Organic Admixtures Research Articles

Importance of adsorption compared with complexation for retarding C3S hydration via adding sodium gluconate

Adsorption effect on particle surfaces and complexation effect with free Ca2+ mostly determine the retarding performance of organic admixtures on cement hydration. However, it is difficult to identify which effect plays a more important role in retarding hydration by experimental methods. Here, a theoretical model was developed to investigate the retarding mechanisms of sodium gluconate (SG) on hydration of tricalcium silicate (C3S). Based on obstruction theory and complexation reaction kinetics, effects of adsorption and complexation were simulated to examine the retarding performance of C3S hydration with addition of SG. The proposed model well predicted the effect of additional dosing of SG on the retarding performance of C3S hydration. Theoretical parameter studies demonstrated that adsorption ratio contributed much largely to the delays in C3S hydration, compared with rate constant of complex generation. Therefore, it is confirmed that adsorption plays a more important role in regulating the retarding mechanism of C3S hydration.

Improved Low-field NMR porosity characterization of cementitious materials containing water-soluble organic admixtures

Water-soluble organic admixtures (WSOAs) are widely used in cementitious materials, and may affect the porosity, but their effects on low-field nuclear magnetic resonance (LF-NMR) measurement are often overlooked. Using viscosity modifying admixture (VMA) as an example, this study demonstrates the presence of WSOAs would lead to an overestimation of porosity and a leftward shift of pore size distribution using LF-NMR. This is attributed to the formation of hydrogen bonds between polymer and water molecules, and the decreased distance between nuclear spins, respectively. A strategy is proposed to improve the accuracy of the porosity characterization by eliminating the additional effects of WSOAs in LF-NMR testing. The results show that the addition of small molecular mass non-ionic VMAs replacing mixing water (within a 20 % replacing rate) does not alter the porosity of the paste. This method can be extended to characterize the porosity of various porous materials containing WSOAs.

Sustainable production of WMA with pine gum wax modification

Warm mix asphalt (WMA) (S®-WMA) produced with Sasobit® (S®), a widely used organic admixture, shows a significant increase in softening point value and a decrease in stripping resistance. These two characteristics of S®-WMA are considered as some problems to be solved. Therefore, this study was established to evaluate possible solutions to these two problems through another modification process. In this study, it was investigated whether modifying S®-WMA using a previously unstudied product, pine gum wax (PGW), could be a solution to the problem. In this context, WMA was produced with S® at 1, 2 and 3 in percent by mass of bitumen. As PGW has not been previously used as an additive to modify S®-WMA, it was added within a limit of 1% (by bitumen mass) for initial investigation. Physical and rheological standard tests were performed on each sample to demonstrate the change in properties of S®-WMA produced with 1% PGW compared to S®-WMA. The results indicated that the addition of 1% PGW to S®-WMA resulted in a significant reduction in softening point and an improvement in stripping resistance compared to S®-WMA. Thus, it seems that the use of PGW could be a potential solution for the two mentioned problems. It can also be pointed out that modifying the S®-WMA specimen with PGW without compromising its properties can help in an efficient, economical and environmentally friendly solution. However, due to the use of PGW, more in-depth research is required.

A critical review of the effect of chemical organic admixtures for OPC-based materials

Chemical organic admixtures play a significant role in engineering structures. This paper reviews the effects of organic admixtures with different molecular scales and functional groups on the cement hydration process and discusses their roles in the microstructure and properties of cement-based materials. According to the current research, the molecular structure of admixtures determines their adsorption performance on cement, which in turn affects their mechanism of action and durability in cement-based materials. Incorporating organic admixtures can regulate the properties of cement-based materials. Most admixtures can adsorb onto the surface of cement particles and complex with Ca2+ in the liquid phase, thus exhibiting a retarding effect. The hydration products of cement develop more completely, potentially positively impacting the durability of concrete, particularly its impermeability.

