Research on the Compatibility of Cement-Based Biomass Materials Modified by Early-Strength Agents

2015 ◽  
Vol 775 ◽  
pp. 287-291
Author(s):  
Hong Qi ◽  
Wei Qi ◽  
Guo Dong Sheng
Keyword(s):  
Hydration Heat ◽  
Hydration Process ◽  
Maximum Temperature ◽  
Mixed System ◽  
Maximum Temperature Difference ◽  
Early Hydration ◽  
Retarding Effect ◽  
Biomass Materials ◽  
Early Strength ◽  
Better Than

Aim at the slow and complicated hydration process of straw-cement mixed system and the retarding coagulation of cement-based biomass material in C3S reaction. To investigate the improving effect of early-strength agents on the hydration process of straw-cement mixed system by adding CaCl2, FeCl3 and Al2(SO4)3 which could increase the release of hydration heat, accelerate the hydration of cement and weaken the retarding effect of dissolved substances from straw. By testing the variation of temperatures in hydration process to analyze the highest hydration temperature (Tmax), the time of reaching the highest hydration temperature (t), the maximum temperature difference (△T) and the compatibility coefficients (CA) of cement-based biomass materials with modified agents and with no modified agents, and evaluate the compatibility of straw-cement mixed system. Experimental results show that Tmax, t and △T these indexes can intuitively reflect the changing characteristics of early hydration heat of cement-based biomass materials, while CA could reflect the early hydration behavior comprehensively and objectively. Meanwhile, when the dosage of early-strength agents is between 3%~8%, the growth of CA shows as follows: CaCl2 is the best, and FeCl3 is better than Al2(SO4)3.

Study on Compatibility of Modified the Cement-Based Composite Biomass Materials by Agent

2013 ◽  
Vol 539 ◽  
pp. 215-219
Author(s):  
Jun Liu ◽  
Chao Lin ◽  
Wen Hui Sun ◽  
Xu Ming Wang
Keyword(s):  
Temperature Difference ◽  
Testing Temperature ◽  
Maximum Temperature ◽  
Mixed System ◽  
Maximum Temperature Difference ◽  
Early Hydration ◽  
Maximum Value ◽  
Complex Process ◽  
Visual Aid ◽  
Biomass Materials

Abstract. For the slow process of hydration and complex process of hydration of cement-based composite biomass materials, the paper study the compatibility of straw cement mixed system was evaluated in process of hydration. By testing temperature changes in process of hydration of cement-based composite biomass materials and analyzing the maximum value of hydration temperature, the maximum temperature difference and compatibility coefficient of modified the cement-based composite biomass materials by agent, taken before or after that. It was evaluated that compatibility performance of modified the cement-based composite biomass materials by agent. The results show that the characteristic changes of early hydration heat was reflected with a visual aid by some indexes that are the maximum value of hydration temperature, the maximum temperature difference, and so on. And the early hydration behavior was more comprehensive objective reflected by compatibility coefficient in cement-based composite biomass materials. At the same time, the modified effect of sodium silicate was superior to the polyvinyl acetate (PVAc) in the early hydration of the cement-based composite biomass materials.

The Arch Support Construction and Hydration Heat Analysis of the First Bridge over Yangtze River in Hejiang

2013 ◽  
Vol 291-294 ◽  
pp. 1122-1127
Author(s):  
Yan Feng Luo ◽  
Da Yan Qin ◽  
Yun Zhang
Keyword(s):  
Yangtze River ◽  
Casting Process ◽  
Hydration Heat ◽  
Maximum Temperature ◽  
Mass Concrete ◽  
Element Analysis ◽  
Early Hydration ◽  
Mix Proportion ◽  
Arch Support ◽  
Heat Preservation

The arch support of the First Bridge over Yangtze River in Hejiang used the stratified and graded casting process in mass concrete pouring process. By means of optimizing the concrete mix proportion design, using high mixing amount of fly ash concrete, reducing heat release rate of concrete early hydration heat, delaying the time of maximum temperature rise, and combining turn-over forms and water storage and other surface heat preservation measures, the temperature difference between inside and outside concrete was reduced and the cracking of mass concrete was avoided. Finite element analysis of hydration heat was done to verify the feasibility of the construction scheme.

