scholarly journals Effect of Different Activators on Rheological and Strength Properties of Fly Ash-Based Filling Cementitious Materials

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Liu Fangfang ◽  
Feng Xiyang ◽  
Chen Li
Keyword(s):  
Fly Ash ◽  
Cementitious Materials ◽  
Strength Properties ◽  
Orthogonal Test ◽  
Activation Mechanism ◽  
Hydration Products ◽  
Cement Slurry ◽  
Hydration Degree ◽  
Bleeding Rate ◽  
Optimal Scheme

In this paper, lime, gypsum, NaOH, and Na2SO4 are mainly used to study the activation degree and activation mechanism of fly ash, and L9 (34) orthogonal table is used for the orthogonal test. The influence of different activators on the rheological and strength properties of slurry was analyzed. The microstructure and hydration products of fly ash cement cementitious body were studied by SEM and XRD. The results show that the bleeding rate of slurry containing activator fly ash system is between 2.24% and 3.37%, which is much higher than that of pure cement slurry (9.25%). Therefore, the addition of this system can improve the fluidity of slurry, and the optimal scheme is a3b2c2d2. The results show that the compressive strength of cement with activator fly ash system is much lower than that of pure cement, but the increase of strength is between 31% and 85%, which is much greater than that of pure cement (35%–46%). The optimal scheme is A2B2C3D3 or A3B2C3D3 at 3 days and A1B3C2D3 at 28 days. According to the scanning results of SEM and XRD, the addition of activator can significantly improve the hydration degree of fly ash and form a more complex network structure without obvious gap.

MECHANICAL AND DURABILITY CHARACTERISTICS OF GGBS DOLOMITE GEOPOLYMER CONCRETE

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Aikot Pallikkara Shashikala ◽  
Praveen Nagarajan ◽  
Saranya Parathi
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Setting Time ◽  
Cementitious Materials ◽  
Strength Properties ◽  
Industrial Wastes ◽  
Geopolymer Concrete ◽  
By Products

Production of Portland cement causes global warming due to the emission of greenhouse gases to the environment. The need for reducing the amount of cement is necessary from sustainability point of view. Alkali activated and geopolymeric binders are used as alternative to cement. Industrial by-products such as fly ash, ground granulated blast furnace slag (GGBS), silica fume, rice husk ash etc. are commonly used for the production of geopolymer concrete. This paper focuses on the development of geopolymer concrete from slag (100% GGBS). Effect of different cementitious materials such as lime, fly ash, metakaolin, rice husk ash, silica fume and dolomite on strength properties of slag (GGBS) based geopolymer concrete are also discussed. It is observed that the addition of dolomite (by-products from rock crushing plants) into slag based geopolymer concrete reduces the setting time, enhances durability and improves rapidly the early age strength of geopolymer concrete. Development of geopolymer concrete with industrial by-products is a solution to the disposal of the industrial wastes. The quick setting concrete thus produced can reduce the cost of construction making it sustainable also.

scholarly journals Equivalent CO2 Emission and Cost Analysis of Green Self-Compacting Rubberized Concrete

2021 ◽  
Vol 14 (1) ◽  
pp. 137
Author(s):  
Sylvia E. Kelechi ◽  
Musa Adamu ◽  
Abubakar Mohammed ◽  
Ifeyinwa I. Obianyo ◽  
Yasser E. Ibrahim ◽  
...  
Keyword(s):  
Fly Ash ◽  
Co2 Emission ◽  
Calcium Carbide ◽  
Crumb Rubber ◽  
Cementitious Materials ◽  
Strength Properties ◽  
Cementitious Material ◽  
Ternary Blend ◽  
Fine Aggregate ◽  
Concrete Production

Global warming and climate changes are the major environmental challenges globally. With CO2 emission being one of the main greenhouse gases emitted to the environment, and cement and concrete production amounting to about 10% of the global CO2 emission, there is a need for the construction industry to utilize an environmentally sustainable material as an alternative to cement. This study analyzed the cost, CO2 emission and strength properties of green self-compacting concrete (SCC) ternary blend containing fly ash, calcium carbide residue (CCR), and crumb rubber (CR) as a replacement material by volume of cement, cementitious material, and fine aggregate, respectively. Cement was replaced with fly ash at 0 and 40% by volume. CCR was used as a replacement at 5 and 10% by volume of cementitious materials, CR replaced fine aggregate in proportions of 10 and 20% by volume. The result indicated that the mix with 0% fly ash and 20% CR replacement of fine aggregate was the most expensive and had the highest CO2 emission. However, the mix with 10% CR, 40% fly ash, and 10% CCR had the lowest CO2 emission and was therefore the greenest SCC mix. The 28-day maximum compressive strength of 45 MPa was achieved in a mix with 0% CR, 0% fly ash, and 10% CCR, while the utmost 28-day splitting tensile strength of 4.1 MPa was achieved with a mix with 10% CR, 0% fly ash, and 5% CCR, and the highest flexural strength at 28 days was 6.7 MPa and was also obtained in a mix with 0% CR, 0% fly ash, and 5% CCR. In conclusion, a green SCC can be produced by substituting 40% cement with fly ash, 10% fine aggregate with CR, and 10% CCR as a replacement by volume of cementitious material, which is highly affordable and has an acceptable strength as recommended for conventional SCC.

