scholarly journals Mechanical properties of lightweight foam concrete filler for roadbed of high-speed railway

2021 ◽  
Vol 14 (10) ◽  
Author(s):  
De-Gou Cai ◽  
Shao-Wei Wei ◽  
Yang-Sheng Ye ◽  
Qian-Li Zhang ◽  
Zhong-Guo Li ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Fly Ash ◽  
Frost Resistance ◽  
High Speed ◽  
Ash Content ◽  
Dynamic Elastic Modulus ◽  
Filling Material ◽  
Foam Concrete ◽  
High Speed Railway ◽  
Lightweight Foam

AbstractA high-speed railway has high requirements for line smoothness, and uneven settlement control is the primary factor considered in the design and operation of the subgrade. The emergence of lightweight subgrade structures meets the needs of the development of the high-speed railway. As a kind of filling material with good performance, lightweight foam concrete can effectively reduce the load and excessive settlement of subgrade and effectively reduce the cost of foundation treatment. This paper studied the dynamic characteristics of lightweight foam concrete with different wet densities and water-bearing states under train loading. The effects of wet density and fly ash content on the compressibility, impermeability, and frost resistance of lightweight foam concrete were analyzed in detail. The results show that the lightweight foam concrete still has high residual strength after compression, which is about 60% of its peak strength. Under different mix ratios, the critical dynamic stress of the lightweight foam concrete is generally 0.2–0.3 times the unconfined compressive strength, and the dynamic elastic modulus increases with the increase of wet density and cyclic stress amplitude. With the fly ash content increasing, the volume water absorption of lightweight foam concrete decreases first and then increases, and the critical value of fly ash content is 40%. The frost resistance of lightweight foam concrete gradually increases with the increase of wet density, and the dynamic elastic modulus of the sample with 279 kg·m−3 density lost 41.1% after 20 freeze–thaw cycles. When the content of fly ash is 20%, the frost resistance of lightweight foam concrete is equivalent to that of pure cement.

Study on the Frost Resistance of Artificial Aggregates Recycled Concrete

2012 ◽  
Vol 509 ◽  
pp. 82-87
Author(s):  
Jin Bang Wang ◽  
Zong Hui Zhou
Keyword(s):  
Elastic Modulus ◽  
Fly Ash ◽  
Silica Fume ◽  
Frost Resistance ◽  
Mechanical Performance ◽  
Recycled Concrete ◽  
Dynamic Elastic Modulus ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Freeze Thaw

The recycled concrete was prepared by using the high-strength artificial aggregates. This kind of concrete can be completely regenerated to be cement, and the recycling utilization of the concrete can also be truly realized. The frost resistance and influencing factors of the recycled concrete were studied. The results show that the mechanical performance and frost resistance of artificial aggregates recycled concrete are better than those of the ordinary concrete under the same water/cement ratio condition. When the water/cement ratio is 0.40, the relative dynamic elastic modulus, weight loss and frost durability factor of the recycled concrete are 98.7%, 0.5% and 65.8 after 200 times freeze-thaw cycles. When the fly ash and silica fume were added into the recycled concrete, the frost resistance can be improved. The optimal amounts of fly ash and silica fume are 30% and 15% of cement by weight, respectively. The recycled concrete was prepared with the optimal fly ash and silica fume content, respectively. After 200 times freeze-thaw cycles, the relative dynamic elastic modulus of the recycled concrete are 99.1% and 99.2%, and the weight losses of the recycled concrete are 0.4% and 0.3%, and antifreeze durability coefficient of the recycled concrete are 66.07 and 66.13. Therefore, the recycled concrete with silica fume has better frost resistance performance than that with fly ash as admixture.

Influence of coarse fly ash on the performance of foam concrete and its application in high-speed railway roadbeds

2018 ◽  
Vol 170 ◽  
pp. 153-166 ◽  
Author(s):  
Wei She ◽  
Yi Du ◽  
Guotang Zhao ◽  
Pan Feng ◽  
Yunsheng Zhang ◽  
...  
Keyword(s):  
Fly Ash ◽  
High Speed ◽  
Foam Concrete ◽  
High Speed Railway

Studies the Properties of Polyaspartic Polyurea Coated Concrete under Coaction of Salt Fog and Freeze-Thaw

2012 ◽  
Vol 455-456 ◽  
pp. 781-785
Author(s):  
Ping Lu ◽  
Xin Mao Li ◽  
Xue Qiang Ma ◽  
Wei Bo Huang
Keyword(s):  
Elastic Modulus ◽  
Frost Resistance ◽  
Dynamic Elastic Modulus ◽  
Freeze Thaw ◽  
Decrease Rate ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Salt Fog

