scholarly journals The impact of changes in pore structure on the compressive strength of sulphoaluminate cement concrete at high temperature

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
J.J.K. Tchekwagep ◽  
P. Zhao ◽  
S. Wang ◽  
S. Huang ◽  
X. Cheng
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Elevated Temperatures ◽  
Nitrogen Adsorption ◽  
Cement Concrete ◽  
Constant Weight ◽  
Sulphoaluminate Cement ◽  
Structure Changes ◽  
The Impact ◽  
The Relationship

Abstract The internal pore structure of sulphoaluminate cement concrete (SACC) significantly affects its mechanical properties. The main purpose of this study was to establish the relationship between pore structure changes and compressive strength after exposure to elevated temperatures. SACC samples that had been cured for 12 months were dried to a constant weight and then exposed to different temperatures (100 °C, 200 °C and 300 °C), after which the compressive strength and pore structure were measured. The pore structure of SACC was quantitatively described by mercury intrusion porosimetry (MIP) and nitrogen adsorption results. The results showed that with increased temperature, the porosity of the SACC samples also increased and the pore structure was gradually destroyed. Moreover, the SACC’s compressive strength gradually decreased with increasing temperature. The relationship between compressive strength and porosity was in close agreement with the compressive strength–porosity equation proposed by Schiller. Therefore, after extensive exposure to elevated temperature, the changes in SACC’s compressive strength can be quantitatively described by the Schiller equation.

scholarly journals Fire Resistance Behaviour of Geopolymer Concrete:An Overview

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 82
Author(s):  
Salmabanu Luhar ◽  
Demetris Nicolaides ◽  
Ismail Luhar
Keyword(s):  
Compressive Strength ◽  
Thermal Resistance ◽  
Building Materials ◽  
Elevated Temperatures ◽  
Construction Materials ◽  
Flexural Behavior ◽  
Thermal Shrinkage ◽  
Physico Chemical ◽  
The Impact ◽  
Loss Of Strength

Even though, an innovative inorganic family of geopolymer concretes are eye-catching potential building materials, it is quite essential to comprehend the fire and thermal resistance of these structural materials at a very high temperature and also when experiencing fire with a view to make certain not only the safety and security of lives and properties but also to establish them as more sustainable edifice materials for future. The experimental and field observations of degree of cracking, spalling and loss of strength within the geopolymer concretes subsequent to exposure at elevated temperature and incidences of occurrences of disastrous fires extend an indication of their resistance against such severely catastrophic conditions. The impact of heat and fire on mechanical attributes viz., mechanical-compressive strength, flexural behavior, elastic modulus; durability—thermal shrinkage; chemical stability; the impact of thermal creep on compressive strength; and microstructure properties—XRD, FTIR, NMR, SEM as well as physico-chemical modifications of geopolymer composites subsequent to their exposures at elevated temperatures is reviewed in depth. The present scientific state-of-the-art review manuscript aimed to assess the fire and thermal resistance of geopolymer concrete along with its thermo-chemistry at a towering temperature in order to introduce this novel, most modern, user and eco-benign construction materials as potentially promising, sustainable, durable, thermal and fire-resistant building materials promoting their optimal and apposite applications for construction and infrastructure industries.

Effects of Elevated Temperatures on the Compressive Strength of HFCC

2011 ◽  
Vol 261-263 ◽  
pp. 416-420 ◽  
Author(s):  
Fu Ping Jia ◽  
Heng Lin Lv ◽  
Yi Bing Sun ◽  
Bu Yu Cao ◽  
Shi Ning Ding
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Relative Strength ◽  
Ordinary Concrete ◽  
Residual Compressive Strength ◽  
Fly Ash Concrete ◽  
The Relationship

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

The Influence of Pore-Strucrure on the Campressive Strength of Hardened Cement Paste

1984 ◽  
Vol 42 ◽  
Author(s):  
Huang Yiun-Yuan ◽  
Ding Wei ◽  
Lu Ping
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Pore Structure ◽  
Cement Paste ◽  
Total Porosity ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
New Information ◽  
The Relationship ◽  
Empirical Constants

