Manufacturing Of Cementitious Materials Research Articles

The Impact of Milled Wood Waste Bottom Ash (WWBA) on the Properties of Conventional Concrete and Cement Hydration.

Wood waste bottom ash (WWBA) is a waste generated in power plants during the burning of forest residues to produce energy and heat. In 2019, approximately 19,800 tons of WWBA was generated only in Lithuania. WWBA is rarely recycled or reused and is mostly landfilled, which is both costly for the industry and unsustainable. This study presents a sustainable solution to replace a part of cement with WWBA at 3%, 6%, 9%, and 12% by weight. Problems are also associated with the use of this material, as WWBA could have a relatively large surface area and a high water demand. For the evaluation of the possibilities of WWBA use for cementitious materials, the calorimetry test for the cement paste as well as X-ray diffraction (XRD), thermography (TG, DTG), and porosity (MIP) for hardened cement paste with the results of physical and mechanical properties, and the freeze-thaw resistance of the concrete was measured and compared. It was found that WWBA with a large quantity of CO2 could be used as a microfiller with weak pozzolanic properties in the manufacture of cementitious materials. As a result, concrete containing 6% WWBA used to substitute cement has higher density, compressive strength at 28 days, and ultrasonic pulse velocity values. In terms of durability, it was verified that concrete modified with 3%, 6%, 9%, and 12% WWBA had a freeze-thaw resistance level of F150. The results show that the use of WWBA to replace cement is a valuable sustainable option for the production of conventional concrete and has a positive effect on durability.

Performance of nano titania-reinforced slag/basalt geopolymer composites

In Egypt, basalt manufacturing generates waste materials at a rate of about 33%. The disposal of basalt waste through the manufacturing of cementitious materials is an economically feasible approach. This work involved the fabrication of a one-part slag/basalt waste geopolymer cement (GP) enhanced by nano-TiO2. The physico-mechanical properties of the different GP mixes were investigated. The durability against fire at up to 750 °C, sulfate (SO4−2) attack, and irradiation with significant dosages of γ-rays at up to 1500 kGy were assessed. Phase composition and microstructure were explored through various techniques as XRD, TG, and SEM. The findings demonstrated that basalt incorporation up to 20% within the GP mix boosted its mechanical characteristics after 28 and 90 days of curing by 8.5 and 2.5%, respectively, while 60% replacement diminished the strength by 30%. Slag/basalt GP showed a comprehensible resistance to SO4−2 ions attack, and its strength was intensified by 14% after 4 months of immersion. Additionally, the blended GP mixes could preserve 40% of their strength after being exposed to 1500 kGy of γ-rays and about 50% of their strength after firing at 750 °C. Admixing GP by NT showed a synergic impact for diminishing setting times, boosting compressive strength by 5 ~ 15% compared to reference mix along with an improvement in the microstructure. Furthermore, distributing NT through GP greatly improved durability after firing at 500 and 700 °C and irradiating with high dosages of γ-rays. This feature is mostly connected to the catalytic capabilities and filling activities of NT in boosting geopolymerization processes.

3D printing as an automated manufacturing method for a carbon fiber-reinforced cementitious composite with outstanding flexural strength (105\xa0N/mm2)

As research interest in the additive manufacturing of cementitious materials for structural uses has been continuously increasing, the question of how to incorporate tensile reinforcement in an automated process has gained further importance. Our research describes a carbon fiber-reinforced cementitious composite produced by common extrusion techniques applied in 3D printing as a means to effectively control fiber alignment. Optimization of the mixture design and consistency allows for admixing up to 3 vol.-% chopped carbon fibers, leading to specimens that can reach a flexural strength exceeding 100 N/mm2 without the addition of further continuous reinforcement. Fiber integrity during the process was checked using optical microscopy. Analysis of the microstructure shows that approximately 70% of the fibers are aligned within ± 5° of a preferential direction. Micromechanical single-fiber push-out tests confirm an interfacial fracture toughness typical for strain-hardening systems. The first insights into a ‘lost formwork’ approach commonly employed in 3D printing show that the reinforcement remains effective even when combined with nonreinforced mortar.

