, U. M. Ahmad

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Analyses of mineral elements were carried out on some coarse grains used as staple food in Kano. The levels of Magnesium, Calcium, Manganese, Iron, Copper and Zinc were determined using atomic absorption spectrophotometer (AAS), and that of Sodium and Potassium were obtained using flame photometer (FES). The result of the study shows that the mean results of the mineral elements ranged from 62.50±0.55 - 84.82±0.74mg/kg sodium, 73.33±0.35 - 317±0.10mg/kg magnesium, 89.22±0.26 - 193.33±0.19mg/kg potassium, 70.00±0.52 - 186.67±0.29mg/kg calcium, 1.00±0.11 - 20.50±1.30mg/kg manganese, 25.00±0.11 - 80.50±0.36mg/kg iron. 4.00±0.08 - 13.00±0.24mg/kg copper and 15.00±0.34 - 50.50±0.24 zinc. There was significant difference (p < 0.05) in levels of sodium, potassium and calcium whereas no significant difference (p > 0.05) occurs in levels of magnesium, manganese, copper and zinc. In comparison with Recommended Daily Allowances of essential and trace metals set by international standard organizations, the coarse grains analysed in this work contribute little to the provision of essential and trace elements requirements.

Keywords: mineral elements, coarse grains, staple food, Kano, Nigeria

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Authors: Yared Assefa Demessie

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This study may help to establish the appropriateness of ceramic waste aggregate for concrete production since it is obviously understood that the rising from continuous urbanization and industrialization development leads depletion of natural construction resource and the disposal of waste material. It can be used as base to conduct a study on the alternative readily available materials like ceramic industrial waste aggregates can lead to environmental concrete. The study assessed the fresh and hardened properties of the concrete produced by replacing part of the natural fine aggregate with an aggregate produced from ceramic industrial waste. In the study, experimental investigation was employed which involved two major tasks: material specifications and experimental evaluation of concrete were done in the laboratory. Experimental investigations such that workability, unit weight, compressive strength test, tensile strength test and flexural strength test for C-25 concrete mixes with different percentages of ceramic industrial waste aggregate after a curing period of 7 and 28 days has done and interpreted the result statically using mean, standard deviation and coefficient of variance.

Keywords: ceramic industrial waste, fresh concrete, hardened concrete, fine aggregate

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Authors: Ndivhudzannyi Rembuluwani, Francis Dacosta, Emmanuel Mhlongo

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The small-scale rock aggregate sector of the mining industry is a major source of employment for a significant number of people, particularly in remote rural areas, where alternative livelihoods are rare. It contributes to local economy by generating income and producing major and essential materials for the building, construction, and other industries. However, the sector is confronted with many challenges that hamper productivity and growth. The problems that confront this sector includes: health and safety, environmental impacts, low production and low adherence to mining legislations. This study investigated the challenges confronting selected small-scale rock aggregate mines in the Vhembe District of Limpopo province of South Africa, assesses the health, safety, low production and environmental impacts associated with aggregate production and to develop an integrated approach of addressing the multi-faceted challenges.

Keywords: health and safety, legislative framework, productivity, rock aggregate, small-scale mining

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Authors: Ali Jamshidi, Kiyofumi Kurumisawa, Toyoharu Nawa

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Transportation infrastructure assets can be considered as backbone of transportation system. They are routinely developed and or maintained which can be used effectively for movement of passengers, commodities and providing vital services. However, the infrastructure assets construction, maintenance and rehabilitation significantly depend on non-renewable natural resources, such as carbon-based energy carriers and aggregate materials. In this study, effects of thermal properties of aggregate materials were characterized for production of hot-mix asphalt in Japan, as a case study. The results indicated that incorporation of the aggregate with lower required heat energy significantly reduces fuel consumption greenhouse gas emission, irrespective of physical property of aggregate. The results also clearly showed that as 75% high-energy limestone is replaced with low-energy limestone in producing an asphalt mixture at 180 °C, 97,879 Japanese households would be energized per annum using the saved energy without any modification in the current asphalt mixing plants.

