Utilization of Jinchuan Unclassified Tailings in Mine Filling

2014 ◽  
Vol 1073-1076 ◽  
pp. 2158-2162
Author(s):  
You Tuan Wang ◽  
Zhi Qiang Yang ◽  
Qian Gao ◽  
Mao Hui Li
Keyword(s):  
Compressive Strength ◽  
Fine Particle ◽  
Cementitious Materials ◽  
Hydration Products ◽  
Gel Structure ◽  
High Mechanical Strength ◽  
Fine Particle Size ◽  
Unclassified Tailings ◽  
The Cost

In order to utilize the unclassified tailings and reduce the cost of backfill in Jinchuan mine, compressive strength experiments were conducted by taking unclassified tailings as aggregating material. The influence of unclassified tailings on compressive strength was studied, and the influence of unclassified tailings on Hydration products and microstructures was analyzed by XRD and SEM also. The results show that the fine particle size and higher mud content of unclassified tailings have adverse effect on early strength, especially on 3d compressive strength, but it can mprove the long-term strength. The hydration products of the new backfill cementitious materials is mainly C-S-H gel, the flocculent C-S-H gel form dense gel-structure and bond the aggregates together form the high mechanical strength. With the new backfill cementitious materials can achieve 30% utilization of unclassified tailings in Mine Filling, and attained the goal of reducing backfill costs and protecting the environment.

scholarly journals Effect of Soda Residue Addition and Its Chemical Composition on Physical Properties and Hydration Products of Soda Residue-Activated Slag Cementitious Materials

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1789 ◽  
Author(s):  
Yonghui Lin ◽  
Dongqiang Xu ◽  
Xianhui Zhao
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
Cementitious Materials ◽  
Aluminum Silicate ◽  
Chemical Components ◽  
Main Role ◽  
Hydration Products ◽  
Granulated Blast Furnace Slag ◽  
Activated Slag ◽  
Main Components

Soda residue (SR), the solid waste of Na2CO3 produced by ammonia soda process, pollutes water and soil, increasing environmental pressure. SR has high alkalinity, and its main components are Ca(OH)2, NaCl, CaCl2, CaSO4, and CaCO3, which accords with the requirements of being an alkali activator. The aim of this research is to investigate the best proportion of SR addition and the contribution of individual chemical components in SR to SR- activated ground granulated blast furnace slag (GGBS) cementitious materials. In this paper, GGBS pastes activated by SR, Ca(OH)2, Ca(OH)2 + NaCl, Ca(OH)2 + CaCl2, Ca(OH)2 + CaSO4, and Ca(OH)2 + CaCO3 were studied regarding setting time, compressive strength (1 d, 3 d, 7 d, 14 d, 28 d), hydration products, and microstructure. The results demonstrate that SR (24%)-activated GGBS pastes possess acceptable setting time and compressive strength (29.6 MPa, 28 d), and its hydration products are calcium silicate hydrate (CSH) gel, calcium aluminum silicate hydrates (CASH) gel and Friedel’s salt. CaCl2 in SR plays a main role in hydration products generation and high compressive strength of SR- activated GGBS pastes.

Effect of Quartz of Fine Particle Size on Porcelain Properties

2006 ◽  
Vol 530-531 ◽  
pp. 493-498 ◽  
Author(s):  
S.R. Bragança ◽  
C.P. Bergmann
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Thermal Stress ◽  
Fine Particle ◽  
Quartz Particle ◽  
Shock Strength ◽  
Thermal Strength ◽  
Fine Particle Size ◽  
Technical Properties ◽  
The Cost

The mechanical properties of porcelain are strongly influenced by the generated thermal stress during processing. When quartz particle size is reduced its influence on the technical properties of ceramic products such as tiles and porcelains are changed. In this work, the properties of triaxial ceramics materials were evaluated using quartz of different particle size distribution. It was reported strong variations in mechanical strength and thermal shock strength. Although the cost of milling is increased to reduce quartz particle size, it can be compensated by its implicit advantages. The experimental results were very interesting showing the way that quartz particle size influences the analyzed properties. A significant improving in porcelain strength and thermal strength was obtained.

Modified Plasters for Restoration and Finishing Works

2014 ◽  
Vol 923 ◽  
pp. 42-47 ◽  
Author(s):  
Myroslav Sanytsky ◽  
Tetiana Kropyvnytska ◽  
Roman Kotiv
Keyword(s):  
Compressive Strength ◽  
Chemical Composition ◽  
Cementitious Materials ◽  
Quality Parameters ◽  
Supplementary Cementitious Materials ◽  
Cement Matrix ◽  
Hydration Products ◽  
High Quality ◽  
Physico Chemical ◽  
White Portland Cement

The paper is devoted to the research and development of modified plasters for restoration and finishing works based on decorative multicomponent cements containing white Portland cement and supplementary cementitious materials (silica fume, metakaolin and fine ground limestone). This cements are similar to Roman cement by their chemical composition. The use of optimal granulometry of decorative multicomponent cements provide directed formation of microstructure of the cement matrix with the formation of stable hydration products. Compositions of modified plasters by the criterions of workability and compressive strength were designed. Physico-chemical modification of plaster by complex air-entraining admixture allows to obtain high-quality modified plasters with improved quality parameters.

