scholarly journals Tests Research on Grouting Materials of Waste-Concrete-Powder Cement for Goaf Ground Improvement

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhilin Dun ◽  
Mengqi Wang ◽  
Lianwei Ren ◽  
Zhiyuan Dun
Keyword(s):  
Ground Improvement ◽  
Setting Time ◽  
X Ray Diffraction ◽  
Microscopic Mechanism ◽  
Water Separation ◽  
Separation Ratio ◽  
Waste Concrete ◽  
Performance Indexes ◽  
Mixing Proportion ◽  
Grouting Materials

Waste concrete powder (WCP) is proposed to replace part of the cement to seek environmentally friendly grouting materials for ground improvement in mine goaf. The optimal mixing proportion was selected based on the performance indexes of the water-separation ratio, stone rate, viscosity, setting time, and compressive strength. X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests were also conducted to analyze mineralogical phases and investigate the microscopic mechanism. Test results show that the slurry prepared by the substitution rate of 70% and adding 0.05% water-reducing agent meets well the requirements of ground grouting in mine goaf. The WCP produced by grinding mainly exerts microaggregate effect in the slurry due to low activity. A lot of pores on the surface of WCP were shown by SEM which can absorb the water in the slurry and increase the stone rate. The WCP application for ground grouting in mine goaf can not only recycle WC but also provide new grouting materials for goaf ground.

scholarly journals Effects of Aluminum Sulfate and Quicklime/Fluorgypsum Ratio on the Properties of Calcium Sulfoaluminate (CSA) Cement-Based Double Liquid Grouting Materials

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1222 ◽  
Author(s):  
Yuli Wang ◽  
Jie Yu ◽  
Junjie Wang ◽  
Xuemao Guan
Keyword(s):  
Compressive Strength ◽  
Aluminum Sulfate ◽  
Setting Time ◽  
Strength Properties ◽  
X Ray Diffraction ◽  
Cement Slurry ◽  
Calcium Sulfoaluminate ◽  
Optimum Content ◽  
Grouting Material ◽  
Grouting Materials

Grouting materials are used frequently in grouting reinforcement projects, such as mining and coastal engineering. Double liquid grouting materials are mostly used because of the fast setting and high early strength properties when the two slurries are mixed together but high fluidity when the two slurries are separated. In our study, double liquid grouting materials were developed from CSA cement (slurry A), quicklime and fluorgypsum (slurry B). Aluminum sulfate was added in slurry B in order to counteract any adverse effects caused by the fluorgypsum, such as the decreased early compressive strength and the prolonged setting time. The effects of aluminum sulfate content and the quicklime/fluorgypsum ratio on the setting time, hydration heat, and compressive strength of the double liquid grouting materials were investigated, and the hydration products were characterized through thermogravimetry-differential thermal analysis (TG-DTA), X-ray Diffraction (XRD), and Scanning Electron Microscope (SEM) tests. The results show that the addition of aluminum sulfate can shorten the setting time and increase compressive strength at both early and later ages. Considering the setting time and compressive strength of double liquid grouting material at the same time, the optimum content of aluminum sulfate was found to be 2%, and the optimum ratio of quicklime/fluorgypsum was found to be 2:8. The values of the optimum content of aluminum sulfate and ratio of quicklime/fluorgypsum were verified from theoretical analysis.

Properties of Recycled-Cement Produced from Waste Concrete

2011 ◽  
Vol 194-196 ◽  
pp. 1170-1175 ◽  
Author(s):  
Hong Mei Ai ◽  
Jing Wei ◽  
Jun ying Bai ◽  
Pu Guang Lu
Keyword(s):  
Compressive Strength ◽  
Raw Materials ◽  
Setting Time ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Cement Clinker ◽  
X Ray Diffraction ◽  
Waste Concrete ◽  
High Temperature Furnace ◽  
Mineral Components

This research aims to find a new way of “turning trash into treasure” for the waste concrete. In the research, waste concrete was first ground, then, after analyzing its mineral composition, combined with some other ingredients according to the modulus of the cement clinker to become raw materials of cement. Mixed raw materials were made to be a thin cake, and then sent into high temperature furnace (HTF) to sinter for a certain period of time. Properties of cement, such as the compressive strength, required water of standard consistence and setting time were tested. The composition and microstructure of clinker were analyzed with X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) analysis. The experimental results showed that the main mineral components of clinker are C3S, β-C2S, CA2, CA, C3A, C4AF, the compressive strength of the recycled-cement is approximately equal to P.O32.5, there exists an optimum sintering temperature for the recycled-cement clinker with a given mix ratio of raw materials and content of seed crystal added,, and this temperature is usually much lower than the temperature adopted wildly in the cement plants.