Keywords: zero energy infrastructure, sustainable development, greenhouse gas emission, asphalt pavement

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Authors: Chukwuebuka Vincent Azuka, Chidimma Peace Odoh

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Changes in agricultural practices and land use influence the storage and release of soil organic carbon and soil structural dynamics. To investigate this in Nsukka, southeastern Nigeria, soil samples were collected at 0-10 cm, 10-20 cm and 20-30 cm from three locations; Ovoko (OV), Obukpa (OB) and University of Nigeria, Nsukka (UNN) and three land use types; cultivated land (CL), forest land (FL) and grassland (GL)). Data were subjected to analysis of variance (ANOVA) using SPSS. Also, correlations between organic carbon stock, structural stability indices and other soil properties were established. The result showed that Ksat was significantly (p < 0.05) influenced by location with mean values of 68 cmhr⁻¹,121.63 cmhr⁻¹, 8.42 cmhr⁻¹ in OV, OB and UNN respectively. The MWD and aggregate stability (AS) were significantly (p < 0.05) influenced by land use and depth. The mean values of MWD are 0.85 (CL), 1.35 (FL) and 1.45 (GL), and 1.66 at 0-10 cm, 1.08 at 10-20 cm and 0.88 mm at 20-30 cm. The mean values of AS are; 27.66% (CL), 46.39% (FL) and 49.81% (GL), and 53.96% at 0-10cm, 40.22% at 10-20cm and 29.57% at 20-30cm. Clay flocculation (CFI) and dispersion indices (CDI) differed significantly (p < 0.05) among the land use. Soil pH differed significantly (p < 0.05) across the land use and locations with mean values ranging from 3.90-6.14. Soil organic carbon (SOC) significantly (p < 0.05) differed across locations and depths. SOC decreases as depth increases depth with mean values of 15.6 gkg⁻¹, 10.1 gkg⁻¹, and 8.6 gkg⁻¹ at 0-10 cm, 10-20 cm, and 20-30 cm respectively. SOC in the three land use was 8.8 g kg-1, 15.2 gkg⁻¹ and 10.4 gkg⁻¹ at CL, FL, and GL respectively. The highest aggregate-associated carbon was recorded in 0.5 mm across the land use and depth except in cultivated land and at 20-30 cm which recorded their highest SOC at 1mm. SOC stock, total nitrogen (TN) and CEC were significantly (p < 0.05) different across the locations with highest values of 23.43 t/ha, 0.07g/kg and 14.27 Cmol/kg respectively recorded in UNN. SOC stock was significantly (p < 0.05) influenced by depth as follows; 0-10>10-20>20-30 cm. TN was low with mean values ranging from 0.03-0.07 across the locations, land use and depths. The mean values of CEC ranged from 9.96-14.27 Cmol kg⁻¹ across the locations and land use. SOC stock showed correlation with silt, coarse sand, N and CEC (r = 0.40*, -0.39*, -0.65** and 0.64** respectively. AS showed correlation with BD, Ksat, pH in water and KCl, and SOC (r = -0.42*, 0.54**, -0.44*, -0.45* and 0.49** respectively. Thus, land use and location play a significant role in sustainable management of soil resources.

Keywords: agricultural practices, structural dynamics, sequestration, soil resources, management

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Authors: Salisu Dahiru, Jibrin M. Kaura, Abubakar I. Jumare, Sulaiman M. Mahmood

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Reclaimed asphalt, used automobile tires and rice husk, were regarded as waste. These materials could be used in construction of new roads and for roads rehabilitation. Investigation into the production of a Green Hot Mixed Asphalt (GHMA) pavement using Reclaimed Asphalt Pavement (RAP) as partial replacement for coarse aggregate, Crumb Rubber (CR) from waste automobile tires as modifier for bitumen binder and Rice Husk Ash (RHA) as partial replacement of ordinary portland cement (OPC) filler, for roads construction and rehabilitation was presented. 30% Reclaimed asphalt of total aggregate, 15% Crumb Rubber of total binder content, 5% Rice Husk Ash of total mix, and 5.2% Crumb Rubber Modified Bitumen content were recommended for optimum performance. Loss of marshal stability was investigated on mix with the recommended optimum CRMB. The mix revealed good performance with only about 13% loss of stability after 24 hours of immersion in hot water bath, as against about 24% marshal stability lost reported in previous studies for conventional Hot Mixed Asphalt (HMA).

Keywords: rice husk, reclaimed asphalt, filler, crumb rubber, bitumen content green hot mix asphalt

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Authors: Aliakbar Sayadi, Thomas Neitzert, Charles Clifton

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The hydration process of a green concrete with differences on fly ash and the poly-lactic acid ratio was investigated using electrical resistivity measurement. The results show that the hydration process of proposed concrete was significantly different with concrete containing petroleum aggregate. Moreover, a microstructure analysis corresponding to each hydration stage is conducted with scanning microscope for ploy-lactic acid and expanded polystyrene concrete. In addition, specific equations using the variables of this study were developed to understand and predict the relationship between setting time and resistivity development of proposed concrete containing eco-friendly aggregate.

