Effect of Alkaline Solution Content on Strength and Chloride Induced Corrosion of Steel in Geopolymer Concrete Made from Fly Ash

2019 ◽  
pp. 123-137
Author(s):  
Sathishraj Mani ◽  
Bulu Pradhan
Keyword(s):  
Fly Ash ◽  
Alkaline Solution ◽  
Geopolymer Concrete ◽  
Chloride Induced Corrosion ◽  
Corrosion Of Steel

scholarly journals Experimental study of effect additional water on high performance geopolymer concrete

2019 ◽  
Vol 270 ◽  
pp. 01004
Author(s):  
Rachmansyah ◽  
Harianto Hardjasaputra ◽  
Meilanie Cornelia
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Alkaline Solution ◽  
Greenhouse Effect ◽  
Environmental Conservation ◽  
Cement Industry ◽  
Geopolymer Concrete ◽  
Green Concrete ◽  
The World ◽  
Additional Water

The Earth Summit 1997 in Kyoto (Japan), industrialized countries agreed to reduce gas emissions by 21% to avoid global warming due to greenhouse effect with the release of CO2 into the air. From the research result, cement industry sector all over the world contributes about 8 - 10% of total CO2 emission. This number is quite high and if there is not a special action to reduce, CO2 emissions will continue to increase along with the rapid development of infrastructure in various parts of the world including in Indonesia. To support greenhouse effect reduction efforts due to CO2 emissions and environmental conservation, civil engineers in the world are taking steps to achieve Sustainable Concrete Technology, in order to create “Green Concrete”. For that reason in the direction of “Green Concrete”, innovation is needed to reduce or replace cement in the concrete mixing. The ash waste electrical power generating plants of fly ash is a material containing many SiO2 and Al2O3 which can be used to replace the overall of cement in concrete. Geopolymer concrete is a fly ash-based concrete that replaces the entire cement in its manufacture. Workability in mixing geopolymer concrete is very low, due to the rapid reaction of the alkaline solution when it reacts with fly ash. To improve the workability can be added water at the time of mixing. The fly ash used in the mixing from the Paiton power plant in East Java with grain size 12.06 μm with round granules and chemical composition of fly ash containing SiO2, Al2O3 and Fe2O3 with a total of 75.151%. The planned compressive strength of the concrete is 45 MPa, with a variation of 8M, 12M and 16M NaOH molarity and the ratio of NaOH and Na2SiO3 is 1. Addition of water in concrete mixing with variations of 15, 17.5, 20, 22.5 and 25 liters / m3. The results of this study indicate that the more addition of water in the manufacture of geopolymer concrete can also increase the value of slump, but the excessive addition of water will result in a decrease in the compressive strength of the concrete caused by a decrease in the concentration of the alkaline solution. High molarity values will require additional water to reach the same slump value compared to lower NaOH molarity. With the same mix design, the optimal compressive strength at 8M NaOH was 48.18 MPa with 17.5 liters/m3 of water added with a slump of 12 cm, for 12M NaOH the optimal compressive strength was 51.65 MPa with the addition of 20 liter/m3 with 10 cm slump, while for 16M NaOH the optimum compressive strength is 59.70 MPa with 22.5 liters/m3 of water added with a 5 cm slump. The higher the NaOH molarity will result in a higher compressive strength value and geopolymer concrete compressive strength at early age is higher than conventional concrete.

The Influence of Micro Algae on Corrosion of Steel in Fly Ash Geopolymer Concrete: A Preliminary Study

2012 ◽  
Vol 626 ◽  
pp. 861-866 ◽  
Author(s):  
Monita Olivia ◽  
Navid Moheimani ◽  
Reza Javaherdashti ◽  
Hamid R. Nikraz ◽  
Michael A. Borowitzka
Keyword(s):  
Fly Ash ◽  
Corrosion Potential ◽  
Concrete Structures ◽  
Algal Growth ◽  
Microbiologically Influenced Corrosion ◽  
Metallic Surface ◽  
Geopolymer Concrete ◽  
Preliminary Study ◽  
Corrosion Of Steel ◽  
The Impact

Chloride is not the only main cause of corrosion of reinforced concrete structures in seawater environment. Microorganisms, such as bacteria and microalgae, in the seawater can induce microbiologically influenced corrosion (MIC) that leads to degradation of the concrete structures by formation of biofilm on the metallic surface. In this preliminary study, the impact of microalgae on the corrosion of steel reinforced bars in fly ash geopolymer concrete was studied. Corrosion potential, algae cells number, and pH measurement were carried out for fly ash geopolymer concrete and a control mix (Ordinary Portland Cement) samples. The results indicate that the corrosion potential of fly ash geopolymer concrete was influenced by the cathodic reaction during photosynthesis activities. The geopolymer concrete in algae-inoculated medium was found to be more tolerant to algal growth than the control mix (OPC concrete). There was a positive correlation between algae cell densities and the potential reading of the geopolymer.

