The effect of a modified zeolite additive as a cement and concrete improver

This dissertation presents a study that investigated the potential of a modified zeolite additive known as PowerCem to improve the properties of cement mortar and concrete. Improvement of the characteristics of cement mortars and concrete is of interest to various researchers and practitioners in the field of construction materials engineering. The product, a blend of selected alkaloids and zeolite, is commercially available and effectively used in soil stabilization for road construction. However, its influence and effectiveness on the properties of cementitious systems has not been explored. The emphasis of this study was on improvement of the strength and durability properties of cement mortar and concrete using PowerCem (PWC) additive. Tests carried out on mortar samples include flow, flexural strength, compressive strength, oxygen permeability, sorptivity, porosity, resistance to sulphate attack, and resistance to alkali silica reaction. Tests carried out on concrete samples include workability, split tensile strength, compressive strength, oxygen permeability, sorptivity, porosity, and carbonation. The hydration behaviour of sample pastes were observed using differential thermal analysis (DTA) and thermogravimetric analysis (TGA). Improvement of strength and durability properties of cement mortar and concrete was observed when PWC additive was used at optimum proportions. In conclusion, PWC additive showed the potential to effectively improve mortar, concrete strength and durability properties when used at optimum proportions between 0.4 % and 0.6 %

Characteristics of Wood Ash Cement Mortar Incorporating Green-Synthesized Nano-TiO2

Abstract This paper presents the findings of an investigation into the influence of green-synthesized nano-TiO2 on the characteristics of wood ash (WA) cement mortar. Mortar specimens were prepared by partial replacement of cement with WA (10% by weight) and addition of 1, 2 and 3% nano-TiO2 by weight of binder; using constant water-to-binder ratio (w/b) for all mixtures. The properties evaluated are setting time of the binder and flexural and compressive strength with water absorption of the mortar. The results indicated that addition of 1 and 2% nano-TiO2 reduced setting times of WA cement paste. Also, the flexural and compressive strength of WA cement mortar were higher with the incorporation of up to 2% nano-TiO2. The water absorption of WA cement mortar was reduced when nano-TiO2 was added with 2% incorporation having the best result. The incorporation of NT in WA cement mortar improved its workability and strength characteristics

Evaluating the reinforcements efficiency of sawdust and corncob wastes in structural concrete: A comprehensive review

Sawdust (SD) and Corncob (CC) wastes possess up to 89.4% and 83.03% pozzolanic properties with a high impact on the mechanical properties required for high concrete strength reinforcement respectively. Applications of SD and CC wastes in concrete increased the concrete workability by 8.75% and 27.9% respectively. In addition, the use of SD in concrete eased its aggregates’ compatibility rate by 4.4%. The consistency of cement paste with corncob ash (CCA) decreased with an increase in the percentage of CCA included. In addition, the final and initial setting times of paste with sawdust ash (SDA) decreased by 28.2% and 20% with increasing use in the percentage of SDA included, while that of CC increased with an increase in the percentage of CC. The densities of SDA-concrete and CCA – concrete observed were from 300 to 1800kg/m3 and 1998 kg/m3 to 2302kg/m3, and these were classified as lightweight concrete. The review showed that CCA had a high potential for increasing the concrete compressive strength by 34.5%. The blending of CC waste with other admixtures was observed to have increased concrete’s tensile properties by 3.9%. CC waste possessed high potential for composite tensile property enhancement up to 68%. The CCA-concrete’s flexural strength observed was low; the blending of CC with other admixtures has increased the concrete’s flexural strength. SDW-Concrete suggested to high temperature showed an increase in compressive strength until 6000C is reached, after 6000C, there was a reduction in strength. The CCA reduced concrete’s modulus of elasticity by 27%. From the X–ray result, quartz (SiO2) shows an essential and main mineralogical content of CCA. The concrete’s rate of water absorption increased by 74% with the inclusion of SD. The ANN model is efficient and possesses good features for CCA and SD – concrete models. In conclusion, SD and CC wastes possess a good potential for the enhancement of structural concrete, which can be processed into types of cement and concrete composites

The effect of Fly ash, Beta-cyclodextrin and Fly ash-Beta-cyclodextrin composites on cement paste’s viscosity and setting times

