Reducing the Porosity and Sealing Cracks by Using Crystalline Admixture in Conventional Concrete

There is a continuous increase of quality on civil engineering materials in developed countries and parallel increase of need for new constructions in developing countries. Professional community should propose solutions for the durability that can resist in different severe environments. The most important factor that can affect concrete durability is represented by the pore distribution. Transport properties can take place through the porous network inside the cementitious composites and the aggregates interface, permitting the ingress of aggressive agents damaging concrete function intrinsically as a material and the wellfunctioning of the entire structure. The use of a crystalline admixture during the mixing procedure can fill the pores and capillarity of the cement composites, while in case of the appearance of the cracks, can perform as sealing agent, representing a secondary innovative benefit. Concrete structure, in this case will be more durable and there will be no need for unplanned intervention

Reducing the Porosity and Sealing Cracks by Using Crystalline Admixture in Conventional Concrete

There is a continuous increase of quality on civil engineering materials in developed countries and parallel increase of need for new constructions in developing countries. Professional community should propose solutions for the durability that can resist in different severe environments. The most important factor that can affect concrete durability is represented by the pore distribution. Transport properties can take place through the porous network inside the cementitious composites and the aggregates interface, permitting the ingress of aggressive agents damaging concrete function intrinsically as a material and the well-functioning of the entire structure. The use of a crystalline admixture during the mixing procedure can fill the pores and capillarity of the cement composites, while in case of the appearance of the cracks, can perform as sealing agent, representing a secondary innovative benefit. Concrete structure, in this case will be more durable and there will be no need for un-planned intervention

Reducing the Porosity and Sealing Cracks by Using Crystalline Admixture in Conventional Concrete

There is a continuous increase of quality on civil engineering materials in developed countries and parallel increase of need for new constructions in developing countries. Professional community should propose solutions for the durability that can resist in different severe environments. The most important factor that can affect concrete durability is represented by the pore distribution. Transport properties can take place through the porous network inside the cementitious composites and the aggregates interface, permitting the ingress of aggressive agents damaging concrete function intrinsically as a material and the wellfunctioning of the entire structure. The use of a crystalline admixture during the mixing procedure can fill the pores and capillarity of the cement composites, while in case of the appearance of the cracks, can perform as sealing agent, representing a secondary innovative benefit. Concrete structure, in this case will be more durable and there will be no need for unplanned intervention

Reducing the Porosity and Sealing Cracks by Using Crystalline Admixture in Conventional Concrete

There is a continuous increase of quality on civil engineering materials in developed countries and parallel increase of need for new constructions in developing countries. Professional community should propose solutions for the durability that can resist in different severe environments. The most important factor that can affect concrete durability is represented by the pore distribution. Transport properties can take place through the porous network inside the cementitious composites and the aggregates interface, permitting the ingress of aggressive agents damaging concrete function intrinsically as a material and the well-functioning of the entire structure. The use of a crystalline admixture during the mixing procedure can fill the pores and capillarity of the cement composites, while in case of the appearance of the cracks, can perform as sealing agent, representing a secondary innovative benefit. Concrete structure, in this case will be more durable and there will be no need for un-planned intervention

Effect of Class F Fly Ash on Strength Properties of Concrete

Reducing the amount of CO2 emissions in the environment is one of the priorities of the EPA and other environmental agencies. A way to reduce CO2 emissions is by using fly ash in the concrete industry. Aside from environmental benefits, fly ash has numerous quality advantages; some of the positive effects were recognized earlier; however, in this research, the objective is to replace cement with a different percentage of class F fly ash with a low CaO content to produce sustainable concrete. Laboratory tests were performed to examine the rational percentage of cement replaced by class F fly ash in ordinary concrete C–25/30 and high-performance concrete C–50/60. In total, twelve different mix designs were prepared to examine consistency, setting time, shrinkage, and compressive strength in different periods of curing for more than 600 days. Using recycled material in new buildings still has some obstacles, but the future of construction must be green, so this research indicates that the objective of producing ordinary and high-performance concrete was achieved by replacing 30% of cement with class F fly ash. Doi: 10.28991/CEJ-2023-09-09-011 Full Text: PD

Experimental Assessment and Numerical Modeling of Self Healing Capacity of Cement Based Materials via Fracture Mechanics Concepts

