Papers by Keyword: Sodium Silicate

Abstract: The basic material used for advancement in concrete is often composed of essential limiting materials such as concrete, fine aggregate, coarse aggregate, and water. Solid waste management is one of the most important tactics in today's total collection situation. As expected, an effort was made to decrease usual resources and conserve the environment. To increase the strength of concrete, Sodium Silicate (Na₂SiO₃) is added in the amounts of 5%, 10%, 15%, 20%, 30%, 35%, 40%, and 45% by weight of cement. The study entails investigating the effect of adding sodium silicate in various quantities on setting time, workability, and compressive strength. When sodium silicate is added to concrete, there is a significant increase in workability and durability, according to the literature. Setting time and compressive strength were studied, and it was shown that using sodium silicate as a substitute for cement improves workability and durability. When Sodium Silicate is added to concrete buildings, the content of calcium hydroxide drops while the content of calcium silicate hydrate (C-S-H gel) increases as compared to untreated concrete structures. Because the expansive and insoluble C-S-H gels partially fill the micro-pores, micro-voids, and micro fractures in the concrete structures, the sodium silicate-based concrete sealers are basically surface hydrophilic agents. Because of the production of C-S-H gel, the amount of water in the mix is reduced as compared to a traditional one, as is the initial setting time. Sodium Silicate is transformed into a binding agent as well as a superplasticizer after the reaction.

Abstract: Cardava banana pseudostem fibers (BPFs) are recently explored as a composite reinforcement. This is due to its improved thermal and mechanical stability effects for concrete applications. Silica, derived from sodium silicate and a modification additive, was explored as potential matrix in the self-healing applications. Herein, BPFs were prepared to produce BPF – silica composite (BPFSC) as concrete additive. The investigation focused on the interfacial adhesion of BPFs in the silica matrix to self-heal the concrete when subjected to cracks. The synthesized BPFSC has a sheet-like and a rough surface morphology based on the SEM micrographs. BPFs (100 mesh) were used to reinforce silica, and the synthesized composite (BPFSC) was mixed in a cementitious matrix (5% w/w) to test its potential self-healing properties. Results showed that the addition of the silica (SiO₂) improved the mechanical properties of concrete in both the pristine condition and healed samples. Notably, the BPFSC showed better mechanical performance than SiO₂ alone. This explained the good interfacial adhesion of BPF in the BPF – silica matrix. Hence, the prepared composite embedded in concrete showed significant healing potential concerning compressive and tensile strengths after damage, surpassing control specimens. Finally, a synthesis procedure was developed to prepare cardava banana pseudostem fiber – silica composite, showing a potential upcycling route of waste pseudostems for construction materials.

Abstract: The strength of a fine-grained lateritic soil from three (3) different locations on Abuja – Lokoja road where road failure occur was treated with sodium silicate activator (SSA), cement and rice husk ash (RSA) with varying percentage scrutinized by means of Atterberg, compaction and triaxial shear tests. The result reveals that cement additive improved the lateritic soil from Liquid limit values of 41.25 at 0% to 44.36 at 8%, but reduces at 10% to 35.67, while RHA increases at increased percentages. The MDD improved with increase in the quantities of all the additive (SSA, cement and RHA) content, while OMC for both cement and RHA reduces from 18.65% at 0% to 11.71 and 18.05 respectively. It reveals cohesion of the soil at 0, 2, 4, 6, 8 and 10% to be 19, 39, 49, 55, 58 and 65 KN/m² respectively, with highest angle of 65⁰ and lowest of 37⁰. This implies that the cohesion of the improved sample was satisfied since the improved angle of internal friction is above the angle that makes soil very plastic which is 28⁰. Keywords: Geopolymer. Sodium silicate, rice hush ash, Triaxial, Abuja.

Abstract: With the OPC industry being responsible for the 8% of CO₂ global emissions, alternative, eco-friendly building materials, called geopolymers, have been in the center of research interest. Their broader use is limited due to the concentrated alkali solution that is involved in the synthesis process. In this study, a wide range of solid reagents are tested for the development of solid mixtures with suitable alkali and silica content that will substitute the corrosive activation solution. One-part geopolymers were synthesized using Greek fly ash as the aluminosilicate precursor. The produced samples were appropriately characterized by XRD, FTIR and SEM analytical techniques while the mechanical performance was evaluated through uniaxial compressive strength measurements. One-part geopolymers using anhydrous sodium silicates with molar ratios SiO₂/Na₂O ≤ 2 as solid activators, can successfully substitute the activation solution since they achieve identical mechanical performance to that of the two-part geopolymers (≥ 60 MPa).

Abstract: To develop a sustainable concrete and to minimize the depletion of the natural resources, an attempt was made to develop sustainable concrete mixtures benefiting from the geopolymer technology and the use of recycled aggregate in self-compacting geopolymer concrete (SCGC). This study aim to examine the effects of sodium hydroxide (SH) molarity and sodium silicate (Na2SiO3)/ sodium hydroxide (SS/SH) ration the fresh properties of SCGC mixtures containing recycled coarse aggregates (RCA) Mixes were prepared with three different molarity (8M, 10M and 12M) of) and four SS/SH ratios (1.5, 2.0, 2.5 and 3.0). Six mixes were examined in this study. The results were compared with the EFNARC limits for self-compacting concrete (SCC). It was found that the SS/SH ratio and the molarity of SH affect the fresh properties of (SCGC). However, the results showed that, SCGC mixtures containing RCA can be developed and satisfy the requirements of EFNARC for fresh state of SCC.