scholarly journals EFFECT OF CaO CONTENT ON GGBS BASED GEOPOLYMER CONCRETE

2019 ◽  
pp. 8-12
Author(s):  
D. S. Patare ◽  
P. A. Chavana ◽  
S. L. Hake
Keyword(s):  
Fly Ash ◽  
Alkaline Solution ◽  
Design Procedure ◽  
Heat Of Hydration ◽  
Engineering Industry ◽  
Polymerization Process ◽  
Alkaline Solutions ◽  
Strength Increase ◽  
Fine Aggregate ◽  
Geopolymer Concrete

GGBS based Geopolymer concrete is innovative composite material for civil engineering industry for which binding material cement and water is replaced bypozzolanic material like fly ash, GGBS and activated by highly alkaline solutions to act as a binder in the concrete. Mix design procedure used is proposed on the basis of quantity, fineness of fly ash, quantity of water, grading of fine aggregate, fine to total aggregate ratio and GGBS is used for M40 grade of GGBS based Geopolymer concrete. During experimental work, variation of different parameter like ratio of alkaline solution ratio (Na2SiO3/NaOH) of 2 was taken. Different molarities such as 12M and 16M of NaOH was taken. In addition, different percentage of such as 0%, 20%, 40%, 50% of GGBS with solution to fly ash ratio 0.38 and sodium silicate to sodium hydroxide ratio 2 was taken. The samples are cured in oven at 450C temperature for 24 hrs. The results show that the strength of geopolymer concrete increases with increase in percentage of GGBS in the mix. The strength increase up to 40% replacement of fly ash with GGBS after that it starts decreasing. In case of fly ash based geopolymer concrete as there is no CaO content so curing takes place due to polymerization process, but with the addition of GGBS in fly ash based geopolymer concrete curing is due to combine effect of polymerization as well as heat of hydration due to presence of alkaline solution and CaO respectively. As molarity of NaOH increases from 12M to 16M, compressive strength, flexural strength, split tensile strength also increases.

scholarly journals Compressive Strength of Geopolymer Concrete Composites: Modeling and Comprehensive Systematic Review

2021 ◽  
Author(s):  
Hemn Unis Ahmed ◽  
Azad A. Mohammed ◽  
Ahmed S. Mohammed
Keyword(s):  
Systematic Review ◽  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Alkaline Solution ◽  
Construction Material ◽  
Assessment Tools ◽  
Curing Temperature ◽  
Geopolymer Concrete

Abstract The growing concern about global climate change and its adverse impacts on societies is putting severe pressure on the construction industry as one of the largest producers of greenhouse gases. Given the environmental issues associated with cement production, geopolymer concrete has emerged as a sustainable construction material. Geopolymer concrete is cementless concrete that uses industrial or agro by-product ashes as the main binder instead of ordinary Portland cement; this leads to being an eco-efficient and environmentally friendly construction material. Compressive strength is one of the most important mechanical property for all types of concrete composites including geopolymer concrete, and it is affected by several parameters like an alkaline solution to binder ratio (l/b), fly ash (FA) content, SiO2/Al2O3 (Si/Al) of the FA, fine aggregate (F) and coarse aggregate (C) content, sodium hydroxide (SH) and sodium silicate (SS) content, ratio of sodium silicate to sodium hydroxide (SS/SH), molarity (M), curing temperature (T), curing duration (CD) inside the oven and specimen ages (A). In this regard, a comprehensive systematic review was carried out to show the effect of these different parameters on the compressive strength of the fly ash-based geopolymer concrete (FA-GPC). In addition, multi-scale models such as Artificial Neural Network (ANN), M5P-tree (M5P), Linear Regression (LR), and Multi-logistic Regression (MLR) models were developed to predict the compressive strength of FA-GPC composites. For the first time, in the modeling process, twelve effective parameters including l/b, FA, Si/Al, F, C, SH, SS, SS/SH, M, T, CD, and A were considered the modeling input parameters. Then, the efficiency of the developed models was assessed by various statistical assessment tools like Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), Scatter Index (SI), OBJ value, and the Coefficient of determination (R2). Results show that the curing temperature, sodium silicate content, and ratio of the alkaline solution to the binder content are the most significant independent parameters that influence on the compressive strength of the FA-GPC, and the ANN model has better performance for predicting the compressive strength of FA-GPC in compared to the other developed models.