Comparative Studies of the Physico-Mechanical Characterization of Ugwuoba Clay with Admixtures of Corncob and Sugarcane Bagasse Ashes

An investigation into the effects of combustible materials on the refractory properties of Ugwuoba clay, using sugarcane bagasse ash and corncob ash has been undertaken. Ugwuoba clay was sourced from Ugwuoba town in Oji River Local Government Area of Enugu State. Sugarcane bagasse were collected at Lokpanta, a Fulani settlement in Okigwe Community, Imo State, while corncobs were collected at New Artisan Market in Enugu Metropolis. The clay was processed using standard beneficiation and purification procedures at the Ceramics Department of Projects Development Agency (PRODA), Enugu. The sugarcane bagasse and corncobs were each and separately calcined into amorphous ash by heating in a furnace at 650oC. The refractory blends were compounded at the ratio of 90:10, 80:20, 70:30, and 60:40 for Ugwuoba clay (UGC) to Sugarcane Bagasse Ash (SBA) and Ugwuoba Clay (UGC) to Corncob Ash (CCA) separately and respectively. These blends were subsequently molded into the standard test pieces for the various properties determination and subjected to firing at temperatures of 900oC, 1000oC, 1100oC and 1200oC. Thereafter, the fired samples were characterized for fired shrinkages, total shrinkages, apparent porosities, water absorption coefficients, apparent densities, bulk densities and moduli of rupture. The results obtained for each of the blends showed that the values were within the tolerable limits for industrial refractories with the 10%SBA and the 20%CCA blends showing the best results. Comparatively however, the 10%SBA produced the better of these properties than the 20%CCA. A conclusion is drawn to the effect that both sugarcane bagasse ash and corncob ash can serve as good organic admixtures for refractory bricks production for the lining of melting furnaces in the metals industry, hence opening new frontiers for recycling of these agricultural wastes for environmental safety and economic development in Nigeria.

Study of Ecofriendly Admixture in Concrete

To enhance workability and strength, water-reducing chemicals are commonly used, but their production emits CO2 and poses environmental and cost concerns. The research explores the potential of plant extract, specifically cypress extract, as an eco-friendly and cost-effective alternative admixture for concrete. Previous studies have shown positive effects of organic admixtures, including polysaccharides and bio-admixtures from water hyacinth, on concrete rheology and strength. This research aims to determine the viability of cypress extract as a sustainable admixture, offering an environmentally friendly solution to reduce reliance on imported, patented chemicals and mitigate the environmental impact of the cement industry.

Hydration characteristics of steel slag in the presence of diethanol-isopropanolamine

Steel slag (SS) as a supplementary cementitious material has low cementitious activity. Diethanol-isopropanolamine (DEIPA) is an organic admixture that can enhance the cementitious activity of cementitious materials. This work aimed to investigate the hydration characteristics of SS under the complexing of DEIPA. The hydration process of SS, the complexation of DEIPA with metal ions, and the dissolution process of C3A and C3S in the presence of DEIPA were systematically investigated. The results showed that DEIPA enhanced the hydration of aluminate (C3A and C12A7), ferrate (C2F) and silicate phases (C3S and C2S), which formed a large amount of monocarboaluminate, paraalumohydrocalcite and C–S–H gels. In the early stages of hydration, the hydration products were mainly C–S–H gels, monocarboaluminate and paraalumohydrocalcite, and in the later stages of hydration, the hydration products were mainly C–S–H gels, paraalumohydrocalcite. The monocarboaluminate may be transformed to paraalumohydrocalcite at a later stage. This hydration-promoting effect was related to the complexation of DEIPA. DEIPA facilitated the dissolution of mineral phases and the precipitation of complexed metal ions by complexing with metal ions. The stronger complexation of Al3+ by DEIPA made it more solubilizing for C3A. As a result, more aluminum-containing hydration products were formed. The weaker complexation of Ca2+ by DEIPA made it a weaker solubilizing for C3S, which also led to a weaker promotion of silicate hydration by DEIPA. The solubilization of DEIPA to minerals enhanced the cementitious activity of SS, which ultimately led to the increase in the compressive strength of the hardened SS paste at each age.

