Optimization of cement-based grouts using chemical additives

Grout injection is used for sealing or strengthening the ground in order to prevent water entrance or any failure after excavation.There are many methods of grouting.Permeation grouting is one of the most common types in which the grout material is injected to the pore spaces of the ground.In grouting operations,the grout quality is important to achieve the best results.There are four main characteristics for a grout mixture including bleeding,setting time,strength,and viscosity.In this paper,we try to build some efficient grouting mixtures with different water to cement ratios considering these characteristics.The ingredients of grout mixtures built in this study are cement,water,bentonite,and some chemical additives such as sodium silicate,sodium carbonate,and triethanolamine(TEA).The grout mixtures are prepared for both of the sealing and strengthening purposes for a structural project.Effect of each abovementioned ingredient is profoundly investigated.Since each ingredient may have positive or negative aspect,an optimization of appropriate amount of each ingredient is determined.The optimization is based on 200 grout mixture samples with different percentages of ingredients.Finally,some of these grout mixtures are chosen for the introduced project.It should be mentioned that grouting operations depend on various factors such as pressure of injection,ground structure and grain size of soils.However,quality of a grout can be helpful to make an injection easier and reasonable.For example,during the injection,a wrong estimated setting time can destroy the injected grout by washing the grout or setting early which prevents grouting.This paper tries to show some tests in easy way to achieve a desirable sample of grout.

Mechanism and Optimal Application of Chemical Additives for Accelerating Early Strength of Lime-flyash Stabilized Soils

To accelerate the early strength of lime-flyush stabilized soil for extending its further uses in highway and shortening highway constraction time, five kinds of chemical odditives were chosen on the basis of mechanism analysis of accelerating early strength in highway as a semi-rigid base materhd, and a series of experiments about the effect of differeat kinds of additives and quantity on the early strength of the stabilized soll were tested. The results show that chemical additives can efftciently improve the early strength of lime-flyush stabilized soil both the 7 d and 28d, and the optimum quantity for above chemical additive is 1.5%-2.5% approximately. Some suggestions for the practical construction were also proposed.

Chemical Control of Ceratovacuna lanigera Zehntner with Multi-rotor Unmanned Aerial Vehicle

[Objective] The paper was to explore chemical control of Ceratovacuna lanigera Zehntner with multi-rotor unmanned aerial vehicle. [Method] According to the outbreak characteristics of C. lanigera,multi-rotor unmanned aerial vehicle was applied for flying control test. Referred to the spraying characteristics of multi-rotor unmanned aerial vehicle,two kinds of microcapsule pesticides,ALV-1501 and ALV-1502,and two kinds of spraying additives,SPA-01 and SPA-02,were designed to control C. lanigera. [Result] The control effect of ALV-1501 at the dose of 2. 25 L/hm;was 60. 02% at 1 d post administration and 54. 14%at 5 d post administration; the control effects of ALV-1502 at the dose of 2. 1 L/hm2 were 76. 35% and 81. 35% at 1 and 5 d post administration,respectively.Compared to individual pesticide,the control effects of ALV-1501 were improved 1. 42-1. 47 times and 1. 16-1. 14 times by adding 0. 6 L/hm;SPA-01 and SPA-02 in pesticide liquid,respectively. The control effects of ALV-1502 were improved 1. 23-1. 25 times and 1. 15-1. 16 times by adding 0. 6 L/hm2 SPA-01 and SPA-02,respectively. The control effects against C. lanigera at three flying speeds of 3,5 and 8 m/s were 99. 72%-99. 97%,81. 6%-99. 81% and63. 52%-68. 77%,respectively. [Conclusion]The results will provide a reference for application of multi-rotor unmanned aerial vehicle in prevention and control of C. lanigera in sugarcane field.

Synergistic effects of chemical additives and mature compost on reducing H_2S emission during kitchen waste composting

Additives could improve composting performance and reduce gaseous emission,but few studies have explored the synergistic of additives on H_(2)S emission and compost maturity.This research aims to make an investigation about the effects of chemical additives and mature compost on H_(2)S emission and compost maturity of kitchen waste composting.The results showed that additives increased the germination index value and H_(2)S emission reduction over 15 days and the treatment with both chemical additives and mature compost achieved highest germination index value and H_(2)S emission reduction(85%).Except for the treatment with only chemical additives,the total sulfur content increased during the kitchen waste composting.The proportion of effective sulfur was higher with the addition of chemical additives,compared with other groups.The relative abundance of H_(2)S-formation bacterial(Desulfovibrio)was reduced and the relative abundance of bacterial(Pseudomonas and Paracoccus),which could convert sulfur-containing substances and H_(2)S to sulfate was improved with additives.In the composting process with both chemical additives and mature compost,the relative abundance of Desulfovibrio was lowest,while the relative abundance of Pseudomonas and Paracoccus was highest.Taken together,the chemical additives and mature compost achieved H_(2)S emission reduction by regulating the dynamics of microbial community.

Preparation and Properties of Modified Sol-Gel Sensing Membrane for Fiber Optic Oxygen Sensor

Modified sensing membranes based on fluorescence quenching were prepared by the sol-gel method,using formamide as the drying control chemical additive,tetraethoxysilane as the main material,Ru(phen) 3Cl 2 as the indicator.The membrane with the optimum thickness of 20-50μm is uniform and crack-free,in which the indicator has a very small leaking rate.The membrane is immersed in water for 50h,the membrane sensing parameter M decreases by less than 5%.The fiber optic oxygen sensor with the sensing membrane has a detection limit of 5×10 -6M(ppm),a response time of less than 30s,excellent reproducibility and stability.

Quantum chemical study on the mechanism of the consecutive addition of HCN to aminoacetonitrile

MINDO/3 method has been used to study the mechanism of the consecutive addition of HCN to aminoacetonitrile.The results obtained for the first three steps show that the reaction is exothermic,and step I is the rate determining step.

Chemical routes toward long-lasting lithium/sulfur cells

Lithium/sulfur （Li/S） cells have great potential to become mainstream secondary batteries due to their ultra-high theoretical specific energy. The major challenge for Li/S cells is the unstable cycling performance caused by the sulfur＇s insulating nature and the high-solubility of the intermediate polysulfide products. Several years of efforts to develop various fancy carbon nanostructures, trying to physically encapsulate the polysulfides, did not yet push the cell＇s cycle life long enough to compete with current Li ion cells. The focus of this review is on the recent progress in chemical bonding strategy for trapping polysulfides through employing functional groups and additives in carbon matrix. Research results on understanding the working mechanism of chemical interaction between polysulfides and functional groups （e.g. 0-, B-, N- and S-） in carbon matrix, metal-based additives, or polymer additives during charge/discharge are discussed.