Fine Grain Portland Cement Concrete with Complex Nanodisperse Admixture for Structure Rehabilitating

2015 ◽  
Vol 1122 ◽  
pp. 105-110
Author(s):  
Galina D. Fedorova ◽  
Gregory N. Alexandrov ◽  
Grigory I. Yakovlev ◽  
Irina S. Polyanskikh ◽  
Igor A. Pudov

The influence of new complex nanodisperse admixture on structure and strength characteristics of fine grain concrete used in rehabilitation of damaged concrete structures has been studied. Concrete without the admixture is more susceptible to cracking than concrete with the complex admixture, thus increasing the working time of structures. At the age of 28 days the compressive strength of fine grain concrete with the admixture reaches 52,35 MPa, the flexural strength is 5,2 MPa. The strength characteristics of concrete increased by 15%.

2012 ◽  
Vol 512-515 ◽  
pp. 2812-2816
Author(s):  
Wei Li ◽  
Xiao Chu Wang ◽  
Hong Tao Liu

This test summers up the research situation of rubber powder modifier. According to tests of density, flexural strength, compressive strength and cleavage strength, this test analyzes the basic mechanical properties and the variation of rubberized portland cement concrete which is mixing the silica fume modifier. The results show that the flexural strength, compressive strength and cleavage strength of concrete may increase when silica fume concrete admixture modifiers is mixed in cement concrete. The workability, density, flexural strength, compressive strength, ratio of compressive strength and cleavage strength of rubberized portland cement concrete gradually reduced with the increase in dosage of rubber. The rubber particles mixed with concrete which can when the rubber particle size is not more than 30% of the dosage of coarse aggregate, the fine pavement of rubberized portland cement concrete can be got.


Author(s):  
Rodolfo De Sá Petrucci ◽  
Daniel Hastenpflug

The search of reduction for the permeability of concrete structures, and consequently, increase in the durability of the structural elements has led to develop products for this purpose. One of the options is the use of crystalline waterproofing admixture (CWA). This research evaluated the influence of the use of crystalized admixture for waterproofing on the Portland cement concrete porosity. Water absorption and compressive strength of concretes with crystalline waterproofing admixture at the dosage recommended by the supplier were evaluated and the results were compared with regular concrete, without addition of admixture. The results show a reduction of porosity with reduction of absorption from 3.30% to 0.32% at 56 days of age after specimens molding. A reduction of compressive strength by 7.89% in concrete with admixture was also observed.


2021 ◽  
Vol 6 (8) ◽  
pp. 113
Author(s):  
Mazen J. Al-Kheetan ◽  
Seyed Hamidreza Ghaffar ◽  
Said Awad ◽  
Mehdi Chougan ◽  
Juliana Byzyka ◽  
...  

Portland Cement Concrete (PCC) pavement was studied with incorporation of an environmentally friendly eco-additive, sodium acetate (C2H3NaO2). This additive was added to PCC pavement in three different percentages of 2%, 4% and 6% of binder weight. For a comprehensive elucidation of the eco-additive incorporation on the performance of PCC pavement, casted samples were cured in three different environments, namely: water, outdoors and pond water. Water absorption tests, flexural and compressive strength tests after 7 and 28 days of curing were conducted and results compared with the control samples without any addition of sodium acetate. Results demonstrated a significant improvement in the impermeability, compressive strength and flexural strength of PCC pavement when sodium acetate concrete is cured in a water bath and outdoors. However, no/little improvement in the impermeability, compressive strength and flexural strength was observed in sodium acetate samples that were cured in pond water. Microstructural analysis of treated samples by using scanning electron microscopy (SEM) illustrated the strengthening effect that sodium acetate provides to the pore structure of concrete pavement.


2016 ◽  
Vol 680 ◽  
pp. 392-397
Author(s):  
Zhu Ding ◽  
Meng Xi Dai ◽  
Can Lu ◽  
Ming Jie Zhang ◽  
Peng Cui

Magnesium phosphate cements (MPC) had been used as repair materials for deteriorated Portland cement concrete structures. In this paper a new MPC was prepared and the basic properties including workability and compressive strength were tested. The acid attack resistance of MPC was investigated by immersing the MPC mortars in solutions at pH 3, 5, and 7, for 14d, 28d and 60d respectively. The compressive strength of MPC mortars after acid attack was tested and the microstructure of MPC were examined. The results showed that the compressive strength of MPC decreased after immersion in acid solution for 14d and 28d, however the strength of MPC with suitable materials mixture can recovered again after 60d immersion. The results indicated MPC has high acid attack resistance in static acid solution. The behavior of MPC in flowing acid solutions is need to be studied further.


