scholarly journals Effects of Environmental Factors on Concrete Carbonation Depth and Compressive Strength

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2167 ◽  
Author(s):  
Ying Chen ◽  
Peng Liu ◽  
Zhiwu Yu
Keyword(s):  
Compressive Strength ◽  
Phase Composition ◽  
Relative Humidity ◽  
Co2 Concentration ◽  
Crystal Structure Analysis ◽  
Hydration Products ◽  
Carbonation Depth ◽  
Concrete Carbonation ◽  
Before And After ◽  
Compressive Strength Of Concrete

The influence of temperature, CO2 concentration and relative humidity on the carbonation depth and compressive strength of concrete was investigated. Meanwhile, phase composition, types of hydration products and microstructure characteristics of samples before and after the carbonation were analyzed by XRD and ESEM. Research results demonstrate that temperature, CO2 concentration and relative humidity influence the carbonation depth and compressive strength of concrete significantly. There is a linear relationship between temperature and carbonation depth, as well as the compressive strength of concrete. CO2 concentration and relative humidity present a power function and a polynomial function with carbonation depth of concrete, respectively. The concrete carbonation depth increases with the increase of relative humidity and reaches the maximum value when the relative humidity is 70%. Significant differences of phase composition, hydration products and microstructure are observed before and after the carbonation. Carbonization products of samples are different with changes of temperatures (10 °C, 20 °C and 30 °C). The result of crystal structure analysis indicates that the carbonation products are mainly polyhedral spherical vaterite and aragonite.

scholarly journals Effect of Temperature on Concrete Carbonation Performance

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Peng Liu ◽  
Ying Chen ◽  
Zhiwu Yu ◽  
Rongling Zhang
Keyword(s):  
Compressive Strength ◽  
Phase Composition ◽  
Strain Curve ◽  
Crystal Form ◽  
Surface Strain ◽  
Effect Of Temperature ◽  
Linear Segment ◽  
Hydration Products ◽  
Carbonation Depth ◽  
Before And After

In this study, the effect of temperature on macroperformance and microcharacteristic of carbonized concrete was investigated. The carbonation depth, compressive strength, and surface strain of concrete under different simulated environments for 28 d were measured. XRD and ESEM-EDS analysis were conducted to present the phase composition, types of hydration products, and microstructure characteristics of samples before and after carbonation. The results showed that the effects of temperature on carbonation depth, strain, and compressive strength were significant. There was a linear relation between temperature and carbonation depth as well as compressive strength of concrete. The effects of environment factors on concrete surface strain after carbonation manifested as the strain value and the slope of linear segment of strain curve. Significant differences of phase composition and hydration products were observed before and after the carbonation, which mainly manifested as attenuation and disappearance of diffraction peaks of hydration products. Temperature affects the crystal form of the carbonation products.

Mechanical Property of Phosphoaluminate Cement

2010 ◽  
Vol 150-151 ◽  
pp. 1754-1757 ◽  
Author(s):  
Peng Liu ◽  
Zhi Wu Yu ◽  
Ling Kun Chen ◽  
Zhu Ding
Keyword(s):  
Mechanical Property ◽  
Compressive Strength ◽  
Phase Composition ◽  
Electrical Properties ◽  
Pore Size Distribution ◽  
Pore Size ◽  
High Strength ◽  
Curing Time ◽  
Hydration Products ◽  
Resistance Value

The influence of curing time on the mechanical property of the phosphoaluminate cement (PAC) was investigated, and the mechanism was discussed as well. The phase composition and morphology of hydration products, electrical properties, porosity and pore size distribution of PAC cured different age were analyzed with XRD, EIS and MIP. The results showed PAC has the property of early-high strength, and the compressive strength of PAC cured for 1 day was about 70% of 28 days’. The main hydration products of PAC are micro-crystal phase and gel of phosphate and phosphoaluminate which formed compacter microstructure. In addition, there are no calcium hydroxide (CH) and ettringite (AFt) produced during the process of hydration. The compressive strength of PAC increased with age, which was due to more products continuously produced. The ac resistance analysis manifested as the change of the nyquist pattern and resistance value.

scholarly journals Research on Mechanical Performance & Behaviour of Geopolymer Concrete Subjected to Elevated Temperatures

2019 ◽  
Vol 8 (2S8) ◽  
pp. 883-887
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Geopolymer Concrete ◽  
Sem Images ◽  
Before And After ◽  
Alkaline Conditions ◽  
Compressive Strength Of Concrete