Study on Early Cracking Resistance of PC Box Girder Bridge

2010 ◽  
Vol 163-167 ◽  
pp. 1786-1792
Author(s):  
Wei Chun Zhong ◽  
Xiao Yi Zhang ◽  
Hui Zhou ◽  
Chuang Sheng Zheng
Keyword(s):  
Hydration Heat ◽  
Maximum Temperature ◽  
Strength Development ◽  
Cracking Resistance ◽  
Construction Stage ◽  
Maximum Temperature Difference ◽  
Construction Technique ◽  
Box Girder ◽  
Mixture Ratio ◽  
Girder Bridges

Early cracks of box girder are widespread during the construction stage of PC box girder bridges. The cracking resistance of a prestressed concrete continuous beam bridge was conducted from the point of construction technique. Experimental study on hydration heat and mechanical properties of box girder concrete at early age were carried out. The results shown that the casting temperature of the concrete, the peak temperature and the maximum temperature difference between inside and outside of the hydration heat were very low, which were 15.7°C, 8°C and 10.2°C, respectively. The strength development of the concrete was stable, and the mixture ratio was optimal. The concrete appearance quality was fairly good without visible cracks in the construction stage. The study reveals that the crack of girder bridges during the construction stage can be avoided by taking effective measures in the construction.

Study on Influences Mold Shape Imposes on Bread Heating Distribution

2013 ◽  
Vol 395-396 ◽  
pp. 925-929
Author(s):  
Ze Hua Chen ◽  
Shao Bo Gao ◽  
Shang Xin Yang ◽  
Hai Yang Zhang
Keyword(s):  
Theoretical Model ◽  
Numerical Model ◽  
Great Influence ◽  
Maximum Temperature ◽  
Maximum Temperature Difference ◽  
Distribution Uniformity ◽  
Boundary Curvature ◽  
3D Numerical Model ◽  
Bread Production ◽  
Better Than

A 3D numerical model for heating distribution of bread mold in the oven is presented in this study. In the process of bread production, heat effect is influenced by the shape of the mold. Being consistent with the results of calculation, the shape of the mold imposes great influence on the heating distribution uniformity and maximum temperature difference. Because of even boundary curvature, circular mold behaves better than elliptical and rectangular mold. By utilizing the introduced theoretical model, we are able to get the spatial heating distribution of all kinds of mold. And taking three kinds of mold as example, we illustrate that the more uneven the boundary curvature is, the less uniform the heating distribution will be.

The Effect of Cementation on the Mechanical Properties of Muddy Soil of East-South Coastal Area of China

2013 ◽  
Vol 740 ◽  
pp. 636-639
Author(s):  
Chao Hua Jiang ◽  
Fei Wu ◽  
Tao Wang ◽  
Ke Fan
Keyword(s):  
Mechanical Properties ◽  
Late Stage ◽  
Coastal Area ◽  
Mixing Ratio ◽  
Cement Type ◽  
Early Hydration ◽  
Increase Rate ◽  
Early Strength ◽  
Cement Soil ◽  
Better Than

Based on characteristic of the muddy soil residing in east-south coastal area of China, the effect of cement grade, cement-mixing ration and cement type on mechanical properties of cement-soil was carried out in this paper. The results show that cement-soil increases obviously with increasing of hydration age for different cement types. At early hydration age, strength of cement-soil increases quickly. And at the age of 28d~90d, strength of cement-soil still show quite obvious increasing, but increase rate is slow. Increasing cement-mixing ratio improve strength of cement-soil obviously and 0.15~0.20 cement-mixing ratio is suitable to use. Higher cement grade can bring higher strength of cement-soil. Early strength of cement-soil solidified with P.S32.5 increases slowly, but the middle and late stage strength of cement-soil solidified with P.S32.5 increase quickly. The solidification effect of P.S 32.5 is better than that of AEC32.5 and P.MSR32.5.

