Acid Resistance Test Research Articles

Sustainable Approach for Linz‐Donawitz Slag Waste as a Replacement of Cement in Concrete: Mechanical, Microstructural, and Durability Properties

Linz‐Donawitz (LD) slag, solid waste produced during steel manufacture in basic oxygen furnace, is difficult when it comes to handling and disposal and has very limited utilization. To increase its reusability, the suitability of supplanting cement with LD slag in concrete was examined. To study the impact of partially replacing cement with LD slag on strength, microstructure, and durability of concrete, more than 150 samples were cast. The test results reveal that the highest compressive and flexural strengths were attained at 20% LD slag replacement and, beyond that, the strength decreased. The hydration products detected by X‐ray Diffraction (XRD) and Fourier‐transform infrared spectroscopy (FTIR) were calcium silicate hydrate (C‐S‐H), ettringite, and calcium aluminosilicate hydrate (C‐A‐S‐H). The scanning electron microscope (SEM) images of binary cement concrete showed denser microstructure and lesser voids. The sulphuric acid resistance, electrical resistivity, and carbonation resistance tests done reveal that acceptable durability could be achieved when cement is replaced by LD slag. It is deduced that LD slag can be utilized in partially replacing cement to achieve the desired strength. This research gives another comprehension of simultaneously managing steel industry waste for sustainable development and contributing added advantages to the economy.

Durability Behaviour of Geopolymer Concrete with Metakaolin and GGBS

This study consists of preparation of Geopolymer concrete mix with Ground Granulated Blast furnace Slag (GGBS) which is followed by the usage of Metakaolin in replacement of GGBS with 5% variation from 0 to 25%. From previous researches on geopolymer concrete with GGBS, an optimized mix is selected and tested for durability behaviour. A 12 Molarity sodium hydroxide solution along with sodium silicate in the ratio of 1:2.5 is used as activator in this study. La Hypercrete S25 which belongs to the category of carboxylic is used as admixture for escalating the workability. Water absorption, Acid resistance, and Rapid Chloride Penetration (RCPT) are the durability tests performed on the specimens. The prepared specimens are water cured at room temperature for the required days in accordance with the codal guidelines and tested for durability. For water absorption test, concrete cylinders of 50mm dia and 100mm height are prepared. 100 mm size cube specimens prepared for acid resistance test. The specimens for RCPT include preparation of discs of 100 mm dia and 50 mm height. In all the test specimens, GGBS is replaced by Metakaolin. It is believed from the test results that geopolymer concrete with Metakaolin and GGBS performs well in durability aspects.

Experimental investigation on strength properties of concrete using polypropylene pellets

The handmade tiles are manufactured in Athangudi, Sivagangai district. We observed that these tiles are reducing foot pain and appearing aesthetic look. But one disadvantage was that these Athangudi tiles were getting easily cracked. We studied that these tiles are getting cracks. Due to its lesser resistance. It shows some cracks on surface of tiles after setting and hardening process. In this project, we gave solution to rectify the problem for this purpose we adding the zirconium di oxide to cement paste at the time of manufacturing process. Because the zirconium di oxide possess high crack resistance property in these tiles. The field test (water penetration test), abrasion test, water absorption test and acid resistance test were conducted on Athangudi tiles with zirconium di oxide and without zirconium di oxide. Then the test result was compared between normal tiles and zirconium di oxide used tiles. Hence we conclude that zirconium di oxide used tiles are somewhat better than normal Athangudi tiles from the above result. We will conduct more tests and come with the conclusion that zirconium di oxide used tiles having better cracking resistance in future.

