Compacted Concrete Research Articles

Effect of Different Steel Fibres on Strength Parameters of Self Compaction Concrete

Effect of Different Steel Fibres on Strength Parameters of Self Compaction Concrete

Surface Bubbles Emergence as an Indicator for Optimal Concrete Compaction.

Compaction quality significantly influences the strength and durability of concrete in structures. Under-compacting can retain entrapped air, reducing strength, while over-compacting can lead to segregation, creating local variances in strength distribution and modulus of elasticity in the concrete structure. This study examines the widely adopted concept that compaction is optimal when bubbles cease to emerge on the concrete surface. We recorded the surface activity of six comparable concrete specimens during the compaction process using a 4K video camera. Four specimens were compacted using a table vibrator and two with a poker vibrator. From the video frames, we isolated the bubbles for analysis, employing digital image processing techniques to distinguish newly risen bubbles per frame. It was found that the bubbles continuously rose to the surface in all specimens throughout the compaction process, suggesting a need for extended compaction, with some specimens showing a slow in the rate of the bubbles' emergence. However, upon examining the segregation levels, it was discovered that all the specimens were segregated, some severely, despite the continued bubble emergence. These findings undermine the reliability of using bubble emergence as a principle to stop compaction and support the need for developing online measurement tools for evaluating compaction quality.

Sensitivity analysis of gyratory compactor variables to mimic roller compacted concrete pavement performance

ABSTRACT The compaction parameters suggested for Superpave gyratory compactor by ASTM C1800 are primarily derived from the asphalt mix (ASTM D6925). Since the rheological behaviour of Roller Compacted Concrete Pavement (RCCP) is significantly different from asphalt mixes, conventional Superpave compaction parameters cannot be directly adopted for RCCP. Hence, the current study focuses on formulating compaction parameters for the design of RCCP to resemble the field behaviour. For this task, response surface methodology was employed to investigate the effect of gyratory compactor parameters such as internal angle (0.82–3°), compaction pressure (600–1000 kPa), and gyration levels (60–120) on the performance of RCCP specimens. The accuracy of the response prediction model was verified with ANOVA analysis. Further, multiobjective optimization was performed and validated with experimental findings. For validation of laboratory findings, a field test section was constructed using a duplex roller (dual drum vibratory roller). The results showed that the ASTM C1800 suggested gyratory parameters resulted in lower fresh density and strength properties of 4% and 7–45%, respectively, than the field specimens. However, the specimens fabricated at 1.92° internal angle, 120 gyrations, 1000 kPa, and 1 aspect ratio in the gyratory compactor could provide comparable field properties.

Analytical Review of the Current State of Technology, Structure Formation, and Properties of Variatropic Centrifugally Compacted Concrete.

Current regulatory documents and the scientific literature lack a theoretical framework and practical guidance for calculating centrifugally compacted reinforced concrete structures, taking into account the variatropy of their structure and the material's characteristics across the section. A problem related to this research lies in the need to form a systematized, theoretical, and practical knowledge base about variatropic concretes, the importance of which has been proven by various scientists without, to date, the creation of a unified scientific methodological base. The importance of this study is linked to the need for the world's construction projects and processes to transition to the most economically, materially, and resource-efficient types of building structures, which, of course, include structures made of variable-type concrete. This study's objective is to fill these scientific and engineering gaps. The purpose of this study was to systematize the existing knowledge base about the technology, structure formation, and properties of variatropic concrete, using an analytical review of previously conducted studies by ourselves and others, both in Russia and abroad. A theoretical justification for the formation of the structure of variatropic materials is presented. An analysis of the basic physical and mechanical properties of variatropic concretes is carried out and the features of their microstructures are considered. The main structures created using centrifugation technology are considered. Variatropic concrete has an increased amount of mechanical characteristics compared to traditional concrete, on average by up to 45%. The durability of variatropic concrete is improved, on average, by up to 30% compared to conventional concrete.