Effects of the Addition of Corncob Ash on the Technological Properties of Ugwuoba Clay, Nigeria

An investigation into the effects of combustible materials on the refractory properties of Ugwuoba clay, using corncob ash has been undertaken. Ugwuoba clay was sourced from Ugwuoba town in Oji River Local Government Area of Enugu State, Nigeria, while corncobs were collected at New Artisan Market in Enugu Metropolis. The clay was processed using standard beneficiation and purification procedures at the Ceramics Department of Projects Development Agency (PRODA), Enugu. The corncobs were calcined into amorphous ash by heating in a furnace at 650oC. The refractory blends were compounded at the ratio of 90:10, 80:20, 70:30, and 60:40 for Ugwuoba clay (UGC) to Corncob Ash (CCA) respectively. These blends were subsequently moulded into the standard test pieces for the various properties determination and subjected to firing at temperatures of 900oC, 1000oC, 1100oC and 1200oC. Thereafter, the fired samples were characterized for fired shrinkages, total shrinkages, apparent porosities, water absorption coefficients, apparent densities, bulk densities and cold crushing strengths. The results obtained for each of the blends showed that the values were within the tolerable limits for industrial refractories with the 20%CCA blends showing the best results when compared with the other blends. A conclusion is drawn to the effect that corncob ash can serve as good organic admixtures for refractory bricks production for the lining of melting furnaces in the metals industry, hence opening new frontiers for recycling of these agricultural wastes for environmental safety and economic development in Nigeria.

Organic Admixtures as Additive: An Initiative to Reduce Carbon Dioxide Emission due to Concrete

AbstractConcrete is a material which is being used extensively for construction worldwide. Concrete provides high strength, durability, impermeability, fire resistance, and hence provides a safe place for living. It is the composite of cement, aggregates, and water. In modern construction, chemical admixtures are also used to elaborate the properties of concrete like strength, workability, etc. but the chemical admixtures have adverse effects on environment at the time of production and post‐production also. Whereas organic admixtures are extracted organically from plants and animals without addition of any external chemicals. Many organic admixtures are used in lime concrete/mortar traditionally. The purpose of this paper is to enlighten the effect on quality of concrete by addition of organic additives jaggery and sticky rice pulp, which will in turn reduce the cement requirement and overall CO2 emission in the environment.

Assessing the interactions of retarding admixtures and fine materials in long-term flowability of cement pastes

The incorporation of supplementary fine materials into mortars and concretes is a common strategy employed to enhance both their rheological and mechanical properties. While organic molecule-based admixtures are primarily utilized to regulate the setting time in pre-mixed concretes and mortars, their effects become more intricate in the presence of fine materials. This study delves into the interplay between flowability and setting times of cement pastes with 50 wt% of fines (basalt filler, fly ash and quartz filler) in place of cement and three organic admixtures at 0.5 % and 1.0 % (wt% of cement). The results unveil compelling insights: the incorporation of retarding additives proves notably advantageous, markedly decreasing viscosity and prolonging the initial stage of paste formation by as much as 305 h. Nevertheless, the efficacy of these additives diminishes significantly in the presence of fine particles, especially when utilizing basalt filler. This prompts an in-depth exploration into the intricate interactions transpiring between the fine materials and the setting retardants. The implications of these interactions underscore their pivotal role in refining the application of retarding additives in scenarios involving fine materials.

Membrane separation techniques– removal of inorganic and organic admixtures and impurities from water environment – review

Membrane separation techniques– removal of inorganic and organic admixtures and impurities from water environment – review

