scholarly journals Study of the Influence of an Air-Entraining Agent on the Rheology of Motars

2018 ◽  
Vol 149 ◽  
pp. 01054
Author(s):  
Nadia Tebbal ◽  
Zine El Abidine Rahmouni ◽  
Lamis Rabiaa Chadi

The objective of this study is to analyze the effect of the air entrainment on the fresh rheological properties as well as on the compressive mechanical resistances of the mortars. The hardened concrete contains a certain amount of randomly spread air, coming either from a drive during kneading or from the evaporation of the mixing water. The air quantity is in the order of 20 l / m3, ie 2% of the volume. However, the presence of a large volume of air bubbles causes the mechanical resistances to fall in compression. On the other hand, the use of air entrainment could improve the rheological properties of fresh concrete. Experimental studies have been carried out to study the effect of air entrainment on compressive strength, density and ingredients of fresh concrete mix. During all the study, water cement ratio (w/c) was maintained constant at 0.5. The results have shown substantial decreasing in water and mortar density followed with decreasing in compressive strength of mortar. The results of this study has given more promising to use it as a guide for mortar mix design to choose the most appropriate concrete mix design economically.

2018 ◽  
Vol 279 ◽  
pp. 266-270
Author(s):  
Beata Łaźniewska-Piekarczyk

The research results of stability of air-entrainment of concrete acc. PN-EN 480-1 in case of innovate air-entraining multi-component cement CEM II/B-V is presented in the paper. The influence of PCE, naphthalene and phosphonamidite based superplasticizers and w/c ratio: 0.45, 0.50 and 0.55 on air-entrainment and consistency of fresh concrete mix was investigated. The research results indicated that with increasing w/c ratio the air-entrainment of concrete increases. Moreover, in case of an increase in the degree of liquidity of the air-entrained concrete made of participation of the innovative, air-entraining multi-component cement CEM II/B-V, first and new generation superplasticizers based on modified naphthalene, and then modified phosphonamidite should be used. PCE based superplasticizer cause the too high air-entrainment of concrete. The research results proved, that the porosity of hardened concrete meets the European standards for frost-resistant concrete.


2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Julia Widia Nika ◽  
Anisah Anisah ◽  
Rosmawita Saleh

This research aims to utilize green mussel shell waste as a partial replacement for cement by establishing the best temperature that should be used to obtain the chemical substance if the sehell ashes to optimize the chemical substance for replacement of cement. This research replaces 10% of total weight cement with shell ash which has been combusted with a temperature of 700 ° C, 800 ° C and 900 ° C and control concrete. The compressive strength of the concrete plan is 20 MPa. Concrete mix design is 1:2:3. The results of this study indicate with subtitutes 10% semen with green shell ash with temperature 700 ° C, 800 ° C and 900 ° C is 20,53MPa; 16,76 MPa and 19,74 MPa and for control concrete has compressive strength 20,18 MPa. The maximum concrete compressive strength was obtained on the concrete of green shell ash with a combustion temperature of 700 ° C which is 20.53 MPa. In the concrete the green shells ash with a burning temperature above 700 ° C experience a decrease in compressive strength and cannot meet the compressive strength of the plan.


Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1256 ◽  
Author(s):  
Patryk Ziolkowski ◽  
Maciej Niedostatkiewicz

Concrete mix design is a complex and multistage process in which we try to find the best composition of ingredients to create good performing concrete. In contemporary literature, as well as in state-of-the-art corporate practice, there are some methods of concrete mix design, from which the most popular are methods derived from The Three Equation Method. One of the most important features of concrete is compressive strength, which determines the concrete class. Predictable compressive strength of concrete is essential for concrete structure utilisation and is the main feature of its safety and durability. Recently, machine learning is gaining significant attention and future predictions for this technology are even more promising. Data mining on large sets of data attracts attention since machine learning algorithms have achieved a level in which they can recognise patterns which are difficult to recognise by human cognitive skills. In our paper, we would like to utilise state-of-the-art achievements in machine learning techniques for concrete mix design. In our research, we prepared an extensive database of concrete recipes with the according destructive laboratory tests, which we used to feed the selected optimal architecture of an artificial neural network. We have translated the architecture of the artificial neural network into a mathematical equation that can be used in practical applications.


2019 ◽  
Vol 1 (2) ◽  
pp. 124-132
Author(s):  
Hermansyah ◽  
Moh Ihsan Sibgotuloh

The more widespread use of concrete construction and the increasing scale of construction, the higher the demand for materials used in concrete mixes. One of the innovations of concrete is fiber concrete. Hope the addition of fiber in concrete mixes such as wire fiber to increase the compressive strength value of normal concrete that is often used, so the purpose of this study is to determine the effect of adding wire fiber to the ease of working (workability) of the concrete mixture and to determine the effect of adding wire fiber to concrete compressive strength. In this study, the fiber used is the type of wire fiber with a diameter of 1 mm and a length of 60 mm. Fiber variations used are 0%, 0.4%, 0.6% and 0.8% based on the weight of fresh concrete. Concrete mix (mix design) using SNI 03-2834-2000 about concrete mix planning with a test life of 28 days. The test results showed that the lowest average compressive strength of 12,291 MPa occurred at 0% variation and the highest average compressive strength value of 20,656 MPa at 0.8% fiber variation. The increase is caused by the even distribution of fibers in the concrete produced, the higher the variation that is given by the fiber, the better the fiber spread, from these fibers provide a fairly good contribution to the fiber concrete