The investigative studies on mechanical performance & behaviour, of Geopolymer Concrete (GPC) before and after the exposure to elevated temperatures (of 200 0 C -1000 0 C with an increment of 100 0 C). Indicate that the GPC Specimens Exhibited better Compressive strength at higher temperatures than that of those made by regular OPC Concrete with M30 Grade. The chronological changes in the geopolymeric structure upon exposure to these temperatures and their reflections on the thermal behaviour have also been explored. The SEM images indicate GPC produced by fly ash , metakaolin and silica fume, under alkaline conditions form Mineral binders that are not only non-flammable and but are also non-combustible resins and binders. Further the Observations drawn disclose that the mass and compressive strength of concrete gets reduced with increase in temperatures.

scholarly journals Time Impacts of Treating Pervious Concrete with NaHCO3

2021 ◽  
Author(s):  
Nara Almeida ◽  
Liv Haselbach
Keyword(s):  
Compressive Strength ◽  
Chemical Reactions ◽  
Magnesium Chloride ◽  
Cement Mortar ◽  
Post Treatment ◽  
Pervious Concrete ◽  
Concrete Pavements ◽  
Concrete Carbonation ◽  
Before And After ◽  
Time Frames

Abstract Magnesium chloride deicers applications onto pervious concrete pavements can deteriorate the material, and studies investigate treatments to increase the concrete resistance to MgCl2 attacks. In this paper, pervious concrete specimens are subjected to a treatment with NaHCO3 solution, which seems to accelerate concrete carbonation and might hamper chemical reactions between MgCl2 deicer and hydroxides in cement mortar. All specimens had their compressive strength tested and the time frames before and after treatment varied. Results show that at least 2 months should be given post curing before treatment to not harm the concrete, and longer post treatment periods may be beneficial.

scholarly journals PROPERTIES OF CEMENT-FLY ASH MIXTURES WITH SUBSTANDARD FLY ASH AS A PARTIAL CEMENT AND FINE AGGREGATE REPLACEMENT

2021 ◽  
Vol 11 (3) ◽  
pp. 71-88
Author(s):  
Piseth Pok ◽  
Parnthep Julnipitawong ◽  
Somnuk Tangtermsirikul
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Sulfate ◽  
Chloride Penetration ◽  
The Other ◽  
Fine Aggregate ◽  
Carbonation Depth ◽  
Cement Replacement ◽  
Durability Properties ◽  
Compressive Strength Of Concrete

This research investigated the effects of using a substandard fly ash as a partial cement and/or fine aggregate replacement on the basic and durability properties of cement-fly mixtures. Experimental results showed that utilizing the substandard fly ash led to increase in water requirement and autoclave expansion of pastes. The strength activity indexes of the substandard fly ash passed the requirements of TIS 2135 and ASTM C618. Utilization of the substandard fly ash as cement replacement led to higher expansion of mortar bars stored in water and sodium sulfate expansion as compared to that of the OPC mixture. However, sodium sulfate resistance of mortar mixtures improved when utilizing the substandard fly ash as sand replacement material. The compressive strength of concrete at all ages was higher with the increase of the content of the substandard fly ash as sand replacement material. When the substandard fly ash was used as cement replacement material in concrete, the carbonation depth increased. On the other hand, the use of the substandard fly ash as sand replacement material decreased the carbonation depth of the concrete. Utilization of the substandard fly ash, both to replace cement and/or fine aggregate, reduced the rapid chloride penetration of the concrete.

Safety Inspection and Evaluation on the Main Structure of a Framework Wharf

2013 ◽  
Vol 639-640 ◽  
pp. 998-1002
Author(s):  
Zai Hua Zhang ◽  
Bo Wang Chen ◽  
Ran He
Keyword(s):  
Compressive Strength ◽  
Bearing Capacity ◽  
Service Time ◽  
Carbonation Depth ◽  
Main Structure ◽  
Compressive Strength Of Concrete ◽  
Rebar Corrosion ◽  
Cover Thickness

Yiyang rubber machinery group cargo terminal is a vertical frame wharf established in the early 1970’s. A certain degree of deterioration and damage has occurred to the structure because of the long service time and long-term exposure of some parts of the structure. Taken the subsequent use of safety into account, the structure was completely detected. The detection content included array of structure, apparent damage and rebar corrosion situation, carbonation depth and compressive strength of concrete, distributions of reinforcement and cover thickness, verticality of the overall structure and so on. The bearing capacity of the main structure was checked according to the corresponding detection results and standards. Then the safety of the wharf structure was comprehensively assessed and some suggestion about repairing and reinforcement was also made which could provide the reference for the follow-up repair and reinforcement or other similar engineering.

scholarly journals Time impacts of treating pervious concrete with sodium bicarbonate

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Nara Almeida ◽  
Liv Haselbach
Keyword(s):  
Compressive Strength ◽  
Sodium Bicarbonate ◽  
Chemical Reactions ◽  
Magnesium Chloride ◽  
Cement Mortar ◽  
Pervious Concrete ◽  
Concrete Pavements ◽  
Concrete Carbonation ◽  
Before And After ◽  
Time Frames

AbstractMagnesium chloride (MgCl2) deicers applications onto pervious concrete pavements can deteriorate the material, and studies investigate treatments to increase the concrete resistance to MgCl2 attacks. In this paper, pervious concrete specimens are subjected to a treatment with Sodium Bicarbonate (NaHCO3) solution, which seems to accelerate concrete carbonation and might hamper chemical reactions between MgCl2 deicer and hydroxides in cement mortar. All specimens had their compressive strength tested and the time frames before and after treatment varied. Results show that at least 2 months should be given post curing before treatment to not harm the concrete, and longer post treatment periods may be beneficial.

