scholarly journals Fire Resistant Geopolymers Based on Several Clays Mixtures

2021 ◽  
Author(s):  
Ameni Gharzouni ◽  
Clément Alizé ◽  
Sylvie Rossignol
Keyword(s):  
Compressive Strength ◽  
Calcium Carbonate ◽  
Chemical Composition ◽  
Thermal Behavior ◽  
Dwell Time ◽  
Potassium Feldspar ◽  
Alkaline Solutions ◽  
Alkali Concentration ◽  
High Calcium ◽  
Carbonate Decomposition

This chapter aims to highlight the effect of clay mixture mineral composition and alkali concentration of potassium alkaline solutions on the thermal behavior of geopolymer materials. For this, three mixtures composed of kaolin (pure, impure kaolin or mixture of both), calcium carbonate, sand and potassium feldspar and three potassium alkaline silicate solutions with different concentrations were used (5, 6 and 7 mol.L−1). At first, the effect of rotary calcination parameters at 750°C such as the dwell time (30, 60, 120 and 180 min) and weight powder (100, 400 and 500 g) was investigated. It was demonstrated that the kaolin dehydroxylation is quasi complete (> 90%) and do not significantly depend on the dwell time and powder weight. Whereas the carbonate decomposition degree increases with the increase of dwell time and the decrease of powder weight but still not complete (<80%). These differences influence the feasibility of consolidated materials. Indeed, a flash setting occurs for samples based mixtures with high calcium carbonate decomposition degree (> 50%) and low wettability values (500 μL/g) for the three used alkaline solutions. The thermal behavior at 1000°C depends on the chemical composition of the aluminosilicate source and the concentration of alkaline solution. A conservation of the compressive strength at 43 MPa after thermal treatment at 1000°C of geopolymers based on mixture of pure and impure kaolin and a low potassium concentration solution (5 mol.L−1) was evidenced.

scholarly journals The Use of Borax in Deterring Flash Setting of High Calcium Fly Ash Based Geopolymer

2016 ◽  
Vol 857 ◽  
pp. 416-420 ◽  
Author(s):  
Antoni ◽  
Stephen Wibiatma Wijaya ◽  
Juan Satria ◽  
Agung Sugiarto ◽  
Djwantoro Hardjito
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Fly Ash ◽  
Chemical Composition ◽  
Setting Time ◽  
Chemical Properties ◽  
Physico Chemical ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Positive Effect

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.

The Development and Characterisation of Porous Clay - Precipitated Calcium Carbonate

2016 ◽  
Vol 694 ◽  
pp. 189-194 ◽  
Author(s):  
Y. Yasmin ◽  
M.N. Mazlee ◽  
A.H. Norzilah ◽  
J.B. Shamsul ◽  
Rahmat Azmi ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Calcium Carbonate ◽  
Chemical Composition ◽  
Mineralogical Composition ◽  
High Specific Surface Area ◽  
Ceramic Foam ◽  
High Porosity ◽  
Sintering Process ◽  
Precipitated Calcium Carbonate ◽  
X Ray

Ceramic foams, a porous material with a gyroid structures, are becoming highly demanded for various applications such as heat insulation, bone implantation and filtration, because of their unique properties such as high specific surface area, high porosity and low heat transfer rate. In this study, the development of ceramic foam utilised white clay with a combination of precipitated calcium carbonate (PCC). The ceramic foam was successfully developed using this combination after the sample was sintered at 1250 °C for 2 hours holding time. The various compositions of PCC (10.0, 12.5, 15.0, 17.5, 20.0, 22.5 and 25.0 wt.%) affected the chemical composition and compressive strength of the ceramic foam. The chemical composition of ceramic foam was analysed by using X -ray fluorescence (XRF) and the result indicated that the PCC was successfully transformed into calcium oxide (CaO) after the sintering process. The mineralogical composition of the ceramic foam was evaluated using X-ray diffraction (XRD) and has shown the presence of mullite (3Al2O3.2SiO2), gehlenite (Ca2Al2SiO7) and anorthite (2CaAl2Si2O8) after the sintering process. The scanning electron microscope (SEM) analysis showed that the presence of porosity on the strut of the ceramic foam. Meanwhile, the compressive strength of the ceramic foam increased from 0.03 to 1.31 MPa, which is directly proportional to the increased amount of PCC.

