scholarly journals Recycling of Oily Sludge as a Roadbed Material Utilizing Phosphogypsum-Based Cementitious Materials

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Wei Xiao ◽  
Xiao Yao ◽  
Fuyang Zhang
Keyword(s):  
Heavy Metals ◽  
Compressive Strength ◽  
Pore Structure ◽  
Cementitious Materials ◽  
Solid Particles ◽  
Oily Sludge ◽  
Water Stability ◽  
Volume Stability ◽  
Freeze Thaw ◽  
Stability Performance

Oily sludge is a hazardous waste containing emulsified petroleum hydrocarbons, water, heavy metals, and solid particles. The objective of this work is to employ solidification/stabilization (S/S) techniques to utilize oily sludge as a roadbed material with ordinary Portland cement (OPC), fly ash (FA), and silica fume (SF) as binders and phosphogypsum (PG) as a stabilizer. The efficacy of the S/S process is assessed mainly through an unconfined compressive strength (UCS) test and a toxicity leaching test. Road performance, including water stability, freeze-thaw resistance, and volume stability, is also tested on the solidified samples. The mineralogical compositions, microstructures, and pore structure are characterized through X-ray diffractometry (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The results show that the addition of 20% binders (OPC : FA : SF = 1 : 0.7 : 0.8) in combination with phosphogypsum to the oily sludge not only increases the 28-day compressive strength of the solidified samples and remarkably decreases the release of heavy metals but also refines the pore structure and compacts the microstructure. The solidified body had sufficient strength and good water stability performance, freeze-thaw resistance, and volumetric stability. This solidification/stabilization (S/S) process, which combines oily sludge treatment and phosphogypsum resource utilization, significantly enhances environmental protection and renders the solidified product economically profitable.

Autoclaved Brick from Steel Slag and Silicon Tailings

2014 ◽  
Vol 878 ◽  
pp. 194-198 ◽  
Author(s):  
Peng Guan Li ◽  
Feng Qing Zhao
Keyword(s):  
Compressive Strength ◽  
Total Mass ◽  
Bending Strength ◽  
Steel Slag ◽  
Drying Shrinkage ◽  
Load Bearing ◽  
Volume Stability ◽  
Freeze Thaw

The load-bearing brick is made from steel slag and silicon tailings by pressing and autoclaving process. Because of the volume stability, steel slag was ground to above 320 m2/kg and wet cured in 50-60°C at 12-24 hours in the present of additives, before pressure forming and autoclaving process. Tailings account for 63% of the total mass of the brick, while steel slag 30 %. The compressive strength of the brick was up to 13.1MPa, bending strength 3.2MPa, and with low drying shrinkage and good freeze-thaw resistance. The application conditions were discussed.

scholarly journals Mechanical Properties and Micro Structure of Cement Concrete in Freeze-Thaw Environment

2021 ◽  
Vol 233 ◽  
pp. 01011
Author(s):  
Xin jian Lv ◽  
Lei Yu ◽  
Ming ming Chai
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Pore Structure ◽  
Fresh Water ◽  
Pore Diameter ◽  
Dynamic Elastic Modulus ◽  
Freeze Thaw ◽  
Salty Water ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

In order to find the declay law of mechanical property and the performance difference after salty water and fresh water freeze-thaw cycle, freeze-thaw cycle environments under the salty water and fresh water are simulated. The compressive strength, dynamic elastic modulus and the mass lost are tested. The pore structure parameters are also tested by MIP. Plot the pore diameter distribution curve. The result shows that the compressive strength and dynamic elastic modulus are all decreased. The degree of these two properties decreasing under salty water freeze and thaw recycle is more than the one under fresh water. The parameters of porosity and critical pore diameter become larger. The amount of pores whose diameter is between 100nm and 1000nm increase. The amount of pores whose diameter is under 100nm decrease. The deteriorate degree of pore structure is deeper in salty water than in fresh water.

scholarly journals Effect of the Content of Micro-Active Copper Tailing on the Strength and Pore Structure of Cementitious Materials

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1861 ◽  
Author(s):  
Liming Zhang ◽  
Songbai Liu ◽  
Dongsheng Song
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Pore Structure ◽  
Cement Hydration ◽  
Early Stage ◽  
Cementitious Materials ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Strength Increase ◽  
Curing Age

This study investigates the effect of micr-oaggregate filling with copper tailing on the pore structure of cement paste containing copper tailing (CPCT). The particle size of the CPCT and the pore structure of CPCT were analyzed by laser particle size analysis and mercury instruction porosimetry (MIP). Results showed that at the early stage of curing time, with increasing copper tailing content, the compressive strength of cement mortar with copper tailing (CMCT) was lower, and the porosity and pore diameter of CPCT were higher and greater; with the extension of curing age, when the content of copper tailing was less than 30%, the compressive strength of CMCT and the porosity of CPCT changed slightly with the increase of the content of copper tailing. However, the maximum hole diameter of CPCT decreased gradually (a curing age between 7 d and 365 d under standard conditions). Scanning electron microscopy analysis showed that at the early stage of cement hydration in the CPCT, the copper tailing did not fill the pores in CPCT well, while in the later stage of cement hydration, the microaggregates of copper tailing filled the pores well and closely combined with the surrounding hydration products. In the later stage of cement hydration, the microaggregate filling of copper tailing was primarily responsible for the strength increase of the CMCT.

