scholarly journals Models for Strength Prediction of High-Porosity Cast-In-Situ Foamed Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Wenhui Zhao ◽  
Junjie Huang ◽  
Qian Su ◽  
Ting Liu
Keyword(s):  
Compressive Strength ◽  
Prediction Model ◽  
Raw Materials ◽  
Dry Density ◽  
High Porosity ◽  
Curing Time ◽  
Composite Function ◽  
Construction Period ◽  
Foamed Concrete

A study was undertaken to develop a prediction model of compressive strength for three types of high-porosity cast-in-situ foamed concrete (cement mix, cement-fly ash mix, and cement-sand mix) with dry densities of less than 700 kg/m3. The model is an extension of Balshin’s model and takes into account the hydration ratio of the raw materials, in which the water/cement ratio was a constant for the entire construction period for a certain casting density. The results show that the measured porosity is slightly lower than the theoretical porosity due to few inaccessible pores. The compressive strength increases exponentially with the increase in the ratio of the dry density to the solid density and increases with the curing time following the composite function A2ln⁡tB2 for all three types of foamed concrete. Based on the results that the compressive strength changes with the porosity and the curing time, a prediction model taking into account the mix constitution, curing time, and porosity is developed. A simple prediction model is put forward when no experimental data are available.

scholarly journals Experimental Study on the Effect of Water on the Properties of Cast In Situ Foamed Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Wenhui Zhao ◽  
Qian Su ◽  
Wubin Wang ◽  
Lele Niu ◽  
Ting Liu
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Moisture Content ◽  
Water Level ◽  
Immersion Time ◽  
Drying Shrinkage ◽  
Dry Density ◽  
Volumetric Moisture Content ◽  
Foamed Concrete

This study aims to investigate the effect of water on the properties of cast in situ foamed concrete with a dry density of 300–800 kg/m3 (100 kg/m3 is a gradient). Firstly, the shrinkage deformation with the curing time and the volumetric moisture content is studied by the drying shrinkage test and improved drying shrinkage test. Secondly, the influence of volumetric moisture content on mechanical properties is assessed. At last, the effects of immersion time and immersion type on the mechanical properties of foamed concrete are studied by considering the water-level conditions. The achieved results show that the shrinkage deformations increase with the curing time for the drying shrinkage test and the improved drying shrinkage test, while the variations are different. The shrinkage deformation increases with the decrease of volumetric moisture content for six dry densities of foamed concrete. Besides, it gradually changes in the early stage, while it changes fast in the later stage. The compressive strength and elastic modulus decrease with the increase of volumetric moisture content for each density. For the water-level unchanged condition, the compressive strength and elastic modulus initially decrease and then slowly increase with the increase of the immersion time. For the water-level changed condition, the compressive strength and elastic modulus of foamed concrete decrease with the increase of immersion time for each dry density, and the rate of early attenuation is high, whereas the rate of later attenuation is limited.

scholarly journals Investigation and Optimization of the C-ANN Structure in Predicting the Compressive Strength of Foamed Concrete

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1072 ◽  
Author(s):  
Dong Van Dao ◽  
Hai-Bang Ly ◽  
Huong-Lan Thi Vu ◽  
Tien-Thinh Le ◽  
Binh Thai Pham
Keyword(s):  
Compressive Strength ◽  
Civil Engineering ◽  
Mean Squared Error ◽  
Model Performance ◽  
Absolute Error ◽  
Machine Learning Algorithms ◽  
Coefficient Of Determination ◽  
Dry Density ◽  
Statistical Measures ◽  
Foamed Concrete

Development of Foamed Concrete (FC) and incessant increases in fabrication technology have paved the way for many promising civil engineering applications. Nevertheless, the design of FC requires a large number of experiments to determine the appropriate Compressive Strength (CS). Employment of machine learning algorithms to take advantage of the existing experiments database has been attempted, but model performance can still be improved. In this study, the performance of an Artificial Neural Network (ANN) was fully analyzed to predict the 28 days CS of FC. Monte Carlo simulations (MCS) were used to statistically analyze the convergence of the modeled results under the effect of random sampling strategies and the network structures selected. Various statistical measures such as Coefficient of Determination (R2), Mean Absolute Error (MAE), and Root Mean Squared Error (RMSE) were used for validation of model performance. The results show that ANN is a highly efficient predictor of the CS of FC, achieving a maximum R2 value of 0.976 on the training part and an R2 of 0.972 on the testing part, using the optimized C-ANN-[3–4–5–1] structure, which compares with previous published studies. In addition, a sensitivity analysis using Partial Dependence Plots (PDP) over 1000 MCS was also performed to interpret the relationship between the input parameters and 28 days CS of FC. Dry density was found as the variable with the highest impact to predict the CS of FC. The results presented could facilitate and enhance the use of C-ANN in other civil engineering-related problems.

