Investigation on a New Hydraulic Cementitious Binder Made from Phosphogypsum

2013 ◽  
Vol 864-867 ◽  
pp. 1923-1928
Author(s):  
Yue Xu ◽  
Jian Xi Li ◽  
Li Li Kan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Active Carbon ◽  
High Strength ◽  
Tricalcium Silicate ◽  
Dicalcium Silicate ◽  
Cementitious Material ◽  
Saturation Ratio ◽  
Tricalcium Aluminate ◽  
Cementitious Binder

A new kind of high strength cementitious material is made from phosphogypsum (PG), active carbon and fly-ash. Through the orthogonal research, it was showed that the calcination temperature, retention time, dosage of active carbon and fly ash on the compressive strength of cementitious binder are the most important. The result also showed that, in the conditions of temperature 1200°C, time retention 30 min, dosage of active carbon 10%, dosage of fly ash 5%, the compressive strength of the cementitious material for 3d and 28d could reach to 46.35MPa and 92.70MPa, the content of sulfur trioxide was 11.60% accordingly. A lot of active mineral materials, such as dicalcium silicate, tricalcium silicate, tricalcium aluminate were formed in the calcination. The C-S-H gel, calcium hydroxide and ettringite were found in 3d and 28d hydrates. It is found that the lime saturation ratio and silica modulus need to be control between 0.40~0.65 and 4~8 in order to produce high strength cementitious material.

scholarly journals Coupled Preparation of Ferronickel and Cementitious Material from Laterite Nickel Ores

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4992
Author(s):  
Ruimeng Shi ◽  
Xiaoming Li ◽  
Yaru Cui ◽  
Junxue Zhao ◽  
Chong Zou ◽  
...  
Keyword(s):  
Direct Reduction ◽  
Cementitious Materials ◽  
Tricalcium Silicate ◽  
Cementitious Material ◽  
Raw Material ◽  
Tricalcium Aluminate ◽  
Thermodynamic Conditions ◽  
Nickel Ores ◽  
Main Components ◽  
Factsage Software

Nickel slags can be produced through ferronickel preparation by the pyrometallurgical processing of laterite nickel ores; however, such techniques are underutilized at present, and serious environmental problems arise from the stockpiling of such nickel ores. In this study, a modification to the process of ferronickel preparation by the direct reduction of carbon bases in laterite nickel ores is proposed. The gangue from the ore is used as a raw material to prepare a cementitious material, with the main components of tricalcium silicate and tricalcium aluminate. By using FactSage software, thermodynamic calculations are performed to analyze the reduction of nickel and iron and the effect of reduction on the formation of tricalcium silicate and tricalcium aluminate. The feasibility of a coupled process to prepare ferronickel and cementitious materials by the direct reduction of laterite nickel ore and gangue calcination, respectively, is discussed under varying thermodynamic conditions. Different warming strategies are applied to experimentally verify the coupled reactions. The coupled preparation of ferronickel and cementitious materials with calcium silicate and calcium aluminate as the main phases in the same experimental process is realized.

Effect of Chopped Basalt Fiber on the Fresh and Hardened Properties of Fly Ash High Strength Concrete

2014 ◽  
Vol 567 ◽  
pp. 381-386 ◽  
Author(s):  
Nasir Shafiq ◽  
Muhd Fadhil Nuruddin ◽  
Ali Elheber Ahmed Elshekh ◽  
Ahmed Fathi Mohamed Salih
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Strength Concrete ◽  
Basalt Fiber ◽  
High Strength ◽  
Progressive Increase ◽  
Test Results ◽  
Strength Concrete ◽  
Hardened Properties ◽  
Chopped Basalt Fiber

In order to improve the mechanical properties of high strength concrete, HSC, several studies have been conducted using fly ash, FA. Researchers have made it possible to achieve 100-150MPa high strength concrete. Despite the popularity of this FAHSC, there is a major shortcoming in that it becomes more brittle, resulting in less than 0.1% tensile strain. The main objective of this work was to evaluate the fresh and hardened properties of FAHSC utilizing chopped basalt fiber stands, CBFS, as an internal strengthening addition material. This was achieved through a series of experimental works using a 20% replacement of cement by FA together with various contents of CBFS. Test results of concrete mixes in the fresh state showed no segregation, homogeneousness during the mixing period and workability ranging from 60 to 110 mm. Early and long terms of compressive strength did not show any improvement by using CBFS; in fact, it decreased. This was partially substituted by the effect of FA. Whereas, the split and flexural strengths of FASHC were significantly improved with increasing the content of CBFS as well as the percentage of the split and flexural tensile strength to the compressive strength. Also, test results showed a progressive increase in the areas under the stress-strain curves of the FAHSC strains after the CBFS addition. Therefore, the brittleness and toughness of the FAHSC were enhanced and the pattern of failure moved from brittle failure to ductile collapse using CBFS. It can be considered that the CBFS is a suitable strengthening material to produce ductile FAHSC.

scholarly journals Kajian Karakteristik Beton Memadat Sendiri yang Menggunakan Serat Ijuk (Hal. 54-65)

