scholarly journals Study on Modification of Alkali-Free Liquid Accelerator of Mine-Used Wet-Mix Shotcrete

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Chen Lianjun ◽  
Li Pengcheng ◽  
Pan Gang ◽  
Bian Wenhui
Keyword(s):  
Spatial Structure ◽  
Bond Strength ◽  
Research And Development ◽  
Setting Time ◽  
Coal Mines ◽  
Optimum Dose ◽  
High Polymer ◽  
Pore Characteristics ◽  
Time Strength

Compound properties of an alkali-free liquid accelerator are the mainstream of accelerator research and development in the present. Combined with the technical characteristics of wet-mix shotcrete in coal mines, organic high-polymer SWF is used to modify the accelerator because of improving the bond strength of the material and increasing the performance of antisagging. The mechanism of filling and thickening of SWF was analyzed from the aspects of pore characteristics and spatial structure of concrete. Through the determination of setting time, strength, and dispersibility, the optimum dose was determined, and a new style accelerator WIT-1 suitable for wet-mix shotcrete in coal mines was developed and applied on-site. The experimental results show that the addition of SWF increases the dispersibility of the accelerator product and the cohesiveness of concrete under the condition of ensuring strength and setting time, and the effect of modifying the accelerator to reduce the rebound of the wet-mix shotcrete is obvious.

scholarly journals Spectroscopic Determination of an Anion−π Bond Strength

2019 ◽  
Vol 141 (15) ◽  
pp. 6132-6135 ◽  
Author(s):  
Cate S. Anstöter ◽  
Joshua P. Rogers ◽  
Jan R. R. Verlet
Keyword(s):  
Bond Strength ◽  
Spectroscopic Determination

scholarly journals Evaluation of cementitious repair mortars modified with polymers

2017 ◽  
Vol 9 (1) ◽  
pp. 168781401668858 ◽  
Author(s):  
Tsai-Lung Weng
Keyword(s):  
Thermal Expansion ◽  
Bond Strength ◽  
Vinyl Acetate ◽  
Polyvinyl Acetate ◽  
Setting Time ◽  
Drying Shrinkage ◽  
Ethylene Vinyl Acetate ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Repair Mortars

The aim of this study was to evaluate the effects of added polymers on the properties of repair mortars. Two types of polymers, ethylene vinyl acetate and polyvinyl acetate–vinyl carboxylate, were used as a replacement for 3%, 5%, and 8% of the cement (by weight). All tests were conducted using two water–cement ratios of 0.5 and 0.6. The effectiveness of the repair materials was evaluated according to setting time, drying shrinkage, thermal expansion, compressive strength, and bond strength. Specimens containing polyvinyl acetate–vinyl carboxylate at a water–cement ratio of 0.5 presented the highest compressive and bond strength. Specimens containing ethylene vinyl acetate presented strength characteristics exceeding those of the control at 28 days. The drying shrinkage of polyvinyl acetate–vinyl carboxylate specimens was similar to that of the control. At a water–cement ratio of 0.5, the thermal expansion of polyvinyl acetate–vinyl carboxylate specimens was lower than that of ethylene vinyl acetate specimens; however, at a water–cement ratio of 0.6, the thermal expansion was independent of the type of polymer.

scholarly journals Urban spatial structure re-identification as an approach to solving urban transport problem (A case study in Malang)

2018 ◽  
Vol 181 ◽  
pp. 10006
Author(s):  
Dadang Meru Utomo ◽  
Septiana Hariyani
Keyword(s):  
Local Government ◽  
Spatial Structure ◽  
Urban Transport ◽  
Urban Spatial Structure ◽  
Spatial Structures ◽  
Index Method ◽  
Centrality Index ◽  
Effective Result

In an effort to solve the congestion problem, the local government of Malang City has taken various steps. However, unfortunately, the result has not been effective. This shows that the efforts that have been taken so far are sectoral, therefore a more comprehensive approach is needed in order to reach a more effective result. This research aims at re-evaluating the determination of Malang City's urban spatial structure through the delineation of narrower units of area using the centrality index method. The research suggests that urban spatial structures have a very clear pattern of association with congestion locations. It can be concluded that the local government of Malang City needs to put more consideration on evaluating the urban spatial structure to solve the problem of transportation which is ever-growing the in second largest urban area in East Java Province.

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