2014 ◽  
Vol 17 (suppl 1) ◽  
pp. 45-50 ◽  
Author(s):  
Edson Jansen Pedrosa de Miranda Júnior ◽  
Helton de Jesus Costa Leite Bezerra ◽  
Flávio Salgado Politi ◽  
Antônio Ernandes Macêdo Paiva

2018 ◽  
Vol 7 (4.37) ◽  
pp. 138
Author(s):  
Asst. Prof. Dr. Khawla H. H. Shubber ◽  
Eng. Sajjad Hashim Mohamed

This research represents a trial of understanding and improving mechanical properties of base or subbase granular materials, used in pavement construction, stabilized with Portland cement known as cement treated base (CTB) in terms of density, optimum water content (O.W.C), and compression Strength of three curing ages (3, 7, 28) days under different situations. Different Portland cement percent of (0, 5, 7, 10, 12, and 15) % by weight were added to selected base course granular materials (type B according to local standard specification in Iraq). Results showed that the density of mixture increase with increasing added cement percent, while O.W.C takes its maximum value around 7% cement content, and compression strength increase with increasing cement content and curing age. Then effect of replacing 50% of natural granular materials by waste Portland cement concrete (WPCC) was investigated on the results of (0, 7& 15)% cement content on density, O.W.C and compression strength in the three curing ages. Results reveled although density of mixture cooperating WPCC for 0% cement content was higher, CTB of natural granular material were denser. On the other hand compressive strength decrease in case of using WPCC for all percent cement added and curing ages. Finally, effect of soaking in water on CTB with (7 &15)% cement compressive strength of three curing ages was studied, under three period of soaking (1 week, 2 weeks, &one month). Test results exposed that, CTB Compressive strength increase with increasing soaking period but still less than that of un-soaked and for all curing ages. For each test stage mathematics relationships with acceptable correlation were presented proofing test results tendency.  


2008 ◽  
Vol 400-402 ◽  
pp. 121-124
Author(s):  
Zong Hui Zhou ◽  
Ling Chao Lu ◽  
Xing Kai Gao ◽  
Xin Cheng

In this paper, preparation and mechanical properties of Alite-calcium barium sulphoaluminate (Alite-C2.75B1.25A3 ) cement concrete were studied. The results showed the compressive strength of Alite-C2.75B1.25A3 cement concrete was much higher than that of Portland cement concrete, especially the early-age compressive strength. The 24-hour compressive strength of Alite-C2.75B1.25A3 cement concrete could reach 22.81Mpa for w/c=0.45, 17.29Mpa for w/c=0.50 and 17.04Mpa for w/c=0.55 respectively. They were about 50 to 65 percent higher than those of Portland cement concrete. The 7-day compressive strength could reach about 80 to 90 percent of 28-day strength for Alite-C2.75B1.25A3 cement concrete. The 28-day strength could reach 55.85Mpa for w/c=0.45, 48.01Mpa for w/c=0.50 and 44.21Mpa for w/c=0.55 respectively. The results of SEM showed the interfaces between the hardened cement paste and aggregates in Alite-C2.75B1.25A3 cement concrete were more compact than those in Portland cement concrete. Distribution of particulate bulk was more uniformity and a majority of clinker particles was wrapped by hydrated gel in Alite-C2.75B1.25A3 concrete. And, the structure of Alite-C2.75B1.25A3 cement concrete was much more compact than that of Portland cement concrete.


2020 ◽  
Vol 18 (6) ◽  
pp. 1615-1640
Author(s):  
Eric Asa ◽  
Monisha Shrestha ◽  
Edmund Baffoe-Twum ◽  
Bright Awuku

Purpose Environmental issues caused by the production of Portland cement have led to it being replaced by waste materials such as fly ash, which is more economical and safer for the environment. Also, fly ash is a material with sustainable properties. Therefore, this paper aims to focus on the development of sustainable construction materials using 100% high-calcium fly ash and potassium hydroxide (KOH)-based alkaline solution and study the engineering properties of the resulting fly ash-based geopolymer concrete. Laboratory tests were conducted to determine the mechanical properties of the geopolymer concrete such as compressive strength, flexural strength, curing time and slump. In phase I of the study, carbon nanotubes (CNTs) were added to determine their effect on the strength of the geopolymer mortar. The results derived from the experiments indicate that mortar and concrete made with 100% fly ash C require an alkaline solution to produce similar (comparable) strength characteristics as Portland cement concrete. However, it was determined that increasing the amount of KOH generates a considerable amount of heat causing the concrete to cure too quickly; therefore, it is notable to forming a proper bond was unable to form a stronger bond. This study also determined that the addition of CNTs to the mix makes the geopolymer concrete tougher than the traditional concrete without CNT. Design/methodology/approach Tests were conducted to determine properties of the geopolymer concrete such as compressive strength, flexural strength, curing time and slump. In Phase I of the study, CNTs were studied to determine their effect on the strength of the geopolymer mortar. Findings The results derived from the experiments indicate that mortar and concrete made with 100% fly ash C require an alkaline solution to produce the same strength characteristics as Portland cement concrete. However, it was determined that increasing the amount of KOH generates too much heat causing the concrete to cure too quickly; therefore, it is notable to forming a proper bond. This study also determined that the addition of CNTs to the mix makes the concrete tougher than concrete without CNT. Originality/value This study was conducted at the construction engineering and management concrete laboratory at North Dakota State University in Fargo, North Dakota. All the experiments were conducted and analyzed by the authors.


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