The authors’ research group has undertaken for about a lustrum a comprehensive research project, focusing on both experimental characterization and numerical predictive modelling of the self-healing capacity of a broad category of cementitious composites, ranging from normal strength concrete to high performance cementitious composites reinforced with different kinds of industrial (steel) and natural fibers. In this paper reference will be made to normal strength concrete: both autogenous healing capacity has been considered and self-healing engineered through the use of crystalline admixtures. A tailored methodology has been employed to characterize the healing capacity of the investigated concrete, based on comparative evaluation of the mechanical performance measured through 3-point bending tests. Tests have been performed to pre-crack the specimens to target values of crack opening, and after scheduled conditioning times to selected exposure conditions, including water immersion and exposure to open air. The healing capacity has been quantified by means of the definition and calculation of suitable “healing indices”, based on the recovery of the mechanical properties, including load bearing capacity, stiffness, ductility, toughness etc. and correlated to the amount of crack closure also “estimated” through suitable indirect methodologies. Chemical characterization of the healing products by means of SEM has been performed to understand the different mechanisms governing the observed phenomena and also discriminate among the different amounts of recovery of the different mechanical properties. As a further step a predictive modelling approach, based on modified microplane model, has been formulated. This incorporates the self-healing effects, in particular, the delayed cement hydration, as well as the effects of cracking on the diffusivity and the opposite repairing effect of the self-healing on the micro-plane model constitutive laws. The whole experimental and numerical investigation represents a comprehensive and solid step towards the reliable and consistent incorporation of self-healing concepts and effects into a durability-based design framework for engineering applications made of or retrofitted with self-healing concrete and cementitious composites

Evaluating the Potential of Recycled Asphalt for Sustainable Road Construction: An Environmental and Economic Analysis

Objective: This study investigated the possibility of using recycled asphalt for road construction and maintenance in Kosovo. Methods: By analyzing statistical data from the Ministry of Infrastructure based on the status of infrastructure, the life cycle of asphalt, and investments in this area, this study determined the amount of asphalt that needs to be recycled. Results: The results showed that 1454008.5 m3 of asphalt needs to be recycled in Kosovo. We studied using 10%, 15%, and 20% recycled asphalt in asphalt base courses. We determined the benefits of recycled asphalt in terms of environmental protection, energy savings, and low cost. Depending on the percentage of recycled asphalt, the savings in mineral mix ranged from 11% to 23% and the road bitumen dosage from 6 to 8.5%. Novelty/Improvement: The proposed method of reusing recycled materials can reduce the consumption of natural resources, energy, and financial costs and help protect the environment. Doi: 10.28991/CEJ-2023-09-06-014 Full Text: PD

Seismic Activity and Essential Seismological Characteristics of the Kosovo Territory

In this scientific work presented are Seismic basic characteristics. Reliable seismic hazard assessment depends mainly on the level of consistency, quality and amount of data in earthquake catalogues. The lack of good seismic activity data may often affect the quality of the assessment. This short review of the seismic activity affecting the territory of Kosovo throughout the time, points out that this region should be considered having high seismic hazard potential. Having in mind that in the last two decades, the region is undergoing very fast urbanization characterized with extensive infrastructure development and building modern high rise structures with different use: residential, administrative, commercial and buildings belonging to essential facilities such are schools and hospitals it is necessary to be aware of the seismic hazard to which the built environment can be exposed and all possible consequences of such event. In order to be able to assess the seismic hazard, it is necessary to integrate data from various field such as seismology, Seismotectonic, geology, tectonics, geophysics etc

Self-healing of slag-cement ultra-high performance steel fiber reinforced concrete (UHPFRC) containing sisal fibers as healing conveyor

This paper presents the results of a research on the influence of sisal fibers on the self-healing capacity of slag-cement UHPFRC reinforced with steel fibers. In order to evaluate the compos- ite healing capacity, specimens were submitted to pre-cracking by tensile test and then to a 3 months of wetting and drying cycles treatment. Treated specimens were resubmitted to tensile test and evaluated by Optical and Electronic microscopy and CT Scan. Results indicate that the sisal fiber works as a healing conveyor improving by about 20% and 15% the tensile stress and post cracking energy of treated specimens, respectively. Sisal fibers played a major role densifying the interface, working as a vehicle for the healing agents into small interface cracks. All specimens with cracks under 80 μm could completely self-seal mainly by calcium carbonate. Wider cracks could not be completely sealed, though the specimens exhibited a recovery of the mechanical behavior essentially due to late slag-cement hydration

Analysis and Design of Structural Elements for a Closed Swimming Pool Structure. Study of the Connection with Bolts

The topic of this thesis is the analysis and dimensioning of peculiar elements of a wooden structure, respectively the detailed design of the joints of the structural elements to the level for implementation. At the starting stages, the structure was selected to be made of wood, which served as a base model for further treatment of elements with interest for this analysis. Material type for structural elements is defined based on the specific properties of the wood. The main constructive elements consist of laminated wood and the other constituent elements consist of solid wood. The joints in the roof and walls of the structure are made of steel. The possibilities offered by the laminated wood for the design of structures with more complex character in physical aspect, as well as its attribute as the only material that can reduce carbon emissions in the atmosphere, gives this material an advantage to be selected compared to other materials. After analysis, dimensioning and treatment of the joints of the structure, it is important that all the structural elements resist the loads acting on the structure, enabling the durability and functionality during its lifespan