Effect of Hydration Aging and Water Binder Ratio on Microstructure and Mechanical Properties of Sprayed Concrete

In order to study the durability of sprayed concrete （shotcrete）, effects of different hydration aging and water-binder ratio （w/b） on the microstructure of cement paste and basic mechanical properties of test specimens were investigated. The phase composition, mass percentage of ettringite and portland in hydration production and microstructure were characterized by X-ray diffraction （XRD）, thermo gravimetry-differential scanning calorimetry （TG-DSC） and scanning electron microscopy （SEM）, respectively. The experimental results showed that changes in phase composition was more significant than those of water-binder ratio. With hydration aging and water-binder ratio increased, the mass percentage of ettringite and portland was decreased from 4.42%, 1.49% to 3.31%, 1.35%, respectively and the microstructure of paste was significantly compacted. Likewise, the mechanical properties including cubic compressive strength and splitting tensile strength were rised obviously.

Effects of Water/Binder Ratio on the Properties of Engineered Cementitious Composites

The effects of water/binder ratio （w/b） on the toughness behavior, compressive strength and flexural strength of engineered cementitious composites （ECC） were investigated. The w/b ratios of 0.25, 0.31, 0.33 and 0.37 were selected and the specimens were tested at the ages of 7 d and 28 d. The experimental results showed that there was a corresponding increase in first cracking strength, modulus of rupture, compressive strength and flexural strength with the decrease of w/b. Within the w/b range of 0.25-0.37, higher w/b was found to have improved effects on deflection, strain hardening index and toughness index of ECC. In the permission of meeting the requirement of compressive strength grade, selecting higher w/b in mix design will help to obtain robust ECC.

A Simple Cement Hydration Model Considering the Influences ofWater-to-Cement Ratio and Mineral Composition

A simple hydration model is used here by taking the composition of the cement and the initial water: cementratio (w/c) into account explicitly. Its conceptual basis is a combination of the Avrami equation and Bentz’s modelbased on simple spatial considerations. In this model, the Avrami equation determines the initial reaction, andBentz’s model describes the following hydration stage. The model favors engineers for it relies on one experimentalparameter and has a reliable approximation in the practice.

Experimental Study on the Effect of Sediment Composition Ratio on Shallow Water Delta

1 Introduction Shallow water delta in the middle-newborn Stratum Widely developed with huge oil and gas in China(Hu Shengwu et al.,2013).The control factors on the deltadevelopment like Climate,sea level,tectonic subsidence,sediment supply(flow,type),the geometric characteristics of the upstream river,the energy(wave,

High-Precision Direct Determination of the ^(87)Sr/^(86)Sr Isotope Ratio of Bottled Sr-Rich Natural Mineral Drinking Water Using MC-ICP-MS

Strontium has four naturally occurring stable isotopes,84Sr,86Sr,87Sr,and 88Sr,with abundances of 0.56,9.87,approximately 7.04,and 82.53 atomic %,respectively.The 87Sr/86Sr isotope ratio is variable due to the addition of radiogenic 87Sr produced by the beta decay of 87Rb with a half-life of 4.88 ± 0.05 Ga.Thus,

Genome-wide association study identifies novel loci and candidate genes for drought stress tolerance in rapeseed

Rapeseed(Brassica napus)is one of the most important oil crops worldwide;however,drought seriously curtails its growth and productivity.Identifying drought-tolerant germplasm is an efficient strategy for addressing water shortages.Here,we phenotyped a panel of 264 B.napus accessions at full-bloom stage using water loss ratio(WLR)as drought-tolerant index.It identified 8 low-WLR and 6 high-WLR accessions,regarded as droughttolerant and drought-sensitive,respectively.Comparing with drought-sensitive accessions at the seedling stage,drought-tolerant accessions had shown better performance in maintaining fresh and dry weights,and performed the higher expression of drought-induced marker genes under drought stress.Subsequently,a total of 139 SNPs(single nucleotide polymorphisms)were identified associated with the WLR using a genome-wide association study(GWAS)among 264 B.napus accessions,with the largest number SNPs at chromosome A10,and 13 SNPs significantly were associated with the WLR(-log_(10)(p-value)>6).Furthermore,4 putative candidate genes(BnaC09.RPS6,BnaC09.MATE,BnaA10.PPD5 and BnaC09.Histone)were screened involving in drought tolerance in B.napus.Together,our results highlight the WLR's importance in drought tolerance and establish the foundation for improving WLR-associated drought tolerance in rapeseed.