Effect of Green Admixtures on the Mechanical Properties of Concrete Composite

The study was carried out to evaluate the suitability of organic admixture in concrete production. Six sets of concrete were made by partially replacing the fine aggregates (sand) and coarse aggregates (gravel) with 0, 5, 10, 15, 20 and 25% of sawdust and periwinkle shells respectively, in the presence of 0, 0.5, 1, 1.5, 2 and 2.5% cassava starch. The compressive strength and density of the six concrete groups were tested, in accordance with American Society for Testing and Materials (ASTM) International approved guidelines. Findings from the laboratory investigations indicated that the sawdust and periwinkle admixtures generally reduced the concrete compressive strength, as their proportion in the concrete increased from 0 to 25%; while the cassava tends to increase the concrete’s compressive strength. The compressive strength of the concrete declined from 25.2 to 10.3 MPa, 27.1 to 11.7 MPa, 30.7 to 13.6 MPa, 31.4 to 14.5 MPa, 30.9 to 14.2 MPa, and 28.4 to 13.8 MPa, after the incorporation of 25% sawdust and 25% periwinkle shells, as partial replacement for sand and gravels respectively, in the presence of 2.5% cassava starch. Furthermore, the results revealed that the compressive strength of the concrete increased non-linearly, as the cassava starch volume increased from 0 to 2.5%. However, the concrete set produced from 20% sawdust and 20% periwinkle shells was light-weight and its compressive strength was within the limit of 17 MPa recommended by Nigeria Industrial Standard (NIS) for light-weight concrete required for residential buildings construction. The findings of this study revealed that agricultural waste materials are suitable admixture materials in the concrete industry.

Employing spatial, hybrid and amplitude roughness parameters for unveiling the surface roughness features of mineral and organic admixtures

Scanning electron microscopy (SEM) permits to evaluate the surface morphology and surface roughness of pozzolans and admixtures. The field of mineral and organic admixtures has considerable interest in using SEM. However, several challenges are encountered which hamper the precision of quantitative roughness evaluation of mineral and organic admixtures using SEM and these challenges are usually bypassed in literature. In this research, surface roughness properties of pozzolans and admixtures were analysed from six perspectives: spatial parameters, hybrid parameters, amplitude parameters, surface roughness profiles, bearing ratio curves (BRCs) and amplitude density functions (ADFs). The generated roughness characteristics provided detailed information of roughness properties of the pozzolans and admixtures in a time efficient and cost effective way, which is usually very hard to achieve using experimental works. The comparisons of the obtained roughness data for the specimens showed considerable agreement with the roughness profiles and verified the interpretation of the established roughness profiles. Using the ADFs and BRCs for evaluating heights of the roughness profiles provided significant data encapsulated in the shapes of ADFs and BRCs. Moreover, the interpretation of the transformed logarithmic profiles seemed to have nearly retained similar meanings with the conventional profiles, although their scrutiny was observed to be complex. With brand new discussions on spatial, hybrid and amplitude parameters of mineral and organic admixtures, this research is a step forward in characterisation of roughness parameters of mineral and organic admixtures. This study expands the characterisation of pozzolans and admixtures, highlighting significant parameters to be considered in the application of mineral and organic admixtures.

Early-age deformation of hydrophobized metakaolin-based geopolymers

This study presents a novel strategy to simultaneously mitigate the early-age shrinkage and achieve hydrophobization of metakaolin-based geopolymer (MKG) pastes through the incorporation of organic admixtures including polydimethylsiloxane (PDMS) and sodium methylsilicate (SMS). The pore structure, wettability, moisture/water adsorption capacity, and internal moisture distribution are investigated through different techniques including MIP and LF-NMR. Results indicate that the autogenous shrinkage of MKG paste is reduced by 91.2 % and 41.6 % when adding 5 % PDMS and replacing with 20 % SMS, and the water contact angle increases to approximately 130° and 140°, respectively. The addition of organic admixtures significantly reduces the moisture adsorption and surface tension of the MKG matrix, and thus internal water tends to be transported into larger pores, leading to less liquid-vapor meniscus and lower capillary stress. Moreover, an underlying mechanism is proposed to explain the shrinkage mitigation of hydrophobized MKG paste, accounting for the moisture transfer tendency and internal stress distribution.