Study on the Preparation and Properties of Fiber Reinforced Foamed Cement Material

2013 ◽  
Vol 327 ◽  
pp. 40-43
Author(s):  
Xiao Long Li ◽  
Guo Zhong Li
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Raw Materials ◽  
Dry Density ◽  
Fiber Reinforced ◽  
Cement Material ◽  
Insulation Materials

The ordinary portland cement was used to prepare foamed cement insulation materials by physical foaming method. The influence of different process of fiber added to the foamed cement insulation materials on its performance was studied and the optimum mix ratio of raw materials was determined. The results showed that the glass fire could be evenly dispersed in the slurry by dry adding technology and got better enhanced effect. When the dosage of glass fire was 0.9%, the performance of the foamed cement material as follows: dry density of 318 kg/m3, 3d flexural strength of 0.61MPa, 3d compressive strength of 1.05MPa, thermal conductivity of 0.065W/(m·k). The reinforce mechanism of glass fire was explored.

scholarly journals Heat Treatment of Basalt Fiber Reinforced Expanded Clay Concrete with Increased Strength for Cast-In-Situ Construction

Fibers ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 67
Author(s):  
Makhmud Kharun ◽  
Sergey Klyuev ◽  
Dmitry Koroteev ◽  
Paschal C. Chiadighikaobi ◽  
Roman Fediuk ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Compressive Strength ◽  
Basalt Fiber ◽  
Construction Costs ◽  
Construction Period ◽  
Analysis And Evaluation ◽  
Infrared Rays ◽  
Heat Treated ◽  
Increased Strength

Expanded clay concrete (ECC) is a promising structural material for buildings due to its light weight and heat- and sound-insulating properties. Adding basalt fibers (BFs) in ECC reduces its brittleness and enhances its mechanical properties. The heat treatment (HT) of BF-reinforced ECC can significantly accelerate the strength growth during cast-in-situ construction, which allows the reduction of the turnover of the formwork and the construction period, as well as leading to lower construction costs. This paper presents an HT technology for load-bearing structures, containing a BF-reinforced ECC mix and using infrared rays for cast-in-situ construction. The issue of the strength growth of BF-reinforced ECC during HT has been studied. Microsilica and fly ash were added to the ECC mix to obtain a compressive strength of more than 20 MPa. Four different mixes of ECC with chopped BFs in the ratios of 1:0, 1:0.0045, 1:0.009 and 1:0.012 by weight of cement were studied. Test specimens were heated by infrared rays for 7, 9, 11, 13, 16 and 24 h. Then, the heat-treated specimens were tested for compressive strength after 0.5, 4, 12 and 24 h cooling periods. The analysis and evaluation of the experimental data were carried out based on probability theory and mathematical statistics. Mathematical models are proposed for forecasting the strength growth of BF-reinforced ECC during cast-in-situ construction.

Thermal Treatment of Self-Compacting Concrete in Cast-In Situ Construction

2017 ◽  
Vol 753 ◽  
pp. 315-320 ◽  
Author(s):  
Makhmud Kharun ◽  
Yury V. Nikolenko ◽  
Nadezhda A. Stashevskaya ◽  
Dmitry D. Koroteev
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Compressive Strength ◽  
Thermal Treatment ◽  
Strength Development ◽  
Labor Costs ◽  
Self Compacting Concrete ◽  
Construction Period ◽  
Cooling Period

Self-compacting concrete (SCC) is an innovative concrete that does not require vibration for placing and compaction. Thermal treatment (TT) of SCC can significantly accelerate the strength growth during cast-in-situ construction. This paper presents a technology of TT of structures for cast-in-situ construction with SCC. Application of this technology allows to reduce the turnover of formwork, the labor costs for construction, and the construction period. We also studied the issue of strength development of SCC during TT. For our study, we used SCC of grade C25. Test samples were cured with TT by infrared radiators for 7, 9, 11, 13, 16 and 24 hours. Then warmed samples were tested for compressive strength after 0.5, 4, 12 and 24 hours of cooling period. Study was carried out on the basis of analyzing, generalizing and evaluations of experimental data. A mathematical model is proposed for determining the compressive strength of SCC after one day of curing of SCC with TT.

Research on the Foamed Concrete with High Volume Fly Ash

2017 ◽  
Vol 727 ◽  
pp. 1062-1066
Author(s):  
Hui Chao Chu ◽  
Xian Jun Lyu ◽  
Yan Zhang
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Water Absorption ◽  
Process Parameters ◽  
High Volume ◽  
Dry Density ◽  
High Volume Fly Ash ◽  
Foamed Concrete

A study has been undertaken to investigate the effects, on the properties of foamed concrete, of replacing large volumes of cement with fly ash. This paper reports the results of the properties of foamed concrete and shows that up to 55% of the cement could be replaced without any significant reduction in compressive strength. Foamed concrete with 55% fly ash and good performance were obtained by optimizing the process parameters. The results showed that the compressive strength, dry density, water absorption and thermal conductivity of foamed concrete with 55% fly ash were 0.71MPa, 244kg/m3, 33%, and 0.045 W/mK respectively.