The Permeability and Strength of Green High Performance Concrete

The permeability,alkali silica reaction,workability and strength of GHPC(green high performance concrete) were studied in this paper.The results show that GHPC has an excellent durability and the effects of mass ratio of flyash to high calcium slag,water binder ratio,content of water reducer,and crushed coarse aggregate type on the workability and strength of GHPC were considerably evident.A new path for the concretes continuous development was put forward.

Photocatalytic degradation of PCP-Na with TiO_2 photocatalysis loaded with platinum

Titanium dioxide(TiO 2) samples of different crystal forms were prepared by hydrolysis tetrabutyl titanate in various water to alkoxide ratios and sintering the hydrolysis product at different temperatures. The photocatalysts coated on hollow glass beads and loaded with platinum varying from 0.2% to 2.4% by weight.The photocatalytic degradation rate of sodium pentachlorophenolate (PCP-Na) depends on the preparing conditions such as: sintering temperatures, water to alkoxide ratios( R ), platinum content and the size. The proper conditions of preparation photocatalysts are as follows: the ratio of TiO 2 : sodium silicate : hollow glass beads : platinum is 10:5:20:0.15(w/w), R is 100, sintering temperature is 650℃, and the size of hollow glass is 0.5-1 mm. Under these conditions, the ratio between acatase and rutile of the photocatalyst is 2:1, and the photocatalytic activity is high.

Self-desiccation Effect of High Performance Concrete

Effects of water to binder ratio (m(W)/m(B)), types and addition content of mineral admixtures ont he autogenous relative humidity (ARH) change of concrete resulting from self-desiccation were studies. The parameters of coefficient of mineral self-desiccation-effect ka nd efficient water to binder ratio r(e) were proposed, and experimental results were fitted non-linearly and analyzed using these proposed parameters. The experimental results indicate that ARH reduction of concrete at different ages increases with the decrease of m(W)/m(B). The ARH changes laws of concrete with m(W)/m(B) lower than 0.4 can be expressed with a non-linear equation. The extent of the effect of types and addition content of mineral admixures on ARH reduction of concrete resulting from self-desiccation can be reflected by the non-linear equation with the parameter of efficient water to binder ratio r(e) effectively.

Analysis of Precipitation Resource and Weather Modification Potential in Anyang

Using ground water vapor pressure and precipitation data at four times of one day during 1985- 2014 in each county（ city） of Anyang,precipitable water at each station was calculated,and temporal-spatial distribution of atmospheric maximum precipitable water and its change trend over the years in the city were analyzed. Results showed that atmospheric maximum precipitable water in Anyang City had the characteristics of summer far more than winter,autumn slightly higher than spring,west and south more,and east and north less,and presented the increasing trend year by year. We further analyzed the characteristic of monthly rainfall enhancement potential in each county,and mean in whole year was 80%. In spring and winter,rainfall enhancement potential in the west was bigger than east,while rainfall enhancement potential in the east was bigger than west in summer and autumn. The research provides reference basis for rationally carrying out artificial rainfall work,which could effectively ease uneven temporal-spatial distribution problem of water resource in Anyang City.

Monthly gravity field recovery from GRACE orbits and K-band measurements using variational equations approach

The Gravity Recovery and Climate Experiment（GRACE） mission can significantly improve our knowledge of the temporal variability of the Earth＇s gravity field.We obtained monthly gravity field solutions based on variational equations approach from GPS-derived positions of GRACE satellites and K-band range-rate measurements.The impact of different fixed data weighting ratios in temporal gravity field recovery while combining the two types of data was investigated for the purpose of deriving the best combined solution.The monthly gravity field solution obtained through above procedures was named as the Institute of Geodesy and Geophysics（IGG） temporal gravity field models.IGG temporal gravity field models were compared with GRACE Release05（RL05） products in following aspects：（i） the trend of the mass anomaly in China and its nearby regions within 2005-2010; （ii） the root mean squares of the global mass anomaly during 2005-2010; （iii） time-series changes in the mean water storage in the region of the Amazon Basin and the Sahara Desert between 2005 and 2010.The results showed that IGG solutions were almost consistent with GRACE RL05 products in above aspects（i）-（iii）.Changes in the annual amplitude of mean water storage in the Amazon Basin were 14.7 ± 1.2 cm for IGG,17.1 ± 1.3 cm for the Centre for Space Research（CSR）,16.4 ± 0.9 cm for the GeoForschungsZentrum（GFZ） and 16.9 ± 1.2 cm for the Jet Propulsion Laboratory（JPL） in terms of equivalent water height（EWH）,respectively.The root mean squares of the mean mass anomaly in Sahara were 1.2 cm,0.9 cm,0.9 cm and 1.2 cm for temporal gravity field models of IGG,CSR,GFZ and JPL,respectively.Comparison suggested that IGG temporal gravity field solutions were at the same accuracy level with the latest temporal gravity field solutions published by CSR,GFZ and JPL.

