scholarly journals A study on the mixed properties of green controlled low strength cementitious

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sung-Ching Chen ◽  
Wei-Ting Lin ◽  
Kae-Long Lin ◽  
Po-Yu Huang
Keyword(s):  
Compressive Strength ◽  
Circulating Fluidized Bed ◽  
Activity Index ◽  
Cementitious Materials ◽  
Test Methods ◽  
The Self ◽  
Industrial Wastes ◽  
Mix Design ◽  
Fluidized Bed Combustion ◽  
Low Strength

Abstract In this study, two industrial wastes – circulating fluidized bed combustion co-fired fly ash (CFA) and ground granulated blast-furnace slag (GGBS) – were used as green materials instead of cementitious materials in controllable low strength material (CLSM). CLSM was used to backfill the pavement. CLSM should meet the compressive strength requirements of the CLSM specification (under 8.24 MPa), and it had the self-consolidating characteristics of fluidized concrete. In order to comply with the characteristics of self-consolidation, a mix design including superplasticizers, adhesives, and accelerators were used to ensure that the proportion could meet the requirements of both CLSM and the self-consolidating properties. The test methods included the slump flow test, ball drop test, strength activity index, compressive strength, mercury intrusion porosimetry, chlo-ride migration test, and scanning electron microscope. A water/cement ratio of 0.85 was used as the mix design for the CLSM requirements. The CFA and GGBS used in CLSM could replace 78 wt.% of the cement, and CLSM could effectively meet the requirements of the workability, strength and microscopic properties.

Retrofitting 25T/h Pulverized Coal-Fired Boiler Into 35T/h Circulating Fluidized Bed Boiler for Burning Mixture of Coal and Bagasse

2005 ◽  
Author(s):  
Han-Ping Chen ◽  
Xian-Hua Wang ◽  
Shi-Hong Zhang ◽  
De-Chang Liu ◽  
Yu-Hua Lai ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Combustion Efficiency ◽  
Economic Benefits ◽  
Pulverized Coal ◽  
Industrial Wastes ◽  
Pollutant Emission ◽  
Fluidized Bed Combustion ◽  
Circulating Fluidized Bed Boiler ◽  
Combustion Technology

In China, there are a large number of pulverized coal-fired industrial boilers, whose steam capacities are usually relatively small. These boilers can burn only high-grade coal and have low combustion efficiency. Furthermore, the combustion emissions, such as SO2 and NOx, pollute the environment severely. Therefore it is very important and urgent to adopt economically efficient and environmentally friendly technologies to retrofit these boilers. At the same time, there are many industrial wastes, such as bagasse, wood waste, rubbish, petroleum coke and so on, need burning disposal in China. Fluidized bed combustion technology is a kind of clear combustion technology, which has many advantages, such as excellence fuel flexibility, high combustion efficiency, low pollutant emission and good turndown capability etc. So, adopting fluidized bed combustion technology, retrofitting pulverized coal-fired boiler into fluidized bed boiler can realize pure burning various wastes or co-firing with coal, which should have great economic benefits and social benefits. And the application prospect of the method is also extensive. The State Key Laboratory of Coal Combustion has successfully retrofitted a 25t/h pulverized coal-fired boiler into circulating fluidized bed boiler with in-bed tubes and downward exhaust cyclone. The retrofitted boiler can burn mixture of coal and bagasse and the steam capacity reaches 35t/h. This paper presents the retrofitting measures and the operation status of the boiler after retrofitting.