Investigation of Composite Deflocculant Influence on the Properties of the Refractory Castable with Chamotte Aggregate

2014 ◽  
Vol 682 ◽  
pp. 256-260 ◽  
Author(s):  
Ina Pundienė ◽  
Irina Demidova-Buiziniene ◽  
A. Volochko
Keyword(s):  
Compressive Strength ◽  
Rheological Properties ◽  
Comparative Studies ◽  
Sodium Tripolyphosphate ◽  
Strength Properties ◽  
Cement Matrix ◽  
Hydration Products ◽  
Drying Process ◽  
Different Types ◽  
Compressive Strength Of Concrete

The influence of different types of deflocculants, PCE and sodium tripolyphosphate, on the rheological properties of the cement matrix was studied. It was established that composite deflocculant consisting of sodium tripolyphosphate and PCE Castament FS 20 provides the best rheological properties of the cement matrix and affects the composition of the hydration products. During the drying process of matrix with composite deflocculants mineral stratlingite additionally formed, which contributes to increment of strength properties. Comparative studies of refractory castable strength properties with chamotte aggregate showed that the compressive strength of concrete samples with composite deflocculants after hardening and after drying and burning is almost two times higher than the strength of samples with separate deflocculants.

scholarly journals Pengaruh Admixture Terhadap Campuran Beton K 350 Ditinjau Dari Kuat Tekan Beton

2018 ◽  
Vol 7 (1) ◽  
pp. 19-26
Author(s):  
Rida Respati
Keyword(s):  
Compressive Strength ◽  
Water Use ◽  
Concrete Compressive Strength ◽  
Normal Concrete ◽  
Before And After ◽  
Medium Quality ◽  
Compressive Strength Of Concrete

In this research, we want to experiment to find out the compressive strength of medium quality concrete K-350 with ingredients added MASTER RHEOBUILD 6, whose function is to accelerate hardening, improve the quality of concrete, reduce water use and increase the value of slump. However, it should be noted that errors in dosages and how to use added ingredients can be detrimental to the quality of concrete. The results of the study show that the addition of 0.25, 0.5 and 0.75 liters per 50 kg of cement can increase the concrete compressive strength. The compressive strength of concrete with the addition of 0.25 liters/50 kg of cement has increased 362.67 kg/cm� from the normal concrete compressive strength of 350.58 kg/cm2. The addition of 0.5 liters/50 kg of cement has increased again to 373.24 kg/cm�, and the addition of 0.75 liters/50 kg of cement has increased the concrete compressive strength to 379.29 kg/cm� of normal concrete. Comparison of compressive strength before and after addition of admixture with an increase of 3.45% in addition of 0.25 liters/50 kg of cement, 6.47% in addition of 0.5 liters/50 kg of cement and 8.19% in addition of 0.75 liters/50 kg of cement.

Effects of Conductive Phase on Properties of Concrete

2019 ◽  
Vol 960 ◽  
pp. 174-179
Author(s):  
Bao Zhen Fan ◽  
Zheng Gang Fang ◽  
Rui Liu ◽  
Hong Bing Shen
Keyword(s):  
Compressive Strength ◽  
Electrical Resistivity ◽  
Carbon Fiber ◽  
Lamellar Structure ◽  
Good Condition ◽  
Conductive Network ◽  
Hydration Products ◽  
Conductive Phase ◽  
Compressive Strength Of Concrete

In this paper, the effects of graphite and carbon fiber on the properties of concrete were studied, the 28d compressive strength and electrical resistivity of concrete were measured, and the microstructure of concrete was observed. The results show that the graphite could improve the conductivity of concrete meanwhile reduce the compressive strength, and that the carbon fiber can improve the compressive strength of concrete, but its influence is considerably limited. Only when the mixing amount of graphite is higher than 1%, the compressive strength of concrete will increase along with the increase of mixing amount of carbon fiber, and the lamellar structure of graphite will be obvious, and the lamellar connection between graphite flakes will be in good condition. When the mixing amount of carbon fiber is 0.8%, dense connection will be formed between the carbon fiber & graphite and the hydration products. The combined mixture of graphite and carbon fiber can form a dense and relatively complete conductive network and is beneficial to the improvement of compressive strength of concrete.

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