THE VELOCITY FIELD OF MULTIPHASE FLOW AND EFFICIENCY OF BIOLOGICAL AERATION FILTER

Aeration is an important factor affecting the biological aeration filter.With a set of experiment device specially designed for the purpose,and the particle image velocimetry technique,the velocity field of the gas-liquid two-phase flow is studied under different conditions.The various simulated aeration states were actually applied to the experimental device of sewage treatment,and the results of the numerical simulation were verified.The final experimental results indicate that the most efficient state occurs when the ratio of water in aeration tank h / w =1,the diameter of capillary tubes d=0.6mm and the velocity of bubbles v=0.3m/s.

Prediction of the undrained shear strength of remolded soil with non-linear regression,fuzzy logic,and artificial neural network

This study aims to predict the undrained shear strength of remolded soil samples using non-linear regression analyses,fuzzy logic,and artificial neural network modeling.A total of 1306 undrained shear strength results from 230 different remolded soil test settings reported in 21 publications were collected,utilizing six different measurement devices.Although water content,plastic limit,and liquid limit were used as input parameters for fuzzy logic and artificial neural network modeling,liquidity index or water content ratio was considered as an input parameter for non-linear regression analyses.In non-linear regression analyses,12 different regression equations were derived for the prediction of undrained shear strength of remolded soil.Feed-Forward backpropagation and the TANSIG transfer function were used for artificial neural network modeling,while the Mamdani inference system was preferred with trapezoidal and triangular membership functions for fuzzy logic modeling.The experimental results of 914 tests were used for training of the artificial neural network models,196 for validation and 196 for testing.It was observed that the accuracy of the artificial neural network and fuzzy logic modeling was higher than that of the non-linear regression analyses.Furthermore,a simple and reliable regression equation was proposed for assessments of undrained shear strength values with higher coefficients of determination.

Fabrication of Porous Mg-Zn Scaffold through Modified Replica Method for Bone Tissue Engineering

Biodegradable scaffolds are essential parts in hard tissue engineering. A highly porous magnesium-zinc （Mg-Zn 4 wt.%） scaffold with different Mg-Zn powder to liquid media ratios （50 wt.%, 70 wt.% and 90 wt.%） and different concentrations of ethanol （0 vol.%, 10 vol.%, 20 vol.% and 40 vol.%） were prepared through modified replica method. The mechanical properties were assessed through compression test and the structures of scaffolds were examined by Scanning Electron Microscope （SEM）. Results show that, the increase in Mg-Zn powder to liquid media ratio （50 wt.% to 90 wt.%） in ethanol free slurry, increases the thickness of struts （37 lam to 74 lam） and the plateau stress （0.5 MPa to 1.4 MPa）. The results obtained from X-ray Diffractometry （XRD） and compression test indicate that consuming ethanol in liquid media of replica, results in higher plateau stress by 46% due to less Mg-water reaction and no formation of Mg（OH）2 in the scaffold. The results of porosity measurement indicate that water-ethanol mixture composition and different solid fractions have no significant effects on true and apparent porosities of the fabricated scaffolds.

Test Study on the Recycled Aggregate and Concrete Regenerated from Worn Cement Concrete Pavement

Regenerate utilization of worn cement concrete is the key technical problem to be solved in traffic field while the cement concrete pavement built long ago durative disrepair. The study aimed at the worn cement concrete which can not be reused in site,get recycled aggregate according to the practically technics of regenerate,and then carry out test study on the aggregate and recycle aggregate cement concrete. Test results show recycled fine aggregate is about 26% of recycled aggregate,and substantive sand pulps are adhere on the surface of recycled while the distinct crackle appears on this sand pulp surface. relative to the natural aggregate,one of the remarkable characters of the recycled aggregate is that the inartificial water ratio is relatively low and the water-absorbing ratio can reach 4%～12%,and the water-absorbing ratio increased while the grain getting fine. the second remarkable characters of recycled coarse aggregate is that the weared stone value and crushed stone value of recycled coarse aggregate are both bigger,the Los-angeles weared stone value is 32.7,the crushed stone value is 26.5. So,the recycled aggregate can not meet the criterion,but after mixed into 40% natural aggregate,it can meet. The mixture ratio test results proved that based on the dosage of cement we can through reduce water cement ratio and augment water quantity to improve the working performance of recycled concrete. The destroy form of recycled concrete goes all the way with natural concrete,the recycled aggregate can absolutely used in cement concrete under C50.