STRENGTH PROPERTIES OF DURABLE CONCRETE MADE WITH VARIOUS ALTERNATIVE CEMENTITIOUS MATERIALS

Author(s):  
Isamu Yoshitake ◽  
Shun Inoue ◽  
Keisuke Miyamoto ◽  
Koichiro Yamato

Many researchers investigated various concrete made with the cementitious materials, hence the effects of various admixture are well known. Most researches focused on an alternative cementitious material, tested concrete properties by varying the cement-replacement ratio. The optimum cement-replacement ratio may be different by each admixture. The present study examined the strength properties of concrete incorporating various admixtures. The cementitious materials tested in this study were fly-ash, blast furnace slag powder, silica-fume, limestone powder, and an artificial admixture which has high resistance to chloride attack. First, fundamental properties of the concrete incorporating the admixture were summarized referring to previous durability tests. Second, the strength properties of concrete made with some cement-replacement ratios by the cementitious materials were examined. In addition, alternative cement efficiency factors (k) of each cementitious material were estimated.

Author(s):  
Isamu Yoshitake ◽  
Keisuke Miyamoto ◽  
Jun Mizushima ◽  
Kurumi Yamamoto ◽  
Koichiro Yamato

Mineral admixtures are often mixed in concrete as an alternative cementitious material. The use of powder materials indirectly contributes to mitigation of environmental impact caused from Portland cement production which is a major source of CO2 emission. Furthermore, some of powder can improve properties of fresh and hardened concretes. A huge number of reports examining effects of admixture have been published in the world. However, it is not easy to compare the effect of admixture under a certain test condition. The present study aims to examining strength properties of concrete incorporating various admixtures. All admixtures tested herein were mixed in concrete as an alternative cementitious material, and the cement replacement ratios were in the range of 0.2 to 0.6. The tested powder materials are limestone powder, fly-ash, blast furnace slag powder, silica-fume, and inorganic admixture which was recently developed to increase chloride resistance. The focus of the study is to quantify the effect of these admixture on concrete strength. The paper reports compressive, split tensile and flexural strengths of these concretes, and discusses the effect of powder materials.


2020 ◽  
Vol 213 ◽  
pp. 02039
Author(s):  
Guangxing Lai ◽  
Jianli Yin ◽  
Junhui Ye ◽  
Yujia Chen ◽  
Wei Xiao

The reasons of C30 concrete bleeding in winter in Guangdong province were studied by collecting the concrete mix proportions of C30 concrete mixing plants in Guangdong, Fujian, Henan, Hunan, Chongqing and Shaanxi regions, the difference between the concrete mix proportions in Guangdong and other regions was investigated. Based on the representative concrete mix proportion in Guangdong province, the concrete bleeding water test was carried out, and the correlation between the amount of different cementing materials and the bleeding rate was investigated. The results showed that compared with other regions, the C30 concrete mix proportion in Guangdong has the lowest total cementitious material, which made it more prone to bleeding. The amount of slag powder and the total amount of cementitious materials have a high correlation with the bleeding rate. With the increase of the amount of slag powder and the total amount of cementitious materials, the bleeding rate decreases.


2021 ◽  
Vol 14 (1) ◽  
pp. 137
Author(s):  
Sylvia E. Kelechi ◽  
Musa Adamu ◽  
Abubakar Mohammed ◽  
Ifeyinwa I. Obianyo ◽  
Yasser E. Ibrahim ◽  
...  