Durability Performance of Fly Ash and Steatite Powder Based Geopolymer Concrete

This paper deals with the study of durability properties of fly ash and steatite powder based Geopolymer concrete. The activating alkali used was 10 M sodium hydroxide and sodium silicate solution. The ratio of sodium hydroxide and sodium silicate ratio was 1:2.5. The range of replacement levels of flyash with steatite powder was from0 – 50 %. In order to improve the workability of geopolymer concrete, a PC based admixture Glenium B233 has been used for all the mixtures. In addition to that the concrete has been cured at oven at 70oC for about 48 hours. The following durability index properties such as water absorption, sorptivity, rapid chloride penetration test and acid attack test were measured at 28days. The observed results indicated that, increase in steatite powder demonstrates low water absorption and low permeability representing that the material was in a high dense pore structure. Additionally in acid resistance test, there was a decline in the percent losses of compressive strength with particular time period but then again the declination was lower when compared to increase in steatite powder.

Rice husk incorporated foam concrete wall panels as a thermal insulating material in buildings

The major segment for energy consumption is found in industry, transport, agricultural, residential and commercial sector. The main part of the energy consumption in residential and commercial buildings is due to the use of mechanical devices to maintain a comfortable indoor environment. Thermal conductivity of building materials is one of the factors which influence the heat transfer in buildings. Thermal conductivity can be reduced by the use of materials with low density. The present paper reports the development of a sustainable thermal insulating external wall panel and its mechanical, thermal and durability properties. The wall panel was prepared using foam concrete and rice husk and replacing the cement by fly ash. Strength of panel was tested by conducting in plane bending test and compressive strength test. Thermal conductivity was tested using guarded hot plate apparatus. Durability properties were tested by conducting water absorption test, drying shrinkage and acid resistance test. The test results showed that the rice husk and fly ash content had a major influence on the thermal conductivity and durability properties of the developed wall panels.

Novel natural rubber-based epoxy coating

The use of renewable resources in development of polymeric products is becoming more relevant in the current times, braced by the scarcity of fossil resources and threat from global warming. The manuscript describes the preparation of epoxy resin from epoxidized natural rubber (ENR) via ultraviolet (UV) treatment, followed by investigation on the film properties of the coating produced by blending the natural rubber-based epoxy resin with pentaerythritol tetrakis(3-mercaptopropionate), PETMP as the hardener. The UV treatment involved is responsible to break down the natural rubber into smaller molecular weight fractions so that it becomes more compatible with common solvents and chemicals, and at the same time improves the solubility and viscosity of the resin. The results obtained are very encouraging, with significant reduction in the molecular weight of the rubber observed after 6 hours of UV treatment, and spectroscopic characterization suggests that substantial amount of epoxide group in the ENR was effectively preserved during the treatment for subsequent reaction with PETMP. The epoxide group in the UV-degraded ENR was found to react with the –SH group of PETMP after the two were blended, applied into film, and heated at 80 °C. The properties of the coatings produced were investigated via pencil hardness test, crosshatch adhesion tape test, thermal stability test, water, and chemical resistance test. Most of the coating formulations produced film with excellent hardness, adhesion and chemical resistance. Coating B and C are among the best coating formulations, with both recorded pencil hardness grade ≥ 4H, zero film removal in the adhesion test, no film defect observed during saltwater, acid and alkaline resistance test, and reasonably good thermal stability with onset of degradation above 200 °C.

Influence of superplasticizer family on the durability characteristics of fly ash incorporated cement concrete

Nowadays, researchers are focusing on developing more durable cementitious matrices. Major durability problems are associated with sulphate attack, acid attack, chloride penetration etc. The important method to improve the durability characteristics of concrete is to reduce the permeability of concrete by giving good compaction. Superplasticizer addition is one of the methods to improve the workability and thereby reducing the porosity. A large amount of CO2 is emitted into the atmosphere from the cement plants during the calcination of CaCO3 and also through the burning of fuel in the kiln. The environmental pollution can be reduced by replacing the cement with the pozzolanic materials like fly ash. Portland pozzolana cement (PPC) is nowadays considered as a sustainable substitute of ordinary portland cement (OPC). The combined influence of pozzolanic and superplasticizer from four different families on the durability properties of concrete and mortar is studied is in this work by conducting laboratory tests like the sorptivity test, acid resistance test, RCPT test and sulphate resistance tests. In this study sorptivity value of the superplasticized mixes are found to be less than that of control specimen without superplasticizer. In all durability related aspects, the mixes with PCE based superplasticizer showed better performance than the control mix and that of mixes with other families of superplasticizer. Improvement in durability characteristics is observed for the mixes containing commercially available PPC compared to the mixes prepared with site blended PPC (ie OPC + 25% FA).

