scholarly journals Modified Cement System: Durability and Aesthetics

2009 ◽  
Vol 1 (1) ◽  
pp. 1-4
Author(s):  
Mohamed J. S. Z. ◽  
Mohamed S.N.
Keyword(s):  
Fly Ash ◽  
Cement Hydration ◽  
Structural Defects ◽  
Brick Wall ◽  
Concrete Deterioration ◽  
Water Based ◽  
Cement System ◽  
The Way

Concrete deterioration is one of the most concern matters in construction world. The concrete deterioration such as efflorescence should not be ignored. The efflorescence is a deposit salts, usually white, formed on a surface of concrete. The efflorescence is not a major problem that leads to structural defects but it can build unattractiveness to the structure such as brick wall and concrete mortar. The way to prevent the efflorescence occurrence is by studying the results of testing such as absorption and efflorescence itself to reduce the efflorescence. The non-modified cement system can reduce the efflorescence but cannot avoid it because of the reaction of cement hydration itself. This study is to prove that by using a modified cement system such as Pulverized Fly Ash (PFA) and Polymers (water based latex grade 29Y46), the efflorescence of the mortar can be prevented. The results from this study proved the modified mortar which is a sample with PFA and Polymers has higher strength, durability, and less efflorescence compared with the non-modified cement system.

scholarly journals Effect of Morphologically Controlled Hematite Nanoparticles on the Properties of Fly Ash Blended Cement

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1003
Author(s):  
Pantharee Kongsat ◽  
Sakprayut Sinthupinyo ◽  
Edgar A. O’Rear ◽  
Thirawudh Pongprayoon
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Size Distribution ◽  
Cement Hydration ◽  
Blended Cement ◽  
Spherical Shape ◽  
Particle Sizes ◽  
Fe2o3 Nanoparticles ◽  
Structure And Properties ◽  
Hematite Nanoparticles

Several types of hematite nanoparticles (α-Fe2O3) have been investigated for their effects on the structure and properties of fly ash (FA) blended cement. All synthesized nanoparticles were found to be of spherical shape, but of different particle sizes ranging from 10 to 195 nm depending on the surfactant used in their preparation. The cement hydration with time showed 1.0% α-Fe2O3 nanoparticles are effective accelerators for FA blended cement. Moreover, adding α-Fe2O3 nanoparticles in FA blended cement enhanced the compressive strength and workability of cement. Nanoparticle size and size distribution were important for optimal filling of various size of pores within the cement structure.

Assessment of Hydration Degree of Cement in the Fly Ash-Cement Pastes Based on the Calcium Hydroxide Content

2014 ◽  
Vol 875-877 ◽  
pp. 177-182 ◽  
Author(s):  
Xiang Li ◽  
Hua Quan Yang ◽  
Ming Xia Li
Keyword(s):  
Fly Ash ◽  
Calcium Hydroxide ◽  
Cement Hydration ◽  
Ash Content ◽  
Content Increase ◽  
Hydration Degree ◽  
Equilibrium Calculation ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Water Cement Ratio

The hydration degree of fly ash and the calcium hydroxide (CH) content were measured. Combined with the equilibrium calculation of cement hydration, a new method for assessment of the hydration degree of cement in the fly ash-cement (FC) pastes based on the CH content was developed. The results reveal that as the fly ash content increase, the hydration degree of fly ash and the CH content decrease gradually; at the same time, the hydration degree of cement increase. The hydration degree of cement in the FC pastes containing a high content of fly ash (more than 35%) at 360 days is as high as 80%, even some of which hydrates nearly completely. The effect of water-cement ratio to the hydration degree of cement in the FC pastes is far less distinct than that of the content of fly ash.

Influence of biomass fly ash additive on blast-furnace cement hydration and hardening

2017 ◽  
Vol 29 (8) ◽  
pp. 313-321
Author(s):  
Rimvydas Kaminskas ◽  
Vytautas Cesnauskas ◽  
Raimonda Kubiliute
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Cement Hydration ◽  
Biomass Fly Ash ◽  
Blast Furnace Cement

scholarly journals Effect of Nanosilica on Impermeability of Cement-Fly Ash System

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Huaqing Liu ◽  
Yan Zhang ◽  
Ruiming Tong ◽  
Zhaoqing Zhu ◽  
Yang Lv
Keyword(s):  
Fractal Dimension ◽  
Fly Ash ◽  
Bond Strength ◽  
Pore Structure ◽  
Calcium Hydroxide ◽  
Cement Hydration ◽  
Pozzolanic Reaction ◽  
Surface Protection ◽  
Durability Of Concrete

Surface protection has been accepted as an effective way to improve the durability of concrete. In this study, nanosilica (NS) was used to improve the impermeability of cement-fly ash system and this kind of material was expected to be applied as surface protection material (SPM) for concrete. Binders composed of 70% cement and 30% fly ash (FA) were designed and nanosilica (NS, 0–4% of the binder) was added. Pore structure of the paste samples was evaluated by MIP and the fractal dimension of the pore structure was also discussed. Hydrates were investigated by XRD, SEM, and TG; the microstructure of hydrates was analyzed with SEM-EDS. The results showed that in the C-FA-NS system, NS accelerated the whole hydration of the cement-FA system. Cement hydration was accelerated by adding NS, and probably, the pozzolanic reaction of FA was slightly hastened because NS not only consumed calcium hydroxide by the pozzolanic reaction to induce the cement hydration but also acted as nucleation seed to induce the formation of C-S-H gel. NS obviously refined the pore structure, increased the complexity of the pore structure, and improved the microstructure, thereby significantly improving the impermeability of the cement-FA system. This kind of materials would be expected to be used as SPM; the interface performance between SPM and matrix, such as shrinkage and bond strength, and how to cast it onto the surface of matrix should be carefully considered.