AbstractThe pore-structure strongly influences the carpressive strength of hardened cement paste (hcp) and other porous materials, as well as other mechanical properties. The simplest but most currently used expression representing the relationship between the pore-structure and compressive strength is fram Balshin: σ = σ0 (l-P)A, in which only the total porosity P is involved as a single parameter and σ0 and A are empirical constants. The influence of pore size distribution and pore shapes etc. are not considered.The authors introduce second parameter w - the factor of relative specific surface area of the pores other than the total porosity P into consideration and a new expression is proposed:σc=K11-p/1+2p(K2(1-p))K3w+K4 all the constants K1 - K4 can be determined experimentally. By using of this expression the new information relating the influence of pore-structure on the caopressive strength of hcp can be predicted.

scholarly journals The Impact of Extended Heat Exposure on Rapid Sulphoaluminate Cement Concrete Up To 120°C

2021 ◽  
Author(s):  
Jean Jacques Kouadjo Tchekwagep ◽  
Anol K. Mukhopadhyay ◽  
Shoude Wang ◽  
Shifeng Huang ◽  
Xin Cheng
Keyword(s):  
Color Change ◽  
Heat Exposure ◽  
Cement Concrete ◽  
Rebound Hammer ◽  
Sulphoaluminate Cement ◽  
Physicochemical Processes ◽  
The Matrix ◽  
Hydrated Product ◽  
The Stability ◽  
The Impact

This study examined the stability of rapid sulphoaluminate cement concrete (R-SACC) when exposed to heat for extended periods of time. The physicochemical processes present in R-SACC as a function of temperature were determined through various tests. The general behavior of rapid sulphoaluminate cement (R-SAC) at a range of temperatures is summarized. The results show that observing color change could be a simple way to identify deterioration of R-SACC, along with the rebound hammer. The matrix formation of ettringite was broken and the mass of the hydrated product decreased with heat exposure; the major mineral composition of the paste consisted of CaSO4, CaCO3 and β-C2S; and the interface between aggregate and paste in the R-SACC become loosely structured with cracks. Between 50°C and 120°C, the rapid sulphoaluminate cement (R-SAC) paste first expanded and then shrank, and the shrinkage rate of R-SAC was much greater than that of R-SACC.

scholarly journals Parametric Strategy for Composite Cement Concrete Blended with Fly Ash & Glass Fiber

2020 ◽  
pp. 162-176
Author(s):  
Madhurima Das ◽  
Siba Prasad Mishra
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Glass Fiber ◽  
Building Materials ◽  
Cement Concrete ◽  
Strength Performance ◽  
X Ray ◽  
Natural Building ◽  
The Impact ◽  
Scanning Electron

Coping with population growth, houses are built to meet the hike. The prerequisites for concrete and steel reinforcements have surged up globally since last 3 to 4decades. Shortage of natural building materials, increased wastes from coal based industries to augment carbon foot print has worried the engineers to reuse their wastes (such as fibres, powders, granules, etc.) as building materials ingredient. Glass fibre has improved flexural capabilities with fly ash dosages in cement concrete and alternately helps in restricting environmental degradation. Present research aims at investigating the impact of glass fiber (at 1%, 2% and 3% addition) and fly ash (dosages of 10% and 20% over the existing fly ash in PPC). The ingredients and microstructure of composites are found by either X-ray fluorescent spectroscopy or scanning electron microscope. Experimental evaluation results of the blended composite concrete parameters of RCC are experimentally evaluated and compared have shown that concrete with 10% cement substitution with fly ash and 3% fibre showed optimum compressive strength performance than the concrete without fibre and fly ash and also chemically resistant against commonly used M-20 grade of Concrete.

scholarly journals STUDI PENDAHULUAN BATAS MAKSIMUM KADAR LUMPUR PADA AGREGAT BETON GEOPOLIMER

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Djedjen Achmad ◽  
Desi Supriyan
Keyword(s):  
Compressive Strength ◽  
Concrete Aggregate ◽  
Fine Aggregate ◽  
Geopolymer Concrete ◽  
Test Results ◽  
Cement Concrete ◽  
Flexural Tensile Strength ◽  
Binder Ratio ◽  
The Impact ◽  
Water Binder Ratio