Acid Resistance Test of Probiotic Isolated from Silage Forage Swamp on In Vitro Digestive Tract

Antibiotics are commonly used in poultry ration, and afterward these drug residues may persist in foods. There is an alternative source of antibiotics in poultry rations, one of which is using probiotics. Probiotics are living microorganisms capable of reaching the gastrointestinal tract and benefiting health, leaving no residue in the body. Probiotics can be originated from bacteria such as lactic acid bacteria (LAB) which produced lactic acid and antimicrobial components. LAB must be able to live in the digestive system with various pH condition. pH resistance testing of LAB was performed by introducing diluted bacteria into several buffer solutions with different pH and a predetermined incubation time, then was grown in MRS agar medium. This study was conducted to determine the resistance of LAB isolates as probiotics from silage forage swamp at different pH distributed in vitro digestant. The design used was a complete randomized design consist of 3 treatments and 3 replications. The treatments were using isolate of Kumpai Tembaga silage (P1), isolate of 50% Kumpai Tembaga silage and 50% Kemon Air silage (P2), and isolate of Kemon Air silage (P3). The results showed that all isolates used were lactic acid bacteria, and the treatment significantly affected the value of LAB resistance test against low pH and high pH. Isolate from Kumpai Tembaga silage (P1) is a lactic acid bacterium with higher ability to survive in pH of in vitro digestive system.

FORMULATION AND DEVELOPMENT OF LENALIDOMIDE LOADED DELAYED RELEASE MINI TABLETS IN CAPSULES

Objective: Formulation and development of delayed release mini tablets in the capsule of drug lenalidomidein terms of dissolution and stability was the objective of the present work.Methods: Tablets of less than or equal to 3 millimetres diameter are Mini-tablets, which were filled into a capsule. Direct compression method using multi-tip punch was used for compression and coated with eudragit L100 as a seal coating material and with eudragit L30D55 as an enteric coating material was done. Different formulations were prepared and subjected for evaluation like weight variation, hardness, friability, disintegration, and dissolution studies. The optimized formulation was compared to marketed product based on drug released profile and also subjected for stability studies.Results: The results revealed that the in vitro drug release of prepared formulations, F1, F2, F3, and F4 was subjected for acid resistance test for 2 h in 0.1N HCl and has a comparable dissolution profile in phosphate buffer of 6.8 pH. FormulationF4 was subjected for stability studies and no significant difference was observed in 3 mo 40 °C/75% RH accelerated stability condition.Conclusion: The dissolution profile of formulation F4 was found better than that of market product. Based on evaluation results, the study concluded that F4formulationwas considered as an optimized formulation.

The Research and Development of Acid Resistant Steel Q315NS

In this paper the main use of acid resistant steel Q315NS is introduced, and the actual working conditions of the steel is detected. Based on the effect of Cu, Cr and Sb alloy elements in steel materials, the composition design of medium and thick plates is completed. And also the corresponding production process is formulated. The microstructure of the steel plate was analyzed and the acid resistance test is carried out.