Abstract: The possibility of increasing the usage of Fly ash (FA) in concrete has been a subject of interest and investigation by the authors. In the previous work, a composite of Fly ash- β- cyclodextrin (FA-β-CD) has been seen to have the tendencies of improving hydration reaction. To have further insight on how this composite can affect the mechanical properties of concrete, its rheological properties (viscosity and setting time) are assessed in this article. FA was used in percentages of 30 and 50, while β-CD was used in 0.025, 0.05 and 0.1 percentages. These percentages were based on the total percentage of cement (by mass). The results showed that increased in FA and β-CD contents, reduced the viscosity of the cement paste. Also, higher contents of FA and β-CD, reduced the water required for consistency and extended the setting times

Investigation of the fly ash - β cyclodextrin composite on concrete’s durability indexes

Abstract: Concrete quality can be assessed by its ability to withstand its design life without failing, which is a function of its strength and durability. The effect of fly ash (FA)-β- cyclodextrin (β-CD) composite on concrete’s durability indexes was investigated in this paper. Two durability index tests (oxygen permeability and sorptivity) were used for the assessment. FA (30% and 50% by mass of cement), β-CD (0.025%, 0.05% and 0.1%) and FA-β-CD composite were incorporated in the concrete mix. Twenty four different concrete mixes were investigated at 0.5 water-binder ratio (W/B) and 0.4 W/B. The tests were performed on the concrete samples after being cured for 28 and 90 days. The results showed that β-CD and FA-β-CD composite decrease oxygen permeability and sorptivity of concrete when used at optimum percentages

Machine learning algorithms in wood ash-cement-Nano TiO2-based mortar subjected to elevated temperatures

Mortar is subjected to high temperatures during fire attacks or when it is near heat-radiating equipment like furnaces and reactors. The physical and microstructure of mortar were considerably altered by high temperatures. In this investigation, the effects of elevated temperatures on the flexural and compressive strengths of wood ash (WA) cement mortar modified with green-synthesised Nano titanium oxide (NT) were examined. In order to produce mortar samples, the cement was replaced with 10% WA, and 1–3% NT by weight of binder were added at constant water-binder ratio. The specimens were heated to 105, 200, 400, 600, and 800 °C with an incremental rate of 10 °C per min in the electric furnace for a sustained period of 2 h to measure their strengths. The machine learning algorithm of artificial neural networks with Levenberg-Marquardt backpropagation training techniques of different network architectures was engaged to predict the compressive strength of WA-cement-NT-based mortar produced. The findings showed that higher temperatures reduced compressive strength after 400 °C and flexural strength after 200 °C. The mortar specimen with a 3% NT addition showed the highest residual compressive strength increase, ranging from 18.75 to 27.38%. Compared to compressive strength, flexural strength is more severely affected by high temperatures. The backpropagation training algorithm revealed that each hidden layer displayed its unique strong prediction. However, Levenberg-Marquardt backpropagation training technique of 7–10-10-1 network structures yielded the best performance metrics for training, validation, and testing compared to 7-10-10-10 and 7-10-1 network architectures

Machine learning algorithms in wood ash-cement-Nano TiO2-based mortar subjected to elevated temperatures

Mortar is subjected to high temperatures during fire attacks or when it is near heat-radiating equipment like furnaces and reactors. The physical and microstructure of mortar were considerably altered by high temperatures. In this investigation, the effects of elevated temperatures on the flexural and compressive strengths of wood ash (WA) cement mortar modified with green-synthesised Nano titanium oxide (NT) were examined. In order to produce mortar samples, the cement was replaced with 10% WA, and 1–3% NT by weight of binder were added at constant water-binder ratio. The specimens were heated to 105, 200, 400, 600, and 800 °C with an incremental rate of 10 °C per min in the electric furnace for a sustained period of 2 h to measure their strengths. The machine learning algorithm of artificial neural networks with Levenberg-Marquardt backpropagation training techniques of different network architectures was engaged to predict the compressive strength of WA-cement-NT-based mortar produced. The findings showed that higher temperatures reduced compressive strength after 400 °C and flexural strength after 200 °C. The mortar specimen with a 3% NT addition showed the highest residual compressive strength increase, ranging from 18.75 to 27.38%. Compared to compressive strength, flexural strength is more severely affected by high temperatures. The backpropagation training algorithm revealed that each hidden layer displayed its unique strong prediction. However, Levenberg-Marquardt backpropagation training technique of 7–10-10-1 network structures yielded the best performance metrics for training, validation, and testing compared to 7-10-10-10 and 7-10-1 network architectures