Preparation and Performance Testing of Foamed Concrete

2013 ◽  
Vol 743-744 ◽  
pp. 166-170
Author(s):  
Ting Song Yang ◽  
Ling Chao Lu ◽  
Shou De Wang ◽  
Chen Chen Gong
Keyword(s):  
Compressive Strength ◽  
Mixing Time ◽  
Performance Testing ◽  
Dry Density ◽  
Preparation Technology ◽  
Foaming Agent ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Foamed Concrete ◽  
And Performance

The key influences of foamed concrete and the optimum preparation technology were studied. The performance of foamed concrete was analyzed by the compressive strength testing, SEM. Results show that the flowability of cement paste is good when water-cement ratio is 0.4. The amount of foam added in sulphoaluminate cement is not able to exceed 3.5L/kg. However, the dilution multiple of foaming agent is near concentration and the mixing time depends on the foam quantity. When the water-cement ratio is 0.4, the foam quantity is 3 L/kg and the foaming agent is diluted 30 times. When the mixing time is 60s, the dry density is around 380kg/m3 and the 7d compressive strength reaches to 0.9MPa.

scholarly journals Experiments on Foamed Concrete for the Development of Building Blocks

2020 ◽  
Vol 8 (5) ◽  
pp. 2824-2829
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Building Blocks ◽  
Ash Content ◽  
Partial Replacement ◽  
Dry Density ◽  
Load Bearing ◽  
Concrete Building ◽  
Concrete Blocks ◽  
Foamed Concrete

Foamed concrete is an innovative and versatile lightweight building material, which is a cement-based mortar consisting of at least 20% of its volume filled with air. Use of lightweight foamed concrete blocks with densities less than 1800 kg/m3 as infills will lead to the design of slender sections. Further, the thermal insulation properties of foamed concrete blocks made it more popular in construction industry. This paper discusses the development of foamed concrete building blocks for load bearing and non-load bearing structures. To make the mix more sustainable, the feasibility of fly ash as a partial replacement to cement is also explored. The variables considered for the production of foamed concrete are foam volume, water/powder (mix of cement and fly ash) ratio, fly ash content and sand/powder ratio. Analytical model is also developed for compressive strength and dry density of foamed concrete considering different variables and it is validated. Compressive strength is found to be increasing with the increase in dry density and with increase in fly ash content. Thermal conductivity is observed to be reduced by the addition of fly ash content

scholarly journals Some Engineering Properties of Foamed Concrete for Sustainable Technological Development

2021 ◽  
Vol 6 (3) ◽  
pp. 53-57
Author(s):  
Felix A. Oginni ◽  
Samuel N. John
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Comparative Study ◽  
Modulus Of Elasticity ◽  
Technological Development ◽  
Drying Shrinkage ◽  
Engineering Properties ◽  
Dry Density ◽  
Concrete Production ◽  
Foamed Concrete

A study of the technology of foamed concrete production is carried out. The engineering properties and applications of this type of concrete are presented for varying densities so as to effectively tap the advantages of its use for specific purposes. The properties considered are the 7-day compressive strength, thermal conductivity, modulus of elasticity and drying shrinkage. A study of the behaviours of foamed concrete at varying dry densities for the different characteristics was undertaken. Results indicate that as the dry density increases, the engineering properties increase though at different rates for the 7-day Compressive strength, Thermal conductivity, and Modulus of elasticity. The drying shrinkage decreases as the dry density increases. A comparative study of the 7-day Compressive strength and Modulus of elasticity show that they both follow the same trend over the varying dry density except at a dry density of 1200 kg/m3. A comparative study of the thermal conductivity and the percent drying shrinkage indicate that the thermal conductivity is inversely proportional to the percent drying shrinkage. Economics and other considerations together with its multipurpose applications of foamed concrete can open up business opportunities in Africa and sustainability. This can also help in providing needed funds for infrastructural development.

Effect of Sintering Temperature on the Physical Properties and Microstructure of In Situ Nitrides Bonded MgAl2O4-C Refractories

2016 ◽  
Vol 697 ◽  
pp. 591-594
Author(s):  
Shao Hua Wang ◽  
Cheng Ji Deng ◽  
Hong Xi Zhu ◽  
Wen Jie Yuan
Keyword(s):  
Compressive Strength ◽  
Physical Properties ◽  
Bulk Density ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Silicon Powder ◽  
Flake Graphite ◽  
High Quality ◽  
Liquid Calcium

The in situ nitrides bonded MgAl2O4-C refractories were prepared by using high quality fused spinel (MgAl2O4≥ 97%), natural flake graphite (C ≥ 96%) and silicon powder (Si ≥ 98%) as raw materials and the liquid calcium lignosulfonate with a concentration of 1.25 g/ml was used as binder (4 wt%). The effect of sintering temperatures on physical properties and phase compositions were investigated. The results show that β-sialon and α-Si3N4were formed in the samples sintered at 1400°C, 1450°C and 1500°C, and AlON and AlN were formed in the samples sintered at 1550°C. The sample that sintered at 1450°C exhibits the best bulk density and apparent porosity of 2.84 g/cm3 and 14.73%, respectively, and the highest compressive strength

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