Effects of water cooled ferrochrome slag as fine aggregate on the properties of concrete

The present study aims to represent the outcomes of investigation carried out to assess the use of water cooled ferrochrome slag (WCFS) as an alternative to natural sand in concrete making. Various destructive tests such as compressive strength, splitting tensile strength, flexural strength and modulus of elasticity were conducted on various concrete samples containing 0–50% of the WCFS on replacement of equal weight of natural sand. Non-destructive test like ultrasonic pulse velocity (UPV) test was conducted to compare the results of destructive tests. Rapid chloride permeability test (RCPT), acid resistance and sulphate resistance tests were addressed to access the durability of concrete containing the WCFS. Optical micro structural study was conducted to examine the microstructure of concrete with the WCFS. The WCFS is found similar to natural sand. The results indicated that there is a little decrease in strength properties of concrete due to inclusion of the WCFS but can be used up to 30% with minor scarification of strength. This little scarification may not be considered important when compared with the advantages on reuse of industrial waste and thus conservation of natural resources. Inclusion of the WCFS up to 30% has almost no negative impact on durability of concrete.

Screening assays of termite gut microbes that potentially as probiotic for human to digest cellulose as new food source

According to UN, earth population will increase approximately 7.3 billion people up to 11.2 billion from 2015 until 2100. On the other side, food needs are not balance with the availability of food on earth. People of the world need solution for a new food source. By cellulose digesting ability, people analyzed can consume cellulose as the new food source to get glucose. The aims of research is obtaining termite gut cellulase bacteria selected which is potential as probiotic to split cellulose. Method used was as follows; isolation of termite gut microbes, microbial cellulase purification by screening method and probiotic test includes microbial pathogenicity test and human stomach acid and salt osmotic concentration resistance test. The result shows, 3 pure isolates of termite gut microbes can break down cellulose in the medium 1% CMC and 0.1% congo red (indicator of cellulose degradation activity) and life at pH 2- 2.5 and osmotic salt condition. Two isolates show the activity of gamma hemolysis (non-pathogenic in terms of pathogenicity on human blood). In conclusion, there are isolated termite gut microbes can be used as probiotic candidate for human to digest cellulose of the new food source for global food scarcity era.

A Study on Dredged Sea Sand as an Optimum Replacement for Fine Aggregate in Concrete

This paper deals with the study and feasibility on utilization of dredged sea sand by conducting various experiments on physical properties like sieve analysis, gap grading. Chemical properties like percentage of organic content, chloride content, sulfur content, presence of deleterious material and volatile solids in dredged sea sand have been determined. The experiments like rapid chloride penetration test, water absorption test, alkalinity test, accelerated corrosion test, sulphur resistance test, acid resistance test, and sorptivity. Durability and strength of concrete have been studied by considering various properties of fine aggregate. The mix design have been done for M30 grade of concrete and the percentage of replacements 25%, 50%, 75%, and 100% of M-Sand (Manufacture Sand) of concrete specimen for all the experiments is considered. As we all know our current scenario of increase in demand of fine aggregate leads to scarcity of river sand. This has increased in research on dredged sea sand as a fine aggregate in concrete to reduce the demand on fine aggregate in construction industries. Comparative study of M-sand, river sand and dredged sea sand has been done. The dredged sand which is used for the study and testing is dredged to increase the sea bed depth of Ennor port for the accessibility of mother ship, it was collected from the coastal areas of Ennore Port (Kamarajar Port) and subjected to rain, and atmospheric conditions for a year.

In vitro resistance of enterococcus faecium and lactobacillus helveticus against stress conditions, sodium chloride and curing salts: preliminary study aimed application as starter culture in fermented sausage

The objective of this study was to evaluate the Enterococcus faecium (ATCC 8459) and Lactobacillus helveticus (ATCC 15009) in vitro resistance against stress conditions (acidity and bile salts); curing salts (sodium nitrate and nitrite) and sodium chloride, aiming application as starter culture in fermented sausage. Acid resistance test was carried out at pH values (3, 4 and 5) and bile salts (0, 0.15 and 0.30%), both monitored at times 0 and 4 hours. For resistance to curing salts was used concentration of 0.1% and sodium chloride concentrations tested were 1.0, 2.0 and 3.0%. Enterococcus faecium and Lactobacillus helveticus were resistant to bile salts; however, E. faecium was more sensitive to acidity. In presence of sodium chloride and curing salts, Lactobacillus helveticus showed the highest sensitivity. Both microorganisms had satisfactory results for this test, indicating that they may be used as starter culture in the preparation of meat products, such as fermented sausages. Moreover, these products composition may affect positively the starter culture viability in final product.