Study on the Effects of Natural Pozzolan and Limestone Powder on Mechanical Properties of Roller Compacted Concrete Pavements

2011 ◽  
Vol 250-253 ◽  
pp. 3619-3623 ◽  
Author(s):  
Morteza Madhkhan ◽  
Armin Hamidi ◽  
Navid Salehi
Keyword(s):  
Compressive Strength ◽  
Cementitious Materials ◽  
Production Costs ◽  
Limestone Powder ◽  
Concrete Pavements ◽  
Natural Pozzolan ◽  
Two Factors ◽  
Long Term Performance ◽  
Term Performance

Due to high maintenance and production costs of conventional asphalt pavements in recent years, substitution of concrete pavements has been taken into account. One important factor of such pavements is the long-term performance. The substitution of pozzolanic materials with existing cement in the mixture is a common choice to improve the durability factors and to increase the long term compressive strength. Owing to this change in cementitious materials, a general anticipation of the pozzolanic behavior to be observed is that the early age compressive strength gets decreased. On the other hand, this defect will be compensated in the long-term compressive strength. Furthermore, as conventional loads of road pavements are concerned, the tensile and flexural strengths have their own importance. Regarding these two factors, the related tests were also performed and the results were analyzed. The main purpose is to find the optimum material among these 2 types of pozzolanic supplements and its percentage of substitution with the preference of having the best average strength in both long and short term performances. Altogether, the natural pozzolan had better performance than limestone powder.

Study on Desulfurized Gypsum-Steel Slag Composite Gelled Material Mechanics Properties

2012 ◽  
Vol 174-177 ◽  
pp. 974-977
Author(s):  
Run Xia Hao ◽  
Xiao Yan Guo
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Aluminum Sulfate ◽  
Steel Slag ◽  
Sem Analysis ◽  
Raw Material ◽  
Hydration Products ◽  
Gel Structure ◽  
Aluminium Sulfate ◽  
Mechanics Performance

Using desulfurized gypsum and steel slag as raw material make desulfurized gypsum-steel slag composite gelled material, by adding cement, triethanolamine, aluminium sulfate, compound activator improve gelled material mechanics performance of materials. The experimental results show that when the proportion of desulfurized gypsum and steel slag for 85:15, mixing the compound activator that aluminum sulfate mixed quantity is 1%, cement mixed quantity is 3%, triethanolamine mixed quantity is 0.8%, sample’s 14d flexural strength can reach 5.83 MPa and compressive strength can reach 16.14 MPa. SEM analysis shows that a lot of C-S-H gel structure in hydration products is conducive to improve desulfurized gypsum-the strength of steel slag gelled material, reach the purpose of improving gelled material mechanics performance.

scholarly journals Mechanism Analysis of the Influence of Delay Period on Mechanical Properties of Reactive Powder Concrete

2021 ◽  
Vol 7 ◽  
Author(s):  
Xiaohui Wang ◽  
Qingxin Zhao ◽  
Xiaojun He ◽  
Shuang Zhang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Delay Period ◽  
Reactive Powder Concrete ◽  
Hydration Products ◽  
X Ray ◽  
Significant Difference ◽  
Calcium Silicon ◽  
Reactive Powder

In order to analyze the influence mechanism of delay period on the mechanical properties of reactive powder concrete (RPC), the compressive strength of RPC with delay periods of 18, 24, and 30 h was tested at the age of 7, 28, and 90 days, respectively. The results show that compared with the RPC with delay period of 18 h, the compressive strength of the RPC with delay periods of 24 and 30 h increases by 3.2 and 4.2%, respectively, and the long-term strength reduction ratio decreases by 22.8 and 71.9%, respectively. The constitutive model curves of RPC under different delay period show that the initial elastic modulus E increases with the delay period and the strength and rigidity of RPC increase with the extension of delay period. According to the non-evaporation water quantity test, it could be speculated that the quantities of hydration products of the RPC with delay periods of 24 and 30 h slightly increase compared with the RPC with delay period of 18 h. X-ray diffraction (XRD) analysis show that the delay periods of 24 and 30 h consume more 3CaO·SiO2 (C3S) and 2CaO·SiO2 (C2S) compared with delay period of 18 h. Seen from the scanning electron microscope (SEM) image, the structures of the three groups of samples are relatively dense and have no significant difference. Through energy dispersive X-ray spectroscopy (EDS) analysis, the calcium-silicon ratios of hydration products of the RPC with delay periods of 18, 24, and 30 h are 1.81, 1.56, and 1.54, respectively. The existence of C-S-H gel and Ca(OH)2 in hydration products is confirmed by thermogravimetric-differential scanning calorimetry (DSC-TG) analysis. An appropriate delay period (30 h in this paper) generates more hydration products, then improves the compactness of the internal structure and reduces the calcium-silicon ratio of hydration products, and it is conducive to the growth of RPC compressive strength and the stability of long-term compressive strength.