Machine learning algorithms in wood ash-cement-Nano TiO2-based mortar subjected to elevated temperatures

Mortar is subjected to high temperatures during fire attacks or when it is near heat-radiating equipment like furnaces and reactors. The physical and microstructure of mortar were considerably altered by high temperatures. In this investigation, the effects of elevated temperatures on the flexural and compressive strengths of wood ash (WA) cement mortar modified with green-synthesised Nano titanium oxide (NT) were examined. In order to produce mortar samples, the cement was replaced with 10% WA, and 1–3% NT by weight of binder were added at constant water-binder ratio. The specimens were heated to 105, 200, 400, 600, and 800 °C with an incremental rate of 10 °C per min in the electric furnace for a sustained period of 2 h to measure their strengths. The machine learning algorithm of artificial neural networks with Levenberg-Marquardt backpropagation training techniques of different network architectures was engaged to predict the compressive strength of WA-cement-NT-based mortar produced. The findings showed that higher temperatures reduced compressive strength after 400 °C and flexural strength after 200 °C. The mortar specimen with a 3% NT addition showed the highest residual compressive strength increase, ranging from 18.75 to 27.38%. Compared to compressive strength, flexural strength is more severely affected by high temperatures. The backpropagation training algorithm revealed that each hidden layer displayed its unique strong prediction. However, Levenberg-Marquardt backpropagation training technique of 7–10-10-1 network structures yielded the best performance metrics for training, validation, and testing compared to 7-10-10-10 and 7-10-1 network architectures

Modification of fly Ash structure using Cyclodextrin for concrete strength and durability development

Abstract: Fly ash (FA) is a promising industrial waste, which has been used in concrete technology as a cement replacement. However, its utilization is still limited compared to the quantity (approximately 36 million tons per year) of the FA being generated by ESKOM (the major South African electricity producer) as industrial waste. There is a need to improve the utilisation of the large amount of unused FA (approximately 94% of ash generated). The exploitation of the unique chemistry of FA is needed to make it more applicable in concrete, especially with a view to improving early strength and early durability development when it is used in concrete. This study aimed at investigating the effectiveness of using FA-cyclodextrin (an enzymatic modification of starch) composite, a novel composite, to beneficially modify concrete’s hydration products and hence increase FA usage in concrete technology. Fly ash-cyclodextrin (FA-CD) composites were synthesized using two types of cyclodextrins (β and α) and two synthesis methods (physical mixtures and solution mixtures). The chemical structure and the microstructure of these composites were studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Scanning electron microscope (SEM). In these studies, the additional peaks in the X-ray diffractogram and IR-spectra of the composite materials indicated interaction between the cyclodextrins and FA. The change in the surface morphology, particle size and pore size, between the composite materials and constituent materials were also observed. Since the use of these composites are relatively new in concrete technology, compressive strength, split tensile strength, permeability, water sorptivity and porosity were determined on samples made using two composites synthesis methods with different percentages of β-cyclodextrin (0.1%, 0.2% and 0.5%) and 30% FA on concrete strengths (compressive and split tensile) and durability (permeability, sorptivity and porosity). Based on these tests results, further...D.Ing

Indicative tests on the effect of fly ash - β cyclodextrin composite on concrete workability and strength.

Fly ash – βcyclodextrin interaction has shown to have formed a composite that might be useful in concrete technology [1]. Since the effect of this composite on concrete properties has not been documented in an open literature, there is a need to run indicative tests that will give guidance for on-going research. This paper presents the results of the indicative tests on the effect of fly ash-β cyclodextrincomposite on concrete workability and strength (compression and split tensile). All the mixtures included 30 % fly ash (FA) by mass. The βcyclodextrin (β-CD) was mixed with the FA, in separate mixtures, in proportions of 0.1 %, 0.2 % and 0.5 %. Two sample preparation procedures were followed for FA-β-CD composites mixtures; firstly, physical mixtures of a pre-weighed amount of β-CD and FA were adopted for the dry mixtures and secondly, 0.0103M, 0.0206M and 0.0516Mβ-CD solutions were added to the concrete at the mixing stage for solution mixtures.The results obtained showed that an increased content (0.5%) of β-CD in concrete both for dry and solution mixtures had a detrimental effect on both workability and strength. However, lower percentages (0.1% and 0.2%) of β-CD improved both workability and the strength of the concrete