Characterization and acid resistance test of one-part geopolymer from fly ash and water treatment sludge

Development of geopolymers from wastes or by-products introduces a sustainable approach to replace ordinary Portland cement (OPC)-based concrete with an eco-material of lower green-house gases emissions. However, safety concerns related to the conventional two-part geopolymer has limited large-scale applications of the product. In this context, a novel one-part geopolymer from coal fly ash and water treatment sludge has been presented. The transformation of raw materials to geopolymer was observed by FTIR, SEM and XRD analyses. Acid resistance test has proved that the new binder had great durability against sulphuric acid attack. After 28 days immersion in 5% H2SO4 solution, weight of all samples was hardly changed. Compressive strength, on the other hand, has not decreased but significantly increased as curing time increased. The properties were also compared to those of control samples cured in water. It was demonstrated that strong acid immersion did not create any noticeable effect on the weight and strength of one-part geopolymer system developed from coal fly ash and water treatment sludge.

Synthesis of a one-part geopolymer system for soil stabilizer using fly ash and volcanic ash

A novel approach one-part geopolymer was employed to investigate the feasibility of enhancing the strength of in-situ soil for possible structural fill application in the construction industry. Geopolymer precursors such as fly ash and volcanic ash were utilized in this study for soil stabilization. The traditional geopolymer synthesis uses soluble alkali activators unlike in the case of ordinary Portland cement where only water is added to start the hydration process. This kind of synthesis is an impediment to geopolymer soil stabilizer commercial viability. Hence, solid alkali activators such as sodium silicate (SS), sodium hydroxide (SH), and sodium aluminate (SA) were explored. The influence of amount of fly ash (15% and 25%), addition of volcanic ash (0% and 12.5%), and ratio of alkali activator SS:SH:SA (50:50:0, 33:33:33, 50:20:30) were investigated. Samples cured for 28 days were tested for unconfined compressive strength (UCS). To evaluate the durability, sample yielding highest UCS was subjected to sulfuric acid resistance test for 28 days. Analytical techniques such as X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscope/energy-dispersive X-ray spectroscopy (SEM/EDX) were performed to examine the elemental composition, mineralogical properties, and microstructure of the precursors and the geopolymer stabilized soil.

폴리실라잔계 실란트를 이용한 정전척 실링특성 향상 연구

We have analyzed chemical properties of polysiloxane and polysilazane films, respectively, as sealing materials for electrostatic chuck (ESC) and have investigated the possibility of polysilazane as an alternative sealant to polysiloxane. It has been revealed that Si-O with organic bonding (<TEX>$Si-CH_3$</TEX>) existed in polysiloxane films compared to only pure Si-O bonding in polysilazane films. The sealing property of polysilazane has been found outstanding even in a short time of application. In the polysiloxane films containing <TEX>$H_2O$</TEX>, pin holes have been found possibly due to <TEX>$CO_2$</TEX> gas evolution, and low adhesion with Si substrate has been observed after heat stress test in connection with the existence of organic bonding. After acid resistance test in 0.5 vol.% HF, 68 wt.% <TEX>$HNO_3$</TEX>, and 37 wt.% HCl solution, polyilazane films have shown a longer survival times. Compared to the conventional polysiloxane sealant, polysilazane is expected as a new sealing material because of good thermal and chemical stability.

Influences of bicarbonate on processes of enamel subsurface remineralization and demineralization: assessment using micro-Raman spectroscopy and transverse microradiography.

