scholarly journals Properties of Phosphorus-Slag-Based Cementitious Pastes for Stabilizing Lead

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3831 ◽  
Author(s):  
Xuquan Huang ◽  
Liang Liu ◽  
Xiaorong Zhao ◽  
Cilai Tang ◽  
Xiaoshu Wang
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Energy Dispersive Spectrometer ◽  
Lead Ion ◽  
X Ray Diffraction ◽  
Hydrated Calcium Silicate ◽  
Surface Areas ◽  
Phosphorous Slag ◽  
Hydrated Calcium ◽  
Better Than

The properties and curing mechanism of leaded samples solidified with phosphorous-slag-based cementitious pastes are studied. The compressive strength, pH of percolate, and lead-ion concentrations of leaded samples stabilized with the phosphorous-slag-based cementitious pastes and cement were analyzed. Results confirmed that the phosphorous-slag-based cementitious paste performed much better than cement in terms of solidifying lead. The cured form of lead with phosphorous-slag-based cementitious pastes had higher compressive strength, lower lead leaching, and smaller change in pH. Higher lead content corresponded with more obvious advantagees of phosphorus-slag-based cementitious pastes and lower risk of environmental pollution. By means of X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Energy Dispersive Spectrometer-Scanning Electron Microscope (EDS-SEM) analyses, we found that the hydration of phosphorus-slag-based cementitious pastes produced hydrated calcium silicate gels, ettringite and other minerals with large specific surface areas, as well as some leaded products that can combine with lead ions to form chemically stable leaded products. This finding well explained the high performance of phosphorus-slag-based cementitious pastes in terms of lead solidification and stabilization.

Activation Mechanism of Cement Paste for Waste Concrete Autoclaved Products

2010 ◽  
Vol 168-170 ◽  
pp. 949-953
Author(s):  
Chang Jun Ke ◽  
Hao Wang ◽  
Tao Ke
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Activation Mechanism ◽  
X Ray Diffraction ◽  
Hydrated Calcium Silicate ◽  
Waste Concrete ◽  
Mix Proportion ◽  
Hydrated Calcium ◽  
Calculated Amount

studied types and amount of hydration products in cement paste in waste concretes and effect of the cement paste in waste concrete for compressive strength of autoclaved waste concrete samples simulated by hydrated cement with X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Infrared Spectroscopy (IR). The results showed, compressive strength of autoclaved waste concrete products increased with cement paste in waste concrete increasing, and the effect reduced obviously when amount of cement paste exceed 12.5% in waste concrete. Cement paste calculated amount exceeds 12.5% according to present national specification for mix proportion design of ordinary concrete. And it shows that effect of cement paste in waste concrete is weakly for compressive strength of autoclaved waste concrete sample. And compressive strength of autoclaved waste concrete samples is unrelated to mix and age of waste concretes. Hydrated products such as hydrated calcium silicate (C-S-H), α-C2SH and hydrated calcium aluminate sulfate (AFm or AFt) in cement paste forming during normal temperature curing play a role of crystal seed in autoclaved waste concrete samples.

scholarly journals The Compressive Strength of High-Performance Concrete and Ultrahigh-Performance

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
E. H. Kadri ◽  
S. Aggoun ◽  
S. Kenai ◽  
A. Kaci
Keyword(s):  
Experimental Data ◽  
Compressive Strength ◽  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Strength Gain ◽  
Proposed Model ◽  
Partial Cement Replacement ◽  
Better Than

The compressive strength of silica fume concretes was investigated at low water-cementitious materials ratios with a naphthalene sulphonate superplasticizer. The results show that partial cement replacement up to 20% produce, higher compressive strengths than control concretes, nevertheless the strength gain is less than 15%. In this paper we propose a model to evaluate the compressive strength of silica fume concrete at any time. The model is related to the water-cementitious materials and silica-cement ratios. Taking into account the author's and other researchers’ experimental data, the accuracy of the proposed model is better than 5%.