Development of sustainable construction material from fly ash class C

2020 ◽  
Vol 18 (6) ◽  
pp. 1615-1640
Author(s):  
Eric Asa ◽  
Monisha Shrestha ◽  
Edmund Baffoe-Twum ◽  
Bright Awuku
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Alkaline Solution ◽  
Sustainable Construction ◽  
Geopolymer Concrete ◽  
Curing Time ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Content Type

Purpose Environmental issues caused by the production of Portland cement have led to it being replaced by waste materials such as fly ash, which is more economical and safer for the environment. Also, fly ash is a material with sustainable properties. Therefore, this paper aims to focus on the development of sustainable construction materials using 100% high-calcium fly ash and potassium hydroxide (KOH)-based alkaline solution and study the engineering properties of the resulting fly ash-based geopolymer concrete. Laboratory tests were conducted to determine the mechanical properties of the geopolymer concrete such as compressive strength, flexural strength, curing time and slump. In phase I of the study, carbon nanotubes (CNTs) were added to determine their effect on the strength of the geopolymer mortar. The results derived from the experiments indicate that mortar and concrete made with 100% fly ash C require an alkaline solution to produce similar (comparable) strength characteristics as Portland cement concrete. However, it was determined that increasing the amount of KOH generates a considerable amount of heat causing the concrete to cure too quickly; therefore, it is notable to forming a proper bond was unable to form a stronger bond. This study also determined that the addition of CNTs to the mix makes the geopolymer concrete tougher than the traditional concrete without CNT. Design/methodology/approach Tests were conducted to determine properties of the geopolymer concrete such as compressive strength, flexural strength, curing time and slump. In Phase I of the study, CNTs were studied to determine their effect on the strength of the geopolymer mortar. Findings The results derived from the experiments indicate that mortar and concrete made with 100% fly ash C require an alkaline solution to produce the same strength characteristics as Portland cement concrete. However, it was determined that increasing the amount of KOH generates too much heat causing the concrete to cure too quickly; therefore, it is notable to forming a proper bond. This study also determined that the addition of CNTs to the mix makes the concrete tougher than concrete without CNT. Originality/value This study was conducted at the construction engineering and management concrete laboratory at North Dakota State University in Fargo, North Dakota. All the experiments were conducted and analyzed by the authors.

scholarly journals Analisis Kuat Beton Geopolimer Menggunakan Fly Ash dan Abu Sekam Padi

2021 ◽  
Vol 9 (2) ◽  
pp. 63-70
Author(s):  
Ika Sulianti ◽  
Indrayani - ◽  
Agus Subrianto ◽  
Efrilia Rahmadona ◽  
Oktri Yanti ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Rice Husk ◽  
Alkaline Solution ◽  
Rice Husk Ash ◽  
Energy Utilization ◽  
Alkaline Solutions ◽  
Geopolymer Concrete ◽  
The Right ◽  
Optimum Variation

One of concrete construction development is the use of geopolymer concrete which is environmentally friendly and efficient in regard to energy utilization. In this study, four combinations of fly ash (FA) and rice husk ash (RHA) was used, namely: i) 100% FA and 0% RHA, ii) 75% FA and 25% RHA, iii) 50% FA and 50% RHA, and iv) 25% FA and 75% RHA, with addition of alkaline solution mix of Na2SiO3 and NaOH with a ratio of 5:1 at 7 days, 14 days, and 28 days of concrete age, with cube samples and will be done a compressive strength test of 225 kg/cm2 (28 days of concrete age). This study aims to determine the optimum variation and analyze the compressive strength of geopolymer concrete using FA and RHA with the addition of an alkaline solution of Na2SiO3: NaOH = 5: 1. Results found that the optimum variation was in the geopolymer concrete mix of 100% FA and 0% RHA with a compressive strength value of 395.643 kg/cm2 (28 days of concrete age), whereas other variations have shown a decrease of compressive strength compare to the normal concrete. Therefore, the geopolymer concrete variation of 100% FA and 0% RHA has a higher compressive strength because the cement substitute used (100% fly ash) contains the right chemical composition in which it can react with alkaline solutions properly. Meanwhile, rice husk ash contains a composition that is not appropriate to be reacted with alkaline solutions. This shows that fly ash is a suitable substitute for cement for geopolymer concrete. In the other hand, rice husk ash is not suitable for use as a substitute for cement in geopolymer concrete.

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