05-11-2016, 03:23 PM
Strength and durability study ofGeopolymer Concrete Incorporating Metakaolin and GGBS with 10M Alkali Activator Solution
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ABSTRACT
Background/Objectives: Energy conservation in building innovation is among the most basic issues on the planet. In this way it is a need to create reasonable contrasting option to traditional cement using more ecological agreeable materials. Methods/Statistical Analysis:One of the potential outcomes to work out is the enormous use of geo polymer cement to swing them to valuable natural well-disposed and innovatively favorable circumstances cementations materials.Findings: In the present study metakaolin and ground Granulated Blast heater slag (GGBS) is utilized to deliver geopolymer concrete. Geopolymer cement is set up by utilizing soluble arrangement of sodium silicate and sodium hydroxide. This settled proportion is 2.5 and the concentration of sodium hydroxide is 10M. The geo polymer concrete samples aretried for compressive, Split Tensile and Flexural Strengths for 3, 7 and 28 days and cured at surrounding temperature.Applications/Improvements:This study helps in gaining knowledge about the morophological composition of concrete which might result in path-breaking trends in construction industry.
Key words: Geo-polymer, Ground Granulated Blast Furnace Slag, Metakaolin, Alkali Activator.
1. INTRODUCTION
1.1 General
Concrete is synthesized with the aid of Odinary Portland cement (OPC) as the primary binder which generates huge amounts of carbon dioxide causing danger to the environment. On the other side, the wealth and accessibility of fly fiery debris, GGBS overall make chance to use this by-result of smoldering coal, as halfway swap for OPC. Nonetheless, within the sight of water and in surrounding temperature1-6, fly fiery debris is the common hydration procedure of OPC. In another plan, pozzolans, for example, impact heater slag might be enacted utilizing soluble fluids to shape a folio and thus absolutely supplant the utilization of OPC in cement6-15.
Cement is a standout amongst the most generally utilized development materials.On the other hand, natural issues came about because of bond creation has turned into a noteworthy concern today.Geopolymer cement is made by responding aluminate and silicate bearing materials with an acidic activator slag. Geopolymer are inorganic fasteners, which are recognized by the accompanying fundamental property of Compressive strength has relationship with the time taken for the process of curing and the corresponding temperature16-25.
Cement is a standout amongst the most generally utilized development material. Portland concrete generation is a noteworthy giver to carbon-di-oxide emanations. The a worldwide temperature alteration is created by the emanation of nursery gasses Numerous endeavors are being made keeping in mind the end goal to lessen the utilization of Portland bond in concrete
MATERIALSUSED
2.1 Metakaolin (or) kaolinite.
2GGBS:
Ground-granulated slag (GGBS) is synthesized through the process of quenching. It is amorphous in nature and formed as a result of slag quenching from blast funrnace. It can be seen as auxillary product during production of steel which can aid in concrete tehnology3
METHODOLOGY:
3.1 Mix
The essential distinction between geopolymer cement and others is the fastener. To frame geopolymer glue antacid activator arrangement used to respond with silicon and aluminum oxides which are available in Metakaolin and GGBS. This basic activator arrangement ties coarse total and fine total to frame geopolymer blend. The fine and coarse total involve about 75% to 80% mass of geopolymer cement. The fine total was taken as 30% of aggregate. The thickness of geopolymer cement is taken 2400 kg/m3.The workability and quality of cement are impacted by properties of materials that make geopolymer concrete.
3.2 Preparation of Alkali Solution
From table 3, the preparation of solution is done by dissolving the following ingredients in water.A concentration of 10MNaOHis calculated.
3.3Test Specimens
3.3.1 Water
Potable water with a pH value of 6 and free from impurities and chemical contaminants was used in all the mixes. Every 1 part of water content is combined with 3 equal parts of binder for all kinds of mix proportions.
3.3.2Mixing
The alkaline activator solution is prepared before 24 hours of casting. Initially, all dry materials were mixed properly for three minutes. Alkaline activator solution is added slowly to the mixture. Mixing is done for 5 minutes to get uniform mix.
3.3.3. Casting
The sizes of the moulds used are cube (150mmx150mmx150mm), cylinder (150mm dia and 300mm height), and prism(500mmx100mmx100mm). Mixing in dry environement is performed for 180-300 seconds and further cubical shape moulds are obtained in the size 150 x 150x 150 mm.
3.3.4 Curing
Moulds were demoded after 1 day. The average temperature recorded during the period of curing was 38ºC. The curing is done for3, 7 and 28 days.Curing simulates solidification of the material which is essential requirement for cement setting.
3.3.5 Testing
UTM and CTM is used to test the cured cubes with average loading capacity of 14mpa/min for 3, 7 and 28 days.
4. RESULTSAND DISCUSSIONS
4.1Compressive strength
The optimal mixture of GGBS to Mk for obtaining maximum rigidity is 9:1. From the results obtained, the optimal mix is obtained at 7th and 28th day.
Split tensile strength
The tensile strength of green concrete for given mix proportion varies in direct relation to percentage of slag(GGBS) at 28days. The optimal mixture of GGBS and Mk is obtained at the 28th day as we can ee from the variation of strength. The specimen shows improved strength of MPs for 10% replacement of metkaolin. (T = 2P/ π LD).
Flexural strength
The strength of green concrete for 28 days is tabulated in Table 14.The results infer that strength varies in direct relation to percentage of Meta kaolin. {T = 3P/ BD2.}. The graph is obtained for various compositions of the mixtures. On the other hand the strength varies in direct relation with the percentage of GGBS and MK content.
The counterpart Geopolymer concrete specimens were preparedwithgeopolymer. The concrete cubes were allowed to set for 24 hours, demoulded and placed in water pond for 15 days foreffective curing.
GPC-cubes after curing in different environment Fig 19-21
The compressive strength of the cubes was measured with the help of Universal Testing Machine (UTM) and the change in mineralogy due to ingress of aggressive solution was also studied by X-ray diffraction (XRD). XRD analysis was done by using a GBC Scientific Equipment (Australia), Model - EMMA 125 diffracto meter.
CONCLUSIONS:
• Strengths of Geopolymer Concrete are decrease with Decrease in METAKAOLIN (MK) i.e MK 0-GGBS100.
• Compressive strength, split tensile strength and flexural strength of green concrete tend to vary in direct relation to percentage of slag content.
• The strength variation for Compressive strength is 33.5%, split tensile is 30.9%, flexural strength is 25.7%
• During initial age period of 7 days of curing, rate of increase in strength and rigidity in terms of compressive and tensile is very fast. Sooner, the strength tends to vary in indirect relation with time.
• Strength and rigidity of the concrete material developed in terms of compressive, flexural and tensile tends to vary in direct relation with time (age).
• The green concrete resists the attack of various chemicals and therefore, it is durable for the given mix proportion.
• The green concrete resists the attack of various chemicals and therefore, it is durable for the given mix proportion