Review of Carbonation Resistance in Hydrated Cement Based Materials

Marangu, Joseph Mwiti; Thiong’o, Joseph Karanja; Wachira, Jackson Muthengia

doi:10.1155/2019/8489671

Cited by 44 publications

(24 citation statements)

References 60 publications

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“…This observation is in agreement with the experimental findings. When high w/c is involved, there is a poor packing of cement grains and aggregates which makes the hydrated cement matrix more porous [21]- [23]. Increased porosity of hydrated cement subsequently results in reduced compressive strength of the cement based structure.…”

Section: Ann Model Predicted Compressive Strength (At 28 Day)mentioning

confidence: 99%

Prediction of Compressive Strength of Calcined Clay Based Cement Mortars Using Support Vector Machine and Artificial Neural Network Techniques

Marangu¹

2020

jscmt

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Prediction of strength in cement based materials is vital in construction industry as it forms the basis upon which important tasks can be performed such as the time for mortar form removal, project scheduling and quality control among others. The paper reports both experimental and simulated findings on compressive strength of laboratory prepared blended cement mortars. The blended cement was prepared by blending calcined clays with Ordinary Portland Cement (OPC) at replacement levels ranging from 35% to 50% by mass of OPC. In the experimental approach, mortars measuring 160 mm x 40 mm x 40 mm were cast using the blended cement at a water to cement (w/c) ratio of 0.40, 0.50 and 0.60 separately and cured for 2, 7 and 28 days in a laboratory set-up. Compressive strength measurements were taken at each of the curing ages. Part of the experimental data obtained was used to train both Support Vector Machine (SVM) and Artificial Neural Network (ANN) models while the other was used in validation of the models. The trained models were used to predict the 28 day compressive strengths at w/c of 0.35 and 0.65 and also at a cement replacement of greater than 50% and also less than 35 %. The results showed that in training and testing, ANN exhibited stronger potential for predicting compressive strength at w/c of 0.35 and w/c of 0.65 than SVM. In addition, ANN was further found to give more accurate prediction of compressive strength than SVM at all the percentage replacement ranging from 0-60 % with calcined clays. In conclusion, the testing performance of both SVM and ANN was 0.88 and 0.95 respectively.

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Section: Ann Model Predicted Compressive Strength (At 28 Day)mentioning

confidence: 99%

Prediction of Compressive Strength of Calcined Clay Based Cement Mortars Using Support Vector Machine and Artificial Neural Network Techniques

Marangu¹

2020

jscmt

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“…The use of temperature-programmed desorption mass spectrometry (TPD-MS) in work made it possible to obtain data on the effects of nanotitanium, anatase titanium, and surfactants on the thermal properties of concrete samples. The introduction of additives into concrete mixtures gave the result of a decrease in the temperature of maximum heating of the experimental samples to 520-530 °С and the prevalence of endothermic processes over exothermic ones [11].…”

Section: Introductionmentioning

confidence: 99%

Influence of Fine Additives and Surfactants on the Strength and Permeability Degree of Concrete

Шкромада

Paliy

Yurchenko

et al. 2020

EUREKA: Physics and Engineering

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The results of studies to determine the effect of titanium dioxide nanoparticles (nanoTiO 2 ), finely dispersed anatase crystalline titanium dioxide (anatazTiO 2 ) and surface-active substances (surfactants) on the compressive strength, degree of permeability and thermal stability of concrete samples are presented. Adding particles of nanotitanium, anatase titanium and surfactants up to 2 % to cement accelerates the hydration process and increases the strength of concrete, and also has a strong effect on its microstructure.As a result of the studies, it is experimentally proved that the compressive strength of concrete increases with the addition of titanium dioxide (nanoTiO 2 ) nanoparticles by 23.2 %, finely dispersed anatase crystalline titanium dioxide (anatazTiO 2 ) by 21.7 % to 5 % concentration by weight. Original Research Article: full paper (2020), «EUREKA: Physics and Engineering» Number 2 20Chemical EngineeringIn addition, the introduction of these additives reduces the permeability of concrete. This is due to a decrease in the absorption of concrete by water with the addition of nanotitanium and anatase titanium. The introduction of additives from 1 % to 5 % by weight in concrete reduces the depth of chloride penetration by 10-15 times, compared with the control.The use of temperature-programmed desorption mass spectrometry (TPD-MS) method has shown that an increase in the percentage of TiO 2 nanoparticles to 5 % in concrete mixtures correlates with an increase in microporosity and dispersion level of these mixtures, which causes a shift in the peaks of intense gas evolution from the samples when heated to the side low temperatures (for example, carbon dioxide CO 2 ).The resulting concrete samples are planned to be used for the manufacture of floors in livestock buildings. The injected additives are selected because they are not toxic substances and, in contact with the biological environment of livestock buildings (urine, feces), will not react with them.