Keywords: green concrete, SEM, hydration mechanism, eco-friendly aggregate

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Authors: Theo Ndereyimana, Yann Dufresne, Micael Boulet, Stephane Moreau

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The DEM (Discrete Element Method) is used a lot in the industry to simulate large-scale flows of particles; for instance, in a fluidized bed, it allows to predict of the trajectory of every particle. One of the main limits of the DEM is the computational time. The CGM (Coarse-Graining Method) has been developed to tackle this issue. The goal is to increase the size of the particle and, by this means, decrease the number of particles. The method leads to a reduction of the collision frequency due to the reduction of the number of particles. Multiple characteristics of the particle movement and the fluid flow - when there is a coupling between DEM and CFD (Computational Fluid Dynamics). The main characteristic that is impacted is the energy dissipation of the system, to regain the dissipation, an ADM (Additional Dissipative Mechanism) can be added to the model. The objective of this current work is to observe the influence of the choice of the ADM and the factor of coarse-graining on the numerical results. These results will be compared with experimental results of a fluidized bed and with a numerical model of the same fluidized bed without using the CGM. The numerical model is one of a 3D cylindrical fluidized bed with 9.6M Geldart B-type particles in a bubbling regime.

Keywords: additive dissipative mechanism, coarse-graining, discrete element method, fluidized bed

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Authors: Farzaneh Tahmoorian, Bijan Samali, John Yeaman

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Road networks are increasingly expanding all over the world. The construction and maintenance of the road pavements require large amounts of aggregates. Considerable usage of various natural aggregates for constructing roads as well as the increasing rate at which solid waste is generated have attracted the attention of many researchers in the pavement industry to investigate the feasibility of the application of some of the waste materials as alternative materials in pavement construction. Among various waste materials, construction and demolition wastes, including Recycled Construction Aggregate (RCA) constitute a major part of the municipal solid wastes in Australia. Creating opportunities for the application of RCA in civil and geotechnical engineering applications is an efficient way to increase the market value of RCA. However, in spite of such promising potentials, insufficient and inconclusive data and information on the engineering properties of RCA had limited the reliability and design specifications of RCA to date. In light of this, this paper, as a first step of a comprehensive research, aims to investigate the feasibility of the application of RCA obtained from construction and demolition wastes for the replacement of part of coarse aggregates in asphalt mixture. As the suitability of aggregates for using in asphalt mixtures is determined based on the aggregate characteristics, including physical and mechanical properties of the aggregates, an experimental program is set up to evaluate the physical and mechanical properties of RCA. This laboratory investigation included the measurement of compressive strength and workability of RCA, particle shape, water absorption, flakiness index, crushing value, deleterious materials and weak particles, wet/dry strength variation, and particle density. In addition, the comparison of RCA properties with virgin aggregates has been included as part of this investigation and this paper presents the results of these investigations on RCA, basalt, and the mix of RCA/basalt.

Keywords: asphalt, basalt, pavement, recycled aggregate

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Authors: Tri Harianto, Lawalenna Samang, St. Hijraini Nur, Arwin

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Recently, a port development is constructed in Makassar city, South Sulawesi Province, Indonesia. Makassar city is located in lowland area that dominated by soft marine clay deposit. A two kilometers causeway construction was built which is situated on the soft clay layer. In order to investigate the behavior of causeway embankment, a full-scale test was conducted of high embankment built on a soft clay deposit. The embankment with 3,5 m high was supported by two types of reinforcement such as raft and raft-aggregate column foundation. Since the ground was undergoing consolidation due to the preload, the raft and raft-aggregate column foundations were monitored in order to analyze the vertical ground movement by inducing the settlement of the foundation. In this study, two types of foundation (raft and raft-aggregate column) were tested to observe the effectiveness of raft-aggregate column compare to raft foundation in reducing the settlement. The settlement monitored during the construction stage by using the settlement plates, which is located in the center and toe of the embankment. Measurements were taken every day for each embankment construction stage (4 months). In addition, an analytical calculation was conducted in this study to compare the full-scale test result. The result shows that the raft-aggregate column foundation significantly reduces the settlement by 30% compared to the raft foundation. A raft-aggregate column foundation also reduced the time period of each loading stage. The Good agreement of analytical calculation compared to the full-scale test result also found in this study.