Protecting the environment and natural resources using green Roller Compacted Concrete (RCC) containing fine and coarse recycled copper slag aggregates

As the environmental policies and protection guidelines of natural resources are among the great challenges in the concrete production/construction industry, they can be properly addressed if effort is made to produce green, nature-friendly concretes by different waste materials. To this end, the current study has replaced natural fine and coarse aggregates of the roller compacted concrete (RCC) with 0 %, 10 %, 20 %, 30 %, 40 %, 50 % and 60 % copper slag (CS) aggregates, which are largely-produced waste materials. Numerous tests were done to evaluate the mechanical properties and durability of different-age CS concretes and determine their environmental and economic benefits. According to the results, the compressive strength of the 91-day specimens increased up to 40%, and their tensile and flexural strengths increased up to 60 % compared to the control specimen. Scanning electron microscope (SEM) images revealed that using low CS volumes strengthened the concrete microstructure and filled the voids. In CS concretes, the surface water absorption was less than 7 %, and at 60 % CS, the capillary water absorption, water penetration depth, and ultrasonic wave penetration reduced by, respectively, 47.32 %, 2.76 %, and 12.22 % compared to the CS-free concrete. In general, the green CS-RCC involves many environmental benefits and reduces the production costs by about 7.70–46.18 %.

Experimental study of strength and microstructure of roller compacted concrete containing waste glass aggregate

Experimental study of strength and microstructure of roller compacted concrete containing waste glass aggregate

Marcus Antonius ταμίας ἀντιστράτηγος: first known case of Roman quaestors being granted praetoral powers

The article analyzes the inscription from the Delos island (ID 2. 1603), in which the official status of Marcus Antonius Orator is designated as ταμίας ἀντιστράτηγος - quaestor-propraetor, which is the first known case of Roman republican quaestors being granted the powers of praetors (quaestor pro praetore). Other epigraphic and narrative sources are involved into analysis. The author of the article dates the empowerment of quaestor M. Antonius with the powers of propraetor to 113 BC and rejects his case as an evidence that the pro praetore proquaestors were officially called quaestors in inscriptions (as was accepted in the historiography of the issue).

Fabricating a Sustainable Roller Compacted Concrete Containing Recycled Waste Demolished Materials: A Literature Review

Fabricating a Sustainable Roller Compacted Concrete Containing Recycled Waste Demolished Materials: A Literature Review

Double sill stilling basin to enhance energy dissipation for a strong hydraulic jump with a high Froude number

Roller Compacted Concrete (RCC) is a new and viable construction material for concrete gravity dams. It is gaining popularity due to its low cost and fast deployment. The design of a stilling basin, part of a dam that controls the hydraulic jump and dissipates energy, is crucial. One of the important considerations is the Froude number at the spillway toe (F1), which determines the type of hydraulic jump that will occur. An energy dissipator is also required to prevent scour caused by the change in flow conditions from supercritical to subcritical. Double sills installed downstream of the steep chute way channel can be used as an energy dissipator. This study uses hydraulic modeling to evaluate the flow energy reduction and subcritical flow conditions in a stilling basin with double sills. The investigation is expected to provide better information on hydraulic jump control.

Self Compaction Concrete

Abstract: In this paper, we present the main objective of this study is to gain an absolute knowledge on self-compacting concrete (SCC) and to sort out the research gap in field of self-compacting concrete containing admixtures. This research study is carried out in the three phases and the details are Phase – I to develop the mix design of M50 grade using Nan-Su method. To optimize the developed mix proportions by using statistical (DOE) design; ranging content of the key variables of self-compacting concrete cement. To study the fresh concrete properties (rheological) and mechanical properties (compressive strength) of selfcompacting concrete by varying different parameters such as fine aggregate, coarse aggregate, super plasticizer (SP) and water/binder ratio.