Chloride Ingress Control and Promotion of Internal Curing in Concrete Using Superabsorbent Polymer

2021 ◽  
Vol 888 ◽  
pp. 67-75
Author(s):  
Ariel Verzosa Melendres ◽  
Napoleon Solo Dela Cruz ◽  
Araceli Magsino Monsada ◽  
Rolan Pepito Vera Cruz
Keyword(s):  
Compressive Strength ◽  
Cementitious Materials ◽  
Internal Curing ◽  
Mix Design ◽  
Chloride Ingress ◽  
Superabsorbent Polymer ◽  
Cement Slurry ◽  
Chloride Permeability ◽  
Cement Ratio ◽  
Water To Cement Ratio

Chloride ingress into concrete from the surrounding environment can result in the corrosion of the embedded steel reinforcement and cause damage to the concrete. Superabsorbent polymer (SAP) with fine particle size was incorporated into the structure of concrete for controlling the chloride ingress and improving its compressive strength via promotion of internal curing. The SAP used in this study was evaluated for its absorbency property when exposed to cementitious environment such as aqueous solution of Ca (OH)2 and cement slurry. The results were compared to that in sodium chloride solution, the environment where absorbency of most of the SAP found in the market are well studied. Results showed that although SAP absorbency decreased with increasing concentration of Ca (OH)2 and cement, the results suggest that water containing cementitious materials are able to be absorbed by SAP. Chloride ingress into 28-day cured concrete specimens were determined using Rapid Chloride Penetration Test (RCPT) method employing 60V DC driving force. Concrete samples with size of 50 mm height x 100 mm diameter were prepared using a M25 mix design with 0.4 and 0.45 water to cement ratios and different percentages of SAP such as 0.05%, 0.1% and 0.15% with respect to cement mass. Results showed that concrete with 0.15% SAP gave the best result with 14% less chloride permeability than concrete with no SAP for a 0.4 water to cement ratio. Concrete samples for compressive strength tests with size of 200 mm height x 100 mm diameter were prepared using the same mix design and percentages of SAP and cured for 28 days. Results showed that the best results for compressive strength was found at 0.1% SAP at a 0.4 water to cement ratio which can be attributed to internal curing provided by SAP.

Low Strength Self Compacting Concrete Compressive Strength Test

2013 ◽  
Vol 275-277 ◽  
pp. 2041-2044
Author(s):  
Feng Yan ◽  
Nan Pang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Compression Strength ◽  
Strength Test ◽  
The Self ◽  
Concrete Compressive Strength ◽  
Self Compacting Concrete ◽  
Intensity Index ◽  
Compressive Strength Test ◽  
Low Strength

In this paper,the mechanical properties were studied,the self compacting concrete cubic compression strength,prismatic compressive strength test,discussed two kinds of relationship between intensity index.

scholarly journals Experimental Study of Stabilized Soil Utilizing Circulating Fluidized Bed Combustion Desulfurization Ash with Carbide Slag and Desulfurization Gypsum

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Dezhi Shao ◽  
Jinlong Liu ◽  
Xin Huang
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Composite Foundation ◽  
Industrial Wastes ◽  
Fluidized Bed Combustion ◽  
Soil Mixing ◽  
Carbide Slag ◽  
Stabilized Soil ◽  
Cement Soil ◽  
Circulating Fluidized Bed Combustion

This paper discusses the feasibility of preparing soil stabilizer which is circulating fluidized bed combustion ash-based, supplemented with carbide slag and desulfurization gypsum, composed entirely of complete industrial wastes. The results show that CFBC ash has better pozzolanic activity than fly ash. When stabilizer total content is 10% and the ratio of CFBC ash : carbide slag : desulfurization gypsum is 7.2 : 1.8 : 1, compressive strength of stabilized soil can reach the maximum of 2.12 MPa at the age of 28 d of curing. Stabilizer can meet the strength requirements of cement-soil mixing pile composite foundation and cement-soil mixing pile waterproof curtain.

scholarly journals Assessment of Mechanical, Thermal and Durability Properties of High-Volume GGBS Blended Concrete Exposed to Cryogenic Conditions

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2129
Author(s):  
Giyeol Lee ◽  
Okpin Na
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Reduction Rate ◽  
High Volume ◽  
Test Methods ◽  
Heat Of Hydration ◽  
Mix Design ◽  
Mechanical And Thermal Properties ◽  
Thermal Cracks ◽  
Better Than