scholarly journals Development of Fly Ash Composite Binder and Optimization of Slurry Ratio

2021 ◽  
Author(s):  
Qingfeng Zhuo ◽  
Lei Ba ◽  
Jing Wang ◽  
Qifeng Wang
Keyword(s):  
Fly Ash ◽  
Mass Fraction ◽  
Cementitious Materials ◽  
Physicochemical Analysis ◽  
Ratio Test ◽  
Composite Binder ◽  
Bleeding Rate ◽  
Slag Powder ◽  
Body Strength ◽  
Cemented Backfill

In view of the high cost of cement filling, the new cementitious materials are developed by using solid waste resources. Firstly, on the basis of material physicochemical analysis, the fly ash composite cementation ratio test and optimization test are carried out to determine the optimal ratio. Then, the filling body strength and pipeline transportation characteristics test are carried out to analyze they influence law. Finally, the genetic algorithm is used to optimize the slurry ratio. The results show that the strength of cemented backfill increases linearly with the increase of slurry concentration; The slump and bleeding rate of slurry decrease with the increase of slurry mass fraction, and increase with the decrease of binder sand ratio, the optimal proportion of fly ash (FA) based composite binder is w(FA): w(clinker): w (desulfurized gypsum (DG)): w (slag powder (SP)) =40:12:12:36; The optimum slurry ratio is 1:4 of binder/sand and 72% of concentration.

Hydrates and Paste Structure of Slag-Fly Ash Based Cementitious Materials

2012 ◽  
Vol 450-451 ◽  
pp. 557-562
Author(s):  
Cheng Hong Fu ◽  
Wen Ni ◽  
Hui Wu ◽  
De Zhong Li
Keyword(s):  
Fly Ash ◽  
Raw Materials ◽  
High Volume ◽  
Cementitious Materials ◽  
Sem Analysis ◽  
Cement Clinker ◽  
Hydration Reaction ◽  
Hydration Products ◽  
Chemical Action ◽  
Oxygen Tetrahedron

Cascade grinding mode is often applied to prepare Slag-Fly Ash Based cementitious materials with high volume of fly ash and slag and less cement clinker. This process has low water requirement and well fluidity, which is suitable to prepare HPC．When the W/C is 0.36, the 28d compressive strength is 58.93 Mpa, 28d flexural strength is 14.26 Mpa. By X-Ray diffraction analysis (XRD) and Scanning Electron Microscope (SEM) analysis the results show that main materials in grinded sample are well activated by mechanical force and chemical action; more Aft are produced and observed in 3 days hydration products and the great amount of C-S-H gel has continuously generated with the growth of hydration time. By Infrared(IR) analysis, the results show that in the hydration products, the network of Silicon Oxygen Tetrahedron and Aluminum Oxygen Tetrahedra have depolymerized significantly; in the hydration process and various raw materials mutually promoted each other to accelerate the hydration reaction. The hydrates and paste structure of slag-fly ash based cementitious materials were explained．

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.

The Assessment of Expansion Performance of Expansive Agent in Composite Cementitious Materials and its Mix Design

2010 ◽  
Vol 168-170 ◽  
pp. 2028-2032 ◽  
Author(s):  
Miao Miao ◽  
Pei Yu Yan ◽  
Jing Jing Feng
Keyword(s):  
Fly Ash ◽  
Critical Value ◽  
Cementitious Materials ◽  
Ash Content ◽  
Orthogonal Test ◽  
Mix Design ◽  
Slight Improvement ◽  
Expansive Agent ◽  
Binder Ratio ◽  
Water Binder Ratio

The expansion performance of expansive agent in cement-HCSA-fly ash cementitious materials and its coordination with strength were studied by orthogonal test. Shrinkage-compensating mortars were prepared. The results show that the restrained expansion rate (RER) of mortars cured moistly, RER residue and expansion decline rate of mortars stored drily after 7d are well consistent with each other to assess the expansion performance of expansive agent. Increase of expansive agent content and decrease of fly ash content can lead to the growth of RER. The impacts of all the factors on RER of moistly-cured mortars are becoming steady when the age is longer than 7days. The 7-day RER of 6.35×10-4 is the critical value to judge whether the shrinkage of expansive mortar occurs after it moved from moisture into dry air at 7d. The expansive agent content has no need to exceed 10% in view of compensation efficiency unless slight improvement of expansion performance is desired. 35~50%, 20~50% and 20~35% of fly ash content are recommended respectively for water-binder ratio of 0.32 0.36 and 0.40 to obtain better coordination of expansion and strength.

