Mechanical performance and micro-structure of bentonite-fly ash and bentonite-sand mixes for landfill liner application

In order to solve the environment pollution of limestone powder during production of limestone manufactured sand and gravel and problem of lack of high quality fly ash or slag powder in ocean engineering, ultra-fine limestone powder was selected for preparation of green high-performance marine concrete containing fly ash and limestone powder and that containing slag powder and limestone powder for tests on workability, mechanical performance, thermal performance, shrinkage, and resistance to cracking and chloride ion permeability. And comparison was made between such green high-performance concrete and conventional marine concrete containing fly ash and slag powder. Moreover, the mechanism of green high-performance marine concrete was preliminary studied. Results showed that ultra-fine limestone powder with average particle size around 10μm had significant water reducing function and could improve early strength of concrete. C50 high-performance marine concrete prepared with 30% fly ash and 20% limestone powder or with 30% slag powder and 30% limestone powder required water less than 130kg/m3, and showed excellent workability with 28d compressive strength above 60MPa, 56d dry shrinkage rate below 300με, cracking resistance of grade V, 56d chloride ion diffusion coefficient not exceeding 2.5×10-12m2/s. Mechanical performance and resistance to chloride ion permeability of limestone powder marine concrete were quite equivalent to those of conventional marine concrete. But it had better workability, volume stability and cracking resistance. Moreover, it can serve as a solution to the lack of high quality fly ash and slag powder.

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Mix design and mechanical performance of geopolymeric binders and mortars using biomass fly ash and alkaline effluent from paper-pulp industry

Journal of Cleaner Production ◽

10.1016/j.jclepro.2018.10.213 ◽

2019 ◽

Vol 208 ◽

pp. 1188-1197 ◽

Cited By ~ 18

Author(s):

Manfredi Saeli ◽

David M. Tobaldi ◽

Maria Paula Seabra ◽

João A. Labrincha

Keyword(s):

Fly Ash ◽

Mechanical Performance ◽

Mix Design ◽

Paper Pulp ◽

Pulp Industry ◽

Biomass Fly Ash

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Mechanical Performance of Glass-Based Geopolymer Matrix Composites Reinforced with Cellulose Fibers

Materials ◽

10.3390/ma11122395 ◽

2018 ◽

Vol 11 (12) ◽

pp. 2395 ◽

Cited By ~ 3

Author(s):

Gianmarco Taveri ◽

Enrico Bernardo ◽

Ivo Dlouhy

Keyword(s):

Fly Ash ◽

Mechanical Performance ◽

Fiber Surface ◽

Cellulose Fiber ◽

Maximum Effect ◽

Matrix Composites ◽

Curing Conditions ◽

Chevron Notch ◽

Geopolymer Matrix ◽

Mechanical Performances

Glass-based geopolymers, incorporating fly ash and borosilicate glass, were processed in conditions of high alkalinity (NaOH 10–13 M). Different formulations (fly ash and borosilicate in mixtures of 70–30 wt% and 30–70 wt%, respectively) and physical conditions (soaking time and relative humidity) were adopted. Flexural strength and fracture toughness were assessed for samples processed in optimized conditions by three-point bending and chevron notch testing, respectively. SEM was used to evaluate the fracture micromechanisms. Results showed that the geopolymerization efficiency is strongly influenced by the SiO2/Al2O3 ratio and the curing conditions, especially the air humidity. The mechanical performances of the geopolymer samples were compared with those of cellulose fiber–geopolymer matrix composites with different fiber contents (1 wt%, 2 wt%, and 3 wt%). The composites exhibited higher strength and fracture resilience, with the maximum effect observed for the fiber content of 2 wt%. A chemical modification of the cellulose fiber surface was also observed.

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Thermal and mechanical behavior of composite mortars containing natural sorptive clays and fly ash

Science of Sintering ◽

10.2298/sos1901039t ◽

2019 ◽

Vol 51 (1) ◽

pp. 39-56 ◽

Cited By ~ 2

Author(s):

Anja Terzic ◽

Lato Pezo ◽

Ljiljana Milicic ◽

Nevenka Mijatovic ◽

Zagorka Radojevic ◽

...

Keyword(s):

Fly Ash ◽

Mechanical Behavior ◽

Mechanical Performance ◽

Thermal Characteristics ◽

Principal Component ◽

Effective Dosage ◽

Factor Space ◽

Ann Model ◽

River Sand ◽

Mineral Additives

Mineral additives are extensively applied as cement replacement materials in both construction concrete and mortar. Fly ash is one of the most commonly utilized additives which improve rheological properties, as well as thermal and mechanical behavior of mortar, and as such it has been widely investigated. This industrial byproduct comprises heavy metals in its composition; therefore further research is needed to optimize its effective dosage. Moreover, certain sorptive clays, such as natural zeolite and bentonite, can prevent migration of toxic elements from fly ash by immobilizing them in their structure. Ten experimental mortars are prepared with Portland cement, river sand and addition of fly ash, zeolite and/or bentonite in accordance with chemometric experimental design rules. The aim of the study was to investigate the effect of mineral additives on thermal and mechanical performances of mortar. Thermal characteristics were monitored via dilatometric analysis and DTA method. Principal component analysis was used on the results of physico-mechanical testing (workability, bulk density, water absorption, shrinkage, compressive and flexural strength) to enable the divisions of the observed samples into groups in the factor space. The performance of Artificial Neural Network was compared with the experimental data in order to develop rapid and accurate method for prediction of mechanical parameters of mortar. The ANN model showed high overall prediction accuracy (r2 = 0.989, during training cycle). The test results indicate that incorporation of the mineral additives gave cost effective mortars with sufficiently good properties. However, tools of analytical modeling highlighted mortar with zeolite and fly ash as the optimal composition regarding its mechanical performance.