2018 ◽  
Vol 4 (4) ◽  
pp. 54
Author(s):  
Iis Nurjamilah ◽  
Abinhot Sihotang
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Coarse Aggregate ◽  
Fresh Concrete ◽  
High Strength ◽  
Self Compacting Concrete ◽  
Palm Fiber ◽  
Fiber Concrete ◽  
Dilute Mixture

ABSTRAKKajian karakteristik beton memadat sendiri yang menggunakan serat ijuk merupakan sebuah kajian yang dilakukan untuk mengetahui pengaruh penambahan serat ijuk terhadap karakteristik beton memadat sendiri (SCC). Beton memadat sendiri yang menggunakan serat ijuk (PFSCC) didesain memiliki campuran yang encer, bermutu tinggi (= 40 MPa) dan memiliki persentase kekuatan lentur yang lebih baik. PFSCC  didapatkan dari hasil pencampuran antara semen sebanyak 85%, fly ash 15%, superplastizicer 1,5%, serat ijuk 0%, 0,5%; 1%; 1,5%; 2% dan 3% dari berat binder (semen + fly ash), kadar air 190 kg/m3, agregat kasar 552,47 kg/m3 dan pasir 1.063 kg/m3. Semakin banyak persentase penambahan serat ijuk ke dalam campuran berdampak terhadap menurunnya workability beton segar. Penambahan serat ijuk yang paling baik adalah sebanyak 1%, penambahan tersebut dapat meningkatkan kekuatan tekan beton sebesar 13% dan lentur sebesar 1,8%.Kata kunci: beton memadat sendiri (SCC), beton berserat, beton memadat sendiri yang menggunakan serat ijuk (PFSCC), serat ijuk ABSTRACTThe study of characteristics self compacting concrete using palm fibers is a study conducted to determine the effect of adding palm fibers to characteristics of self compacting concrete (SCC). palm fibers self compacting concrete (PFSCC) is designed to have a dilute mixture, high strength (= 40 MPa), and have better precentage flexural strength. PFSCC was obtained from mixing of 85% cement, 15% fly ash, 1.5% superplastizicer, 0%, 0.5%, 1%, 1.5%, 2% and 3% palm fibers from the weight of binder  (cement + fly ash), water content 190 kg/m3, coarse aggregate 552.47 kg/m3 and sand 1,063 kg/m3. The more persentage palm fibers content added to the mixture makes workability of fresh concrete decreases. The best addition of palm fiber is 1%, this addition can increases the compressive strength 13% and flexural strength 1.8%.Keywords: self compacting concrete (SCC), fiber concrete, Palm fiber self compacting concrete (PFSCC), palm fiber

scholarly journals X-ray diffraction analysis of MTA-Plus, MTA-Angelus and DiaRoot BioAggregate

2014 ◽  
Vol 08 (02) ◽  
pp. 211-215 ◽  
Author(s):  
Yeliz Guven ◽  
Elif Bahar Tuna ◽  
Muzaffer Emin Dincol ◽  
Oya Aktoren
Keyword(s):  
Crystal Structure ◽  
Tantalum Oxide ◽  
Xrd Analysis ◽  
Tricalcium Silicate ◽  
Dicalcium Silicate ◽  
Glass Slide ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray ◽  
Tricalcium Aluminate

ABSTRACT Objective: The purpose of this study was to investigate and compare the crystalline structures of recently released MTA Plus (MTA-P), MTA Angelus (MTA-A), DiaRoot BioAggregate (BA) by X-ray diffraction (XRD) analysis. Materials and Methods: Phase analysis was carried out on powder and set forms of tested materials. The powder specimens placed into sample holders that were packed with a glass slide and the set samples prepared according to the manufacturer's instructions were placed into molds. The samples after being set for three days at 37°C and 100% humidity in an incubator were mounted onto the XRD machine and phase identification was accomplished using a search-match software program. Results: XRD findings indicated that major constituents of MTA-P were bismuth oxide, portlandite, dicalcium silicate and tricalcium silicate. The crystal structure of MTA-A were similar to those of MTA-P except for the absence of portlandite. Additionally, MTA-A had tricalcium aluminate differing from MTA-P. BA mainly differed from MTA-P and MTA-A by the radiopacifier (tantalum oxide-TO) in its composition. Conclusions: The majority of constituents of the tested materials have shown similarity except for the presence of tricalcium aluminate in MTA-A and the inclusion of TO in BA. In addition, set MTA-P showed a strong peak of portlandite.

