scholarly journals Influence of stone cutting waste and ground waste clay brick on the hydration and packing density of cement pastes

2013 ◽  
Vol 6 (4) ◽  
pp. 661-680 ◽  
Author(s):  
C. A. A. Rocha ◽  
G. C. Cordeiro ◽  
R. D. Toledo Filho
Keyword(s):  
Compressive Strength ◽  
Binary Mixture ◽  
Packing Density ◽  
Cement Hydration ◽  
Clay Brick ◽  
Cement Pastes ◽  
Strength Tests ◽  
Stone Cutting ◽  
Small Acceleration ◽  
Compressible Packing Model

The present work aims to study the replacement of Portland cement (PC) by stone cutting waste (SW) and ground waste clay brick (BW) in binary and ternary pastes. Thermogravimetry and differential thermal analysis tests were carried out at various ages in order to investigate the development of the cement hydration reactions in the presence of those wastes. The packing density was calculated in accordance with the Compressible Packing Model to understand the physical effect of those wastes. Compressive strength tests were also performed and the results were related to hydration and packing. Considering the substitution levels studied, the results indicated that the use of SW in the binary mixture accelerated the hydration reactions, and the particles packing density and compressive strength were maintained. The use of BW in the binary mixture caused a small acceleration in the hydration reactions and there was an indication of pozzolanic activity, although the compressive strength was reduced in comparison with the reference paste. In the ternary mixture, the combined effect of both wastes resulted in the maintenance of compressive strength for cement replacement content of 30%.

Influences of Micropowder Gradation on Rheological Properties of Cement-Based Composite Pastes

2007 ◽  
Vol 353-358 ◽  
pp. 1398-1401
Author(s):  
Jian Qing Gong ◽  
Han Ning Xiao ◽  
Zheng Yu Huang ◽  
Jiu Su Li ◽  
Jing Nie ◽  
...  
Keyword(s):  
Shear Stress ◽  
Rheological Properties ◽  
Packing Density ◽  
High Performance ◽  
High Performance Concrete ◽  
Plastic Viscosity ◽  
Rheological Parameters ◽  
Ultra High Performance Concrete ◽  
Cement Pastes ◽  
Compressible Packing Model

The rheological parameters of cement pastes were investigated by varying the type and content of micropowders and the ratio of water to binder. Compressible packing model was used to calculate the packing density and to evaluate the influence of micropowders gradation on the rheological properties of fresh cement pastes. Results indicate that the higher the packing density is, the lower the yielding shear stress and plastic viscosity will be. When the ratio of water to binder is less than 0.20, the cement paste with 15% UFA and 15% SF has highest packing density and lowest yielding shear stress and plastic viscosity, which is beneficial to the workability of ultra-high performance concrete.

Effects of Packing Density of Micropowders on the Compressive Strength of Cement Pastes

2007 ◽  
Vol 353-358 ◽  
pp. 1394-1397
Author(s):  
Jian Qing Gong ◽  
Han Ning Xiao ◽  
Zheng Yu Huang ◽  
Jiu Su Li ◽  
Rong Kui Cao ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Packing Density ◽  
Cement Pastes

This study was performed to evaluate the effects of micropowders content on the compressive strength of cement-based composite pastes. Granular ground blast slag (GGBS), grade I fly ash (FAI), ultra fine fly ash (UFA) and silica fume (SF) were selected as the micropowders. The compressive strength was tested after 3d, 7d and 28d curing. Results show that the paste containing both UFA and SF has the highest packing density and corresponding excellent compressive strength. The higher the packing density is, the better the compacting and filling effect of micropowders will be, which contributes to developing higher compressive strength of cement-based pastes.