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Research on Mechanical Performance & Behaviour of Geopolymer Concrete Subjected to Elevated Temperatures

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.b1001.0882s819 ◽

2019 ◽

Vol 8 (2S8) ◽

pp. 883-887

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Silica Fume ◽

Elevated Temperatures ◽

Mechanical Performance ◽

Geopolymer Concrete ◽

Sem Images ◽

Before And After ◽

Alkaline Conditions ◽

Compressive Strength Of Concrete

The investigative studies on mechanical performance & behaviour, of Geopolymer Concrete (GPC) before and after the exposure to elevated temperatures (of 200 0 C -1000 0 C with an increment of 100 0 C). Indicate that the GPC Specimens Exhibited better Compressive strength at higher temperatures than that of those made by regular OPC Concrete with M30 Grade. The chronological changes in the geopolymeric structure upon exposure to these temperatures and their reflections on the thermal behaviour have also been explored. The SEM images indicate GPC produced by fly ash , metakaolin and silica fume, under alkaline conditions form Mineral binders that are not only non-flammable and but are also non-combustible resins and binders. Further the Observations drawn disclose that the mass and compressive strength of concrete gets reduced with increase in temperatures.

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Influence of Partial Replacement of Micro-Silica by Fly-Ash on Strength Properties of Reactive Powder Concrete

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.c5453.029320 ◽

2020 ◽

Vol 9 (3) ◽

pp. 2932-2937

Keyword(s):

Tensile Strength ◽

Compressive Strength ◽

Fly Ash ◽

Mechanical Performance ◽

Cementitious Materials ◽

Partial Replacement ◽

Reactive Powder Concrete ◽

Experimental Investigations ◽

Reactive Powder ◽

Micro Silica

Reactive powder concrete (RPC) is the ultra-high strength concrete made by cementitious materials like silica fumes, cement etc. The coarse aggregates are completely replaced by quartz sand. Steel fibers which are optional are added to enhance the ductility. Market survey has shown that micro-silica is not so easily available and relatively costly. Therefore an attempt is made to experimentally investigate the reduction of micro-silica content by replacing it with fly-ash and mechanical properties of modified RPC are investigated. Experimental investigations show that compressive strength decreases gradually with addition of the fly ash. With 10 per cent replacement of micro silica, the flexural and tensile strength showed 40 and 46 per cent increase in the respective strength, though the decrease in the compressive strength was observed to be about 20 per cent. For further percentage of replacement, there was substantial drop in compressive, flexural as well as tensile strength. The experimental results thereby indicates that utilisation of fly-ash as a partial replacement to micro silica up to 10 per cent in RPC is feasible and shows quite acceptable mechanical performance with the advantage of utilisation of fly-ash in replacement of micro-silica.

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Effects of a Real Exposure Class XC4 Mediterranean Climate Environment in the Behavior of Mortars Made Using Ternary Binders with Addition of Slag, Fly Ash and Limestone

Materials ◽

10.3390/ma14195848 ◽

2021 ◽

Vol 14 (19) ◽

pp. 5848

Author(s):

Javier Ibáñez-Gosálvez ◽

Teresa Real-Herraiz ◽

José Marcos Ortega

Keyword(s):

Fly Ash ◽

Mediterranean Climate ◽

Mechanical Performance ◽

Ultrasonic Pulse Velocity ◽

Pore Network ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Cement Industry ◽

Granulated Blast Furnace Slag ◽

Compressive And Flexural Strengths

For improving the contribution of the cement industry to mitigate global warming, many strategies have been put into practice, such as the use of eco-friendly cements with the incorporation of additions substituting clinker. Nevertheless, the use of ternary binders for the production of commercial cements is still reduced, particularly in Spain. The purpose of this research is to characterize the long-term influence produced by the exposure to a real in situ inland Mediterranean climate condition in the pore network, parameters related to durability and mechanical performance of mortars made with ternary binders, which incorporated limestone, fly ash, and ground granulated blast-furnace slag, in comparison with mortars without additions and binary blended mortars. The site verified the specifications of exposure class XC4 of Eurocode 2. The ternary and binary binders accomplished the prescriptions of cement type CEM II/B. The pore network was studied with mercury intrusion porosimetry and electrical resistivity. Water absorption, diffusion coefficient, carbonation depth, ultrasonic pulse velocity, compressive and flexural strengths have been determined. The exposure to the environment produced after 250 days an increase in porosity, a loss of pore refinement, a rise of the carbonation depths, and a reduction in the mechanical strengths, highlighting the better overall performance of ternary mortar with both fly ash and slag.

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