scholarly journals Effect of Functional Superplasticizers on Concrete Strength and Pore Structure

2020 ◽  
Vol 10 (10) ◽  
pp. 3496
Author(s):  
Wuju Xun ◽  
Changlong Wu ◽  
Xuefei Leng ◽  
Jiye Li ◽  
Desheng Xin ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
High Performance ◽  
Concrete Strength ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Polycarboxylic Acid ◽  
X Ray Diffraction ◽  
Hydration Rate ◽  
Compressive Strength Of Concrete

The current work investigates the fluidity and the loss of the flow rate of cement paste and mortar over time, as well as the pore structure and compressive strength of concrete and mortar in the presence of functional polycarboxylic acid high-performance water-reducing agents. The hydration rate, hydration products, and pore structure of the concrete containing different functional polycarboxylic acid superplasticizers were analyzed by means of mercury intrusion test, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results show that water-reducing agent Z significantly improves the pore structure of concrete and further compacts the structure of concrete and mortar, thereby improving the compressive strength of concrete. Moreover, the shorter side chains and ester functional groups in the structure of water-reducing agent H can slow down cement hydration rate, which lowers the early strength of mortar; nevertheless, at later stages, the pore structure of the concrete and mortar including superplasticizer H is less different from that of the concrete and mortar containing polycarboxylic acid water-reducing agents. Water-reducing agent J performs best but has a weaker effect on the pore structure of concrete and mortar compared to superplasticizer Z; it is also better than naphthalene-based water-reducing agents.

scholarly journals Study of Concrete Strength and Pore Structure Model Based on Grey Relation Entropy

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 432
Author(s):  
Min Zhang ◽  
Xianhua Yao ◽  
Junfeng Guan ◽  
Lielie Li ◽  
Juan Wang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Pore Size ◽  
Concrete Strength ◽  
Sensitivity Coefficient ◽  
Structure Model ◽  
Proposed Model ◽  
Compressive Strength Of Concrete ◽  
The Relationship ◽  
Grey Relation

The Grey Relation Entropy (GRE) theory is used to analyze the sensitive pore size that affects the compressive strength of concrete. The relationship between the strength and pore structure is revised based on the sensitivity coefficient. The revised model is used to calculate the compressive strength of concrete. In order to verify the validity of the proposed model, the calculated results are compared with experimental ones, showing satisfactory agreement with a larger correlation than existing methods.

scholarly journals The Influence of Water Reducing Agents on Early Hydration Property of Ferrite Aluminate Cement Paste

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 731
Author(s):  
Chunlong Huang ◽  
Zirui Cheng ◽  
Jihui Zhao ◽  
Yiren Wang ◽  
Jie Pang
Keyword(s):  
Setting Time ◽  
Critical Role ◽  
Hydration Product ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Hydration Process ◽  
Early Hydration ◽  
Cement Pastes ◽  
Hydration Rate ◽  
Aluminate Cement

The ferrite aluminate cement (FAC) could rapidly lose fluidity or workability due to its excessive hydration rate, and greatly reduce the construction performance. Chemical admixtures are commonly used to provide the workability of cement-based materials. In this study, to ensure required fluidity of FAC, chemically different water reducing agents are incorporated into the FAC pastes. The experiments are performed with aliphatic water reducing agent (AP), polycarboxylic acid water reducing agent (PC) and melamine water reducing agent (MA), respectively. Influence of the water reducing agents on fluidity, setting time, hydration process, hydration product and zeta potential of the fresh cement pastes is investigated. The results show that PC has a better dispersion capacity compared to AP and MA. Besides decreasing water dosage, PC also acts as a retarder, significantly increasing the setting times, delaying the hydration rate and leading to less ettringite in the hydration process of FAC particles. The water reducing agents molecules are adsorbed on the surface of positively charged minerals and hydration products, however, for PC, steric hindrance from the long side chain of PC plays a critical role in dispersing cement particles, whereas AP and MA acting through an electrostatic repulsion force.

Study on corrosion effect of high-performance concrete under the action of sulfate and chlorine

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940054 ◽  
Author(s):  
Rongrong Yin ◽  
Jie Hu ◽  
Yu Liu ◽  
Qing Wu ◽  
Chenchen Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Growth Stage ◽  
High Performance Concrete ◽  
Slow Growth ◽  
Concrete Strength ◽  
Corrosion Damage ◽  
Chloride Salt ◽  
Single Action ◽  
Two Stages