Keywords: full-scale, preloading, raft-aggregate column, soft clay

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Authors: I. Apostol, M. Mosoarca

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Romania is a seismic country, with two major seismic zones, Vrancea and Banat. One of the most important cities from Banat seismic area is Timisoara, where a lot of valuable historical buildings were built before any design codes, but still they kept their stability during past earthquakes. This article presents the influence of the adjacent buildings during an earthquake and the way that the specific failure mechanism is changed when the building is part of an aggregate. The investigation was made using nonlinear analysis based on Tremuri software, first analyzing the buildings as isolated and second, considering the entire aggregate of buildings. There were noticed significant differences through the two situations regarding the specific failure mechanism activated for each building, showing the fact that in some situations, the presence of the adjacent buildings has positive or negative contribution for the seismic behavior of the analyzed one. The difference between the failure mechanism of the same buildings considered isolated and in aggregate aims to provide explications for the good structural state of the existing historical areas of Timisoara, as part of a larger multidisciplinary study, which will help local authorities to prioritize the consolidation works for the historical buildings in order to assure that the history of the city will be kept alive for the next generations.

Keywords: failure mechanism, analysis, aggregate, masonry, earthquake

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Authors: Khandaker Fariha Ahmed, Md. Noman Munshi, Tarin Sultana, Md. Zoynul Abedin

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Suitability number (SN) is perhaps one of the most important parameters of coarse-grained soil in assessing its appropriateness to use as a backfill in retaining structures, sand compaction pile, Vibro compaction, and other similar foundation and ground improvement works. Though determined in an empirical manner, it is imperative to study SN to understand its relation with other aggregate properties like fineness modulus (FM), and strength and density properties of sandy soil. The present paper reports the findings of the study on the examination of the properties of sandy soil, as mentioned. Random numbers were generated to obtain the percent fineness on various sieve sizes, and fineness modulus and suitability numbers were predicted. Sand samples were collected from the field, and test samples were prepared to determine maximum density, minimum density and shear strength parameter φ against particular fineness modulus and corresponding suitability number Five samples of SN value of excellent (0-10) and three samples of SN value fair (20-30) were taken and relevant tests were done. The data obtained from the laboratory tests were statistically analyzed. Results show that with the increase of SN, the value of FM decreases. Within the SN value rated as excellent (0-10), there is a decreasing trend of φ for a higher value of SN. It is found that SN is dependent on various combinations of grain size properties like D10, D30, and D20, D50. Strong linear relationships were obtained between SN and FM (R²=.0.93) and between SN value and φ (R²=.94). Correlation equations are proposed to define relationships among SN, φ, and FM.

Keywords: density, fineness modulus, shear strength parameter, suitability number

Procedia PDF Downloads 104

Authors: I. Miličević, M. Hadzima Nyarko, R. Bušić, J. Simonović Radosavljević, M. Prokopijević, K. Vojisavljević

Abstract:

This paper investigates the effects of different treatment methods of rubber aggregates for self-compacting concrete (SCC) on compressive strength and modulus of elasticity. SCC mixtures with 10% replacement of fine aggregate with crumb rubber by total aggregate volume and with different aggregate treatment methods were investigated. The rubber aggregate was treated in three different methods: dry process, water-soaking, and NaOH treatment plus water soaking. Properties of SCC in a fresh and hardened state were tested and evaluated. Scanning electron microscope (SEM) analysis of three different SCC patches were made and discussed. It was observed that applying the proposed NaOH plus water soaking method resulted in the improvement of fresh and hardened concrete properties. It resulted in a more uniform distribution of rubber particles in the cement matrix, a better bond between rubber particles and the cement matrix, and higher compressive strength of SCC rubberized concrete.