Study of Modification of High Temperature Melting Compound Steel Slag-Fly Ash

2011 ◽  
Vol 291-294 ◽  
pp. 1851-1855
Author(s):  
Yue Long ◽  
Yan Shi ◽  
Yun Bo Lei ◽  
Hong Wei Xing ◽  
Jie Li ◽  
...  
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
Steel Slag ◽  
Tricalcium Silicate ◽  
Dicalcium Silicate ◽  
Experimental Result ◽  
Aggregation State ◽  
Melting Compound ◽  
Cementitious Activity ◽  
Temperature Melting

Reconstruction of high temperature melting compound steel slag-fly ash can be effectively digest f-CaO in steel slag. The experimental result shows that the f-CaO contents in modified slag is greatly affected by fly ash addition(respectively 5%, 7%, 14%) when the temperature is 1580°C and constant temperature is 30min, the digestion rates are respectively 56.99%,63.69%,68.55%. Modified mineral content of the steel slag changes greatly, mainly reflects at enormous increase in magnetite, dicalcium silicate, tricalcium silicate, wustite and vitreous. By micro-structure analysis of several kinds of modified slag mineral, tricalcium silicate mainly shape for branch of tree, dicalcium silicate is in the form of a circular, wustite and vitreous mainly distribute in aggregation state. The above minerals can increase cementitious activity for modified slag becoming cement.

scholarly journals Strength Characteristics of High Strength Concrete (HSC) with and without Coarse Aggregate

2019 ◽  
Vol 9 (2) ◽  
pp. 4701-4704
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Silica Fume ◽  
High Strength Concrete ◽  
Mechanical Characteristics ◽  
Coarse Aggregate ◽  
High Strength ◽  
Set Up

This paper aimed to investigate the mechanical characteristics of HSC of M60 concrete adding 25% of fly ash to cement and sand and percentage variations of silica fumes 0%,5% and 10% to cement with varying sizes of 10mm,6mm,2mm and powder of granite aggregate with w/c of 0.32. Specimens are tested for compressive strength using 10cm X 10cmX10cm cubes for 7,14,28 days flexural strength was determined by using 10cmX10cmX50cm beam specimens at 28 days and 15cm diameter and 30cm height cylinder specimens at 28 days using super plasticizers of conplast 430 as a water reducing agent. In this paper the experimental set up is made to study the mechanical properties of HSC with and without coarse aggregate with varying sizes as 10mm, 6mm, 2mm and powder. Similarly, the effect of silica fume on HSC by varying its percentages as 0%, 5% and 10% in the mix studied. For all mixes 25% extra fly ash has been added for cement and sand.

Preparation and Properties of Lightweight, High-Strength Insulation Materials Using Fly Ash Floating Beads

2016 ◽  
Vol 697 ◽  
pp. 599-603
Author(s):  
Ya Peng Dai ◽  
Xing Yong Gu ◽  
Wei Xia Dong ◽  
Ting Luo
Keyword(s):  
Compressive Strength ◽  
Heat Conduction ◽  
Fly Ash ◽  
High Strength ◽  
Volume Density ◽  
Particle Sizes ◽  
Heat Conduction Coefficient ◽  
Insulation Materials ◽  
Test Instrument ◽  
Save Energy

In our paper, to save energy conservation and environmental protection, and in view of waste fly ash floating bead with excellent properties such as light and refractory, lightweight insulation materials was prepared using fly ash floating beads as the main materials. Firstly, two different fly ash floating bead contents on the properties of the light and refractory material were investigated. Then, on the basis of the optimum fly ash floating bead content, effects of various different particle sizes and firing temperature on the bulk density, compressive strength and the heat conduction coefficients of the samples were studied. The microstructure of the light-weight refractory materials was characterized by XRD and SEM. The heat conduction coefficient (λ') of the samples were also measured by the self-made test instrument. The experimental results showed that the properties of the as-prepared sample using 80% fly ash floating beads was superior to that of 95 % fly ash floating beads. The optimal volume density of 0.60-1.04 g/cm3, compressive strength of 10.6-39.5 MPa and the heat conduction coefficient of 0.183-0.25 °C·g/ min·cm2 were achieved in the presence of 80% fly ash floating beads with 120-160 particle size at 1200°C-1300°C, which has the potential application in lightweight insulation materials.

T.e.m. studies of cement clinker compounds, their hydration and strong cement pastes

1983 ◽  
Vol 310 (1511) ◽  
pp. 79-83 ◽  
Keyword(s):  
Calcium Chloride ◽  
Ion Beam ◽  
High Strength ◽  
Calcium Sulphate ◽  
Tricalcium Silicate ◽  
Cement Clinker ◽  
Cement Pastes ◽  
Tricalcium Aluminate ◽  
Transmission Electron ◽  
Alkaline Calcium

Ion-beam thinned specimens of cement-forming compounds and cement pastes have been examined by transmission electron microscopy (t.e.m.). The triclinic lattice of pure tricalcium silicate has been confirmed and twins corresponding to domains of the superlattice have been observed. Thinned specimens of tricalcium aluminate show a copious amorphous reaction product at the surface after dipping into alkaline calcium sulphate solution, confirming the mechanism of retardation by blocking access to the surface. Observations of tricalcium silicate after it has been dipped into solution in contact with hydrating tricalcium silicate both with and without calcium chloride suggest that calcium chloride additive may accelerate hydration by improving access to the surface. Cement pastes of high strength (‘ macro-defect-free ’ pastes) show a similar fine-scale microstructure to cement pastes of low water content made by conventional techniques.

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