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“…ere is need to recognize the effects that global climate change may have on a cement-based infrastructure in order to develop resilient construction materials [12]. Due to climate change, there is a prevalence of significant quantities of carbon dioxide (CO 2 ) and elevated temperatures in the atmosphere, and under these conditions, cement-based materials are susceptible to carbonation [13,14]. Carbonation of cementitious materials occurs due to a reaction between atmospheric CO 2 and the hydrated phases of cement, leading to a drop in its pH [15].…”

Section: Introductionmentioning

confidence: 99%

Physicochemical Properties of Hydrated Portland Cement Blended with Rice Husk Ash

Marangu

M’thiruaine

Bediako

2020

Journal of Chemistry

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In the presence of significant quantities of carbon dioxide (CO2) and elevated temperatures in the atmosphere due to climate change, cement-based materials are susceptible to carbonation. Blended cements are more prone to carbonation attack than Portland cement. There is a need to evaluate the carbonation resistance of blended cements in a carbonation-prone environment. This paper presents experimental findings obtained from an evaluation of carbonation resistance tests on Rice Husk Ash- (RHA-) blended cement. The blended cement was made by intergrinding of Portland Cement (PC) and RHA to make the test cement (PC-RHA). The RHA dosage in the PC-RHA was varied from 0 to 30% by mass of PC. Pozzolanicity, standard consistency, and setting time tests were conducted on PC-RHA. Mortar prisms measuring 160 mm × 40 mm x 40 mm were separately cast at a water/cement ratio ( w / c ) of 0.50 and 0.60 and cured in water for 2, 7, 14, 28, and 90 days. Compressive strength tests were conducted on the mortar prisms at each of the testing ages. The prepared mortars were also subjected to accelerated carbonation tests in two Relative Humidity (RH) curing regimes, one maintained at an RH greater than 90% and the other between 50–60%. Carbonation resistance of the mixtures was evaluated in terms of the changes in carbonation depth using a phenolphthalein test at the age of 7, 14, 28, and 56 days of curing in a continuous flow of CO2. Compressive strength measurements were also taken during each of the carbonation testing ages. For comparison, similar tests were conducted using commercial PC. The results showed that PC-RHA was pozzolanic while PC was nonpozzolanic. Higher water demand and longer setting times were observed in PC-RHA than in PC. Moreover, there was increased strength development in water-cured samples with increased curing duration. Carbonation results indicated that there was a marked increase in carbonation depth with increased dosage of RHA in PC-RHA binders, increased duration of exposure to CO2, and decreased RH (RH between 50–60%). PC-RHA binders exhibited lower carbonation resistance than PC. In conclusion, for mortars at any w / c ratio, carbonation resistance decreased with increase in RHA dosage and increased w / c ratio.

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Review of Carbonation Resistance in Hydrated Cement Based Materials

Cited by 44 publications

References 60 publications

Prediction of Compressive Strength of Calcined Clay Based Cement Mortars Using Support Vector Machine and Artificial Neural Network Techniques

Prediction of Compressive Strength of Calcined Clay Based Cement Mortars Using Support Vector Machine and Artificial Neural Network Techniques

Influence of Fine Additives and Surfactants on the Strength and Permeability Degree of Concrete

Physicochemical Properties of Hydrated Portland Cement Blended with Rice Husk Ash

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