scholarly journals Study on the Preparation and Fracture Behavior of Red Mud-Yellow Phosphorus Slag-Based Concrete

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Xianhai Li ◽  
Qin Zhang ◽  
Song Mao ◽  
Longjiang Li ◽  
Jingbo Wang
Keyword(s):  
Red Mud ◽  
Crack Width ◽  
Fracture Behavior ◽  
Vertical Direction ◽  
Image Correlation ◽  
Cement Concrete ◽  
Slag Cement ◽  
Yellow Phosphorus ◽  
Maximum Crack ◽  
Phosphorous Slag

Serious environmental pollution issues caused by the storage and exposure of large amounts of red mud (RM) and yellow phosphorus slag (YPS) have raised significant concerns. Red mud-yellow phosphorous slag-cement concrete (RM-YPS-CC) is prepared with 25% yellow phosphorus slag content (YPSC) and 10% red mud content (RMC) to replace a portion of the cement at the age of 28 days and was found in this study to satisfy the mechanical property requirements. More ettringite and portlandite were generated with the RM-YPS-CC than with the yellow phosphorous slag-cement concrete (YPS-CC). In addition, the cementitious materials were more interlaced, and there was more disorder in the crystals of the RM-YPS-CC, which formed a more complex spatial structure than the YPS-CC did. Without RM, the initial cracking strength on the surface of the concrete was 5–6 MPa, the maximum crack width was 3.96 mm, and the crack number was 8. However, the cracking strength was 26.5–27 MPa with RMC5, the maximum crack width was 0.66 mm with RMC15, and the crack number was 3 with RMC15. Moreover, studies using the digital image correlation (DIC) method indicated that the displacement distribution and evolution of the first crack area changed quickly at 10 MPa in either horizontal or vertical direction, and a similar trend was maintained from 10 MPa to 27.1 MPa for the YPS-CC. However, with a small distribution and evolution of horizontal or vertical displacement from 5 MPa to 25 MPa, the evolution would change rapidly when reaching 30 MPa for RM-YPS-CC. This study aims to provide new insights into the wide application of YPS and RM for saving energy and reducing emissions and to develop a new method to study the fracture behavior of concrete.

scholarly journals Study on Preparation and Interfacial Transition Zone Microstructure of Red Mud-Yellow Phosphorus Slag-Cement Concrete

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2768
Author(s):  
Zhennan Su ◽  
Xianhai Li
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Transition Zone ◽  
Red Mud ◽  
Ordinary Portland Cement ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Average Pore ◽  
Environmental Pressures ◽  
Yellow Phosphorus

Open stockpiling and the continual production of industrial solid wastes such as red mud (RM) and yellow phosphorus slag (YPS) have caused serious environmental pollution issues. Additionally, concrete prepared easily and with high strength is a widely applied building material. Therefore, replacing part or all of the cement for preparing concrete with RM and YPS will greatly reduce this kind of solid waste and, thus, decrease environmental pressures. This study investigated the best ratio for the replacement of concrete with RM and YPS, testing the mechanical properties as well as the morphology, material composition, and microporous structure of the interface transition zone (ITZ). The results showed for the concrete prepared with ordinary Portland cement replaced by 10.00 wt.% RM and 18 wt.% YPS, compared to ordinary Portland cement concrete, the compressive strength of concrete with basalt aggregate and dolomite aggregate increased by 25.04% and 27.27%, respectively, when the concrete was cured with steam for 28 days. Furthermore, it had a smaller average pore diameter and crystal size in the ITZ. The aggregate and matrix were more closely intertwined. This was because RM had a low cementitious activity and mainly had a filling effect when added to concrete, while the highly active silica in YPS could react with the Ca(OH)2 crystal (CH) produced from cement hydration to form calcium silicate hydrate (CSH) gel, improving the mechanical properties and microstructure of the concrete.

Effect of Natural and Polypropylene Fibers on early Age Cracking of Mortars

2022 ◽  
Author(s):  
Mahmoud Saad ◽  
Vincent Sabathier ◽  
Anaclet Turatsinze ◽  
Sandrine Geoffroy
Keyword(s):  
Crack Width ◽  
Natural Fiber ◽  
Natural Fibers ◽  
Fiber Reinforcement ◽  
Image Correlation ◽  
Polypropylene Fibers ◽  
Great Ability ◽  
Hemp Fibers ◽  
Plastic Shrinkage ◽  
Maximum Crack

Throughout time, the use of lignocellulosic resources has been implemented in the development of building materials. Among these resources, natural fibers are used as mineral binders reinforcement due to their specific mechanical properties. This experimental investigation focused on effect of flax and hemp fiber reinforcement on the resistance of pozzolanic-based mortars to cracking due to restrained plastic shrinkage. Results were compared with polypropylene fiber reinforcement and with control mortar without fibers. The quantity of fibers added to the mortar mix were respectively 0.25% - 0.5% by mass of binder for polypropylene fibers and 0.5% - 1% by mass of binder for flax and hemp fibers. All fibers have a similar length of 12 mm. The cracking sensitivity was evaluated based on two different methods: the first consists in casting the mortar in a metal mold with stress risers whose criteria are inspired by the ASTM standards. The second consists in pouring the mortar on a brick support. In order to assess the effect of fibers on cracking due to restrained plastic shrinkage, the number of cracks, total crack area and maximum crack width within the first 6 hours after casting were determined using digital image correlation (DIC). Results showed that the flax and hemp fibers were more effective in controlling restrained plastic shrinkage cracking compared to polypropylene fibers. With a natural fiber of 1% by mass of binder, maximum crack width was reduced by at least 70% relative to control mortar based specimens. Natural fibers show great ability to propensity for cracking due to restrained plastic shrinkage; so that, they could be an alternative and ecological solution for polypropylene fibers.