Effect of Heat Setting Methods on Structures and Properties of High Strength Polyvinyl Alcohol Fibre

2015 ◽  
Vol 815 ◽  
pp. 643-648
Author(s):  
Yin Zhu ◽  
Jiong Xin Zhao
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Polyvinyl Alcohol ◽  
Setting Time ◽  
High Strength ◽  
Single Fibre ◽  
X Ray Diffraction ◽  
Heat Setting ◽  
Heat Treated ◽  
Setting Process

The effect of heat setting methods on the structures and mechanical properties of high strength polyvinyl alcohol (PVA) fibre is studied in this article. The microstructure and mechanical properties of heat treated PVA fibre is investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and single fibre electronic tensile strength tester. Results show that the heat setting method with constant tension is a good heat setting method which can largely enhance the tensile strength of PVA fibre. During the heat setting process, the mechanical properties of PVA fibre are greatly affected by the temperature, tension and setting time. When the temperature is 220°C, tension is 5cN/dtex and setting time is 90sec, the tensile strength of PVA fibre increases from 12.0cN/dtex to 16.4cN/dtex in compare with the PVA fibre without heat setting

Thermal and mechanical characterization of a new material based on two gypsums from different localities : High Atlas of Marrakech and Safi Basin, Morocco

2021 ◽  
Author(s):  
imane baba ◽  
Mounsif Ibnoussina ◽  
Omar Witam ◽  
Latifa Saadi
Keyword(s):  
Setting Time ◽  
Density Measurement ◽  
Mechanical Resistance ◽  
Mechanical And Thermal Properties ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
High Atlas ◽  
New Material ◽  
Indoor Comfort

<p>Over the last few decades, the construction industry has become interested in materials that are durable, environmentally friendly and easily recyclable. This interest is due to the advantages these materials offer, among others local availability, low carbon footprint, energy efficiency and indoor comfort. The objective of this work is to study the properties of plasters prepared from a mixture of two types of gypsum. We were interested in the evolution of thermal conductivity, mechanical resistance and setting time as a function of the percentage of addition.</p><p>Two types of gypsum were studied, the first one belongs to the Safi basin and the second one comes from the High Atlas of Marrakech.</p><p>The characterization of the gypsums was necessary to determine its physical and geotechnical properties, its mineralogy, its thermal behavior and its microscopic structure. Several analyses were developed such as density measurement by pycnometer, X-ray diffraction, infrared spectroscopy and scanning electron microscopy.</p><p>We have made samples, of standardized dimensions, of mixtures based on both types of plaster. The water/gypsum mass ratio was set at 0.75.</p><p>The results revealed that the properties of gypsum as well as the percentage of addition affect the mechanical and thermal properties and the setting time of the composite material. The addition of the High Atlas gypsum of Marrakech allowed improving the material in terms of thermal insulation. The results of the other tests will be communicated later.</p>

scholarly journals Properties and Reaction Mechanisms of Magnesium Phosphate Cement Mixed with Ferroaluminate Cement

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2561 ◽  
Author(s):  
Liang Jia ◽  
Fangli Zhao ◽  
Jian Guo ◽  
Kai Yao
Keyword(s):  
Water Resistance ◽  
Energy Dispersive Spectrometer ◽  
Setting Time ◽  
Cementitious Materials ◽  
Magnesium Phosphate ◽  
Curing Time ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Composite Cement ◽  
Hydrated Product

A certain amount of ferroaluminate cement (FAC) was substituted for MgO during the magnesium phosphate cement (MPC) preparation to obtain the MPC–FAC composite cement. The influence of FAC on the strength, water resistance, pH, and setting time of MPC–FAC composite cement were examined. The microstructure and chemical composition were also analyzed by adopting scanning electron microscopic energy-dispersive spectrometer and X-ray diffraction, respectively. The study showed that setting time of MPC–FAC composite cement was dramatically prolonged when FAC substitution for MgO was between 30 and 40 wt %. The strength of MPC–FAC did not decrease during the early curing time (1 h and 1 d), whereas it increased during the late curing time (3, 7, and 28 days). Moreover, the existence of FAC decreased the hydrated product K-struvite during the early curing time and thus dramatically enhanced the water-resistance of MPC–FAC. With the addition of FAC, a large number of cementitious materials of AFt and AFm, as well as flocculent colloidal substances of AH3, C–S–H, and FH3, were generated during the hydration of MPC, which were filled in the internal pore of the hydrate. Thus, the internal compactness of the sample increased, while the compact protective covering layer was generated on the surface to enhance the water resistance and strength in the late curing time.

