scholarly journals Soft Computing and Multi-Scal Model Technics to Predict the Early Age Compression Strength of Cement Paste as a Function of Polymer Contents, Water-to-Cement-Ratio, and Curing Ages

2021 ◽  
Author(s):  
Ahmed Mohammed ◽  
Kawan Ghafor ◽  
Wael Mahmood ◽  
Warzer Sarwar ◽  
Lajan Burhan
Keyword(s):  
Cement Paste ◽  
Compression Strength ◽  
Building Materials ◽  
Training Data ◽  
Early Age ◽  
Polymer Content ◽  
Data Set ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
The Impact

Abstract In this study, the effect of two water reducer polymers with smooth and rough surfaces on the compression strength of Ordinary Portland cement (OPC) was investigated. Three different initial ratios between water and cement (w/c) 0.5, 0.6, and 1 were used in this study. The amount of polymer contents varied from 0 to 0.06 % (%wt) for the cement paste with initial w/c of 0.5 and the polymer contents ranged between 0 to 0.16% (%wt) for the cement paste with initial w/c of 0.6 and 1 were investigated. SEM test was conducted to identify the impact of polymers on the behavior of cement paste. The compression strength of OPC cement was increased significantly with increasing the polymer contents. Because of a fiber net (netting) around cement paste particle was developed when the polymers were added to the cement paste which leads to decrease the void between the particles, binding the cement particles, therefore, increased the viscosity and compression strength of the cement rapidly. In this analysis, the hardness of cement paste with polymer contents has been evaluated and modeled using four different model technics. More environmentally sustainable construction, and lower cost than conventional building materials and early age strengths of the cement. To overcome the mentioned matter, this study aims to establish systematic multiscale models to predict the compression strength of cement paste containing polymers and to be used by the construction industry with no theoretical restrictions. For that purpose, a wide data a total of 280 tested cement paste modified with polymers, has been conducted, analyzed, and modeled. Linear, Nonlinear regression, M5P-tree, and Artificial Neural Network (ANN) technical approaches were used for the qualifications. In the modeling process, the most relevant parameters affecting the strength of cement paste, i.e. polymer incorporation ratio (0-0.16% of cement's mass), water-to-cement ratio (0.5-1), and curing ages (1 to 28 days). According to the correlation coefficient (R), mean absolute error and the root means a square error, the compression strength of cement paste can be well predicted in terms of w/c, polymer content, and curing time using four various simulation techniques. Among the used approaches and based on the training data set, the model made based on the Non-linear regression, ANN, and M5P-tree models seem to be the most reliable models. The sensitivity investigation concludes that the polymer content is the most dominating parameter for the prediction of the compression strength of cement paste with this data set.

An Experimental Study of Water in Pore System of Hardened Cement Paste by Magnetic Resonance

2013 ◽  
Vol 539 ◽  
pp. 14-18
Author(s):  
An Ming She ◽  
Wu Yao ◽  
Wan Cheng Yuan
Keyword(s):  
Cement Paste ◽  
Water Distribution ◽  
Transverse Relaxation Time ◽  
Bimodal Distribution ◽  
Early Age ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Initial Water ◽  
Cement Ratio ◽  
Water To Cement Ratio

The water distribution in hardened cement paste with different ages, water to cement ratio (w/c) and different cured methods were investigated by low field NMR. The transverse relaxation time, T2, was used as a parameter to describe the water phase constrained in pores. The results show that the T2 distributions of pastes in the early age are bimodal distribution. As the curing time increase, the T2 distribution peaks shift gradually to the short T2 values reflecting the decrease of mean pore dimension as well as the increase of specific surface area resulted from the gel products. In addition, the influences of initial water to cement ratio and cure methods on water distribution are occurred mainly during the early age. When cured to 28 days, the differences of water distribution in various samples are unconspicuous.

Underwater Acoustic Target Recognition Based on Generative Adversarial Network Data Augmentation

2021 ◽  
Vol 263 (2) ◽  
pp. 4558-4564
Author(s):  
Minghong Zhang ◽  
Xinwei Luo
Keyword(s):  
Data Augmentation ◽  
Target Recognition ◽  
Training Data ◽  
Small Samples ◽  
Generative Adversarial Network ◽  
Data Set ◽  
Underwater Acoustic ◽  
Adversarial Network ◽  
Acoustic Target ◽  
The Impact

Underwater acoustic target recognition is an important aspect of underwater acoustic research. In recent years, machine learning has been developed continuously, which is widely and effectively applied in underwater acoustic target recognition. In order to acquire good recognition results and reduce the problem of overfitting, Adequate data sets are essential. However, underwater acoustic samples are relatively rare, which has a certain impact on recognition accuracy. In this paper, in addition of the traditional audio data augmentation method, a new method of data augmentation using generative adversarial network is proposed, which uses generator and discriminator to learn the characteristics of underwater acoustic samples, so as to generate reliable underwater acoustic signals to expand the training data set. The expanded data set is input into the deep neural network, and the transfer learning method is applied to further reduce the impact caused by small samples by fixing part of the pre-trained parameters. The experimental results show that the recognition result of this method is better than the general underwater acoustic recognition method, and the effectiveness of this method is verified.