Global warming and climate changes are the major environmental challenges globally. With CO2 emission being one of the main greenhouse gases emitted to the environment, and cement and concrete production amounting to about 10% of the global CO2 emission, there is a need for the construction industry to utilize an environmentally sustainable material as an alternative to cement. This study analyzed the cost, CO2 emission and strength properties of green self-compacting concrete (SCC) ternary blend containing fly ash, calcium carbide residue (CCR), and crumb rubber (CR) as a replacement material by volume of cement, cementitious material, and fine aggregate, respectively. Cement was replaced with fly ash at 0 and 40% by volume. CCR was used as a replacement at 5 and 10% by volume of cementitious materials, CR replaced fine aggregate in proportions of 10 and 20% by volume. The result indicated that the mix with 0% fly ash and 20% CR replacement of fine aggregate was the most expensive and had the highest CO2 emission. However, the mix with 10% CR, 40% fly ash, and 10% CCR had the lowest CO2 emission and was therefore the greenest SCC mix. The 28-day maximum compressive strength of 45 MPa was achieved in a mix with 0% CR, 0% fly ash, and 10% CCR, while the utmost 28-day splitting tensile strength of 4.1 MPa was achieved with a mix with 10% CR, 0% fly ash, and 5% CCR, and the highest flexural strength at 28 days was 6.7 MPa and was also obtained in a mix with 0% CR, 0% fly ash, and 5% CCR. In conclusion, a green SCC can be produced by substituting 40% cement with fly ash, 10% fine aggregate with CR, and 10% CCR as a replacement by volume of cementitious material, which is highly affordable and has an acceptable strength as recommended for conventional SCC.


2021 ◽  
Vol 28 (3) ◽  
pp. 111-115
Author(s):  
Ameer Baiee ◽  

For sustainability purposes, supplementary cementitious materials (SCMs) are considered essential components for gaining ultra-high strength properties of concrete and mortar. This study experimentally investigates the influence of single, binary, and ternary partial cement replacements of the SCMs on the performance of ultra-high-strength mortar. The investigated SCMs were included ground granulated blast furnace slag (GGBS), densified silica fume (DSF), un-densified silica fume (UDSF), and Fly ash (FA). Three replacements ratios were implemented; 10%, 20%, and 30% in addition to mortar without SCMs to work as a control mix for comparison reasons. 27 mixes were designed to quantify the replacement ratio that explains the best performance, through examining the workability, compressive and tensile strength of each mix. In addition, XRD test was carried out to identify the various decomposition phases of the hardened mortar. The results indicated that binary replacement of 15% GGBS and 15% UDSF exhibited the best performance among all other replacements ratios.


2020 ◽  
Vol 71 (7) ◽  
pp. 775-788
Author(s):  
Quyet Truong Van ◽  
Sang Nguyen Thanh

The utilisation of supplementary cementitious materials (SCMs) is widespread in the concrete industry because of the performance benefits and economic. Ground granulated blast furnace slag (GGBFS) and fly ash (FA) have been used as the SCMs in concrete for reducing the weight of cement and improving durability properties. In this study, GGBFS at different cement replacement ratios of 0%, 20%, 40% and 60% by weight were used in fine-grained concrete. The ternary binders containing GGBFS and FA at cement replacement ratio of 60% by weight have also evaluated. Flexural and compressive strength test, rapid chloride permeability test and under-water abrasion test were performed. Experimental results show that the increase in concrete strength with GGBFS contents from 20% to 40% but at a higher period of maturity (56 days and more). The chloride permeability the under-water abrasion reduced with the increasing cement replacement by GGBFS or a combination of GGBFS and FA


Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4992
Author(s):  
Ruimeng Shi ◽  
Xiaoming Li ◽  
Yaru Cui ◽  
Junxue Zhao ◽  
Chong Zou ◽  
...  

Nickel slags can be produced through ferronickel preparation by the pyrometallurgical processing of laterite nickel ores; however, such techniques are underutilized at present, and serious environmental problems arise from the stockpiling of such nickel ores. In this study, a modification to the process of ferronickel preparation by the direct reduction of carbon bases in laterite nickel ores is proposed. The gangue from the ore is used as a raw material to prepare a cementitious material, with the main components of tricalcium silicate and tricalcium aluminate. By using FactSage software, thermodynamic calculations are performed to analyze the reduction of nickel and iron and the effect of reduction on the formation of tricalcium silicate and tricalcium aluminate. The feasibility of a coupled process to prepare ferronickel and cementitious materials by the direct reduction of laterite nickel ore and gangue calcination, respectively, is discussed under varying thermodynamic conditions. Different warming strategies are applied to experimentally verify the coupled reactions. The coupled preparation of ferronickel and cementitious materials with calcium silicate and calcium aluminate as the main phases in the same experimental process is realized.