scholarly journals Solidification and Leachability of Cr (VI) in Rice Husk Ash-Blended Cement

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Neeraj Jain
Keyword(s):  
Rice Husk ◽  
Rice Husk Ash ◽  
Setting Time ◽  
Blended Cement ◽  
X Ray Diffraction ◽  
Retention Capacity ◽  
Allowable Limit ◽  
X Ray ◽  
Curing Period ◽  
Leaching Procedure

Investigations carried out to study the effect of Cr (VI) (1000–3000 mg/l) on solidification and hydration behavior of Ordinary Portland cement (OPC) and rice husk ash (RHA) blended (10%, 20%, and 30%) cement show that addition of RHA accelerates final setting as compared to control samples (OPC) and retardation in setting time has been observed on increase in rice husk ash concentration (10%–30%). Solidification studies show that the compressive strength of controls and rice husk ash blended samples increases with increase in the curing period and maximum strength was observed with 20% RHA blended samples. With the increase in Cr (VI) concentrations, the strength of OPC and RHA blended samples decreases as compared to controls (without chromium). The results of Toxicity Characteristics Leaching Procedure (TCLP) test, (pH≅3), show that the retention capacity of OPC and RHA blended samples was in the range of 92% to 99% and the leached Cr (VI) concentration was under the allowable limit (5 mg/l) of U.S. EPA. The chemistry of influence of Cr (VI) on hydration of cement was examined by X-ray diffraction which shows the formation of various crystalline phases during solidification in rice hush ash blended cement.

scholarly journals Effect of Burn Joss Paper Ash on Properties of Ground-Granulated Blast Furnace-Based Slag Geopolymer

2020 ◽  
Vol 10 (14) ◽  
pp. 4877
Author(s):  
Wen-Ten Kuo ◽  
Chuen-Ul Juang ◽  
Zhi-Rong Chen
Keyword(s):  
Blast Furnace ◽  
Setting Time ◽  
Microscopic Analysis ◽  
Waste Recycling ◽  
Engineering Properties ◽  
X Ray Diffraction ◽  
Granulated Blast Furnace Slag ◽  
Substitution Ratio ◽  
Dry Shrinkage ◽  
Peak Value

The purpose of this study is to make geopolymers using burned joss paper ash (BJPA)—which is used in traditional Chinese festivals—and ground-granulated blast-furnace slag (GGBFS). GGBFS-based geopolymers were replaced by BJPA, by mass, at levels of 0%, 20%, 40%, 60%, 80% and 100% and the liquid-to-solid ratios (L/Ss) were 0.3, 0.4 and 0.5. The properties of fresh, hardening, durability and microscopic analysis were examined to determine the effect of BJPA-substitution ratios and L/S on the engineering properties of composite geopolymers. The results show that among the fresh properties, as the amount of BJPA replacement increases, the setting time tended to increase, but the fluidity slowed down. The maximum compressive strength reached 81.1 MPa. As the amount of BJPA replacement increased, the elastic modulus of the geopolymer increased and the brittleness decreased. However, in the dry shrinkage test, it was found that an increase in BJPA helped reduce the dry shrinkage of the geopolymer. X-ray diffraction analysis revealed that a rise in the BJPA-substitution ratio increased the peak value of calcium carbonate. Scanning electron microscope images showed that microcrack size decreased with an increase in the BJPA-substitution ratio, with maximum and minimum crack sizes of 5.80 μm and 176.8 nm, respectively. This was because BJPA was unable to undergo complete polymerization and therefore was able to fill the cracks produced during the polymerization. In conclusion, BJPA may be used for waste recycling in the production of geopolymers.

scholarly journals Controllable synthesis of pomelo peel-based aerogel and its application in adsorption of oil/organic pollutants

2019 ◽  
Vol 6 (2) ◽  
pp. 181823 ◽  
Author(s):  
Guangyu Shi ◽  
Yizhu Qian ◽  
Fengzhi Tan ◽  
Weijie Cai ◽  
Yuan Li ◽  
...  
Keyword(s):  
High Speed ◽  
Chemical Properties ◽  
Absorption Capacity ◽  
High Porosity ◽  
X Ray Diffraction ◽  
Water Separation ◽  
Physico Chemical ◽  
Wide Range ◽  
Oil Water Separation ◽  
Oil Water