Nanofibrillated cellulose as nanoreinforcement in Portland cement: Thermal, mechanical and microstructural properties

2016 ◽  
Vol 51 (17) ◽  
pp. 2491-2503 ◽  
Author(s):  
Roukaya Mejdoub ◽  
Halim Hammi ◽  
Joan Josep Suñol ◽  
Mohamed Khitouni ◽  
Adel M‘nif ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Cement Hydration ◽  
Coefficient Of Thermal Expansion ◽  
Nanofibrillated Cellulose ◽  
Partial Replacement ◽  
Cellulose Content ◽  
Cement Pastes ◽  
Eucalyptus Pulp ◽  
Reinforced Cement ◽  
Mechanical And Microstructural Properties

Nanofibrillated cellulose from eucalyptus pulp, produced by high-pressure homogenization, was used as cement partial replacement for cement paste at a content ranging from 0% to 0.5% by weight of cement. The effect of the content of nanofibrillated cellulose on porosity, thermal properties, compressive strength and degree of cement hydration was investigated. Results have shown an improvement in the compressive strength by more than 50% with 0.3 wt% of added nanofibrillated cellulose. The porosity was reduced by nanofibrillated cellulose addition, and the greatest result was achieved with mixture incorporating 0.3 wt% nanofibrillated cellulose. The coefficient of thermal expansion and the thermal conductivity measurements, relative to nanofibrillated cellulose-reinforced cement pastes, have pointed out the reinforcement effectiveness of nanofibrillated cellulose. The degree of cement hydration has increased with nanofibrillated cellulose content. This trend was confirmed by X-ray diffraction and Fourier Transform Infrared spectroscopy. These analyses have revealed that the presence of nanofibrillated cellulose promoted the hydration of cement, by producing more portlandite and calcium silicate gel, which is likely the main reason accounting for the strong enhancement in the compressive strength.

Effects of Packing Density of Micropowders on the Compressive Strength of Cement Pastes

2007 ◽  
pp. 1394-1397
Author(s):  
Jian Qing Gong ◽  
Han Ning Xiao ◽  
Zheng Yu Huang ◽  
Jiu Su Li ◽  
Rong Kui Cao ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Packing Density ◽  
Cement Pastes

scholarly journals The effects of seawater on the hydration, microstructure and strength development of Portland cement pastes incorporating colloidal silica

2019 ◽  
Vol 10 (8) ◽  
pp. 2627-2638 ◽  
Author(s):  
Pawel Sikora ◽  
Krzysztof Cendrowski ◽  
Mohamed Abd Elrahman ◽  
Sang-Yeop Chung ◽  
Ewa Mijowska ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Synergistic Effect ◽  
Portland Cement ◽  
Colloidal Silica ◽  
Cement Hydration ◽  
Pozzolanic Reaction ◽  
Strength Development ◽  
Hydration Kinetics ◽  
Cement Pastes ◽  
Noticeable Improvement

AbstractThis contribution investigates the effects of seawater and colloidal silica (NS) in the amounts of 1, 3 and 5 wt%, respectively, on the hydration, strength development and microstructural properties of Portland cement pastes. The data reveal that seawater has an accelerating effect on cement hydration and thus a significant contribution to early strength development was observed. The beneficial effect of seawater was reflected in an improvement in compressive strength for up to 14 days of hydration, while in the 28 days compressive strength values were comparable to that of cement pastes produced with demineralized water. The combination of seawater and NS significantly promotes cement hydration kinetics due to a synergistic effect, resulting in higher calcium hydroxide (CH) production. NS can thus react with the available CH through the pozzolanic reaction and produce more calcium silicate hydrate (C-S-H) gel. A noticeable improvement of strength development, as the result of the synergistic effect of NS and seawater, was therefore observed. In addition, mercury intrusion porosimetry (MIP) tests confirmed significant improvements in microstructure when NS and seawater were combined, resulting in the production of a more compact and dense hardened paste structure. The optimal amount of NS to be mixed with seawater, was found to be 3 wt% of cement.