ABSTRACTHas been researched the impact of mud in aggregate on geopolymer concrete with studies using the cement concrete as a reference. In this study both of concrete are mixed with a variation of mud of 0%, 0.75%, 3% and 5.75% of the combined aggregate weight. Compressive strength of cement concrete is designed with a target of 300 kg / cm2 and geopolymer concrete is made with water binder ratio (w/b) 0.25, Molarity 12 M, the ratio of sodium silicate and sodium hydroxide 1.5. At the age of 3, 7, 14 and 28 day tested of compressive strength, while the spliting test, flexural tensile strength, and modulus of elasticity are tested at 28 days. From the test results, the higher mud content in aggregate , the mechanical properties of the concrete are decreased. Based on testing of compressive strength in cement concrete at 28 days, with a 3% mud content (the content of the reference mud) turns of compressive strength decreased by 77.356%. Of the percentage reduction on the compressive strength of the cement concrete, can be compared to the mud content in geopolymer concrete at 2.04%. Thus the maximum mud on geopolymer concrete aggregate is, for coarse aggregate of 0.68% and a maximum mud content for fine aggregate was 3.4%.Key words : Mud, aggregate, concrete, cement, geopolimer, strengthABSTRAKTelah diteliti dampak kadar lumpur pada agregat untuk beton geopolimer dengan penelitian menggunakan benda uji beton semen sebagai acuan dan beton geopolimer. Dalam penelitian ini ke dua beton tersebut dicampur dengan lumpur gabungan agregat kasar dan agregat halus dengan variasi 0 %, 0.75 %, 3 % dan 5,75 % dari berat agregat gabungan. Beton semen dirancang dengan target kuat tekan 300 kg/cm2 dan beton geopolimer dibuat dengan campuran water binder ratio (w/b) 0.25, Molaritas 12 M, perbandingan sodium silikat dan sodium hidroksida 1.5. Pada umur 3, 7, 14 dan 28 hari dilakukan uji kuat tekan, sedangkan uji kuat tarik belah, uji kuat tarik lentur, dan modulus elastisitas dilakukan pada umur 28 hari. Dari hasil uji terlihat bahwa semakin tinggi kadar lumpur pada agregat, karakteristik mekanis kedua beton tersebut mengalami penurunan. Berdasarkan pengujian kuat tekan pada beton semen umur 28 hari, dengan kadar lumpur 3 % (kadar lumpur referensi) ternyata beton semen mengalami penurunan kuat tekan sebesar 77.356 %. Dari persentase penurunan kuat tekan beton semen tersebut, diplot pada grafik kuat tekan beton geopolimer maka persentase kadar lumpur gabungan yang mengalami penurunan 77.356 % adalah 2.04 %. Dengan demikian kadar lumpur maksimum pada agregat beton geopolimer adalah, untuk agregat kasar sebesar 0.68 % dan kadar lumpur maksimum untuk agregat halus adalah 3.4 %.Kata kunci : Lumpur, agregat, beton, semen, geopolimer, kekuatan

Study on the Permeability Model of the Porous Concrete

2011 ◽  
Vol 374-377 ◽  
pp. 1369-1373 ◽  
Author(s):  
Fang Ran Zhao ◽  
Mian Mian Chen ◽  
Zhao Lu Ding
Keyword(s):  
Pore Structure ◽  
Test Piece ◽  
Experimental Results ◽  
Effective Model ◽  
Permeability Model ◽  
Porous Concrete ◽  
Structure Changes ◽  
Proposed Model ◽  
Capillary Bundle ◽  
The Relationship

This paper presents an effective model which can equivalently regard the pores in the porous concrete as a series of capillary bundles with the same diameter due to the complexity of the pores in the porous concrete. The proposed model was used to calculated the total flows of all capillary bundles in the test piece by the single capillary bundle calculation approach from the Hagen-Poiseuille theorem, and together with the well known Darcy theorem to determine the relationship among the flow of the porous concrete, the diameter of pore and the minus of up and down water pressures. The experimental results show that the permeability of the porous concrete mainly depends on the pores with diameter more than 4.12mm, and the pore structure changes obviously when the valid porosity of the porous concrete is greater than 25%.

scholarly journals Effect of the Curing Condition and High-Temperature Exposure on Ground-Granulated Blast-Furnace Slag Cement Concrete

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Eskinder Desta Shumuye ◽  
Jun Zhao ◽  
Zike Wang
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Curing Temperature ◽  
Stable Phase ◽  
Cement Concrete ◽  
Slag Cement ◽  
High Temperature Exposure ◽  
Curing Condition ◽  
Temperature Exposure