Characteristics of Hydrated Calcium Silicate and Paper Filler

2013 ◽  
Vol 395-396 ◽  
pp. 577-581
Author(s):  
Quan Xiao Liu ◽  
Yan Na Yin ◽  
Wen Cai Xu
Keyword(s):  
Tensile Strength ◽  
Calcium Silicate ◽  
Crystalline State ◽  
X Ray Diffraction ◽  
Hydrated Calcium Silicate ◽  
X Ray ◽  
Color Density ◽  
Paper Filler ◽  
Hydrated Calcium ◽  
Tearing Strength

The X-ray diffraction of hydrated calcium silicate is analyzed and is applied in papermaking. It shows that hydrated calcium silicate have certain crystalline state. The tensile strength, tearing strength and folding strength of paper decrease in different degree with the increase of dosage of hydrated calcium silicate while the whiteness and the printing color density of paper improve. T tensile strength and folding strength of paper decrease in varying degrees with the increase of dosage of PAM while the tearing strength of paper and the whiteness improve. And the printing color density of paper is the same.

scholarly journals Photocatalytic Degradation of 2,4-Dichlorophenol by TiO2 Intercalated Talc Nanocomposite

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Manqing Ai ◽  
Wenli Qin ◽  
Tian Xia ◽  
Ying Ye ◽  
Xuegang Chen ◽  
...  
Keyword(s):  
Energy Dispersive Spectrometer ◽  
Photon Absorption ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
Average Pore ◽  
Thermogravimetric Analyzer ◽  
Surface Areas ◽  
Transmission Electron ◽  
Strong Adsorption ◽  
Bet Method

Novel nanocomposites have been prepared by intercalating TiO2 nanoparticles into talc. The nanocomposites have been verified by X-ray diffraction (XRD) from the appearance of a characteristic diffraction peak of TiO2. Thermal behavior of the prepared samples is examined by thermogravimetric analyzer (TGA), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS), which have shown no TiO2 particles on the surface of the talc. The TiO2 particles are found in the layers of talc by transmission electron microscopy (TEM) and the Brunauer-Emmett-Teller (BET) method, which have shown the increase of specific surface areas and total pore volumes and the decline of average pore diameters. As the strong adsorption ability of talc can intensify the power of photon absorption and capture-recombination carriers, more than 99.5% of 2,4-dichlorophenol can be degraded in 1 h by the nanocomposite under an ultraviolet lamp in neutral solution and room temperature after reaching adsorption equilibrium, and the result of adsorbance is in accord with the first-order kinetic. The degradation rate was maintained at about 99% after 20 times. Therefore, the prepared talc/TiO2 nanocomposite is an efficient, stable, and recyclable material for wastewater treatment.

Pozzolanic Reaction of Supplementary Cementitious Materials and Its Effects on the Strength of Mass Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 505-511 ◽  
Author(s):  
Hua Shan Yang ◽  
Kun He Fang ◽  
Sheng Jin Tu
Keyword(s):  
Cementitious Materials ◽  
Pozzolanic Reaction ◽  
Supplementary Cementitious Materials ◽  
Mass Concrete ◽  
X Ray Diffraction ◽  
X Ray ◽  
Slag Powder ◽  
Phosphorous Slag ◽  
Better Than

The present study aims to investigate the opportunity to largely substitute low heat Portland cement of mass concrete with supplementary cementitious materials. The pozzolanic reaction of two types of supplementary cementitious materials, phosphorous slag powder and fly ash , were determined by X-ray diffraction, differential thermal analysis–thermogravimetry and scanning electron microscopy from 28 to 90 days. The properties of mortar and mass concrete containing 30% of supplementary cementitious materials were also investigated. Results showed that supplementary cementitious materials could decrease the amount of calcium hydroxide, fill the capillary pores, thus making the mortar and mass concrete more compact and durable. Long-term strength of mass concrete containing 30% of supplementary cementitious materials were comparable (or even better) than the control concrete (without supplementary cementitious materials) at constant workability, while the Young’s modulus was lower than the control concrete.