A method for measuring the in-plane compressive strength and the compression behavior of coating layers

TAPPI Journal ◽  
2011 ◽  
Vol 10 (7) ◽  
pp. 29-34
Author(s):  
TEEMU PUHAKKA ◽  
ISKO KAJANTO ◽  
NINA PYKÄLÄINEN
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Calcium Carbonate ◽  
Coating Layer ◽  
Test Methods ◽  
Coating Films ◽  
Precipitated Calcium Carbonate ◽  
Coating Color ◽  
Mineral Coatings ◽  
Styrene Butadiene

Cracking at the fold is a quality defect sometimes observed in coated paper and board. Although tensile and compressive stresses occur during folding, test methods to measure the compressive strength of a coating have not been available. Our objective was to develop a method to measure the compressive strength of a coating layer and to investigate how different mineral coatings behave under compression. We used the short-span compressive strength test (SCT) to measure the in-plane compressive strength of a free coating layer. Unsupported free coating films were prepared for the measurements. Results indicate that the SCT method was suitable for measuring the in-plane compressive strength of a coating layer. Coating color formulations containing different kaolin and calcium carbonate minerals were used to study the effect of pigment particles’ shape on the compressive and tensile strengths of coatings. Latices having two different glass transition temperatures were used. Results showed that pigment particle shape influenced the strength of a coating layer. Platy clay gave better strength than spherical or needle-shaped carbonate pigments. Compressive and tensile strength decreased as a function of the amount of calcium carbonate in the coating color, particularly with precipitated calcium carbonate. We also assessed the influence of styrene-butadiene binder on the compressive strength of the coating layer, which increased with the binder level. The compressive strength of the coating layer was about three times the tensile strength.

Transjøen, a Groundwater Influenced Lake with Special Redox and Sulphate Conditions

1976 ◽  
Vol 7 (5) ◽  
pp. 307-320 ◽  
Author(s):  
G. S. Bremmeng ◽  
A. E. Kloster
Keyword(s):  
Calcium Carbonate ◽  
Chemical Composition ◽  
Lower Layer ◽  
Calcium Content ◽  
Meromictic Lake ◽  
Redox Potentials ◽  
Precipitated Calcium Carbonate

Transjøen, a lake in S.E. Norway investigated hydrographically from October 1969 to October 1971, consists of two basins, both of which are meromictic (lake with lower layer which does not participate in the periodic circulations). The lake has a large influx of groundwater of very varying chemical composition. The calcium content is high and precipitated calcium carbonate and electrolyte rich groundwater is assumed to be the main reason for the meromictic stability. The redox potentials of monimolimnion (the lower layer which does not participtate in the periodic circulation) are extremely low, but in spite of this fact the content of sulphate is high.

Research on Process Mineralogy of Potassium-Rich Shale

2010 ◽  
Vol 158 ◽  
pp. 197-203 ◽  
Author(s):  
Jie Liu ◽  
Yue Xin Han ◽  
Wan Zhong Yin
Keyword(s):  
Chemical Composition ◽  
Mineral Composition ◽  
Potassium Feldspar ◽  
Composition Analysis ◽  
Research Results ◽  
Dsc Analyses ◽  
Process Mineralogy ◽  
Mineral Compositions ◽  
Chemical Composition Analysis

The process mineralogy of potassium-rich shale from Chaoyang of Liaoning, China, was studied. Research results showed there are much less variety and smaller quantities in mineral compositions. Calculated mineral composition by means of chemical composition analysis combined with XRD, MLA, IR and TG-DSC analyses showed that main minerals with were Potassium-feldspar, muscovite, biotite and illite, and gangue minerals were quartz and small amounts of hematite. Potassium-rich minerals such as potassium-feldspar and muscovite contact smoothly with quartz respectively, and there was the direction arrangement among potassium-feldspar, quartz and muscovite in the shale. And quartz and hematite were main cement in the shale. The influences of the research results on the potassium extraction from potassium-rich shale were distinct.

scholarly journals Novel Analytical Method for Mix Design and Performance Prediction of High Calcium Fly Ash Geopolymer Concrete

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 900
Author(s):  
Chamila Gunasekara ◽  
Peter Atzarakis ◽  
Weena Lokuge ◽  
David W. Law ◽  
Sujeeva Setunge
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Gradient Algorithm ◽  
Geopolymer Concrete ◽  
Statistical Regression ◽  
Solid Ratio ◽  
Marquardt Algorithm ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Matlab Programming