Study on Performance of New JJH Soil Solidifying Agent

2013 ◽  
Vol 742 ◽  
pp. 166-169
Author(s):  
En Yu Sun ◽  
Xi Kuan Zhang
Keyword(s):  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Technical Specification ◽  
Raw Material ◽  
Water Stability ◽  
Stability Coefficient ◽  
Freeze Thaw ◽  
National Technical ◽  
New Type ◽  
Train Of Thought

The paper is on the basis of the study on mechanism of Soil solidifying agent,and created a New JJH Soil solidifying agent compounded of NaOH and slag micropowder which are the main raw material,then studied its properties. The results show that the unconfined compressive strength, water stability and freeze thaw stability of the new soil solidified agent are performance. It can meet the requirements in relevant national technical specification, the 7d age strength of solidified soil is more than 2MPa and water stability coefficient is more than 0.8. opens up a new train of thought to a new type of soil solidifying agent.

scholarly journals Two-Year Non-Destructive Evaluation of Eco-Efficient Concrete at Ambient Temperature and after Freeze-Thaw Cycles

2021 ◽  
Vol 13 (19) ◽  
pp. 10605
Author(s):  
Mohammed A. Abed ◽  
Bassam A. Tayeh ◽  
B. H. Abu Bakar ◽  
Rita Nemes
Keyword(s):  
Compressive Strength ◽  
Ambient Temperature ◽  
High Performance Concrete ◽  
Surface Hardness ◽  
Cementitious Materials ◽  
Pulse Velocity ◽  
Recycled Concrete ◽  
Supplementary Cementitious Materials ◽  
Freeze Thaw ◽  
Non Destructive

The increasing demand for eco-efficient concrete puts pressure on the industry to innovate new alternatives for its constituent materials. Coarse recycled concrete aggregates (RA) and supplementary cementitious materials (SCMs) are considered promising substitutes for coarse natural aggregates (NA) and cement, respectively. Using destructive and non-destructive testing methods, the present work aims to evaluate the effect of RA and different types of waste SCMs on the long-term performance of self-compacting high-performance concrete (SCHPC). Twenty-one mixes that were prepared with a 0.35 water-to-binder ratio were tested for their compressive strength, surface hardness, and ultrasonic pulse velocity. These tests were conducted over a two-year period at ambient temperature and again after exposure to up to 150 freeze–thaw cycles. Study findings demonstrated the possibility of developing eco-efficient SCHPC mixes using RA and waste SCMs. In addition, correlations have been introduced for predicting the compressive strength of SCHPC.

scholarly journals Using Alkali-Activated Cementitious Materials to Solidify High Organic Matter Content Dredged Sludge as Roadbed Material

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Zhong Gu ◽  
Sudong Hua ◽  
Weixing Zhao ◽  
Sisheng Li ◽  
Zhen Gao ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Matter Content ◽  
Matter Content ◽  
Hydration Products ◽  
Volume Stability ◽  
Freeze Thaw ◽  
High Organic Matter Content ◽  
Stability Performance ◽  
High Organic Matter ◽  
Dredged Sludge

It is difficult to treat dredged sludge with high organic matter content by solidification. A new solidification of dredged sludge with high organic matter content was developed, using cement, fly ash, slag, and phosphogypsum as a solidifier and strong oxidant KMnO4and GH as additives, to improve the engineering performance of dredged sludge and make it as a roadbed material possible. The properties of the solidified samples were determined in terms of unconfined compressive strength, products of hydration, toxicity characteristics, water stability, freeze-thaw resistance, and volume stability. The microstructure and hydration products of the dredged sludge after solidification were evaluated by X-ray diffraction analysis, scanning electron microscopy, and thermogravimetry-differential scanning calorimetry analysis. Experimental results showed that the strength of the solidified samples has been significantly improved after treatment by strong oxidants. The effect of GH is better than that of KMnO4. Hydration products (ettringite) were well formed. After solidification by using the binders and strong oxidant GH, the samples had sufficient strength and good water stability performance, freeze-thaw resistance performance, and volume stability performance. The leach liquid of the dredged sludge solidified body meets the standard requirements. So, the dredged sludge after solidification can reach the requirement of the roadbed material.

scholarly journals Study on Solidification of Chromium-Containing Sludge With Alkali Slag Combined With Attapulgite

2021 ◽  
Author(s):  
Huirong Lin ◽  
Linghao Zeng ◽  
Pengpeng Zhang ◽  
Bingquan Jiao ◽  
YanChyuan Shiau ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Compressive Strength ◽  
Cementitious Materials ◽  
Ftir Analysis ◽  
Chemical Immobilization ◽  
Heavy Metal Leaching ◽  
Orthogonal Experiments ◽  
Leaching Toxicity ◽  
Solidified Body