Influence of Slurry Impregnation Technique of Recycled Concrete Aggregates on the Roller Compacted Concrete Pavement

Influence of Slurry Impregnation Technique of Recycled Concrete Aggregates on the Roller Compacted Concrete Pavement

Sustainable Roller Compacted Concrete: Assessing the Potential of Rice Husk Ash as a Cement Partial Replacement

Sustainable Roller Compacted Concrete: Assessing the Potential of Rice Husk Ash as a Cement Partial Replacement

Assessment of engineering geology and grouting applications in Yalnızardıç Dam Site (Antalya, Türkiye)

The Yalnızardıç roller compacted concrete (RCC) dam, constructed in 2015, is located in the Mediterranean region of Turkey, intended for electric power production. It is approximately 303 m long and 92 m in height. In this paper, it is aimed to determine the performance of the grouting method, conducted to control the water seepage and improve the foundation of the Yalnızardıç dam. The engineering properties of the site were introduced by geological mapping, drilling, and laboratory tests. The seepage of the foundation was determined by the in-situ Lugeon test method, also referred to as a water pressure test, which is estimate the mean hydraulic conductivity of rock mass. As a result of the tests, high-permeable and permeable zones were determined in the dam axis area. To make a barrier layer for these permeable zones, grout curtains were built in the left abutment, thalweg and right abutment with two lines of grouting holes which is proposed according to the Lugeon test and rock quality designation (RQD) results. Consolidation grouts were built to increase the density of the soil which makes the strength of the dam's foundation. After the groutings, check boreholes were drilled and water pressure tests were performed to control the seepage along the foundation and dam site. The results indicated that average Lugeon (LU) values reduced, and the values were within the recommended limit. The process shows considerable accuracy in evaluating grouting efficiency.

Deformation health diagnosis of RCC dams considering construction interfaces based on monitoring data and numerical simulation

The health diagnosis procedure applied to determine the deformation of a roller compacted concrete (RCC) dam is different from that of a conventional concrete dam. Hence, in this study, a deformation health diagnosis model was established for an RCC dam considering the construction interfaces by combining the hydrostatic component simulated using ABAQUS (2016) with the temperature and aging components calculated using a statistical method. The combined method can help monitor the structural health of RCC dam and determine the physical meaning and statistical law of the deformation of RCC dams. During the simulation process, the geometric characteristics of the construction interfaces were modeled using the interface equivalent expansion method. The material properties were modeled using multi-output least-squares support vector regression optimized with the Jaya algorithm. A case study demonstrated that the established deformation health diagnosis model has good fitting and prediction ability. The model and methods proposed in this study provide a new idea for the behavior analysis and numerical simulation of mass composite structures similar to RCC dams.

Comparative Study on the Mechanical Properties of Steel Fiber Reinforced Self-Compacting Concrete

Self-compacting concrete (SCC) is a flowable concrete which can consolidate under its own weight without the need of external vibration. The highly fluid nature of SCC makes it suitable for placing in difficult environments like congested reinforcement and thinner sections. Use of SCC can also help in decreasing noise pollution at worksites which is caused by vibration of concrete. SCC is used in bridges, buildings, and tunnel construction. The addition of small closely spaced and uniformly dispersed fibres to concrete would act as a crack resistor and would substantially improve its properties. This type of concrete is known as fibre reinforced concrete. In fact, the fibre reinforcement mechanisms can convert the brittle behaviour of this cement-based material into a pseudo-ductile behaviour up to a crack width that is acceptable under the structural design point-of-view. Fibre addition, however, increases the complexity of the mix design process, due to the strong perturbation effect that steel fibres cause on fresh concrete flow. In the present study, the effect of steel fibres on fresh and hardened properties are studied by adding steel fibres of different percentages such as 0%, 1% and 2% for M70 grade of concrete. An experimental investigation has been carried out to determine different properties like workability and strength of Fiber Reinforced Self Compact Concrete and Self- Compacting Concrete (SCC). For testing the properties of SCC and Fiber Reinforced SCC (FRSCC) in fresh state slump-flow, T50 Test, L-box, U-box, and V-funnel tests were conducted. Whereas for testing the properties in hardened state compressive strength, split tensile strength and flexural strengths are carried out. Detailed studies have revealed that the Steel Fiber Reinforced Self Compacting Concrete made with the Steel fibres displays a better performance. The investigations and results are presented from the study. Index Terms: Self compacting concrete, Steel fibre reinforced concrete, Super plasticizer, Silica fume, Fly ash, Steel fibre.