Despite extensive in-depth research into high calcium fly ash geopolymer concretes and a number of proposed methods to calculate the mix proportions, no universally applicable method to determine the mix proportions has been developed. This paper uses an artificial neural network (ANN) machine learning toolbox in a MATLAB programming environment together with a Bayesian regularization algorithm, the Levenberg-Marquardt algorithm and a scaled conjugate gradient algorithm to attain a specified target compressive strength at 28 days. The relationship between the four key parameters, namely water/solid ratio, alkaline activator/binder ratio, Na2SiO3/NaOH ratio and NaOH molarity, and the compressive strength of geopolymer concrete is determined. The geopolymer concrete mix proportions based on the ANN algorithm model and contour plots developed were experimentally validated. Thus, the proposed method can be used to determine mix designs for high calcium fly ash geopolymer concrete in the range 25–45 MPa at 28 days. In addition, the design equations developed using the statistical regression model provide an insight to predict tensile strength and elastic modulus for a given compressive strength.

Influence of High-Calcium Ash Composition on the Composite Binders’ Properties

2021 ◽  
Vol 316 ◽  
pp. 1019-1024
Author(s):  
O. A. Ignatova ◽  
A. A. Dyatchina
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Cement Stone ◽  
Normal Density ◽  
Fine Aggregate ◽  
Equivalent Amount ◽  
High Calcium ◽  
Composition Structure ◽  
Kinetics Of ◽  
Positive Effect

The paper presents the studies’ results of chemical composition, structure, and physico-mechanical properties of high-calcium ashes from the Kansk-Achinsk coals (2017-2019 selection). It was found that ash has a complex poly-mineral composition and contains hydraulically active minerals and oxides of СаОfr, β-C2S, CA, C3A, C4AF, C2F, CaSO4. According to the content of CaOfr, MgO does not meet standards’ requirements. The uniformity of the volume change is maintained by the composition with 50% of cement. The structure and hardening kinetics of ash and ash-cement stone compositions, obtained from the test of normal density, were analyzed. It was established that the hardening of compositions with ash from the Kansk-Achinsk coals was largely influenced by ash minerals. An equivalent amount of cement in composite binders cannot be replaced. In order to obtain a positive effect, compositions with ash instead cement of no more than 30% and a part of fine aggregate, without exceeding the ratio of ash: cement = 1: 1, should be used.

scholarly journals Synthesis of Geopolymer from Inorganic Construction Waste

2013 ◽  
Vol 30 ◽  
pp. 45-51 ◽  
Author(s):  
Arbind Pathak ◽  
Vinay Kumar Jha
Keyword(s):  
Compressive Strength ◽  
Coal Fly Ash ◽  
Chemical Society ◽  
Raw Material ◽  
Curing Temperature ◽  
Alkali Concentration ◽  
Curing Time ◽  
Mass Ratio ◽  
Construction Waste ◽  
Alumino Silicate

Recently, the demolition of old houses and the construction of new buildings in Kathmandu valley are in the peak which in turn generates a huge amount of construction waste. There are two major types of construction wastes which are burden for disposal namely cement-sand-waste (CSW) and the coal fly ash (CFA). These construction wastes are rich source of alumino-silicate and thus used as raw material for the synthesis of geopolymer in this study. Geopolymers have been synthesized from CSW and CFA using NaOH-KOH and Na2SiO3 as activators. Some parameters like alkali concentration, amount of Na2SiO3 and curing time have been varied in order to improve the quality of geopolymeric product. The geopolymerization process has been carried out using 3-8M KOH/NaOH solutions, Na2SiO3 to CFA and CSW mass ratio of 0.25-2.00 and curing time variation from 5-28 days. The curing temperature was fixed at 40ºC in all the cases. 6M NaOH and 7M KOH solutions were found appropriate alkali concentrations while the ratio of sodium silicate to CSW and CFA of 0.5 and 1.75 respectively were found suitable mass ratio for the process of geopolymer synthesis. The maximum compressive strength of only 7.3 MPa after 15 days curing time with CSW raw material was achieved while with CFA, the compressive strength was found to be 41.9 MPa with increasing the curing time up to 28 days.DOI: http://dx.doi.org/10.3126/jncs.v30i0.9334Journal of Nepal Chemical Society Vol. 30, 2012 Page:  45-51 Uploaded date: 12/16/2013    

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