Добірка наукової літератури з теми "Self-consolidating earth concrete (SCEC)"

Despite the fact that the self-consolidating concrete is present on the market since the 1990s, it still faces a number of problems that limit its use in many countries. In Poland, in addition to economic barriers (the standard self-compacting concrete is much more expensive than standard concrete, which is most obtainable at low classes such as C16/20 and C20/25), there are also problems with a higher shrinkage resulting from the large amounts of grout There are also frequent problems with a high viscosity of the standard self-consolidating concrete, limiting the areas of its use. Development of a concrete technology and, in particular, the new generation of stabilizers (VMA) produced an alternative to the traditional self-consolidating concretes, i.e. the self-consolidating concretes with a low binder content - less than 380 kg/m3 , or even down to 315 kg/m3 . The low binder content in the new generation of the self-consolidating concretes, comparable to the binder content of standard products, makes them more economically competitive. The low viscosity of these mixtures result in much easier application, and the contraction rate lower in comparison to the standard self-consolidating concrete, which make them ideal substitutes of standard concretes. In the age of sustainable development, the requirements of the certification related to multi-criteria evaluation system such as LEED, BREEAM and DGNB, considerable importance to the issue of CO2 emission reduction. The production of self-compacting concrete with low binder content and recycled aggregates result in lower CO2 emissions than production of other self-consolidating concretes with high binder content. The use of recycled aggregates coupled with reducing the binder content make the self-compacting concrete more attractive in terms of their environmental impact. This solution allows for reduction in both the heat of hydration due to low cement content, and also for higher scores in multi-criteria evaluation building systems, due to the use of waste materials. This paper attempts to present the advantages and disadvantages of economical and ecological analyze of waste material usage such as recycled aggregates in SCC solutions.

Self-consolidating concrete (SCC) is increasingly used in a number of concrete applications, some of which are highly susceptible to attack by sulfuric acid. This work aimed to study the resistance of a wide range of different SCCs to sulfuric attack. The main variables studied included binder material type (highly reactive materials), limestone powder, and hybrid fibers in this work, compaction, L-box, and V-hopper were performed for the new mixtures. In this study, the specimens were immersed in a solution of sulfuric acid at a concentration (0.5%) for up to 289 days after normal curing for 28 days. Laboratory results show that concrete containing pozzolanic material has reduced mechanical properties compared to a mixture containing only limestone powder. The study also showed that there was an improvement in the resistance of concrete to acid solutions when hybrid fibers were added to the concrete mix. From the stress graph, the strain at given axial stress will be less than once the failure becomes more severe, it will become less rigid than immersing the specimen for six months.

This study investigates the effects of basic mix design variables such as water/cement ratio (w/c), slump flow, coarse-to-total aggregate ratio (CA/TA), and maximum aggregate size (Dmax) on the main characteristics of self-consolidating concrete. The w/c of the mixtures was either 0.42 or 0.50. The CA/TA ranged between 0.45 and 0.53. Slump flow was adjusted to 550, 650 or 720 ±20 mm by varying the superplasticizer content. Dmax was varied as 10, 15 and 20 mm. V-funnel, L-box, rheometer, sieve segregation tests and a new test method, recently developed by the authors, for dynamic segregation resistance were performed. The effect of each variable on the test results were effectively summarized in a table. Increasing the w/c, CA/TA and Dmax decreased the superplasticizer demand and increased the flowability. When the slump flow, w/c and CA/TA were higher, viscosity was found to be lower. Higher values of CA/TA and Dmax were found to reduce the passing ability. Increasing the slump flow (or superplasticizer content), CA/TA and Dmax disturbed the stability. Generally, the effects of w/c and slump flow on the SCC characteristics were more pronounced when compared to those of CA/TA and Dmax. Good correlations were obtained between several test results.

This paper presents an experimental study of the four-point simple bending behaviour of low strength reinforced concrete beams, reinforced with self-compacting concrete (SCC) with two different strength classes (30 and 40MPa) and ordinary strength concrete (30MPa).And to compare the simple bending behaviour of beams reinforced with (SCC) to that of beams reinforced with ordinary concrete, is taken as a reference control concrete. The rheological properties of the materials used were determined using the slump-flow, L-box, V-funnel and sieve stability tests. The mechanical properties of studied concretes were evaluated at 7 and 28 days of cure. The results obtained have shown that self-compacting concrete (SCC) appears to be a very promising material for the reinforcement of concrete structures. The (SCC) offer increased stability, manoeuvrability and adequate filling capacity. This contributed to the improved performance of the self-compacting concrete (SCC) reinforcement configuration compared to ordinary concrete as a reinforcement material.