The combination of conventional Roller Compacted Concrete (RCC) with the substitution of fly ash for fine aggregate replacement

This study aimed to investigate the characteristics of roller-compacted concrete when fine aggregate is replaced with fly ash. The investigation focused on assessing workability, compressive strength, flexural strength, and split tensile strength of the concrete mixtures. Four testing methods were employed, including the slump test for workability assessment, the compression test for determining compressive strength, the flexural test for evaluating flexural strength, and the split tensile test for measuring split tensile strength. The fly ash used in this project was sourced from the powerplant in Malaysia. Various fly ash contents, specifically 0%, 55%, 65%, and 75%, were utilized to replace the fine aggregate. The concrete mixtures were subjected to water curing for 7, 14, and 28 days before testing. Following the mixing process using a concrete mixer, the mixtures underwent a slump test to evaluate their workability. It was observed that the workability of the concrete decreased as the percentage of fly ash used to replace the fine aggregate increased. Mixtures with fly ash exhibited zero slump, while the control mixtures displayed true slump. Subsequently, compression, flexural, and split tensile tests were conducted after 7, 14, and 28 days of water curing. In terms of compression strength, an increase in fly ash content resulted in higher compressive strength in the concrete mixtures. The mixture with 65% fly ash content demonstrated the highest compressive strength at 49.84 MPa. Regarding flexural strength, the concrete with 75% fly ash content exhibited the highest value, measuring 5.45 MPa. However, for split tensile strength, the concrete without fly ash content showed the highest value at 8.84 MPa compared to other mixtures, indicating that the fly ash content exceeded the optimum amount for the mix design. In summary, the concrete mixtures with fly ash displayed several advantages, but their suitability depends on the specific type of construction.

Inovadora brita graduada tratada com cimento de alto desempenho como concreto compactado com rolo

Abstract The main causes of poor performance of cement-treated crushed stones (CTCS) pavement layers are material-related heterogeneity, porosity, and brittle cementitious matrix, leading to fast fatigue degradation. Seeking to improve CTCS mechanical properties and structural response it was studied different grading curves such as DER-SP, EN 14227-1 CBGM 2 and RCC-ACI were studied. The aim of the laboratory study was to rank and select among the classical particle size distribution models like Talbot & Richart, and analytical models as compressible packing model – CPM, the best grading curve which was capable of producing mixtures with the best aggregate interlocking and improved mechanical resistances. The effect of cement content (4% and 5%) as well as the potential of using silica fume in suspension (percentages of 5, 7 and 10% of cement mass) to improve the interfacial transition zone were evaluated. It was found that CPM is a powerful tool for aggregates ranking aggregates and designing well-graded mixtures like CTCS; the CBGM 2 EN 14227-1 mean curve achieved the best packing density. The effect of increasing the cement content from 4 to 5% in terms of mechanical strength has the same result as the addition of 7% of silica fume in mixtures with 4% cement. Eventually, mixtures with 5% cement and 10% silica fume showed modulus of elasticity similar to traditional CTCS; nonetheless, the HP-CTCS (high performance CTCS) split tensile strength was significantly higher (about 28%), leading to a lower Et,sp/fct,sp relationship, which is a highly positive outcome to improve mechanical durability of this innovative dry compacted concrete.