AbstractIn this study, the effect of curing temperature on the properties of slag cement concrete after high-temperature exposure was studied, and elevated curing temperature (45 ± 2 °C and 95% relative humidity (RH)) was selected to compare with the standard curing temperature (20 ± 2 °C and 95%RH). Four different concrete mixes with the same mix proportion, except for different slag replacement ratios, were used: 0% (reference), 30% (slag), 50% (slag), and 70% (slag). After high-temperature exposure at 200, 400, 600, and 800 °C, the effect of slag replacement, high temperature, and curing temperature on the compressive strength and mineralogical and microstructural properties of slag cement concrete were studied. Test results indicated that the compressive strength of concrete cured for 7 d at elevated temperatures increased by 28.2, 20.7, 28.8, and 14.7% compared with that cured at the standard curing condition at slag percentages of 0, 70, 50, and 30%, respectively. X-ray diffraction (XRD) and Scanning electron microscope (SEM) results revealed that concrete cured at elevated temperatures exhibited a more condensed phase and contained a higher percentage of hydrates than that cured for 7 d in the standard curing condition. However, after 56 d of curing, concrete in the standard curing condition exhibited a more stable phase and a higher concentration of hydrates.

scholarly journals Study on the Relationship between Pore Structure and Uniaxial Compressive Strength of Cemented Paste Backfill by Using Air-Entraining Agent

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Fengwen Zhao ◽  
Jianhua Hu ◽  
Dongjie Yang ◽  
Ye Kuang ◽  
Hongxing Xiao ◽  
...  
Keyword(s):  
Pore Structure ◽  
Fractal Theory ◽  
Total Pore Volume ◽  
Linear Increase ◽  
Theory Analysis ◽  
Structure Changes ◽  
Small Pore ◽  
Paste Backfill ◽  
Air Entraining Agents ◽  
The Relationship

To control pores in the backfill, the air-entraining agents (AEAs) are used as an admixture to realize the pore structure changes under artificial action and explore the effect of pore structure on strength. Two AEAs at different dosages were added to the backfill. The relationship was then analyzed between them from the macro- and mesoscopic aspects. The results indicate that AEA can regulate pore structure changes of AEACPB. With the increase in AEA content, the total pore volume of different pore sizes in AEACPB increases, in which the proportion of big and medium pore gradually increases while the proportion of small pore gradually decreases. The AEACPB’s UCS is linearly negatively correlated with the porosity and pore percentage, which is the primary factor affecting the AEACPB of the pore structure. When the total pores’ volume in the AEACPB is constant, the influence of different pore structures differs. A higher proportion of small pores leads to a linear increase in strength; a higher proportion of medium pores leads to a linear decrease in strength; and a higher proportion of big pores leads to an exponential decrease in strength. And the fractal dimension has a linear negative correlation with the UCS by fractal theory analysis.

scholarly journals Biobased Polyurethane Composite Foams Reinforced with Plum Stones and Silanized Plum Stones

2021 ◽  
Vol 22 (9) ◽  
pp. 4757
Author(s):  
Karolina Miedzińska ◽  
Sylwia Członka ◽  
Anna Strąkowska ◽  
Krzysztof Strzelec
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Compressive Strength ◽  
Cellular Structure ◽  
Polyurethane Composite ◽  
Composite Foams ◽  
Biobased Polyurethane ◽  
The Impact ◽  
The Relationship ◽  
Natural Fillers

In the following study, ground plum stones and silanized ground plum stones were used as natural fillers for novel polyurethane (PUR) composite foams. The impact of 1, 2, and 5 wt.% of fillers on the cellular structure, foaming parameters, and mechanical, thermomechanical, and thermal properties of produced foams were assessed. The results showed that the silanization process leads to acquiring fillers with a smoother surface compared to unmodified filler. The results also showed that the morphology of the obtained materials is affected by the type and content of filler. Moreover, the modified PUR foams showed improved properties. For example, compared with the reference foam (PUR_REF), the foam with the addition of 1 wt.% of unmodified plum filler showed better mechanical properties, such as higher compressive strength (~8% improvement) and better flexural strength (~6% improvement). The addition of silanized plum filler improved the thermal stability and hydrophobic character of PUR foams. This work shows the relationship between the mechanical, thermal, and application properties of the obtained PUR composites depending on the modification of the filler used during synthesis.

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