Papers by Keyword: Admixture

Abstract: Lignin is the largest component of biomass and the second most abundant natural polymer. Lignin-based products are commonly applied as binders, and are utilized for polymer applications. The purpose of this study is to use lignin as an admixture in mortar. The lignin dissolved in 1M NaOH solution, and the ratio was 1:5 by weight. The lignin contents utilised in this study were 1%, 2%, 3% by weight of cement and a cement water rasio of 0.4. Lignin as an admixture in mortar increased the flowability value. The flowability value increased as the lignin content rose. the highest compressive strength and flexural strength occured at 1% lignin content. They were 35.71 MPa and it was 5.49 MPa, at the age of 28 days. The longest setting time was obtained at 3% lignin content for initial setting time of 285 minutes, and final setting time of 540 minutes. Based on the results of the setting time test, it has been determined that the more lignin was mixed in, the longer the setting time will be. Therefore lignin as an admixture to the mortar makes changes its characteristics.

Abstract: The study investigates the impact of quaternary ammonium and pyridinium salts on the rheological properties of metakaolin-based geopolymer pastes, with a focus on their application in 3D printing technology The experimental results demonstrated that the addition of these salts increased both the plastic viscosity and yield stress of the geopolymer mixtures, with the effect intensifying with higher concentrations and longer aliphatic chains. The coefficient of consistency derived from Herschel-Bulkley model increased from 1.78 up to 3.83 Pa·sⁿ and the yield stress rose from 3.4 up to 31.8 Pa. The study also observed a shift from shear-thickening to shear-thinning behaviour and reduction in thixotropic properties with increased dosages of the admixtures, which is beneficial for 3D printing. The mechanical properties of modified geopolymer mortars were also tested and the results revealed quite negligible effect of admixtures on flexural strength. The compressive strength was slightly reduced by up to 12%. The findings suggest that these admixtures are effective in modifying the rheological properties of geopolymers, making them more suitable for advanced applications like 3D printing.

Abstract: At present, there is a high demand for concretes with varying properties. Generally, concrete with high durability can be produced by considering the constituents of the concrete, such as cement, sand, aggregates, and water. The quality of concrete is also dependent on the mix design and production method, such as transporting and pouring of concrete. In recent years, the developed countries have been focusing on the issue of sustainability in construction to create a healthier environment and reduce the environmental impact of a building throughout its lifetime while optimizing its economic viability and ensuring the comfort and safety of the occupants. One way to achieve sustainability is using agricultural waste material such as palm oil fuel ash, rice husk, fly ash slag, sludge, and coconut shell in concrete production. This study performs a series of tests to investigate the effect of using alum sludge (AS) and palm kernel ash (PKA) with coconut shells as a partial replacement of aggregates. The concrete samples were subjected to compressive strength, flexural strength, rebound hammer, ultrasonic pulse velocity, water permeability, water absorption, carbonation, alkali-silica reaction, SEM, and shrinkage tests.

Abstract: Researchers in the field of concrete technology with the application of different admixtures are always in search of suitable admixtures to improve the workability as well as the strength of any concrete grade. An attempt was made in the present research to use chemical admixtures (superplasticizers) like sulphonated naphthalene based Apple Chemie AC-MENT-ALPHA-X5, polycarboxylic ether based Fosroc Auramix 350, sulphonated naphthalene based Fosroc Conplast SP 430, modified polycarboxylate based Du-bond DUPLAST PC P 2 and modified lignosulphate based Sika PLASTIMENT BV 40 for concrete grades M30 and M40. A literature survey revealed that all identified chemical admixtures are used for 20–25% reduced water content. A study was done to compare M30 and M40 grade concrete in both fresh and hardened states, taking water reduction into account. Experimental results showed that all admixtures demonstrate good paste-up consistency of up to 1%. As the percentage of admixtures increases, there is an increase in surface pores due to more significant air entrainment. Compressive strength results of 1% admixture content for Apple Chemie, Fosroc, and Du-bond were observed to be close to their characteristic compressive strengths for both grades, but Sika and Fosroc Auramix 350 have good compressive strength with less than 1%. As the grade of concrete improves, Conplast's effect reduces, but the Du-bond and Fosroc Auramix 350 perform excellently for split tensile strength. As the grade rises, all admixtures show increasing flexural strength levels. However, Auramix 350, with a 1.5% content for M30 grade, consistently outperforms Sika, which has a 1% content. It helped to employ up to 1% of all admixtures, but Sika reveals a cost increase of 2.5 to 7.3% for 1% and 1.5% admixture additions. The study found that Fosroc Auramix 350 could be used for both grades and still have good workability and strength.