Author(s):  
Nanang Budi Setyawan ◽  
Fredy Kurniawan

Development era of globalization has resulted in increasing number of second-hand goods / waste that its existence can be a problem for life in the future. Many things are done in order to recycle paper cement in order to overcome this problem the existence of waste. One way is to use waste paper to be a part of the building. The purpose of this study, to determine the compressive strength and optimum density. Laboratory experimental method uses a variation of 10%, 20%, 30% and testing conducted in the form of compressive strength and density. From the test results obtained by the result of decrease in the compressive strength and density. In addition cellulose concrete mix design with variations determined that 10%, 20%, 30% resulted in a decrease in the compressive strength of concrete,


The present research work analysis the conceptual concrete mix design regarding the packing unit density concept for multi initial trial and error perfect shaped methodologies. In initial, a high strength based concrete with desired target compressive strength of M40 Graded concrete was shaped for various mixing proportion and Also, a stabilized standard chart has been developed for the various packing constituents (percentage) in various parameters, where the aggregates (F/c) ratio 0.5 to 0.8, Binder-Total aggregate (B/Ta) ratio 0.27 to 0.24 and water-binder content (w/b) ratio 0.30. The laboratory experimental research work results contain fly ash percentage replacement level at 25 and 50% in Portland cement and inclusion of both ends hooked type of steel fibers along with 1.50% of superplasticizers by weight of binder content for the various mix produced for the good tracking of the UPV values by using fabricating Plexiglas moulds, Pozzolanic Activity Index (PAI), if the compressive strength increases automatically less volumetric shrinkage takes place.


2013 ◽  
Vol 701 ◽  
pp. 12-16 ◽  
Author(s):  
Mohd Irwan Juki ◽  
Khairunnisa Muhamad ◽  
Mahamad Mohd Khairil Annas ◽  
Koh Heng Boon ◽  
Norzila Othman ◽  
...  

This paper describes the experimental investigation to develop the concrete mix design Nomograph for concrete containing PET as fine aggregate. The physical and mechanical properties were determined by using mix proportion containing 25%, 50% and 75% of PET with water cement ratio (w/c) 0.45, 0.55 and 0.65. The data obtained showed that the inclusion of PET aggregate reduce the strength performances of concrete. All the data obtained were combined into one single graph to develop a preliminary mix design nomograph for PET concrete. The nomograph consist of ; relationship between compressive strength and water cement ratio; relationship between splitting tensile strength water cement ratio; relationship between splitting tensile strength and PET percentage and relationship between compressive strength and PET percentage. The mix design nomograph can be used to assists in selecting the proper mix proportion parameters based on the criteria required.


Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4577 ◽  
Author(s):  
Andrzej Ambroziak ◽  
Patryk Ziolkowski

The technological process of concrete production consists of several parts, including concrete mix design, concrete mix production, transportation of fresh concrete mix to a construction site, placement in concrete framework, and curing. Proper execution of these steps provides good quality concrete. Some factors can disturb the technological process, mainly temperature and excessive precipitation. Changing daily temperature and rainfall during fabrication, transportation, and placement can shape not only the properties of the concrete mix but also the compressive strength of hardened concrete. In this paper, we tried to answer the question of how temperature and precipitation affect concrete production. The scope of this study was to determine the change of compressive strength of the hardened concrete in a specific period for selected concrete mix recipes, taking into account changing daily temperature and precipitation magnitude. The investigated concrete mixes concrete compressive strength beyond that of the concrete grade, termed “concrete superstrength”. This concrete post limiting behaviour of concrete is also discussed.


2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Ching-Yun Kao ◽  
Chin-Hung Shen ◽  
Jing-Chi Jan ◽  
Shih-Lin Hung

Pozzolanic concrete has superior properties, such as high strength and workability. The precise proportioning and modeling of the concrete mixture are important when considering its applications. There have been many efforts to develop computer-aided approaches for pozzolanic concrete mix design, such as artificial neural network- (ANN-) based approaches, but these approaches have proven to be somewhat difficult in practical engineering applications. This study develops a two-step computer-aided approach for pozzolanic concrete mix design. The first step is establishing a dataset of pozzolanic concrete mixture proportioning which conforms to American Concrete Institute code, consisting of experimental data collected from the literature as well as numerical data generated by computer program. In this step, ANNs are employed to establish the prediction models of compressive strength and the slump of the concrete. Sensitivity analysis of the ANN is used to evaluate the effect of inputs on the output of the ANN. The two ANN models are tested using data of experimental specimens made in laboratory for twelve different mixtures. The second step is classifying the dataset of pozzolanic concrete mixture proportioning. A classification method is utilized to categorize the dataset into 360 classes based on compressive strength, pozzolanic admixture replacement rate, and material cost. Thus, one can easily obtain mix solutions based on these factors. The results show that the proposed computer-aided approach is convenient for pozzolanic concrete mix design and practical for engineering applications.


Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2206
Author(s):  
Harry Hermawan ◽  
Peter Minne ◽  
Pedro Serna ◽  
Elke Gruyaert

Self-healing concrete has emerged as one of the prospective materials to be used in future constructions, substituting conventional concrete with the view of extending the service life of the structures. As a proof of concept, over the last several years, many studies have been executed on the effectiveness of the addition of self-healing agents on crack sealing and healing in mortar, while studies on the concrete level are still rather limited. In most cases, mix designs were not optimized regarding the properties of the fresh concrete mixture, properties of the hardened concrete and self-healing efficiency, meaning that the healing agent was just added on top of the normal mix (no adaptations of the concrete mix design for the introduction of healing agents). A comprehensive review has been conducted on the concrete mix design and the impact of healing agents (e.g., crystalline admixtures, bacteria, polymers and minerals, of which some are encapsulated in microcapsules or macrocapsules) on the properties of fresh and hardened concrete. Eventually, the remaining research gaps in knowledge are identified.


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