scholarly journals THE INFLUENCE OF WATER TO POWDER RATIO TO THE RESISTANCE FOR SULFURIC ACID OF HARDENED CALCIUM ALUMINATE CEMENT CONTAINING BLAST FURNACE SLAG

2012 ◽  
Vol 66 (1) ◽  
pp. 437-443
Author(s):  
Tomoaki SUGIYAMA ◽  
Kazuto TABARA ◽  
Minoru MORIOKA ◽  
Etsuo SAKAI
2022 ◽  
Vol 8 ◽  
Author(s):  
Wu Zhiqiang ◽  
Liu Hengjie ◽  
Qu Xiong ◽  
Wu Guangai ◽  
Xing Xuesong ◽  
...  

During the thermal recovery of heavy oil thermal recovery wells, improving the mechanical properties and integrity of the cement ring is of great significance for the safe and efficient exploitation of heavy oil resources. This paper studies the relative properties of calcium aluminate cement and three kinds of slags under the conditions of 50°C × 1.01 MPa and 315°C × 20.7 MPa. CAC-slag composite material performance was evaluated using the cement paste compressive strength and permeability tests to study the physical properties of CAC with blast furnace slag. X-ray diffraction analysis, scanning electron microscopy (SEM), and thermal analysis (DSC/TG) were carried out to investigate the mineralogical composition of CAC with blast furnace slag. Results show that adding blast furnace slag did not affect the performance of cement slurry. Moreover, C2ASH8 curing occurred at low temperature, the microstructure of CAC paste was compact, and the permeability resistance was improved, thus improving the low-temperature properties of neat CAC. When cured at a high temperature, the CAC paste was mainly hydrated with C3ASH4 and AlO(OH), which had a well-developed crystal structure. Adding blast furnace slag can improve the CAC resistance to high temperature.


Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3822
Author(s):  
Wei Fan ◽  
Yan Zhuge ◽  
Xing Ma ◽  
Christopher W. K. Chow ◽  
Nima Gorjian ◽  
...  

Concrete wastewater infrastructures are important to modern society but are susceptible to sulfuric acid attack when exposed to an aggressive environment. Fibre-reinforced mortar has been adopted as a promising coating and lining material for degraded reinforced concrete structures due to its unique crack control and excellent anti-corrosion ability. This paper aims to evaluate the performance of polyethylene (PE) fibre-reinforced calcium aluminate cement (CAC)–ground granulated blast furnace slag (GGBFS) blended strain-hardening mortar after sulfuric acid immersion, which represented the aggressive sewer environment. Specimens were exposed to 3% sulfuric acid solution for up to 112 days. Visual, physical and mechanical performance such as water absorption ability, sorptivity, compressive and direct tensile strength were evaluated before and after sulfuric acid attack. In addition, micro-structure changes to the samples after sulfuric acid attack were also assessed by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) to further understand the deterioration mechanism. The results show that overall fibre-reinforced calcium aluminate cement (CAC)-based samples performed significantly better than fibre-reinforced ordinary Portland cement (OPC)-based samples as well as mortar samples in sulfuric acid solution in regard to visual observations, penetration depth, direct tensile strength and compressive reduction. Gypsum generation in the cementitious matrix of both CAC and OPC-based systems was the main reason behind the deterioration mechanism after acid attack exposure. Moreover, laboratory sulfuric acid testing has been proven for successfully screening the cementitious material against an acidic environment. This method can be considered to design the service life of concrete wastewater pipes.


Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7333
Author(s):  
Solmoi Park ◽  
Namkon Lee ◽  
Gi-Hong An ◽  
Kyeong-Taek Koh ◽  
Gum-Sung Ryu

The use of alternative cementitious binders is necessary for producing sustainable concrete. Herein, we study the effect of using alternative cementitious binders in ultra-high-performance concrete (UPHC) by calculating the phase assemblages of UHPC in which Portland cement is replaced with calcium aluminate cement, calcium sulfoaluminate cement, metakaolin or blast furnace slag. The calculation result shows that replacing Portland cement with calcium aluminate cement or calcium sulfoaluminate cement reduces the volume of C-S-H but increases the overall solid volume due to the formation of other phases, such as strätlingite or ettringite. The modeling result predicts that using calcium aluminate cement or calcium sulfoaluminate cement may require more water than it would for plain UHPC, while a similar or lower amount of water is needed for chemical reactions when using blast furnace slag or metakaolin.


Author(s):  
Paweena Jariyathitipong ◽  
Kazuyoshi Hosotani ◽  
Takashi Fujii ◽  
Toshiki Ayano

2015 ◽  
Vol 754-755 ◽  
pp. 359-363
Author(s):  
M. Azreen ◽  
M.W. Hussin

Ordinary Portland Cement (OPC) concrete is one of the most widely used construction materials globally, though its production in construction has negative environmental impact. About 0.9 ton of CO2is emitted for every one (1) ton of cement produced. In order to reduce the amount of CO2emission from cement industry, the utilization of supplementary cementitious materials such as pulverized fuel ash (PFA), blast-furnace slag and natural pozzolans is common and effective. Geopolymer is an inorganic binder material and can be produced by a geopolymeric reaction of alkali activating solution with silica and alumina rich source materials such as PFA and blast-furnace slag. In this study, the durability of concrete such as the resistance to sulfuric acid and sulfate solutions due to the effect of blended as of PFA and palm oil fuel ash (POFA), along with alkaline activators were investigated. Consequently, the optimum mix design of the blended ash geopolymer (BAG) concrete and OPC concrete specimens were prepared with water to cement ratio of 0.5 by mass as control. The micro structural analysis by X-ray diffraction (XRD) was done. BAG concrete showed better performance in 2% sulfuric acid and 5% sulfate solutions. From micro structural analysis, it was evident that BAG binder gel (N-A-SH) produced more durable material compared with C-S-H binder gel of OPC. The BAG concrete is strongly recommended to be used as an alternative to OPC concrete in addition to its environmental friendliness. Abundant PFA and POFA can be efficiently utilized to produce a high performance concrete.


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