In the present study, we investigated, using micro-Raman spectroscopy (Raman) and transverse microradiography, the influence of bicarbonate [sodium hydrogen carbonate (NaHCO3 )] on the effects of carbonate ions in the mineral phase during demineralization (acid resistance test) of subsurface lesions. Baseline lesions were created by demineralizing bovine enamel, and specimens were then exposed to remineralization solutions containing 0, 5, or 50 mM bicarbonate. Acid resistance tests were performed on remineralized and sound enamel specimens. Raman spectra showed that carbonate and phosphate were incorporated into both surface layers and lesion bodies during remineralization in the presence of bicarbonate. Moreover, the presence of bicarbonate did not affect the rates of remineralization, although the average mineral profiles of remineralized enamel differed from those of sound enamel after acid resistance tests. Raman analyses enabled close evaluation of site-specific characteristics of carbonate and phosphate in subsurface lesions. In conclusion, incorporation of carbonate and phosphate ions into enamel subsurface lesions during remineralization does not affect the magnitude of remineralization or acid resistance.

Remineralization of early enamel caries lesions using different bioactive elements containing toothpastes: An in vitro study.

Demineralization can be arrested or reversed when remineralization agents are applied to incipient carious or non-cavitated carious lesions. A large number of therapeutic agents including non-fluoridated products have been developed to promote enamel remineralization. This study aims to evaluate the efficacy of different bioactive elements containing toothpastes in remineralization of artificial enamel lesions. Artificial carious lesions were created on 40 human enamel slabs, and were randomly divided into four groups: (1) control group (no treatment), (2) casein phosphopeptide-amorphous calcium phosphate group (CPP-ACP, GC Tooth Mousse), (3) 8% arginine and calcium carbonate group (ACC, Colgate Sensitive Pro-Relief), (4) calcium sodium phosphosilicate group (CSP, NovaMin®). All samples were subjected to 15 days of pH-cycling. Subsequently, a one-hour acid resistance test was carried out. Surface hardness of the samples was assessed using the Knoop hardness test, and surface morphology and roughness were assessed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Data were analyzed using one-way ANOVA, Tukey's test and paired t test. The three tested toothpastes exhibited a significantly higher remineralization efficacy compared with the control group (P< 0.05 for all). After pH-cycling, the specimens treated with Colgate Sensitive Pro-Relief and NovaMin® showed a significant higher surface hardness (P< 0.001 and P= 0.03, respectively) and lower surface roughness (P< 0.05 for both) compared those treated with GC Tooth Mousse. While after the acid resistance test, all groups showed a significant loss of surface hardness (P< 0.001 for all) and significant increase of surface roughness (P< 0.05). The specimens treated with Colgate Sensitive Pro-Relief and NovaMin® still showed a significant higher surface hardness and lower surface roughness in comparison with those treated with GC Tooth Mousse (P< 0.05 for all). No significant difference was found in surface hardness and roughness between Colgate Sensitive Pro-Relief and NovaMin® during the pH-cycling test and acid resistance test (P= 0.45 and P= 0.83, respectively). Colgate Sensitive Pro-Relief and NovaMin® present an advantage in enhancing remineralization and inhibiting demineralization for early enamel carious lesions in comparison with GC Tooth Mousse.

Durability of Bricks Coated with Red mud Based Geopolymer Paste

The present study is undertaken to assess the durability of concrete blocks coated with red mud - fly ash based geopolymer paste. Concrete blocks of size 200 x 200 x 100mm were coated with geopolymer paste synthesized by varying the percentages of red mud and fly ash. Uncoated concrete blocks were also tested for the durability for comparison. In thermal resistance test, the blocks were subjected to 600°C for an hour whereas in acid resistance test, they were kept in 5% sulphuric acid solution for 4 weeks. The specimens were thereafter studied for surface degradation, strength loss and weight loss. Pastes with red mud percentage greater than 50% developed lot of shrinkage cracks. The blocks coated with 30% and 50% red mud paste showed better durability than the other blocks. The use of blocks coated with red mud - fly ash geopolymer paste improves the aesthetics, eliminates the use of plaster and improves the durability of the structure.