Citric Acid on the Hydration Mechanism of Cement

2011 ◽  
Vol 413 ◽  
pp. 174-179
Author(s):  
Bao Guo Ma ◽  
Jun Xiao ◽  
Hong Bo Tan
Keyword(s):  
Citric Acid ◽  
Key Words ◽  
Cement Hydration ◽  
Hydration Heat ◽  
Hydration Process ◽  
Chemical Shrinkage ◽  
Early Hydration ◽  
Hydration Mechanism ◽  
Diffraction Peaks ◽  
Acid Dosage

This article reports on the study to evaluate the hydration process of cement by the addition of citric acid. Through the test of citric acid of cement paste, hydration heat performance, resistivity, chemical shrinkage, and combined with XRD, SEM, DSC-TG discusses the influence of citric acid on cement hydration process. The results thus obtained were compared to the hydration process of cement with the blank sample and vary of dosage of citric acid. The results show that: The early hydration about 1~2 h resistivity increases, dissolve balance stage was extended; The chemical shrinkage increased significantly, and increases with dosage; With the increase in citric acid dosage, AFt diffraction peaks increases, while the CH peak decreases, indicating that the citric acid accelerated the initial hydration of C3A, while inhibiting C3S hydration and promoting AFt generation. Key words: citric acid, mechanism ,hydration heat, resistivity

scholarly journals The Role of Various Powders during the Hydration Process of Cement-Based Materials

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Shuhua Liu ◽  
Hongling Wang ◽  
Jianpeng Wei
Keyword(s):  
Early Stage ◽  
Steel Slag ◽  
Pozzolanic Reaction ◽  
Hydration Process ◽  
Limestone Powder ◽  
Strength Development ◽  
Early Hydration ◽  
Cement Based Materials ◽  
Early Strength

The role of various powders including glass powder (GP), limestone powder (LP), and steel slag powder (SSP) during the hydration process of cement-based materials was investigated by using X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), and strength tests. GP has adverse impact on early strength, but the pozzolanic reaction at later stage enhances the strength development greatly. LP can significantly improve early strength. SSP has a good contribution to the early and later strength of the paste when its content is less than 15%. GP has little effect on the kind of hydration products but relatively large effects on the quantity. Calcium hydroxide (CH) content of GP paste decreases over curing age gradually, which is different from pure cement paste because its pozzolanic activity consumes more CH than that generated from the cement hydration. SSP and LP mainly play a role of filling effect at early stage. Nucleating effect of LP also promotes the early hydration of cement. The hydration of LP occurs at later stage and forms the calcium carboaluminate hydrates. The hydration of SSP is relatively slow, which generates CH at later stage and is effective in the strength development.

scholarly journals The Influence of Water Reducing Agents on Early Hydration Property of Ferrite Aluminate Cement Paste

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 731
Author(s):  
Chunlong Huang ◽  
Zirui Cheng ◽  
Jihui Zhao ◽  
Yiren Wang ◽  
Jie Pang
Keyword(s):  
Setting Time ◽  
Critical Role ◽  
Hydration Product ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Hydration Process ◽  
Early Hydration ◽  
Cement Pastes ◽  
Hydration Rate ◽  
Aluminate Cement