Effect of Fly Ash on the early Age Cracking Performance of Cement Paste

2014 ◽  
Vol 584-586 ◽  
pp. 894-898
Author(s):  
Ping Zhang ◽  
Guan Guo Liu ◽  
Chao Ming Pang ◽  
Bing Du ◽  
Hong Gen Qin
Keyword(s):  
Computed Tomography ◽  
Fly Ash ◽  
Cement Paste ◽  
Test Method ◽  
Early Age ◽  
Cement Ratio ◽  
X Ray ◽  
Cracking Performance ◽  
X Ray Computed ◽  
Ct Test

The X ray computed tomography (X-CT) was applied to test the cracking resistance of cement paste, and the hydration process was monitored to study the effect of fly ash on the early age cracking performance. The results showed that the hydration heat reduced with the increase of fly ash under the same water-cement ratio. Within 24h, the porosity increased with time. The addition of fly ash increased the proportion of large holes and then changed the internal stress state. Using X-CT test method and by comparing the number of cracks, the sample with 20% FA was found to have the most serious cracks, whereas the sample with 30% FA had the best crack resistance.

Effect of Water-to-Cement Ratio on Cracking Resistance of Concrete at Early Age in Restrained Ring Specimens

2021 ◽  
Author(s):  
Dejian Shen ◽  
Yang Jiao ◽  
Ci Liu ◽  
Jiacheng Kang ◽  
Xiaojian Tang
Keyword(s):  
Development Rate ◽  
Ring Test ◽  
Engineering Practice ◽  
Early Age ◽  
Cracking Resistance ◽  
Multiple Parameters ◽  
Concrete Mixtures ◽  
Water To Cement Ratio ◽  
Study Results ◽  
The Impact

Nowadays, low water-to-cement (w/c) ratio has been put into widespread use in engineering practice. However, low w/c ratio may give rise to high self-desiccation, which may lead to the decrease of early-age cracking resistance. Investigating the impact of w/c ratio on cracking resistance is utterly meaningful to understand the cracking mechanism of concrete better. However, the corresponding investigations remain lacking, especially when the ring test is utilized. Ring tests for three concrete mixtures with different w/c ratios were conducted to investigate the early-age cracking resistance of concrete from multiple parameters in the present study. Results showed that: (1) the development rate of shrinkage of concrete for Mixture W50 was slower than Mixture W33 and W40; (2) the value and development rate of residual stress of concrete decreased when the w/c ratio increased; (3) the relaxed stress for all mixtures developed rapidly at very early age, and reached the maximum quickly; (4) the cracking resistance of concrete increased as the w/c ratio increased at early age.

scholarly journals CO2 Curing Efficiency for Cement Paste and Mortars Produced by a Low Water-to-Cement Ratio

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3883
Author(s):  
Seong Ho Han ◽  
Yubin Jun ◽  
Tae Yong Shin ◽  
Jae Hong Kim
Keyword(s):  
Cement Paste ◽  
Pressure Vessel ◽  
Gas Pressure ◽  
Strength Development ◽  
Co2 Uptake ◽  
Cement Pastes ◽  
Co2 Gas ◽  
Cement Ratio ◽  
Mix Proportion ◽  
Water To Cement Ratio

Curing by CO2 is a way to utilize CO2 to reduce greenhouse gas emissions. Placing early-age cement paste in a CO2 chamber or pressure vessel accelerates its strength development. Cement carbonation is attributed to the quickened strength development, and CO2 uptake can be quantitatively evaluated by measuring CO2 gas pressure loss in the pressure vessel. A decrease in CO2 gas pressure is observed with all cement pastes and mortar samples regardless of the mix proportion and the casting method; one method involves compacting a low water-to-cement ratio mix, and the other method comprises a normal mix consolidated in a mold. The efficiency of the CO2 curing is superior when a 20% concentration of CO2 gas is supplied at a relative humidity of 75%. CO2 uptake in specimens with the same CO2 curing condition is different for each specimen size. As the specimen scale is larger, the depth of carbonation is smaller. Incorporating colloidal silica enhances the carbonation as well as the hydration of cement, which results in contributing to the increase in the 28-day strength.