Keywords: compressive strength, modulus of elasticity, NaOH treatment, rubber aggregate, self-compacting rubberized concrete, scanning electron microscope analysis

Procedia PDF Downloads 108

Authors: Luís Felipe da Cunha Mendonça

Abstract:

Normally, rural roads do not have any type of coating, and when they have any coating, they have a high maintenance cost due to the characteristics of natural materials. The Steel Aggregate has specific technical characteristics, which considerably reduce the maintenance costs of rural roads with the execution of the Primary Coating. For use as a primary coating, it must be mixed with clay due to the physical-chemical properties of the material. The application is mainly in the Primary Coating of rural roads due to the cementitious property in the presence of water, offering greater resistance to wear caused by traffic and consequently a longer useful life of the coating. The Steel Aggregate executed on rural roads has reduced particulate emissions and offers normal traffic in any weather condition, as well as creating sustainability. Contribute to the quality of life of communities through improvements in the conditions of rural and urban unpaved roads. Leading to substantial savings in maintenance. Because the durability, if applied correctly, is about 3 years, but if annual monitoring is carried out, it can be extended for more than 5 years.

Keywords: steel slag, co-product, primary coating, steel aggregate

Procedia PDF Downloads 125

Authors: M. Li, V. D. Thi, M. Khelifa, M. El Ganaoui

Abstract:

This study presents an overview of the work carried out by the use of wood waste as coarse aggregate in mortar. The paper describes experimental and numerical investigations carried on pervious concrete made of wood chips and also sheds lights on the mechanical properties of this new product. The properties of pervious wood-concrete such as strength, elastic modulus, and failure modes are compared and evaluated. The characterization procedure of the mechanical properties of wood waste ash are presented and discussed. The numerical and tested load–deflection response results are compared. It was observed that the numerical results are in good agreement with the experimental results.

Keywords: wood waste ash, characterization, mechanical properties, bending tests

Procedia PDF Downloads 306

Authors: Shofiq Ahmed, Rakibul Hassan, Raquib Ahsan

Abstract:

Concrete is one of the basic elements of RCC structure and also the most crucial one. In recent years, a lot of researches have been conducted to develop special types of concrete for special purposes. Micro-concrete is one of them which has high compressive strength and is mainly used for retrofitting. Micro-concrete is a cementitious based composition formulated for use in repairs of areas where the concrete is damaged & the area is confined in movement making the placement of conventional concrete difficult. According to recent statistics, a large number of structures in the major cities of Bangladesh are vulnerable to collapse. Retrofitting may thus be required for a sustainable solution, and for this purpose, the utilization of micro-concrete can be considered as the most effective solution. For that reason, the aim of this study was to produce micro-concrete using indigenous materials in low cost. Following this aim, the experimental data were observed for five mix ratios with varied amount of cement, fine aggregate, coarse aggregate, water, and admixture. The investigation criteria were a compressive strength, tensile strength, slump and the cost of different mix ratios. Finally, for a mix ratio of 1:1:1.5, the compressive strength was achieved as 7820 psi indicating highest strength among all the samples with the reasonable tensile strength of 1215 psi. The slump of 6.9 inches was also found for this specimen indicating it’s high flowability and making it’s convenient to use as micro-concrete. Moreover, comparing with the cost of foreign products of micro-concrete, it was observed that foreign products were almost four to five times costlier than this local product.

Keywords: indigenous, micro-concrete, retrofitting, vulnerable

Procedia PDF Downloads 327

Authors: M. Murmu, Govardhan, J. Satya Eswari

Abstract:

Concrete is the most common and widely used building material. Concrete is basically made of aggregates, both fine and coarse, glued by a cement paste which is made of cement and water. Each one of these constituents of concrete has a negative environmental impact and gives rise to different sustainability issues. The current concrete construction practice is unsustainable because, not only it consumes enormous quantities of stones, sand, and drinking water, but also one billion tons a year of cement, which is not an environment friendly material. Preventing the reduction of natural resources and enhancing the usage of waste materials has become a challenge to the scientist and engineers. A number of studies have been conducted concerning the protection of natural resources, prevention of environmental pollution and contribution to the economy by using this waste material. This paper outlines the influence of Ground Granulated Blast furnace Slag (GGBS) as partial replacement of fine aggregate on mechanical properties of concrete. The strength of concrete is determined having OPC binder, replaced the fine aggregate with15%, 30%, 45% respectively. For this purpose, characteristics concrete mix of M25 with partial replacement of cement with GGBS is used and the strength of concrete cubes and cylinder have determined. The strength of concrete specimens has been compared with the reference specimen. Also X-ray diffraction (XRD) and scanning electron microscope (SEM) tests have been performed to examine the hydration products and the microstructure of the tested specimens. A correlation has been established between the developmental strength concrete with and without GGBS through analysis of hydration products and the microstructure.

Keywords: GGBS, sand, concrete, workability

Procedia PDF Downloads 503