. This paper mainly studied the properties of PAE polyurea coated concrete under coactions of salt fog and freeze-thaw. After exposed salt fog conditions for 200d, T3, B2, F2 and TM four coated concrete relative dynamic elastic modulus have small changes, but different coated concrete variation amplitude is different. T3 coated concrete after 100 times of freeze-thaw cycle the relative dynamic elastic modulus began to drop, 200 times freeze-thaw cycle ends, relative dynamic elastic modulus variation is the largest, decrease rate is 95%, TM concrete during 200 times freeze-thaw cycle, relative dynamic elastic modulus almost no change, B2 concrete and F2 concrete the extent of change between coating T3 and TM. After 300 times the freeze-thaw cycle coated concrete didn't appear freeze-thaw damage phenomenon. Four kinds of coating concrete relative dynamic elastic modulus variation by large to small order: T3 coated concrete > B2 coated concrete >F2 coated concrete > TM coated concrete, concrete with the same 200d rule. Frost resistance order, by contrast, TM coated concrete > B2 coated concrete > F2 coated concrete > T3 coated concrete.

scholarly journals Use of Silica Fume and GGBS to Improve Frost Resistance of ECC with High-Volume Fly Ash

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yushi Liu ◽  
Xiaoming Zhou ◽  
Chengbo Lv ◽  
Yingzi Yang ◽  
Tianan Liu
Keyword(s):  
Elastic Modulus ◽  
Sodium Chloride ◽  
Mass Loss ◽  
Frost Resistance ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Tap Water ◽  
High Volume ◽  
Dynamic Elastic Modulus ◽  
Freeze Thaw

Fly ash (FA) has been an important ingredient for engineered cementitious composite (ECC) with excellent tensile strain capacity and multiple cracking. Unfortunately, the frost resistance of ECC with high-volume FA has always been a problem. This paper discusses the influence of silica fume (SF) and ground-granulated blast-furnace slag (GGBS) on the frost resistance of ECC with high volume of FA. Four ECC mixtures, ECC (50% FA), ECC (70% FA), ECC (30% FA + 40% SL), and ECC (65% FA + 5% SF), are evaluated by freezing-thawing cycles up to 200 cycles in tap water and sodium chloride solution. The result shows the relative dynamic elastic modulus and mass loss of ECC in sodium chloride solution by freeze-thaw cycles are larger than those in tap water by freeze-thaw cycles. Moreover, the relative dynamic elastic modulus and mass loss of ECC by freeze-thaw cycles increase with FA content increasing. However, the ECC (30% FA + 40% SL) shows a lower relative dynamic elastic modulus and mass loss, but its deflection upon four-point bending test is relatively smaller before and after freeze-thaw cycles. By contrast, the ECC (65% FA + 5% SF) exhibits a significant deflection increase with higher first cracking load, and the toughness increases sharply after freeze-thaw cycles, meaning ECC has good toughness property.

scholarly journals Biofuel Combustion Fly Ash Influence on the Properties of Concrete

2016 ◽  
Vol 7 (5) ◽  
pp. 546-550
Author(s):  
Aurelijus Daugėla ◽  
Džigita Nagrockienė ◽  
Laurynas Zarauskas
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Water Absorption ◽  
Frost Resistance ◽  
Ash Content ◽  
Mineral Admixtures ◽  
Binding Agent ◽  
Materials Used ◽  
Plasticizing Admixture

Cement as the binding agent in the production of concrete can be replaced with active mineral admixtures. Biofuel combustion fly ash is one of such admixtures. Materials used for the study: Portland cement CEM I 42.5 R, sand of 0/4 fraction, gravel of 4/16 fraction, biofuel fly ash, superplasticizer, water. Six compositions of concrete were designed by replacing 0%, 5%, 10%, 15% 20%, and 25% of cement with biofuel fly ash. The article analyses the effect of biofuel fly ash content on the properties of concrete. The tests revealed that the increase of biofuel fly ash content up to 20% increases concrete density and compressive strength after 7 and 28 days of curing and decreases water absorption, with corrected water content by using plasticizing admixture. It was found that concrete where 20% of cement is replaced by biofuel ash has higher frost resistance.

scholarly journals Influential Factors in Transportation and Mechanical Properties of Aeolian Sand-Based Cemented Filling Material

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 116 ◽  
Author(s):  
Nan Zhou ◽  
Haobin Ma ◽  
Shenyang Ouyang ◽  
Deon Germain ◽  
Tao Hou
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Cement Content ◽  
Ash Content ◽  
Influential Factors ◽  
Filling Material ◽  
Aeolian Sand ◽  
Early Hydration ◽  
Filling Materials ◽  
Slag Content

Given that normal filling technology generally cannot be used for mining in the western part of China, as it has only a few sources for filling gangue, the feasibility of instead using cemented filling materials with aeolian sand as the aggregate is discussed in this study. We used laboratory tests to study how the fly ash (FA) content, cement content, lime–slag (LS) content, and concentration influence the transportation and mechanical properties of aeolian-sand-based cemented filling material. The internal microstructures and distributions of the elements in filled objects for curing times of 3 and 7 days are analyzed using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The experimental results show that: (i) the bleeding rate and slump of the filling-material slurry decrease gradually as the fly ash content, cement content, lime–slag content, and concentration increase, (ii) while the mechanical properties of the filled object increase. The optimal proportions for the aeolian sand-based cemented filling material include a concentration of 76%, a fly ash content of 47.5%, a cement content of 12.5%, a lime–slag content of 5%, and an aeolian sand content of 35%. The SEM observations show that the needle/rod-like ettringite (AFt) and amorphous and flocculent tobermorite (C-S-H) gel are the main early hydration products of a filled object with the above specific proportions. After increasing the curing time from 3 to 7 days, the AFt content decreases gradually, while the C-S-H content and the compactness increase.