Assessing the stability of the reservoir rim in moraine deposits for a mega RCC dam

<abstract> <p>Diamer Basha Dam is an under-construction, 272-meter-high, roller compacted concrete (RCC) dam on the Indus River in Pakistan. Once constructed, it will be the world's highest RCC gravity dam with a 105-kilometer-long reservoir. Most of the reservoir lies in unstable moraine deposits with steep slopes. Events like saturation during reservoir filling, alternate wetting, drawdown during reservoir operation, or a seismic event could trigger a large mass movement of these slopes into the reservoir to disrupt the dam functionality. This work identified the 15 most vulnerable slide areas using digital slope maps, elevation maps, and satellite imagery. Deterministic slope stability analysis was carried out on the identified sections under various stages of reservoir operation for static and seismic loading, using pseudo-static and dynamic analysis approaches. Probabilistic analysis was then performed using Monte Carlo simulation. The findings showed that most moraine deposits would collapse under reservoir filling, rapid drawdown, or seismic activity. Following the assessments, landslide susceptibility maps were generated, and an assessment of potential impacts, including the generation of dynamic waves, reservoir blockage, increased sediment loads, and reduced reservoir storage capacity, was also performed.</p> </abstract>

Roller compacted concrete technology for vehicle parking area solutions

The purpose of the article is presenting the application of the roller compacted concrete (RCC) as alternative solution to asphalt parking places and roads, showing the advantages and further possibilities for development of RCC in wide range of projects. RCC is produced similar to conventional concrete. However, RCC is zero slump concrete unlike conventional concrete. In this study the construction for parking area in RCC technology is presented for the real project. Presented cases concern heavy and light vehicles parking areas. The experimental results shows the very good quality of RCC placed on site, high compressive strength of the concrete, good workability of the concrete mixture that allows for proper placing of the concrete. RCC provides better mechanical-durable properties, more economical and less carbon footprint based on proper compaction and on lower water/cement ratio comparing to conventional concrete. The article draws attention to the role of the soil under the RCC as well, which should be designed and prepared on site with an appropriate stiffness and should be made according to the requirements resulting from the use of RCC. Such a comprehensive implementation of the soil-RCC subbase system guarantees the proper quality, load-bearing capacity and durability of the structure of the parking places as well as roads, for the assumed period of operation.

Performance Evaluation of Bottom Ash as Aggregate Replacement in Conventional Roller Compacted Concrete (RCC): An Experimental Study

The escalating demand for construction materials, coupled with the depletion of natural resources such as sand, necessitates environmentally conscious alternatives in concrete production. This study investigates the viability of utilizing bottom ash as an eco-friendly substitute for natural sand in roller compacted concrete (RCC). The focus is on evaluating workability and mechanical properties, examining bottom ash replacements at 0%, 20%, 25%, and 30% for fine aggregate. The research employs a comprehensive methodology, assessing workability and mechanical strength, encompassing compressive, split tensile, and flexural strengths across various concrete formulations. Comparative analyses with conventional concrete provide conclusive insights. Significantly, the study consistently highlights the superiority of RCC specimens featuring a 25% bottom ash replacement, exhibiting the highest strength values. This establishes the 25% replacement ratio as optimal for achieving robust roller-compacted concrete. Despite a slight reduction in workability with increasing bottom ash replacement, it remains within acceptable limits for practical applications. Comparative analyses between bottom ash RCC and conventional RCC underscore the superior mechanical attributes of the former, suggesting its potential as a sustainable alternative in concrete construction. By substituting natural sand with bottom ash, this research addresses environmental concerns related to the depletion of sand reserves. It actively contributes to sustainable practices within the concrete industry, demonstrating the viability of bottom ash as a substitute for natural sand in roller compacted concrete production. In conclusion, the study advocates for environmentally friendly practices and offers a practical solution to mitigate the ecological impact of sand resource depletion in the realm of concrete construction. The findings emphasize that the optimum percentage of bottom ash for compressive strength, split tensile strength, and flexural strength tests is within the range of 0% to 12%.