Properties of Portland cement concrete cast with magnetized water: a review

The water utilized in concrete manufacture plays an important role within the concrete mix, beginning from controlling the process of hydration of cement, besides appropriate curing to achieve the required strength, not to mention controlling the workability and durability of the concrete structure. The utmost significant challenge for concrete technology is to improve the properties of concrete. Nowadays, the engineering field needs to produce structures in harmony with the concept of sustainable development through the utilization of high-performance materials with an eco-friendly impact that is produced at a low-cost. The magnetic water (MW) provides one of the utmost towards this objective. The cost of magnetizing water is low because of the simple instruments used and the cost can be adapted to the scale of the work. In the last two decades, a new technology, so-called MW technology, has been extended to use in concrete manufacturing. Therefore, currently, the researchers are interested in the use of MW in the manufacture of cementitious materials helping to rationalize the cement usage and reducing reliance on chemical additives that have a negative environmental impact. Consequently, this paper presents the effect of the magnetization process in the structure of water molecules, the main properties of water. Additionally, the effect of using MW on the fresh and mechanical properties, as well as the durability characteristics and performance of cementitious materials have been reviewed. Moreover, the factors that affect the magnetization process of water, which highlighted discuss in this study. The results revealed that using MW significantly enhances the flowability and the characteristic strengths of cementitious materials as well as the durability properties.

Application on cementitious materials to promote durability of alkali-activated concrete containing co-fired fly ash and water-quenched slag

In the present study, we evaluated the effects of using co-fired fly ash (waste product of paper making) and water-quenched slag (waste product of iron smelting) in the manufacture of cementitious materials (CM). Rapid chloride permeability results revealed that less charge passes through CM than through ordinary Portland cement (OPC), indicating the superior durability of CM. However, the results of water permeability testing led to the opposite conclusion. Absorption capacity results revealed that the durability of CM is lower than that of OPC. Previous studies have shown that the strength of CM is only 70% that of OPC. This is a clear indication that CM containing co-fired fly ash and slag should not be used for primary structures, i.e., its use should be limited to secondary structures such as bricks or PC-based materials.

Utilization of water glass as an activator in the manufacturing of cementitious materials from waste by-products

In the present paper, the possibility of producing new-type cementless building materials is discussed when water glass as an activating agent is used. The experimental data are presented for a set of raw materials which normally do not show any binding ability. However, if they undergo some physico-chemical treatment and water glass is used, a solid structure of the material is formed. According to the method described here, lots of different mineral waste by-products could be activated, thus gaining binding properties.

Use of waste materials in the construction industry

A Symposium by Correspondence has been organised on behalf of RILEM on the use of waste materials and industrial by-products in the construction industry. 18 countries (excluding the UK for which the authors are providing information) submitted contributions and in this paper these contributions are summarised and analysed. Information about individual materials has been extracted from the national contributions and a chapter devoted to each waste in turn. The properties, occurrence, present uses and possible future applications of each waste are described. Blastfurnace slags and pulverised fuel ashes are the two materials which are being used to the greatest extent. Blastfurnace slags are used overall to some 80% of their production and in several countries virtually all that is produced is used and the slags are regarded as a highly satisfactory material. Pulverised fuel ashes are about 20% used overall but up to 70% is used in some countries. Much of these two materials is used as fill but many more sophisticated uses are developing. These materials can make a particular contribution in conserving energy in the manufacture of cementitious materials and of lightweight aggregates. Overall however the proportion of mineral wastes which is used is only about 5% of the production and most is used in relatively low grade applications such as fill in roads and embankments. The most influential factor in determining whether or not a waste material or by-product is used is the economic cost in comparison with the alternative natural material in a particular application. These costs are primarily made up by handling, processing and transport but the social benefits of using a waste, for example avoiding the dereliction associated with the tipping of a waste material or the quarrying of a natural, should not be forgotten. Possible disbenefits such as pollution arising during processing or a less well proven technical performance should also be taken into account. Adequate knowledge of the properties of the waste materials and products containing them are therefore essential to enable a balanced judgement to be made on the overall advisability of using a waste material in a particular situation.