Research of Steel Fiber Self-Compacting Concrete Frost Resistance

2012 ◽  
Vol 174-177 ◽  
pp. 721-725 ◽  
Author(s):  
Ming Bao Gao ◽  
Yan Ru Zhao ◽  
Xiao Yan He
Keyword(s):  
Elastic Modulus ◽  
Frost Resistance ◽  
Steel Fiber ◽  
Concrete Specimen ◽  
Test Method ◽  
Dynamic Elastic Modulus ◽  
Self Compacting Concrete ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

With the fast freeze-thaw test method, the c50 steel fiber self-compacting concrete was carried out 300 tests of freeze-thaw cycle. In the process of freeze-thaw cycles, it determined by the quality of the concrete specimen, dynamic elastic modulus and strength, and analyzed the steel fibers and their different contents on frost resistance of self-compacting concrete impact. The results showed that: steel fiber self-compacting concrete in freeze-thaw cycle can play constrained role in the quality loss, dynamic elastic modulus and intensity, and can significantly improve the self-compacting concrete frost resistance. Within a certain range, the more steel fiber, the stronger of frost resistance.

Study on the Cement-Improved Loess under the Vibratory Load by Dynamic Tests

2013 ◽  
Vol 838-841 ◽  
pp. 1302-1308 ◽  
Author(s):  
Jia Ding Wang ◽  
Shu Jun Peng ◽  
Wan Li Xie
Keyword(s):  
Elastic Modulus ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Dynamic Deformation ◽  
Damping Ratio ◽  
Test Method ◽  
Dynamic Elastic Modulus ◽  
Dynamic Tests ◽  
Long Time ◽  
Orthogonal Test Method

In this paper based on the foundation construction of Datong Xian high-speed railway, a large number of test samples have been taken. The order and contribution rate of every experiment factor like cement commingle ratio, depths, water dipping conditions, compacting factor and vibration frequency on the dynamic characteristics of cement-improved loess such as dynamic elastic modulus, dynamic deformation, damping ratio by dynamic triaxial test, which orthogonal test method has been applied to. The dynamic load was calculated according to the train vibration attenuation rule of different depth. The dynamic characteristics of cement-improved loess such as dynamic deformation, dynamic elastic modulus, damping ratio were got form the dynamic tests of long time and large number of cycles. The results showed that with the increase of cement ratio, the dynamic characteristics of cement-improved loess are more better, there is no optimal ratio of cement.

Microstructure and life prediction model of steel slag concrete under freezing-thawing environment

2021 ◽  
Vol 10 (1) ◽  
pp. 1776-1788
Author(s):  
Yang Wen ◽  
Hui Sun ◽  
Shuaidong Hu ◽  
Guangmao Xu ◽  
Xiazhi Wu ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Mass Loss ◽  
Frost Resistance ◽  
Mass Loss Rate ◽  
Steel Slag ◽  
Quadratic Function ◽  
Northern China ◽  
Calculation Model ◽  
Dynamic Elastic Modulus ◽  
Resistance Durability

Abstract The goals of this paper are to study the frost resistance of steel slag concrete (SSC), research the damage mechanisms, and predict the service life of SSC in cold regions. First, the stability of steel slag (SS) was tested, and then SS samples with different treatment dosages were used as aggregates to replace natural aggregates of equal volumes in the preparation of C40 concrete. The microstructures of concrete and micro properties of cement hydration products were investigated in nanospace in this research. In addition, rapid frost resistance durability tests were carried out under laboratory conditions. The results revealed that the ordinary concrete (OC) exhibited a more serious damage phenomenon, and the mass loss and relative dynamic elastic modulus of OC were changed by 5.27 and 62.30%, respectively. However, with increases in the SS content, the losses in mass were lowered. Furthermore, the relative dynamic elastic modulus decreased less, and the frost resistance of the specimens was stronger. The range of mass loss rate was between 2.233 and 3.024%, and the relative dynamic elastic modulus range was between 74.92 and 91.09%. A quadratic function with a good fitting degree was selected to establish a freezing-thawing damage calculation model by taking the relative dynamic elastic modulus as the variable. Then, the freezing-thawing durability lifespan of concrete in the colder regions of northern China was successfully predicted by using the damage calculation model. The results of SSC20–60 showed the better frost resistance durability when the content of SS sand was 20% and the dosage of SS stone was 60%. Its frost resistance lifespan was more than twice that of OC, which demonstrated that SS as an aggregate could effectively improve the frost resistance lifespan of concrete to a certain extent.

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