2011 ◽  
Vol 105-107 ◽  
pp. 2204-2208 ◽  
Author(s):  
Run Xia Hao ◽  
Xiao Yan Guo

The properties of flue gas desulphurization (FGD) gypsum were analysized by Thermo-gravimetry/differential scanning calorimetry (TG/DSC), technical performance analysis, optical microscope and Scanning electron microscope (SEM). Mechanical properties of FGD gypsum-steel slag powder cementitious material were researched. The results revealed that FGD gypsum have similar moisture content, major component CaSO4·2H2O with natural gypsum, and has better technical performance than natural gypsum. The results of optical microscope and SEM of the FGD gypsum hydration support this further. When the dosage of steel slag powder is 15%, containing activator ,better mechanical properties can be obtained. Key words: FGD gypsum, Property, Cementitious material


2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Huashan Yang ◽  
Yujun Che

The agglomeration of nano-CaCO3 (NC) is the largest bottleneck in applications in cementitious materials. If nano-CaCO3 modifies the surface of micron-scale limestone powder (LS), then it will form nano-CaCO3/limestone composite particles (NC/LS). It is known that micron-scale limestone is easily dispersed, and the “dispersion” of NC is governed by that of LS. Therefore, the dispersion of nano-CaCO3 can be improved by the NC/LS in cementitious materials. In this work, the preparation of NC/LS was carried out in a three-necked flask using the Ca(OH)2-H2O-CO2 reaction system. The morphology of NC/LS was observed by a field emission scanning electron microscope (FE-SEM). The effects of NC/LS on the hydration products and pore structure of cementitious materials are proposed. 5% NC/LS was added into cement paste and mortar, and the mechanical properties of the specimens were measured at a certain age. Differential scanning calorimetry (DSC), thermal gravimetric analysis (TG), and backscattered electron imaging (BSE) were conducted on the specimens to investigate the hydration products and pore structure. The properties of specimens with NC/LS were compared to that of control specimens (without NC/LS). The results revealed that NC/LS reduced the porosity and improved the mechanical properties of the cementitious materials.


2013 ◽  
Vol 368-370 ◽  
pp. 1112-1117
Author(s):  
Jin Hui Li ◽  
Liu Qing Tu ◽  
Ke Xin Liu ◽  
Yun Pang Jiao ◽  
Ming Qing Qin

In order to solve the environment pollution of limestone powder during production of limestone manufactured sand and gravel and problem of lack of high quality fly ash or slag powder in ocean engineering, ultra-fine limestone powder was selected for preparation of green high-performance marine concrete containing fly ash and limestone powder and that containing slag powder and limestone powder for tests on workability, mechanical performance, thermal performance, shrinkage, and resistance to cracking and chloride ion permeability. And comparison was made between such green high-performance concrete and conventional marine concrete containing fly ash and slag powder. Moreover, the mechanism of green high-performance marine concrete was preliminary studied. Results showed that ultra-fine limestone powder with average particle size around 10μm had significant water reducing function and could improve early strength of concrete. C50 high-performance marine concrete prepared with 30% fly ash and 20% limestone powder or with 30% slag powder and 30% limestone powder required water less than 130kg/m3, and showed excellent workability with 28d compressive strength above 60MPa, 56d dry shrinkage rate below 300με, cracking resistance of grade V, 56d chloride ion diffusion coefficient not exceeding 2.5×10-12m2/s. Mechanical performance and resistance to chloride ion permeability of limestone powder marine concrete were quite equivalent to those of conventional marine concrete. But it had better workability, volume stability and cracking resistance. Moreover, it can serve as a solution to the lack of high quality fly ash and slag powder.


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