The purpose of this study is to suggest the optimum mix design with a high volume of GGBS (Ground Granulated Blast-furnace Slag) replacement and the procedure of the cryogenic test to consider mechanical and thermal properties, and durability performance. To decide the optimum mix design, four mix designs with high-volume of GGBS replacement were suggested, in terms of the slump and retention time. Based on the test results, with respect to the workability and compressive strength, the mixtures with 65% of GGBS (C40-2 and C40-4) were better than the mixtures with 50% and 60% of GGBS (C40-1 and C40-3). After selecting two mixtures, two types of cryogenic test methods were conducted under one-cycle cryogenic condition (Test A) and 50-cycles cryogenic condition (Test B). As a result, in Test A, the compressive strength and elastic modulus of the C40-2 and C40-4 mixtures tended to be decreased over time, because of the volume expansion of ice crystals contained in the capillary pores. In Test B, the mechanical properties of the C40-4 mixture were better than those of the C40-2 mixture, in terms of the reduction rate of compressive strength and elastic modulus. In the view of the heat of hydration, the semi-adiabatic test was conducted. In the results, the C40-4 mixture was better to control the thermal cracks. Thus, the C40-4 mixture would be more suitable for cryogenic concrete and this procedure could be helpful to decide the mixture of cryogenic concrete. In the future, the long-term performance of cryogenic concrete needs to be investigated.

scholarly journals Key Factors Determining the Self-Healing Ability of Cement-Based Composites with Mineral Additives

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4211
Author(s):  
Kamil Tomczak ◽  
Jacek Jakubowski ◽  
Łukasz Kotwica
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Crack Width ◽  
Defect Formation ◽  
Cementitious Materials ◽  
The Self ◽  
Supplementary Cementitious Materials ◽  
Self Healing ◽  
Key Factors ◽  
Important Indicator

This paper reveals the relationships between key factors that determine the ability of cementitious composites to self-heal autogenously and specific measures for quantifying the effects of this process. The following material factors: water-to-binder ratio (w/b), uniaxial compressive strength and age of the composite at the time of defect formation were considered, as well as the method and degree of damage to the tested material. The subjects of this study were mortars and concretes in which Portland cement was partially replaced, to varying degrees, with mechanically activated fluidized bed combustion fly ash (MAFBC fly ash) and siliceous fly ash. The samples were subjected to three-point bending or cyclic compression tests after 14 or 28 days of aging, in order to induce defects and then cured in water for 122 days. Microscopic (MO) and high-resolution scanning (HRS) observations along with computer image processing techniques were used to visualize and quantify the changes occurring in the macro-crack region near the outer surface of the material during the self-sealing process. Techniques based on the measurement of the ultrasonic pulse velocity (UPV) allowed the quantification of the changes occurring inside the damaged materials. Mechanical testing of the composites allowed quantification of the effects of the activity of the binder-supplementary cementitious materials (SCMs) systems. The analysis of the results indicates a significant influence of the initial crack width on the ability to completely close the cracks; however, there are repeated deviations from this rule and local variability of the self-sealing process. It has been shown that the compressive strength of a material is an important indicator of binder activity concerning crack width reduction due to self-sealing. Regardless of the crack induction method, the internal material changes caused by self-sealing are dependent on the degree of material damage.

scholarly journals Effect of Sugarcane Bagasse Ash as Partial Cement Replacement on the Compressive Strength of Concrete

2020 ◽  
Vol 18 (02) ◽  
pp. 44-49
Author(s):  
Sabir Ali ◽  
Aneel Kumar ◽  
Samar Hussain Rizvi ◽  
Mohsin Ali ◽  
Israr Ahmed
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Calcium Hydroxide ◽  
Sugarcane Bagasse ◽  
Activity Index ◽  
Research Work ◽  
Industrial Wastes ◽  
Water Absorption Test ◽  
Sugarcane Bagasse Ash ◽  
Partial Cement Replacement