The thickness of corroded concrete layer and the compressive strength of prisms under the action of sulfate and chloride salt were investigated by ultrasonic test and compression test, respectively. The results show that under the single action of sulfate, the strength of concrete experienced two stages: a slow growth stage and a rapid descent stage. Correspondingly, under the combined action of sulfate and chloride, the concrete strength experienced another two stages: a slow growth stage and a slow degradation stage. The existence of chloride inhibited the corrosion damage of concrete in a certain extent. It was found that higher concentration of chlorine salt would lead to a stronger inhibition effect. A good consistency was observed among corrosion layer thickness, compressive strength and X-ray diffraction results. The inhabitation of chloride to the sulfate corrosion of concrete was proved.

scholarly journals Studi Kuat Tekan Beton Speedcrete Dengan Zat Additive Naphthalene Berdasarkan Variasi Umur

2019 ◽  
Vol 14 (2) ◽  
Author(s):  
Syifa Fauziah ◽  
Anisah Anisah ◽  
Sittati Musalamah
Keyword(s):  
Compressive Strength ◽  
Test Object ◽  
Treatment Process ◽  
Concrete Strength ◽  
Test Machine ◽  
Water Age ◽  
Normal Concrete ◽  
Compressive Strength Of Concrete ◽  
Normal Strength ◽  
Additive Materials

This research aims to determine the maximum compressive strength value of concrete speedcrete using naphthalene additive additive at each test age and compare with normal concrete 28 days. This research used cylindrical test object with diameter 15 cm and height 30 cm. Speedcrete concrete does not undergo the treatment process while the normal concrete test object through the treatment process. Testing compressive strength of concrete speedcrete using Crushing Test Machine tool. In this research the compressive strength was produced by using superplasticizer type naphthalene and compared with normal concrete without using additive. The target quality plan is fc '35 MPa with the use of additive dose of 1.7% of the weight of cement. The results of this research showed an increase in the value of compressive strength of concrete speedcrete with aadditive materials added naphthalene increased with increasing age of concrete. The results showed that the compressive strength of concrete speedcrete with naphthalene additive materials of 12 hours, 18 hours, 28 hours and 48 hours was 0.5 MPa, 17,81 MPa, 31,14 MPa and 45,77 MPa. Normal strength concrete strength with the addition of 20% water age 28 days that is equal to 54.76 MPa.

Research and Applying Evolution of High Efficient Water-Reducing Agent for High Performance Concrete

2012 ◽  
Vol 610-613 ◽  
pp. 573-576
Author(s):  
Zheng Jun Wang ◽  
Jia Bin Liang
Keyword(s):  
High Performance ◽  
Lightweight Concrete ◽  
High Performance Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Reducing Agent ◽  
Mass Concrete ◽  
Green Concrete ◽  
High Efficient ◽  
Strength And Durability

This paper discusses the development of water-reducing agent and the present situation of the application of high performance concrete. The traditional concrete will be substituted by high performance concrete, green concrete. In the course of appearance of high performance and green, concrete admixtures plays an extremely important role. Concrete water-reducing agent is admixture of the main part. In the case of keeping liquidity, it can make water consumption reduce, so the concrete strength and durability can be improved. It is applicable to all kinds of industrial and civil construction engineering, and it can be applied to different strength grade of concrete. It has important significance for mass concrete engineering, marine building facilities, and component and product of high strength lightweight concrete.

scholarly journals Synthesis and characterization of a high performance polycarboxylic acid water reducing agent

2020 ◽  
Vol 198 ◽  
pp. 01018
Author(s):  
Qiong Yan ◽  
Liangke Yao ◽  
Yongzhong Xia ◽  
Shishan Liu ◽  
Lingcong Chen
Keyword(s):  
High Performance ◽  
Chain Transfer ◽  
Reducing Agent ◽  
Acid Water ◽  
Synthesis Process ◽  
Process Conditions ◽  
Polycarboxylic Acid ◽  
Synthetic Process ◽  
Working Performance

The optimal synthesis process conditions of polycarboxylic acid water reducers were investigated and characterized by infrared spectroscopy as well as GPC using high performance polycarboxylic acid water reducers synthesized by isoproterenol polyoxyethylene ether polymerized with acrylic acid and introducing unsaturated monomeric dibasic ester. The results showed that the optimum synthetic process conditions were as follows: acid-ether ratio of 3.0:1, amount of binary ester as 2.8% of monomer mass, amount of initiator as 0.35% of monomer mass, amount of chain transfer agent as 0.35% of monomer mass; the initial slump and initial expansion of the concrete of the synthetic water-reducing agent PCE-H were greater than those of the commercially available polycarboxylic acid water-reducing agent PCE-W, and the working performance of the concrete was better. PCE-H also has no adverse effect on strength.