Oil/water separation is a field of high significance as it might efficiently resolve the contamination of industrial oily wastewater and other oil/water pollution. In this paper, an environmentally-friendly hydrophobic aerogel with high porosity and low density was successfully synthesized with renewable pomelo peels (PPs) as precursors. Typically, a series of sponge aerogels (HPSA-0, HPSA-1 and HPSA-2) were facilely prepared via high-speed dispersion, freeze-drying and silanization with methyltrimethoxysilane. Indeed, the physical properties of aerogel such as density and pore diameter could be tailored by different additives (filter paper fibre and polyvinyl alcohol). Hence, their physico-chemical properties including internal morphology and chemical structure were characterized in detail by Fourier transform infrared, Brunauer–Emmett–Teller, X-ray diffraction, scanning electron microscope, Thermal gravimetric analyzer (TG) etc. Moreover, the adsorption capacity was further determined and the results revealed that the PP-based aerogels presented excellent adsorption performance for a wide range of oil products and/or organic solvents (crude oil 49.8 g g −1 , soya bean oil 62.3 g g −1 , chloroform 71.3 g g −1 etc.). The corresponding cyclic tests showed the absorption capacity decreased slightly from 94.66% to 93.82% after 10 consecutive cycles, indicating a high recyclability.

Influence of Clutch Disc Waste (Grinding Dust) on Portland Cement Hydration

2019 ◽  
Vol 803 ◽  
pp. 284-288
Author(s):  
José da Silva Andrade Neto ◽  
Tiago Assunção Santos ◽  
Raphael Dias Mariano ◽  
Marcio Raymundo Morelli ◽  
Daniel Véras Ribeiro
Keyword(s):  
Portland Cement ◽  
Propagation Velocity ◽  
Pulse Propagation ◽  
Cement Hydration ◽  
Setting Time ◽  
Reference Sample ◽  
Ultrasonic Pulse ◽  
X Ray Diffraction ◽  
Copper Zinc ◽  
Portland Cement Hydration

This paper evaluates the effect of grinding dust (GD), a waste generated in the clutch disc finishing process, on Portland cement hydration. For this, pastes with additions of 5%, 10% and 15% GD, relative to cement weight, were molded and compared with a reference sample. Tests of setting time determination by Vicat needle, calorimetry, monitoring the ultrasonic pulse propagation velocity and mineralogical analysis (X-ray diffraction) in pastes with 1 day of hydration were carried out. It was observed that GD, due to the presence of copper, zinc and phenolic resin in its composition, is responsible for retarding cement hydration and thus increases the setting time and delays the evolution of heat release and pulse propagation velocity. However, the formation of new crystalline phases was not observed.

scholarly journals Effect of TiO2 Addition on Mortars: Characterization and Photoactivity

2019 ◽  
Vol 9 (13) ◽  
pp. 2598 ◽  
Author(s):  
M. J. Hernández-Rodríguez ◽  
R. Santana Rodríguez ◽  
R. Darias ◽  
O. González Díaz ◽  
J. M. Pérez Luzardo ◽  
...  
Keyword(s):  
Mercury Porosimetry ◽  
Setting Time ◽  
Chemical Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Physico Chemical ◽  
Setting Process ◽  
Flow Table ◽  
Negative Effect ◽  
Important Activity

In this study, mortar specimens were prepared with a cement:sand:water ratio of 1:3:0.5, in accordance with standard EN196-1. Portland CEM I 52.5 R grey (G) and white (W) cements were used, together with normalised sand and distilled water. Different amounts of TiO2 photocatalyst were incorporated in the preparation of the mortar samples. The effect of the addition of TiO2 was studied on mechanical properties of the mortar and cement including compressive and flexural strength, consistency (the flow table test), setting time and carbonation. Characterization techniques, including thermogravimetry, mercury porosimetry and X-ray diffraction spectroscopy (XRD), were applied to study the physico-chemical properties of the mortars. It was shown that adding the photocatalyst to the mortar had no negative effect on its properties and could be used to accelerate the setting process. Specimen photoactivity with the incorporated photocatalyst was tested for NOx oxidation in different conditions of humidity (0% RH and 65% RH) and illumination (Vis or Vis/UV), with the results showing an important activity even under Vis radiation.

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