Microclimate Variations with Wall Configurations for Chinese Solar Greenhouses

2013 ◽  
Vol 291-294 ◽  
pp. 931-937 ◽  
Author(s):  
Hui Xu ◽  
Lan Jie Zhao ◽  
Guo Hong Tong ◽  
Yi Qing Cui ◽  
Tian Lai Li
Keyword(s):  
Thermal Stability ◽  
Fly Ash ◽  
Cooling Rate ◽  
Heating Rate ◽  
Small Hole ◽  
Brick Wall ◽  
Optimal Temperature ◽  
Clay Brick ◽  
The North ◽  
Hollow Brick

Five greenhouses with different typical wall configurations were studied, including the hollow brick wall (HB), clay brick wall composed of mural column (MCCB), wall composed of fly ash air block brick (FAABB), clay brick wall composed of plum small hole column (PSHCCB), common clay brick wall with Styrofoam wall outside (SCB) to find out the effects of the north walls on the greenhouse microclimate. The interior temperature and RH environment, as well as the heating rate, cooling rate and the correlation with the outside temperature, were tested and compared, finding that the greenhouse with FAABB exhibits the optimal temperature and RH environment, and also the highest thermal stability. The findings may provide references for greenhouse construction and insulation measures.

Bamboo-Shaped Carbon Nanotubes on Coal Fly Ash Cenospheres for Pb(II) Adsorption

2020 ◽  
Vol 20 (8) ◽  
pp. 5089-5095
Author(s):  
Xiaomin Zhang ◽  
Jin Li ◽  
Bo He ◽  
Heng Li ◽  
Chao Qi ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Fly Ash ◽  
Adsorption Capacity ◽  
Active Sites ◽  
Coal Fly Ash ◽  
Chemical Vapor ◽  
Structural Defects ◽  
3D Network ◽  
Supporting Material ◽  
High Level

The structural defects of bamboo-shaped carbon nanotubes (B-CNTs) provide abundant active sites for ion adsorption during wastewater treatment. However, a suitable supporting material for the growth of B-CNTs growth is less reported. In this paper, the catalytic growth of B-CNTs on the cenospheres (CSs) of coal fly ash was studied. The results showed that all CSs were covered by a layer of B-CNTs during the chemical vapor deposition (CVD) process, regardless of the fluctuation of the iron distribution from 0.52 to 2.09 wt%. B-CNTs with a diameter of 30–40 nm shared a similar morphology of compartment structures, which were uniformly scattered on the surfaces of the CSs and formed a 3D network structure. A high level of structural defects was present on the B-CNTs, which was denoted by an ID/IG value of 1.77 via Raman spectrum analysis. Adsorption experiments of the as-prepared CSs@B-CNTs revealed an excellent adsorption capacity for lead ions of 37.32 mg/g (pH 7, initial concentration of 70 mg/L). By excluding the function of CSs, the adsorption capacity of the pure B-CNTs was estimated to be as high as 275.19 mg/g, which has not been previously reported.

Research on Mechanism of Architectural Wastes Solidified by Alkali-Activated Cement and Fly Ash

2012 ◽  
Vol 446-449 ◽  
pp. 2708-2713 ◽  
Author(s):  
Qin Li ◽  
Xiao Jun Zhou ◽  
Zhuo Yin Jiang ◽  
Ke Wei Sun
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Hydration Products ◽  
Testing Methods ◽  
Fly Ashes ◽  
Comparison Research ◽  
Cement System ◽  
Cementitious System ◽  
Micro Morphology ◽  
Alkali Activated

An comparison research on the effect of pozzolanic reactions of fly ashes in architectural wastes recycle is described in the paper. In the experiment, NaOH and Na2SO4-Ca(OH)2 were used to activate the pozzolanic activities in the fly ashes—cement system to solidify the architectural wastes. The macro and micro testing methods were used to test the compressive strength, phase and electronic micro morphology of the hydration of alkali-activated fly ashes—cement cementitious system. The testing result shows that proper alkali-activated fly ashes—cement cementitious architectural wastes can shorten the incubation time of the pozzolanic reactions of fly ashes, whi ch make the reactions of fly ashes more sufficient. So the hydration products of fly ashes —cement cementitious system with alkali additions were more than those of without alkali add itions, and the compressive strength of the alkali-activated fly ashes—cement cementitious system is higher than that of non alkali-activated fly ashes—cement cementitious system.

Micromechanical Properties of Calcium Silicate Hydrate

2013 ◽  
Vol 539 ◽  
pp. 75-79
Author(s):  
Wu Yao ◽  
Li He
Keyword(s):  
Fly Ash ◽  
Reaction Zone ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Cement Hydration ◽  
Cementitious Materials ◽  
Pozzolanic Reaction ◽  
Indentation Modulus ◽  
Micromechanical Properties ◽  
Secondary Hydration

The indentation modulus of several cementitious materials is discussed with the assumption that the C-S-H gel is an aggregation of precipitated, colloidal-sized particles. At least two kinds of structurally distinct but compositional similar phases are found existent during the hydration process. In addition, the C-S-H originated from the pozzolanic reaction of fly ash is found to be the same to that of cement hydration in micromechanical properties; however, the C-S-H gel formed from the secondary hydration is inclined to develop into high density packing configuration, due to the limitation of reaction zone available.

Effects of colloidal nanoBoehmite and nanoSiO2 on fly ash cement hydration

2015 ◽  
Vol 101 ◽  
pp. 246-251 ◽  
Author(s):  
Jianping Zhu ◽  
Chunhua Feng ◽  
Haibin Yin ◽  
Zhanying Zhang ◽  
Surendra P. Shah
Keyword(s):  
Fly Ash ◽  
Cement Hydration
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