On Effects of Fly Ash as a Partial Replacement of Cement on Concrete Strength

2012 ◽  
Vol 204-208 ◽  
pp. 3970-3973
Author(s):  
Reagan J. Case ◽  
Kai Duan ◽  
Thuraichamy G. Suntharavadivel
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Concrete Strength ◽  
Cementitious Materials ◽  
Partial Replacement ◽  
Replacement Ratio ◽  
Interface Reactions ◽  
Compressive Strength Of Concrete ◽  
Interface Bonding Strength ◽  
Large Research

As a part of a large research program aiming at the cementitious materials containing recycled materials at Central Queensland University – Australia, the current paper presents the preliminary results of a study on the effects of fly ash, which is used to replace cement in concrete, on the concrete compressive strength. For this purpose, systematic experiments have been carried out to investigate the influences of fly ash ratio and age. The compressive strength of concrete specimens with replacement ratios of 15%, 30% and 45%, and aged 7 and 28 days are measured and are compared with those of the concrete specimens without fly ash at the same ages. The results demonstrate that the strength of fly ash containing concrete improves more slowly but more strongly with aging, than their fly ash free counterparts, and an optimum fly ash replacement ratio exists where the maximum compressive strength of fly ash containing concrete can be achieved, and the maximum strength for the specimens aged 28 days and above is higher that of fly ash free concrete. Furthermore, the observation strength behaviours are analysed and discussed in terms of the influences of fly ash on interface reactions and interface bonding strength.

scholarly journals Investigation of Cement-Emulsified Asphalt in Plastic Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Xiaohu Yan ◽  
Zaiqin Wang ◽  
Meijuan Rao ◽  
Mingxia Li
Keyword(s):  
Compressive Strength ◽  
Ct Scanning ◽  
Mean Value ◽  
X Ray Diffraction ◽  
Asphalt Cement ◽  
Time Scanning ◽  
Plastic Concrete ◽  
Gradual Development ◽  
Compressive Strength Of Concrete ◽  
Emulsified Asphalt

The mechanical, mesodamage, and the microproperties of cement-emulsified asphalt concrete have been investigated by computed tomography (CT), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TG) in this work. Emulsified asphalt delayed the hydration of cement, making the early compressive strength of concrete develop slowly. However, the concrete compressive strength increased rapidly with the demulsification of emulsified asphalt. The damage stages of condense, expansion of volume, rapid crack propagation, and damage by real-time scanning have been observed. The CT mean value of the place near the lower end face suffered a larger decline but a smaller decline to the upper part of the sample. The evolution of concrete suffering damage to failure is a gradual development process, and no sharp expansion of brittle failure. The unhydrated cement, incorporation asphalt, fibrous C–S–H gel, CH, needle-shaped ettringite, and other hydration products were interwoven to constitute emulsified asphalt-cement paste, forming a spatial structure.

scholarly journals Effect of basalt aggregates and plasticizer on the compressive strength of concrete

2015 ◽  
Vol 4 (4) ◽  
pp. 520 ◽  
Author(s):  
Mohammad Al-Rawashdeh ◽  
Ashraf Shaqadan
Keyword(s):  
Compressive Strength ◽  
Laboratory Investigation ◽  
Concrete Strength ◽  
Experimental Program ◽  
Sieve Analysis ◽  
Curing Time ◽  
Compressive Test ◽  
Slump Test ◽  
Compressive Strength Of Concrete

The purpose of this research is to investigate the feasibility of using basalt aggregates and plasticizers in concrete mixes. An elaborate experimental program that included a variation of plasticizer and basalt in concrete mixes. The laboratory investigation included measurements of sieve analysis, compressive strength, and slump test. The compressive test was evaluated at 7, 14, 28 days of curing time. The results show significant improvement in concrete strength up to 2% of additive plasticizer after that concrete strength was reduced.

scholarly journals Estimation of In-situ concrete strength using drilling resistance

2019 ◽  
Vol 289 ◽  
pp. 06001
Author(s):  
Serkan Karatosun ◽  
Muhammet Asan ◽  
Oguz Gunes
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Condition Assessment ◽  
Assessment Practice ◽  
Destructive Testing ◽  
Seismic Safety ◽  
Concrete Mixtures ◽  
Priority Task ◽  
Compressive Strength Of Concrete ◽  
Drilling Resistance

Rapid and reliable condition assessment of reinforced concrete structures in high seismicity regions is a priority task in estimating their seismic safety. Non-destructive testing (NDT) methods may contribute to the condition assessment practice by providing fast and reliable strength estimation while causing minimal or no damage to the structure. Drilling resistance is an NDT method that has been used for mechanical characterization of natural stone and wood by measuring the force response for constant penetration rate and rotational speed. This paper focuses on the relationship between drilling resistance and compressive strength of concrete, including when it is combined with other NDT methods. Concrete cube samples produced using 6 different concrete mixtures were tested. Correlation equations were then obtained using statistical analysis. The results reveal that it may be possible to reliably estimate the compressive strength of concrete using drilling resistance method.

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