Abstract In order to solve the harm of hazardous waste chromium-containing sludge to humans and the environment, this paper uses attapulgite to strengthen alkali slag to prepare cementitious materials to solidify/stabilize chromium-containing sludge. Single-factor and orthogonal experiments were used to optimize the preparation parameters of alkali slag cementitious materials. The compressive strength, heavy metal leaching toxicity, and microscopic characterization of chromium-containing sludge solidified body were tested to investigate the solidification effect and mechanism of chromium-containing sludge. The results show that: The best content of attapulgite is 4%. The compressive strength of the solidified body decreased with the increase of chromium sludge content, and the leaching concentration of Cr and Cu increased with the rise of chromium-sludge content. The addition of attapulgite enhanced the compressive strength. Compared with the original chromium-containing sludge, the leaching concentration of heavy metals in the solidified body is significantly reduced. The XRD and FTIR analysis showed that the solidified body might solidify/stabilize heavy metals by physical encapsulation of amorphous form and chemical immobilization. This research realizes the use of waste to treat waste and provides the possibility for the application of solidified products in construction.

scholarly journals Experimental Study on Mechanical Properties and Pore Structure Deterioration of Concrete under Freeze–Thaw Cycles

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6568
Author(s):  
Kai Zhang ◽  
Jing Zhou ◽  
Zhigang Yin
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Pore Structure ◽  
Design Theory ◽  
Damage Model ◽  
Concrete Structures ◽  
Frost Damage ◽  
Dynamic Increase Factor ◽  
Freeze Thaw ◽  
Dynamic Compressive Strength

Understanding the evolution of mechanical properties and microscopic pore structure of concrete after freeze–thaw cycles is essential to assess the durability and safety of concrete structures. In this work, the degradation law of mechanical properties and damage characteristic of micro-structure of concrete with two water-cement ratios (w/c = 0.45 and 0.55) is investigated under the condition of freezing–thawing cycles. The influence of loading strain rate on dynamic compressive strength is studied. The microscopic pore structure after frost damage is measured by low-field nuclear magnetic resonance (LF-NMR) technique. Then, a damage model based on the porosity variation is established to quantitatively describe the degradation law of macroscopic mechanical properties. The test results show that the relative dynamic modulus of elasticity (RDME), dynamic compressive strength, flexural strength, and splitting tensile strength of concrete decrease with the increase of freeze–thaw cycles. Empirical relations of concrete dynamic increase factor (DIF) under the action of freeze–thaw cycles are proposed. Moreover, the experimental results of NMR indicate that the porosity as well as the proportion of meso-pores and macro-pores of concrete gradually increased with the increasing of freeze–thaw cycles. The research results can provide reference and experimental support for the anti-frost design theory and durability life prediction of hydraulic concrete structures in cold regions.

scholarly journals Cost Optimization of Mortars Containing Different Pigments and Their Freeze-Thaw Resistance Properties

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Sadık Alper Yıldızel ◽  
Gökhan Kaplan ◽  
Ali Uğur Öztürk
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Pore Structure ◽  
Water Absorption ◽  
Cost Optimization ◽  
Unit Weight ◽  
Concrete Construction ◽  
Freeze Thaw ◽  
White Cement ◽  
Architectural Mortar

Nowadays, it is common to use colored concrete or mortar in prefabricated concrete and reinforced concrete construction elements. Within the scope of this study, colored mortars were obtained with the addition of brown, yellow, black, and red pigments into the white cement. Those mixtures are examined for their compressive strength, unit weight, water absorption, and freeze-thaw resistance. Subsequent to comparison of these properties, a cost optimization has been conducted in order to compare pigment costs. The outcomes showed that the pore structure in architectural mortar applications plays an important role in terms of durability. And cost optimization results show that light colored minerals can be used instead of white cements.

scholarly journals Test Study on Strength and Permeability Properties of Lime-Fly Ash Loess under Freeze-Thaw Cycles

2014 ◽  
Vol 8 (1) ◽  
pp. 172-176
Author(s):  
Zhiquan Zhang ◽  
Yufen Zhang
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Fly Ash ◽  
Water Stability ◽  
Direct Shear ◽  
Compressive Test ◽  
Freeze Thaw ◽  
Coefficient Of Permeability ◽  
Test Study ◽  
Uniaxial Compressive Test

In order to study the application of lime-fly ash loess in permafrost subgrade engineering, uniaxial compressive test, fast direct shearing test and permeability tests were carried out on lime-fly ash loess under different curing ages and freeze-thaw cycles. Uniaxial compressive strength of lime-fly ash loess increases slowly with the curing ages, and can reach 3.5 Mpa after the curing ages of 90 days (This strength is called 90d strength). 14d strength of lime-fly ash loess has already reached 50% of 90d strength; later strength including 28d strength and 90d strength is basically stable under different freeze-thaw cycles, so lime-fly ash loess has good water stability and freeze-thaw stability. Fast direct shear strength decreases with the number of freeze-thaw cycles without consideration of moisture content; the coefficient of permeability increases with the number of freeze-thaw cycles．All test data show that lime-fly ash loess with good behaviors can be applied in permafrost subgrade engineering.

Sign in / Sign up

Export Citation Format

Share Document