Effects of Fineness on Activity Character of Fly Ash

2011 ◽  
Vol 266 ◽  
pp. 114-117
Author(s):  
Zhong Tao Luo ◽  
Bao Guo Ma ◽  
Jiu Jun Yang ◽  
Jun Xia Liu
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Cement Hydration ◽  
Chemical Activation ◽  
Cement Pastes ◽  
Starting Point ◽  
Aggregate Effect ◽  
Granule Morphology ◽  
Morphology Effect ◽  
Micro Analysis

The hydrated character of cement paste with fly ash was studied, through the methods of compressive strength, non-evaporable water content, reaction degree of fly ash and micro-analysis. The results indicated that the chemical activity of fly ash was an accumulative change process under this test condition. The starting point of chemical reaction of fly ash was nearby 28 days. In front of 28 days, the chemical activation of fly ash was not wakened, and the compressive strength of cement pastes with fly ash at this age was mainly from multiplex effects of cement hydration and the micro-aggregate effect, granule morphology effect and pozzolanic effect of fly ash.

scholarly journals Influence of Gypsum Waste Utilization on Properties and Leachability of Fired Clay Brick

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2800
Author(s):  
Nur Jannah Abdul Hamid ◽  
Aeslina Abdul Kadir ◽  
Nurul Nabila Huda Hashar ◽  
Paweł Pietrusiewicz ◽  
Marcin Nabiałek ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Compressive Strength ◽  
Physical And Mechanical Properties ◽  
Waste Utilization ◽  
Firing Process ◽  
Dry Density ◽  
Clay Brick ◽  
Strength Tests ◽  
Synthetic Precipitation ◽  
Synthetic Precipitation Leaching Procedure

Wastewater treatment activities in the chemical industry have generated abundant gypsum waste, classified as scheduled waste (SW205) under the Environmental Quality Regulations 2005. The waste needs to be disposed into a secure landfill due to the high heavy metals content which is becoming a threat to the environment. Hence, an alternative disposal method was evaluated by recycling the waste into fired clay brick. The brick samples were incorporated with different percentages of gypsum waste (0% as control, 10, 20, 30, 40 and 50%) and were fired at 1050 °C using 1 °C per minute heating rate. Shrinkage, dry density, initial rate of suction (IRS) and compressive strength tests were conducted to determine the physical and mechanical properties of the brick, while the synthetic precipitation leaching procedure (SPLP) was performed to scrutinize the leachability of heavy metals from the crushed brick samples. The results showed that the properties would decrease through the incorporation of gypsum waste and indicated the best result at 10% of waste utilization with 47.5% of shrinkage, 1.37% of dry density, 22.87% of IRS and 28.3% of compressive strength. In addition, the leachability test highlighted that the concentrations of Fe and Al was significantly reduced up to 100% from 4884 to 3.13 ppm (Fe) and from 16,134 to 0.81 ppm (Al), respectively. The heavy metals content in the bricks were oxidized during the firing process, which signified the successful remediation of heavy metals in the samples. Based on the permissible incorporation of gypsum waste into fired clay brick, this study promised a more green disposing method for gypsum waste, and insight as a potential towards achieving a sustainable end product.

Effect of Plasticizing Admixtures on the Development of Hydration Temperatures and the Properties of Cement Pastes

2018 ◽  
Vol 761 ◽  
pp. 116-119
Author(s):  
Martin Sedlmajer ◽  
Jiri Zach ◽  
Jitka Hroudova
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Cement Hydration ◽  
Hydration Heat ◽  
Close Monitoring ◽  
Cement Pastes ◽  
Concrete Members

The hydration of cement is a very intricate process. A great amount of heat is generated during the reaction, which requires close monitoring especially in large concrete members. Modified cement pastes are simpler systems and can be easily used to observe the effect of plasticizing admixtures on the development of temperatures during cement hydration as well as its rheology and mechanical properties. Knowledge of the development of hydration temperatures can be of assistance in deliberate regulation of cement hydration and the generation of hydration heat. The paper describes what influence different amounts of different plasticizers have on the properties of cement pastes, with added focus on the development of their hydration temperatures, rheology and compressive strength.

scholarly journals Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1611
Author(s):  
Gintautas Skripkiūnas ◽  
Asta Kičaitė ◽  
Harald Justnes ◽  
Ina Pundienė
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

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