Self-compacting concrete (SCC) became a strong candidate for various construction applications owing to its excellent workability, low labor demand, and enhanced finish-ability, and because it provides a solution to the problem of mechanical vibration and related noise pollution in urban settings. However, the production of Portland cement (PC) as a primary constituent of SCC is energy-intensive, contributing to about 7% of global carbon dioxide (CO2 emissions. Conversely, the use of alternative geopolymer binders (GBs) in concrete can significantly reduce the energy consumption and CO2 emissions. In addition, using GBs in SCC can produce unique sustainable concrete with unparallel engineering properties. In this outlook, this work investigated the development of some eco-efficient self-compacting geopolymer concretes (SCGCs) obtained by incorporating different dosages of fly ash (FA) and ground blast furnace slag (GBFS). The structural, morphological, and mechanical traits of these SCGCs were examined via non-destructive tests like X-ray diffraction (XRD) and scanning electron microscopy (SEM). The workability and mechanical properties of six SCGC mixtures were examined using various measurements, and the obtained results were analyzed and discussed. Furthermore, an optimized hybrid artificial neural network (ANN) coupled with a metaheuristic Bat optimization algorithm was developed to estimate the compressive strength (CS) of these SCGCs. The results demonstrated that it is possible to achieve appropriate workability and mechanical strength through 50% partial replacement of GBFS with FA in the SCGC precursor binder. It is established that the proposed Bat-ANN model can offer an effective intelligent method for estimating the mechanical properties of various SCGC mixtures with superior reliability and accuracy via preventing the need for laborious, costly, and time-consuming laboratory trial batches that are responsible for substantial materials wastage.

La construction en terre est considérée comme une construction verte en utilisant des matériaux disponibles localement avec un faible impact environnemental et une performance thermique supérieure. Malgré les avantages de ce matériau de construction, le processus de coulage est très consommateur de temps et d'énergie à cause de l’application de la compaction dynamique. Cette étude a pour but d'évaluer la faisabilité de formuler un béton de terre autoplaçant (BTAP) tout en étudiant ses performances rhéo-thermomécaniques et en identifiant les différents défis. Le premier défi est la présence de particules fines dans la terre, en particulier les particules argileuses, qui peuvent entraver la fluidité du BTAP. L’augmentation du temps de prise est le deuxième défi en raison de la faible teneur en ciment. Le dernier défi vient de la diversité des terres avec des comportements différents, ce qui rend difficile la proposition d'une ligne directrice complète pour la conception des BTAP.Des solutions potentielles ont été introduites pour réaliser le BTAP afin de remédier à l'inefficacité des matériaux en terre. Il s’agit essentiellement de comprendre l'efficacité de différents adjuvants chimiques en présence des systèmes de poudre ternaire (c'est-à-dire l'argile, le limon et le ciment). Une nouvelle approche de mortier du béton équivalent (MBE) a été introduite à la Phase 3. En conséquence, le MBE et les formulations de béton ont été étudiés pour vérifier la faisabilité du BTAP. Les caractéristiques hygrothermiques et microstructurales des BTAP optimisés ont été étudiées. Ce nouveau matériau offre une microstructure conduisant à une performance hygrothermique différente de celle des matériaux en terre conventionnels
The earth construction is identified as a green construction by using locally available materials with low environmental impacts and superior thermal performance. Besides all the advantages of this construction material, the casting process can be very time and energy consuming due to the nature of dynamic compaction. This study aimed to evaluate the feasibility of achieving self-consolidating earth concrete (SCEC) with introduction of its potential challenges and investigating its rheo-thermomechanical performance. As the first challenge, the presence of fine particles in earth, especially clay, can hinder the flowability of SCEC. Promoting the setting time is the second challenge due to the low cement content. The last challenge comes from the diversity of earth with different behaviors which makes it difficult to propose a comprehensive guideline to design SCEC.Potential solutions were introduced to achieve SCEC and address the inefficiency of earth materials. The main objective was to understand the efficiency of different chemical admixtures in presence of various ternary powder systems (i.e., clay, silt, and cement). A new concrete-equivalent mortar (CEM) approach was introduced in the Phase 3. Accordingly, the CEM and concrete mixtures were investigated to verify the feasibility of SCEC. The hygrothermal and microstructural characteristics of the selected SCEC mixtures were investigated. This novel material offers a new microstructural system, hence leading to a different hygrothermal performance compared to conventional earthen materials