The disposal of solid waste in open environment is a serious alarming concern that needs immediate attention from the researchers. The hazardous solid agro-industrial wastes which include: wheat straw ash, rice husk ash, corn cob ash and sugarcane bagasse ash (SCBA), having pozzolanic properties, have a versatile use in concrete. The solid pozzolana enhances the various concrete properties by the reaction of silicates with calcium hydroxide in the presence of water, which in result generate a saturated zone of calcium silicate hydrate (CSH) gel. This C-S-H gel reduces the amount of calcium hydroxide C(OH)2 during the hydration process of cement. Very limited research works have been done on concrete by partially replacing cement with SCBA. This research work was focused on evaluating the properties of concrete by partially replacing cement with SCBA at 0, 5, 10, and 15 percentages. Compressive strength, Strength activity index, and water absorption of all mixes were examined. And it was observed that all SCBA mixes showed an increase in compressive strength and at 10% replacement the strength activity index was at a peak of 115.67%, but all the SCBA mixes showed a strength activity index greater than 75% which satisfied the standard specification. The water absorption test for all SCBA mixes showed a slight increase in water absorption.

scholarly journals Conventional Concrete Mix Design for Producing the Low and High Volume of Fly Ash Based Fiber Reinforced Concrete

2019 ◽  
Vol 8 (6) ◽  
pp. 1157-1162 ◽  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Activity Index ◽  
Research Work ◽  
Binder Content ◽  
Fiber Reinforced Concrete ◽  
Mix Design ◽  
Conventional Concrete ◽  
Concrete Mix Design ◽  
Concrete Mix

The present research work analysis the conceptual concrete mix design regarding the packing unit density concept for multi initial trial and error perfect shaped methodologies. In initial, a high strength based concrete with desired target compressive strength of M40 Graded concrete was shaped for various mixing proportion and Also, a stabilized standard chart has been developed for the various packing constituents (percentage) in various parameters, where the aggregates (F/c) ratio 0.5 to 0.8, Binder-Total aggregate (B/Ta) ratio 0.27 to 0.24 and water-binder content (w/b) ratio 0.30. The laboratory experimental research work results contain fly ash percentage replacement level at 25 and 50% in Portland cement and inclusion of both ends hooked type of steel fibers along with 1.50% of superplasticizers by weight of binder content for the various mix produced for the good tracking of the UPV values by using fabricating Plexiglas moulds, Pozzolanic Activity Index (PAI), if the compressive strength increases automatically less volumetric shrinkage takes place.

Greening of Concrete Industry by Incorporating Gypsum-Based Industrial Wastes as Supplementary Cementitious Materials

2013 ◽  
Vol 649 ◽  
pp. 246-249 ◽  
Author(s):  
Ionut Ovidiu Toma ◽  
Daniel Covatariu ◽  
Ana Maria Toma ◽  
George Taranu ◽  
Mihai Budescu
Keyword(s):  
Calcium Sulphate ◽  
Cementitious Materials ◽  
Strength Properties ◽  
The Self ◽  
Industrial Wastes ◽  
Strength Characteristics ◽  
Supplementary Cementitious Materials ◽  
Supplementary Cementitious Material ◽  
Curing Conditions ◽  
Mix Proportion

The paper presents some preliminary results on using a new supplementary Cementitious material based on industrial by-products most of them unrecyclable until recently. The opportunity for using such industrial unrecyclable wastes in construction industry has recently been recognized by researchers as having net benefits for the environment. This strategy has the potential to reduce costs, conserve energy and minimize waste. The concept very much fits into the era of sustainable development. In view of this fact, the effect of curing conditions on the self weight and strength characteristics of an eco-mortar is studied and preliminary encouraging results are presented. The eco-cement, in the form of anhydrous calcium sulphate, is set to replace the ordinary Portland cement in the mix proportion. It is made from industrial wastes and can be entirely recycled after its expiration date. The curing conditions consisted in air curing for 28 days or various time intervals for curing in water until the day of testing. The strength properties at the age of 28 days are investigated in terms of bending tensile strength and compressive strength. The obtained results show that the curing conditions play an important role both on the self weight and on the strength characteristics.

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