Influence of Triethanolamine on the Properties of Cement-Based Materials

2017 ◽  
Vol 898 ◽  
pp. 2010-2017 ◽  
Author(s):  
Xiao Ying Wang ◽  
Ming Zhang Lan ◽  
Wei Fang Hou ◽  
Bin Feng Xiang ◽  
Xu Dong Zhao
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Cement Hydration ◽  
Setting Time ◽  
Cementitious Materials ◽  
Hydration Products ◽  
Initial Setting Time ◽  
Final Setting Time ◽  
Retarding Effect ◽  
Initial Setting

The effects of triethanolamine on the compressive strength and setting time of fly ash cementitious materials, slag cementitious materials, and limestone cementitious materials were investigated. The results show that the dosage of 0.04% of triethanolamine can significantly improve the 3d, 7d and 28d compressive strength of fly ash cementitious materials. It possesses less impact on the setting time. The dosage of 0.04% of triethanolamine can significantly improve the 3d and 7d compressive strength of slag cementitious materials while the effect of late strength is not obvious. It extends the initial setting time and the final setting time is not changed, which has retarding effect. The results of hydration heat and XRD show that triethanolamine extends the induction period of cement hydration, and gypsum is exhausted in advance during the hydration process. Triethanolamine promotes the transformation of AFt to AFm and there is no effect on the type of hydration products.

scholarly journals Concrete Overstrength: Assessment of Field Strength Seeking Insights for Overdesign Optimization

CivilEng ◽  
2022 ◽  
Vol 3 (1) ◽  
pp. 51-65
Author(s):  
Rodrigo Antunes
Keyword(s):  
Compressive Strength ◽  
Linear Optimization ◽  
Optimization Technique ◽  
Cementitious Materials ◽  
Concrete Durability ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Compressive Strength Of Concrete ◽  
Ready Mixed Concrete

This study investigates the high contents of cementitious materials in Portland cement concrete and assesses the required (f’cr) and actual (σ) compressive strength of concrete specimens. A linear optimization technique identifies the required binder content to reach f’cr. Standard specifications have required concrete overdesign (OD) for decades, but few studies have evaluated the actual magnitude of OD from field data. The compressive strength of 958 cylinders prepared in the field represented 8200 m3 of ready-mixed concrete with 300 and 450 kg/m3 of cementitious are analyzed. The actual OD appears to be 7 to 21% higher than required. The required 28-day compressive strength of concrete was achieved in less than seven days. Therefore, the content of the cementitious materials could be reduced by 6 and 17% so that concrete could reach f’cr without cementitious overconsumption. Reducing cementitious content is recommended to improve construction quality and optimize resource utilization. Among the main reasons for this recommendation are the estimated substantial long-term savings, increased concrete durability and more rational use of natural resources required to build the structures.

Fine Particle Mass Monitoring with Low-Cost Sensors: Corrections and Long-Term Performance Evaluation

2019 ◽  
Author(s):  
Carl Malings ◽  
Rebecca Tanzer ◽  
Aliaksei Hauryliuk ◽  
Provat K. Saha ◽  
Allen L. Robinson ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Fine Particle ◽  
Low Cost ◽  
Particle Mass ◽  
Long Term Performance ◽  
Term Performance

Primary varicose veins

Phlebologie ◽  
2010 ◽  
Vol 39 (03) ◽  
pp. 133-137
Author(s):  
H. Partsch
Keyword(s):  
Varicose Veins ◽  
Compression Therapy ◽  
Daily Practice ◽  
Clinical Severity ◽  
Compression Stockings ◽  
Primary Varicose Veins ◽  
The Cost ◽  
Convincing Data ◽  
Long Term Studies

SummaryBackground: Compression stockings are widely used in patients with varicose veins. Methods: Based on published literature three main points are discussed: 1. the rationale of compression therapy in primary varicose veins, 2. the prescription of compression stockings in daily practice, 3. studies required in the future. Results: The main objective of prescribing compression stockings for patients with varicose veins is to improve subjective leg complaints and to prevent swelling after sitting and standing. No convincing data are available concerning prevention of progression or of complications. In daily practice varicose veins are the most common indication to prescribe compression stockings. The compliance depends on the severity of the disorder and is rather poor in less severe stages. Long-term studies are needed to proof the cost-effectiveness of compression stockings concerning subjective symptoms and objective signs of varicose veins adjusted to their clinical severity. Conclusion: Compression stockings in primary varicose veins are able to improve leg complaints and to prevent swelling.

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