Graphene-Carbon Nanotubes-Modified LiFePO4 Cathode Materials for High-Performance Lithium-Ion Batteries

2018 ◽  
Vol 913 ◽  
pp. 818-830 ◽  
Author(s):  
Yu Ting Chen ◽  
Hai Yan Zhang ◽  
Yi Ming Chen ◽  
Gai Qin ◽  
Xing Ling Lei ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
High Performance ◽  
Electrochemical Impedance ◽  
Lithium Ion ◽  
Liquid Electrolyte ◽  
Cyclic Voltammograms ◽  
X Ray Diffraction ◽  
Conducting Networks ◽  
Electron Migration ◽  
Better Than

A nanocrystalline LiFePO4/graphene-carbon nanotubes (LFP-G-CNT) composite has been successfully synthesized by a hydrothermal method followed by heat-treatment. The microstructure and morphology of the LFP-G-CNTs composite were comparatively investigated with LiFePO4/graphene (LFP-G) and LiFePO4/carbon nanotubes (LFP-CNT) by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The LFP-G-CNTs nanoparticles were wrapped homogeneously and loosely within a 3D conducting network of graphene-carbon nanotubes. The conducting networks provided highly conductive pathways for electron transfer during the intercalation/deintercalation process, facilitated electron migration throughout the secondary particles, accelerated the penetration of the liquid electrolyte into the LFP-G-CNT composite in all directions and enhanced the diffusion of Li ions. The results indicate that the electrochemical activity of LFP-G-CNT composite may be enhanced significantly. The charge-discharge curves, cyclic voltammograms (CV) and electrochemical impedance spectroscopy (EIS) results demonstrate that LFP-G-CNT composite performes better than LFP-G and LFP-CNT composites. In particular, LFP-G-CNT composite with a low content of graphene and carbon nanotubes exhibites a high initial discharge capacity of 168.4 mAh g−1 at 0.1 C and 103.7 mAh g−1 at 40 C and an excellent cycling stability.

scholarly journals Development of a New Ecological Material Based on Moroccan Industrial Wastes for Road Construction

2020 ◽  
Author(s):  
Achraf Harrou ◽  
El Khadir Gharibi ◽  
Yassine Taha ◽  
Nathalie Fagel ◽  
Meriam El Ouahabi
Keyword(s):  
Compressive Strength ◽  
Steel Slag ◽  
Road Construction ◽  
Pozzolanic Reaction ◽  
Industrial Wastes ◽  
X Ray Diffraction ◽  
Hydration Kinetics ◽  
Hydrated Calcium Silicate ◽  
Pozzolanic Reactivity ◽  
Kinetics Of

The Black Steel slag (Ss) and phosphogypsum (PG) are industrial wastes produced in Morocco. In order to reduce these two wastes and to evaluate their pozzolanic reactivity in the presence of water, they were incorporated into bentonite (B) mixed with lime (L). The studied mixtures (BLW, BL-PG-W and BL-PG-Ss-W) were analyzed by X-ray diffraction, Infrared spectroscopy, Raman spectroscopy and SEM/EDX analysis. Compressive strength tests were performed on hardened specimens. The results obtained show that the hydration kinetics of the B-L-W and B-L-PG-W mixtures are slow. The addition of PG to a bentonite-lime mixture induces the formation of new microstructures such as hydrated calcium silicate (C-S-H) and ettringite, which increases the compressive strength of the cementitious specimens. The addition of the Ss to a mixture composed by 8%PG and 8%L-B accelerates the kinetics of hydration and activates the pozzolanic reaction. The presence of C2S in the slag helps to increase the mechanical strength of the mixture B-L-PG-Ss. The compressive strength of the mixtures BL-W, BL-PG-W and BL-PG-Ss-W increases from 15 to 28 days of setting. After 28 days of setting, 8% of Sc added to the mixture 8% PG-8%L-B is responsible for an increase of the compressive strength to 0.6 MPa.