scholarly journals Effect of Various Curing on High Strength Concrete Using Slag Cement

2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Rahmi Karolina ◽  
◽  
M.A.P Handana ◽  
Rahmat Jatmikanto ◽  
◽  
...  
Keyword(s):  
Compressive Strength ◽  
Steel Production ◽  
Acid Water ◽  
Maximum Absorption ◽  
Type I ◽  
Cement Concrete ◽  
Slag Cement ◽  
High Quality ◽  
Normal Concrete ◽  
Water Curing

A The current environmental problem is regarding to CO2 gas emissions from cement production and the presence of hazardous material waste (B3) from steel production. One solution for that problem is by applying slag cement as a substitute for type I portland cement in concrete mix to create a high quality concrete that is environmentally friendly with a high durability and initial strength. This research aimed to compare a high quality concrete made from slag cement and a high quality concrete with conventional mixture. The slag cement used was obtained from PT. Indocement Indonesia. It is coupled with the use of Master Ease 3029 superplasticizer. The results showed that from the samples of concrete of 3, 7, 14, 28, 56 and 90 days of age, the maximum absorption value of normal concrete occurs at the age of 90 days with acid water curing of 1.57%. While the maximum absorption value of slag cement concrete occurs at the same age with acid water curing of 1.50%. The curing of normal concrete with water at 56 days of age has the largest compressive strength from all. It is also found that slag cement concrete has higher maximum compressive strength than that of normal concrete with acid water curing at 56 days of curing.

scholarly journals Self-Healing Biogeopolymers Using Biochar-Immobilized Spores of Pure- and Co-Cultures of Bacteria

2020 ◽  
Author(s):  
Jadin Zam S. Doctolero ◽  
Arnel B. Beltran ◽  
Marigold O. Uba ◽  
April Anne S. Tigue ◽  
Michael Angelo B. Promentilla
Keyword(s):  
Image Analysis ◽  
Crack Width ◽  
Ultrasonic Pulse ◽  
Self Healing ◽  
Weak Effect ◽  
Bacterial Cultures ◽  
Healing Agent ◽  
Optimum Response ◽  
Maximum Crack ◽  
Cultured Bacteria

A sustainable solution for crack maintenance in geopolymers is necessary if they are to be the future of modern green construction. This study thus aimed to develop self-healing biogeopolymers that could potentially rival bioconcrete. First, a suitable healing agent was selected from Bacillus subtilis, B. sphaericus, and B. megaterium by directly adding their spores in the geopolymers and subsequently exposing them to a large amount of nutrients for 14 days. SEM-EDX analysis revealed the formation of biominerals for B. subtilis and B. sphaericus. Next, the effect of biochar-immobilization and co-culturing (B. sphaericus and B. thuringiensis) on the healing efficiencies of the geopolymers were tested and optimized by measuring their ultrasonic pulse velocities weekly over a 28-day healing period. The results show that using co-cultured bacteria significantly improved the observed efficiencies, while biochar-immobilization had a weak effect but yielded an optimum response between 0.3-0.4 g/mL. The maximum crack width sealed was 0.65 mm. Through SEM-EDX and FTIR analyses, the biominerals precipitated in the cracks were identified to be mainly CaCO3. Furthermore, image analysis of the XCT scans of some of the healed geopolymers confirmed that their pulse velocities were indeed improving due to the filling of their internal spaces with biominerals. With that, there is potential in developing self-healing biogeopolymers using biochar-immobilized spores of bacterial cultures.

scholarly journals Characterization of alkali-activated hybrid slag/cement concrete

2020 ◽  
Author(s):  
Ismail Amer ◽  
Mohamed Kohail ◽  
M.S. El-Feky ◽  
Ahmed Rashad ◽  
Mohamed A. Khalaf
Keyword(s):  
Cement Concrete ◽  
Slag Cement ◽  
Alkali Activated

Ice Formation as an Indicator of Frost-Resistance on the Concrete Containing Slag Cement in Conditions of Freezing and Thawing

2016 ◽  
Vol 865 ◽  
pp. 145-150
Author(s):  
Oleksandr Moskalenko ◽  
Rayisa Runova
Keyword(s):  
Frost Resistance ◽  
Ice Formation ◽  
Cement Concrete ◽  
Chemical Additives ◽  
Freezing And Thawing ◽  
Slag Cement ◽  
Mineral Supplement

The connection with the icing on the frost resistance of concrete containing slag cement and chemical additives «MC Bauchemie» under freezing and thawing.It is shown that freeze concrete samples at (-) 10°C increase in the amount of slag from 30 to 70 wt.% Of binder in the composition leads to an increase in the index of ice formation in the concrete of 1.7 ... 1.9 times compared with the concrete obtained at a slag containing slag cement with a content of 10 wt.%. Frost resistance of concrete is reduce from F450 to F400.When freezing of concrete samples at (-) 20°C increase in the amount of slag from 30 to 50 wt. % Binder in the composition leads to an increase in the index of ice formation in the concrete of 1.7 times compared with the concrete obtained on slag cement containing slag with a content of 10 wt.%. Frost resistance of concrete is reduce from F400 to F350.The concrete on the slag containing cement with slag 70 wt. % is observed a slight decrease in ice formation. However, its value is 1.4 times higher than ice formation in concretes containing slag in an amount of 10 wt. %. Mark on frost resistance remains at F350.The smallest ice formation, regardless of the content of the slag into the slag containing cement, concrete characterized in that use complex organo-mineral supplement SX (5%) + SP (0.6%) in the amount of 5.6%. According to the degree of influence of additives used to reduce ice formation in the slag in concretes, containing cements can be ranker number: SX (5%) + SP (0.6%) > NC (5%) + SP (0.6%) > SP (0.6%).

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