scholarly journals Mechanical properties, pozzolanic activity and volume stability of copper slag-filled cementitious materials

2019 ◽  
Vol 26 (2) ◽  
pp. 218-224
Author(s):  
Junwei SONG ◽  
Shenglei FENG ◽  
Rongrong XIONG ◽  
Yong OUYANG ◽  
Qingli ZENG ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Fly Ash ◽  
Copper Slag ◽  
Cementitious Materials ◽  
Pozzolanic Activity ◽  
Potential Danger ◽  
Hydration Products ◽  
Volume Stability ◽  
Local Residents

Copper slag is a by-product waste during copper pyrometallurgy. The piling-stack of copper slag not only occupies a large quantity of plowland, but causes potential danger for local residents. In order to reduce the storage of copper slag, this study prepared concretes by replacing ordinary cement by copper slag. The mechanical properties, phase composition, micrographs, pozzolanic activity and volume stability of the compound cementitious materials were evaluated with fly ash as control. It was found that when the content of copper slag was 5%-10%, the best mechanical properties of concretes were obtained. The phase composition of hydration products of copper slag and fly ash based cementitious materials was almost identical. The micrographs and pozzolanic activity showed that copper slag had stronger reactivity than fly ash. Copper slag based pastes had good volume stability. Copper slag presented a potential application in mortars and concretes.

Effect of ground granulated blast funrnace slag and fly ash on strength, permeability, and under-water abrasion of fine-grained concrete

2020 ◽  
Vol 71 (7) ◽  
pp. 775-788
Author(s):  
Quyet Truong Van ◽  
Sang Nguyen Thanh
Keyword(s):  
Fly Ash ◽  
Concrete Strength ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Chloride Permeability ◽  
Cement Replacement ◽  
Fine Grained ◽  
Granulated Blast Furnace Slag ◽  
Compressive Strength Test ◽  
Economic Ground

The utilisation of supplementary cementitious materials (SCMs) is widespread in the concrete industry because of the performance benefits and economic. Ground granulated blast furnace slag (GGBFS) and fly ash (FA) have been used as the SCMs in concrete for reducing the weight of cement and improving durability properties. In this study, GGBFS at different cement replacement ratios of 0%, 20%, 40% and 60% by weight were used in fine-grained concrete. The ternary binders containing GGBFS and FA at cement replacement ratio of 60% by weight have also evaluated. Flexural and compressive strength test, rapid chloride permeability test and under-water abrasion test were performed. Experimental results show that the increase in concrete strength with GGBFS contents from 20% to 40% but at a higher period of maturity (56 days and more). The chloride permeability the under-water abrasion reduced with the increasing cement replacement by GGBFS or a combination of GGBFS and FA

scholarly journals Effect of C-S-H Nucleating Agent on Cement Hydration

2021 ◽  
Vol 11 (14) ◽  
pp. 6638
Author(s):  
Wenhao Zhao ◽  
Xuping Ji ◽  
Yaqing Jiang ◽  
Tinghong Pan
Keyword(s):  
Fractal Dimension ◽  
Cement Hydration ◽  
Nucleating Agent ◽  
Crystal Nucleation ◽  
Enhancement Effect ◽  
Hydration Products ◽  
Hydration Degree ◽  
Hydration Kinetics ◽  
Cement Mortars ◽  
Early Strength

This work aims to study the effect of a nucleating agent on cement hydration. Firstly, the C-S-H crystal nucleation early strength agent (CNA) is prepared. Then, the effects of CNA on cement hydration mechanism, early strength enhancement effect, C-S-H content, 28-days hydration degree and 28-days fractal dimension of hydration products are studied by hydration kinetics calculation, resistivity test, BET specific surface area test and quantitative analysis of backscattered electron (BSE) images, respectively. The results show that CNA significantly improves the hydration degree of cement mixture, which is better than triethanolamine (TEA). CNA shortens the beginning time of the induction period by 49.3 min and the end time of the cement hydration acceleration period by 105.1 min than the blank sample. CNA increases the fractal dimension of hydration products, while TEA decreases the fractal dimension. CNA significantly improves the early strength of cement mortars; the 1-day and 3-days strength of cement mortars with CNA are more than the 3-days and 7-days strength of the blank sample. These results will provide a reference for the practical application of the C-S-H nucleating agent.

Sign in / Sign up

Export Citation Format

Share Document