The ferrite aluminate cement (FAC) could rapidly lose fluidity or workability due to its excessive hydration rate, and greatly reduce the construction performance. Chemical admixtures are commonly used to provide the workability of cement-based materials. In this study, to ensure required fluidity of FAC, chemically different water reducing agents are incorporated into the FAC pastes. The experiments are performed with aliphatic water reducing agent (AP), polycarboxylic acid water reducing agent (PC) and melamine water reducing agent (MA), respectively. Influence of the water reducing agents on fluidity, setting time, hydration process, hydration product and zeta potential of the fresh cement pastes is investigated. The results show that PC has a better dispersion capacity compared to AP and MA. Besides decreasing water dosage, PC also acts as a retarder, significantly increasing the setting times, delaying the hydration rate and leading to less ettringite in the hydration process of FAC particles. The water reducing agents molecules are adsorbed on the surface of positively charged minerals and hydration products, however, for PC, steric hindrance from the long side chain of PC plays a critical role in dispersing cement particles, whereas AP and MA acting through an electrostatic repulsion force.

scholarly journals Seasonal Variations of Daytime Land Surface Temperature and Their Underlying Drivers over Wuhan, China

2021 ◽  
Vol 13 (2) ◽  
pp. 323
Author(s):  
Liang Chen ◽  
Xuelei Wang ◽  
Xiaobin Cai ◽  
Chao Yang ◽  
Xiaorong Lu
Keyword(s):  
Surface Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Maximum Temperature ◽  
Maximum Temperature Difference ◽  
Rapid Urbanization ◽  
The Impact ◽  
The City

Rapid urbanization greatly alters land surface vegetation cover and heat distribution, leading to the development of the urban heat island (UHI) effect and seriously affecting the healthy development of cities and the comfort of living. As an indicator of urban health and livability, monitoring the distribution of land surface temperature (LST) and discovering its main impacting factors are receiving increasing attention in the effort to develop cities more sustainably. In this study, we analyzed the spatial distribution patterns of LST of the city of Wuhan, China, from 2013 to 2019. We detected hot and cold poles in four seasons through clustering and outlier analysis (based on Anselin local Moran’s I) of LST. Furthermore, we introduced the geographical detector model to quantify the impact of six physical and socio-economic factors, including the digital elevation model (DEM), index-based built-up index (IBI), modified normalized difference water index (MNDWI), normalized difference vegetation index (NDVI), population, and Gross Domestic Product (GDP) on the LST distribution of Wuhan. Finally, to identify the influence of land cover on temperature, the LST of croplands, woodlands, grasslands, and built-up areas was analyzed. The results showed that low temperatures are mainly distributed over water and woodland areas, followed by grasslands; high temperatures are mainly concentrated over built-up areas. The maximum temperature difference between land covers occurs in spring and summer, while this difference can be ignored in winter. MNDWI, IBI, and NDVI are the key driving factors of the thermal values change in Wuhan, especially of their interaction. We found that the temperature of water area and urban green space (woodlands and grasslands) tends to be 5.4 °C and 2.6 °C lower than that of built-up areas. Our research results can contribute to the urban planning and urban greening of Wuhan and promote the healthy and sustainable development of the city.

Experimental Study on Mechanical Property of Concrete Based on Seawater and Sea Sand

2013 ◽  
Vol 641-642 ◽  
pp. 574-577 ◽  
Author(s):  
Ying Tao Li ◽  
Ling Zhou ◽  
Mao Jiang ◽  
Yu Zhang ◽  
Jun Shao
Keyword(s):  
Mechanical Property ◽  
Experimental Study ◽  
Fly Ash ◽  
Raw Materials ◽  
Growth Trend ◽  
Sea Sand ◽  
Significant Strength ◽  
Dry Conditions ◽  
Early Strength ◽  
Better Than

In this paper, the mechanical property experiments of concrete based on the seawater and sea sand have been carried in different raw materials preparation and different conservation environments. The results show that the early strength and late strength of concrete based on seawater and sea sand are better than concrete based on freshwater and sand. There is no significant strength decreased for concrete based on seawater and sea sand under accelerated alternating wet and dry conditions. For concrete based on seawater and sea sand mixed with admixture, the downward trend of late strength is significantly delayed, the late strength of concrete based on the seawater and sea sand mixed with slag gets the most obvious growth trend, while the late strength of seawater and sea sand concrete mixed with fly ash gets the largest increment.

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