scholarly journals The Assessment of Strength of Cementitious Materials Impregnated Using Hydrophobic Agents Based on Near-Surface Hardness Measurements

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4583
Author(s):  
Martyna Nieświec ◽  
Łukasz Sadowski
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Concrete Structures ◽  
Surface Hardness ◽  
Cementitious Materials ◽  
Schmidt Hammer ◽  
Near Surface ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
The Impact

Recently, the surfaces of concrete structures are impregnated to protect them against the environment in order to increase their durability. It is still not known how the use of these agents affects the near-surface hardness of concrete. This is especially important for experts who use the near-surface hardness of concrete for estimating its compressive strength. The impregnation agents are colorless and, thus, without knowledge of their use, mistakes can be made when testing the surface hardness of concrete. This paper presents the results of investigations concerning the impact of impregnation on the subsurface hardness concrete measured using a Schmidt hammer. For this research, samples of cement paste with a water–cement ratio of 0.4 and 0.5 were used. The samples were impregnated with one, two, and three layers of two different agents. The first agent has been made based on silanes and siloxanes and the second agent has been made based on based on polymers. The obtained research results allow for the conclusion that impregnation affects the near-surface hardness of concrete. This research highlights the fact that a lack of knowledge about the applied impregnation of concrete when testing its near-surface hardness, which is then translated into its compressive strength, can lead to serious mistakes.

scholarly journals Effects of Nano-SiO2 and SAP on Hydration Process of Early-Age Cement Paste Using LF-NMR

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Haitao Zhao ◽  
Yi Wan ◽  
Jun Xie ◽  
Kaidi Jiang ◽  
Donghui Huang ◽  
...  
Keyword(s):  
Cement Paste ◽  
Bound Water ◽  
Hydration Process ◽  
Early Age ◽  
Superabsorbent Polymer ◽  
Test Results ◽  
Low Field ◽  
Water To Cement Ratio ◽  
Hydration Model ◽  
Zero Points

The effects of nano-SiO2 and superabsorbent polymer on the hydration process of early-age cement paste are investigated through the physically bound water evolution test by means of the low-field nuclear magnetic resonance technology. The test results show that the hydration process can be characterized by four-stage patterns based on the zero points of the second-order differential hydration curve, i.e., the initial, accelerated, decelerated, and steady periods. The beginning time of each stage is postponed and the hydration duration is prolonged with an increasing water to cement ratio. The beginning time of each stage and the hydration duration are shortened with an increasing content of nano-SiO2. And the beginning time of each stage and the hydration duration are prolonged with an increasing content of superabsorbent polymer. Based on the test data and the Avrami–Erofeev model, a modified hydration model taking the influence of nano-SiO2 and SAP into account is proposed, and the predicted results are consistent with the test results.

scholarly journals The impact of methodological decisions on climate reconstructions using WA-PLS

2020 ◽  
pp. 1-16 ◽  
Author(s):  
Mark G. Turner ◽  
Dongyang Wei ◽  
Iain Colin Prentice ◽  
Sandy P. Harrison
Keyword(s):  
Reference Data ◽  
Training Data ◽  
Weighted Averaging ◽  
Data Set ◽  
Last Glacial Period ◽  
Methodological Choices ◽  
Climate Reconstructions ◽  
Significant Difference ◽  
Climate Space ◽  
The Impact

Abstract Most techniques for pollen-based quantitative climate reconstruction use modern assemblages as a reference data set. We examine the implication of methodological choices in the selection and treatment of the reference data set for climate reconstructions using Weighted Averaging Partial Least Squares (WA-PLS) regression and records of the last glacial period from Europe. We show that the training data set used is important because it determines the climate space sampled. The range and continuity of sampling along the climate gradient is more important than sampling density. Reconstruction uncertainties are generally reduced when more taxa are included, but combining related taxa that are poorly sampled in the data set to a higher taxonomic level provides more stable reconstructions. Excluding taxa that are climatically insensitive, or systematically overrepresented in fossil pollen assemblages because of known biases in pollen production or transport, makes no significant difference to the reconstructions. However, the exclusion of taxa overrepresented because of preservation issues does produce an improvement. These findings are relevant not only for WA-PLS reconstructions but also for similar approaches using modern assemblage reference data. There is no universal solution to these issues, but we propose a number of checks to evaluate the robustness of pollen-based reconstructions.

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