Abstract: Ordinary Portland cement (OPC) is the essential binding material to produce the OPC concrete. Production of OPC is recently attaining a rate of 2.6 billion ton per year worldwide and growing 5% annually. OPC contributes at rate of 5 – 8% of human-worldwide CO₂ emissions which are the greenhouse gases pollute the atmosphere. Geopolymer concrete (GPC) is a creative, sustainable, economical and eco-friendly material for construction industry, which is a suitable alternative to the OPC concrete, able to extensively curb the CO₂ emissions. To prepare this kind of concrete, a combination of pozzolanic material such as fly ash (FA), and/or ground granulated blast furnace slag (GGBS) rich with silica and alumina can react with alkaline activator solution producing aluminosilicate gel, acting as a superb binding material for fine and coarse aggregates under special conditions of curing. This study highlights the recent explorations on geopolymer mortars and concrete. Effect of chemicals such as sulphuric acid, effect of fly ash partial replacement with different binding materials, effect of concentration of alkaline activator solutions and the effect of temperature and time of curing variation have been discussed on durability and mechanical properties of geopolymer concrete. Results have shown superb resistance of geopolymer concrete to the detrimental effects of sulphuric acid on weight and compressive strength. Furthermore, fly ash partial replacement with silica fume, OPC or GGBS, or nanosilica inclusion in GPC has a positive effect on the GPC properties. Finally, using high concentration of sodium hydroxide has a detrimental effect on GPC properties.

Abstract: The precipitated silica prepared by reaction of sodium silicate and gas CO₂ on fixed bed column have been production successfully. In this study, silica from bagasse was extraction by sodium hydroxide 2N solution to produce sodium silicate solution. The sodium silicate solution was dilute by demineralize water to produce some concentration in the range of 0.33-0.98 %SiO₂. Fixed bed column has a diameter of 7.5 cm with a height of 50 cm and a pH control apparatus. CO₂ gas and sodium silicate liquid are both flowed from under of the column with a specified flow rate. The precipitate process was carried out on a fixed bed column with high of bed in the range of 10-30 cm. The effect of silica concentration and the high of the bed on the characterize of the precipitated silica product have been studied. The precipitated silica product characterized by XRF, XRD, SEM-EDX and BET. The quality of precipitated silica produced in the range concentration of 95-98 w% SiO₂, surface area (BET) in the range of 46.1 – 58.8 m²/g.

Abstract: Magnesia inorganic lightweight material was prepared by using magnesium cementitious materials as raw materials, sodium silicate solution as modifier, hydrogen peroxide solution as foaming agent, manganese dioxide as activator, calcium stearate as stabilizer and polyacrylamide as thickener in this paper. The effects of sodium silicate addition on the apparent density, mechanical strength, pore structure, crystalline phase and water resistance of magnesia inorganic lightweight material were discussed. The results show that when the content of sodium silicate is 7.5‰, the pore structure presents better morphology and the crystallization contains more 5·1·8 phases (strength phase). At this moment, the compressive strength and bending strength of the composite reached 10.35 MPa and 2.22 MPa, respectively. When the addition of sodium silicate exceeded 7.5‰, SEM and EDS presented that a large amount of sodium silicate and perforation appeared in the pores, meanwhile large number of perforations occurred between pores. XRD showed that the 5·1·8 phases and 3·1·8 phases in the materials changed into Mg (OH)₂ crystals. These results in a significant decrease in material properties. Keywords: Magnesium cementitious material; Sodium silicate; Inorganic light materials; Pore structure

Abstract: For cost reduction of the molds manufacturing, as well as environmental load in foundries sodium silicate binder is often used. However, without treatment with special compositions that accelerate curing and improve their properties, sodium silicate molds have insufficient thermal spalling resistance and often cause the rejection of castings made of heat-resistant alloys. As a result of the research, there was developed a technology of chemical drying of the sodium silicate cover layers in investment casting with the use of aluminoborbophosphate concentrate. It allows to reduce the production time of ceramic molds by 2...3 times, as well as to increase their strength either before baking or after it by 20...25 %. At the same time, as a result of softening effect of aluminoborbophosphate concentrate after baking and cooling of the specimens there has been observed a significant reduction of their retained strength and, as a consequence, better knockout of fire-resistant shells. Industrial tests of the sodium silicate cover chemical drying showed a significant reduction of the investment castings rejection due to the insufficient thermal spalling resistance and the reduction of the cleaning processing time of casting made of heat-resistant alloys.

Abstract: Plasma electrolytic oxidation (PEO) of aluminum alloy 5754 was carried out in a multicomponent electrolyte variating the concentration of sodium silicate. The research has allowed to establish the characteristic features of the plasma electrolytic oxidation process, and also morphological structure of the formed oxide layers. It is established that the applied electrolytic systems can significantly increase the thickness of the formed layers (up to 152 μm), and control their porosity, bringing it up to 30 %.