Influence of Nano-SiO2 on the Strength of High Performance Concrete

2011 ◽  
Vol 686 ◽  
pp. 432-437 ◽  
Author(s):  
Bao Min Wang
Keyword(s):  
Compressive Strength ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
High Performance ◽  
High Performance Concrete ◽  
Mixing Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Injection Experiment ◽  
Scanning Electron

The influence of Nano-SiO2 (NS) on the strength of high-performance concrete (W/B=0.24, W/B=0.29, W/B=0.34) has been studied in this paper. The results show that compressive strengths of concrete in both the early and later stage can be improved by adding Nano-SiO2 content. And the influence on the early compressive strength is greater than that on the later compressive strength. According to the results, 3%-5% Nano-SiO2can be used as the proper mixing ratio. X-ray diffraction, SEM (scanning electron microscope) and mercury injection experiment were used to analyze the action principle of Nano-SiO2 microscopically, the microscopic characteristics of concrete can be significantly improved through interfacial and filling effect effects so that the performance of concrete can be accordingly improved.

scholarly journals Effect of Pre-Wetted Zeolite Sands on the Autogenous Shrinkage and Strength of Ultra-High-Performance Concrete

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2356
Author(s):  
Guang-Zhu Zhang ◽  
Xiao-Yong Wang
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Isothermal Calorimetry ◽  
Autogenous Shrinkage ◽  
Control Group ◽  
X Ray Diffraction ◽  
Ultra High Performance Concrete ◽  
Carrier Effect ◽  
Series Of Experiments

In this study, the carrier effect of zeolite sands in reducing the autogenous shrinkage and optimizing the microstructure of ultra-high-performance concrete (UHPC) is studied. Pre-wetted calcined zeolite sand (CZ), calcined at 500 °C for 30 min, and natural zeolite sand (NZ), with 15 wt.% and 30 wt.% in UHPC, are used to partially replace standard sands. On that basis, a series of experiments are executed on the developed UHPC, including compressive strength, autogenous shrinkage, X-ray diffraction (XRD), and isothermal calorimetry experiments. With the increase of the zeolite sand content, the autogenous shrinkage of UHPC decreases gradually. Moreover, when the added CZ content is 30 wt.% (CZ30 specimen), it is effective in reducing autogenous shrinkage. Meanwhile, at the age of 28 days, the compressive strength of CZ30 is 97% of the control group. In summary, it is possible to effectively reduce the autogenous shrinkage of UHPC containing 30 wt.% CZ, without sacrificing its mechanical properties.

scholarly journals Effect of Functional Superplasticizers on Concrete Strength and Pore Structure

2020 ◽  
Vol 10 (10) ◽  
pp. 3496
Author(s):  
Wuju Xun ◽  
Changlong Wu ◽  
Xuefei Leng ◽  
Jiye Li ◽  
Desheng Xin ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
High Performance ◽  
Concrete Strength ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Polycarboxylic Acid ◽  
X Ray Diffraction ◽  
Hydration Rate ◽  
Compressive Strength Of Concrete

The current work investigates the fluidity and the loss of the flow rate of cement paste and mortar over time, as well as the pore structure and compressive strength of concrete and mortar in the presence of functional polycarboxylic acid high-performance water-reducing agents. The hydration rate, hydration products, and pore structure of the concrete containing different functional polycarboxylic acid superplasticizers were analyzed by means of mercury intrusion test, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results show that water-reducing agent Z significantly improves the pore structure of concrete and further compacts the structure of concrete and mortar, thereby improving the compressive strength of concrete. Moreover, the shorter side chains and ester functional groups in the structure of water-reducing agent H can slow down cement hydration rate, which lowers the early strength of mortar; nevertheless, at later stages, the pore structure of the concrete and mortar including superplasticizer H is less different from that of the concrete and mortar containing polycarboxylic acid water-reducing agents. Water-reducing agent J performs best but has a weaker effect on the pore structure of concrete and mortar compared to superplasticizer Z; it is also better than naphthalene-based water-reducing agents.

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