Abstract: The use of the periwinkle shell in the production of lightweight concrete has been studied and accepted to be used for concrete works. Hard water containing detergent-like chemicals has been observed to be used in mixing locally produced concrete. This exploratory study is on the effect of water mixed with detergent in a concrete prepared with the periwinkle shell as a coarse aggregate. A total of 27 concrete cubes of size 150mmx150mmx150mm were prepared in the laboratory with a mix ratio of 1:2:4. A water-cement ratio of 0.4 was used with the addition of detergent at varying percentages (0%, 0.3% and 0.6). The cubes were cured in water and tested at 7days, 14days and 28days respectively. Laboratory tests, which includes bulk density, specific gravity, grain size analysis, slump and the compressive strength test was carried out on the aggregates and concrete. The periwinkle shell had a bulk density of 1440kg/m³and a specific gravity of 2.50. The workability tested revealed that the slump values increased with increase in the percentages of detergent. The compressive strength at 28days and at 0.3% and 0.6% were 12.58N/mm² and 14.06N/mm² respectively. It was observed that the compressive strength decreased with the addition of detergent because of the tiny air bubbles introduced into the concrete by the detergent. From the results of the study, it can safely be concluded that the use of detergent contaminated water in concrete production will reduce its compressive strength and increase its workability.

Abstract: The article examines a number of regularities in the production of primary cast ingots of AlSi7Mg, AlSi7MgSr, AlSi11Mg, and AlSi11MgSr. Peculiarities of melting and cast of these alloys, as well as the effect silicon and strontium have on the formation of the shrinkage cavities, have been explored. It has been demonstrated that strontium, when used as a modifier, changes not only the morphology of silicon, but also the nature of solidification and shrinkage of the alloy. Defects formed in the ingots manufactured from near – eutectic AlSi11MgSr alloy have been studied in greater detail.

Abstract: This research showed the results of experiments effect use of oil palm fibre (OPF) from oil palm industry as partial replacement for ordinary Portland cement. Research on the reuse of waste materials in the concrete industry has been quite intensive in the past decade. The objective of this research is to identify the Effect of oil palm fibre as a partial cement replacement in the production of concrete. After the treatment, the economical ways to dispose of it is by using landfill method. But due to a limited landfill site in Malaysia and it is the temporary solution for the disposal of the waste, it becomes a problem to Malaysia and the number of the oil palm fibre keeping increase year by year because of the population increase year by year too. The results showed that oil palm fibre (OPF) greatly improved the compressive and flexural strength of concrete. The rate of water absorption of oil palm fibre (OPF) concrete was reduced as oil palm fibre filled up the existing voids, making it more impermeable. However, the compressive strength of the oil palm fibre concrete decreases gradually when the amount of oil palm fibre (OPF) increased. It can be concluded that the optimum percentage of oil palm fibre as a partial cement replacement is 10%. In this direction, an experimental investigation of ultrasonic pulse velocity, carbonation test, compressive strength, flexural strength and water absorption was undertaken to use oil palm fiber and admixtures as partial replacement for cement in concrete.

Abstract: The research was dealing use of ladle slag and its impact on the physical and mechanical parameters of hardened cement composites. The goal was to find a suitable percentage share of ladle slag used as an admixture. The results of compressive strength tests show the possibility of replacement of a significant amount of cements with a specific secondary product. A decrease in compressive strength of about 8% after 28 days has to be taken into account when using Portland cement CEM I 42.5R and a 10% replacement with ladle slag.

Abstract: Basic oxygen furnace slag (BOFS) , a mass supplementary cementitious materials, can be used as an active additive in building materials. The work present the result of granule morphology of two kinds of BOFS powder, cooled by water quenching (BOFS-W) and air splashing method(BOFS-A). Micrographs of two kinds of BOFS powder were observed with a scan electron microscope (SEM), then, length of major axis and minor axis of two-dimension projective outline of every granule in these SEM micrographs was measured manually and their ratio (RLB) was used to represent the granule sphericity. Each BOFS powder was divided into 6 parts with different granularity range. By means of measurement and statistical analysis, the average RLB value of granules with different granularity grade was obtained and the relation between size and sphericity of granule was explored. Result showed that BOFS-W is superior to BOFS-A in sphericity of granule. According to different granularity grade, statistical average values of RLB of BOFS-W and BOFS-A range 1.422-1.496 and 1.490-1.647, respectively. The difference of BOFS-W and BOFS-A on granule sphericity mainly is reflected in coarse granule.

Abstract: Geopolymer that was made with high CaO content fly ash was found to have higher compressive strength than the low CaO fly ash, using the same mixture composition. This effect could be due to the physico-chemical properties of the fly ash, in respect to its particle size or the chemical composition. Although it was not widely published, the occurrence of flash setting of geopolymer was known to occur when using high CaO content fly ash as the precursor. Geopolymer paste may solidify within minutes after the addition of alkali activators, making it very difficult to cast in big volume. This paper investigate the effect of borax addition to the high calcium fly ash-based geopolymer mixture to reduce the occurrence of flash setting. It was found that the setting time can be extended significantly, with the addition of 5% borax, by mass, of fly ash. The addition of borax also have positive effect on increasing the compressive strength of geopolymer.