Correlating Hydration of Alkali-Activated Slag Modified by Organic Additives to the Evolution of Its Properties

This study investigates the relationships between the hydration kinetics of waterglass-activated slag and the development of its physical-mechanical properties, as well as its color change. To modify the calorimetric response of alkali-activated slag, hexylene glycol was selected from various alcohols for in-depth experiments. In presence of hexylene glycol, the formation of initial reaction products was restricted to the slag surface, which drastically slowed down the further consumption of dissolved species and slag dissolution and consequently delayed the bulk hydration of the waterglass-activated slag by several days. This allowed to show that the corresponding calorimetric peak is directly related to the rapid evolution of the microstructure and physical-mechanical parameters and to the onset of a blue/green color change recorded as a time-lapse video. Workability loss was correlated with the first half of the second calorimetric peak, while the most rapid increase in strengths and autogenous shrinkage was related to the third calorimetric peak. Ultrasonic pulse velocity increased considerably during both the second and third calorimetric peak. Despite the modified morphology of the initial reaction products, the prolonged induction period, and the slightly reduced degree of hydration induced by hexylene glycol, the overall mechanism of alkaline activation remained unchanged in the long-term perspective. It was hypothesized that the main issue of the use of organic admixtures in alkali-activated systems is the destabilizing effect of these admixtures on soluble silicates introduced into the system with an activator.

Quantitative study on surface porosity and roughness parameters of mineral and organic admixtures based on multi-scale characterisation techniques

Studying surface porosity and surface roughness of mineral and organic admixtures is vital in cement-based applications as these characteristics play a significant role in the behaviour of cement-based composites. Aiming to enhance the characteristics of coconut shell ash (CSA), gum Arabic (GA), cassava starch (CS), rice husk ash (RHA) and burnt clay powder (BCP) including their influence on cement-based composites, the surface porosity and surface roughness characteristics were comprehensively explored using scanning electron microscopy (SEM) under scale of 100 µm and Gwyddion. The surface morphological measurements, surface porosity and surface roughness of the specimens were respectively assessed using parameters such as skewness (Rsk), Kurtosis coefficient (Rku), roughness average (Ra), root mean square roughness (Rq), waviness average (Wa), root mean square waviness (Wq) and plane porosity. The roughness average values were noticed to range from 19 nm to 77 nm whilst the root mean square roughness values were found to vary from 27 nm to 107 nm. The waviness average and root mean square waviness values of specimens ranged from 26–132 nm and 34–157 nm respectively. The skewness values were observed to range from −0.18–0.72 while Kurtosis coefficient values ranged from 3 to 12. The comparisons in plane porosity quantification findings obtained using the implemented algorithms illustrated that the plane porosity values from threshold method were higher than those from segmentation method. The findings from this study extend characterisation of mineral and organic admixtures and subsequently guide management practices of waste materials through utilisation of mineral and organic admixtures in cement-based composites.

Ageing properties of warm-mix asphalt containing reclaimed asphalt pavement

A study was undertaken to evaluate the influence of an organic and a chemical additive on the short- and long-term ageing properties of warm-mix asphalt containing reclaimed asphalt pavement. Various mechanical tests, including dynamic creep, indirect tensile strength, semi-circular bending and resilient modulus, were conducted. The results indicated that the mixture containing reclaimed asphalt pavement without additives showed a higher flow number in both non-ageing and ageing processes, indicating higher resistance to rutting. The mixture containing the chemical additive demonstrated higher resistance to moisture susceptibility in comparison to the one with the organic admixture. Moreover, the mixtures containing recycled asphalt pavement and the chemical additive showed higher fracture energy than mixtures containing recycled asphalt pavement and the organic additive, while the latter showed the highest resilient modulus in the non-ageing and ageing process.

Effect of citric-acid-modified chitosan (CAMC) on hydration kinetics of tricalcium silicate (C3S)

Studying the mechanism by which organic admixtures affect the hydration and dissolution of tricalcium silicate (C3S) reveals the effect of organic admixtures on ordinary Portland cement and enables target regulation of cement-based materials. In this study, the effects of citric-acid-modified chitosan (CAMC) on the hydration exotherm, hydration products, and microscopic morphology of C3S were investigated. The interface structures, ion adsorptions, and dissolution properties of CAMC and C3S were analyzed using a molecular dynamics simulation method. The results showed the presence of an attraction between the C3S surface and CAMC due to the existence of Op-Hw, Op-Cas, and Hp-Ow ion pairs. CAMC adsorbed most of the Ca ions released upon dissolution of C3S in the aqueous solution and the resulting pairs exhibited low solubilities. The Ca ions were located on the surfaces of C3S particles, preventing the dissolution of the particles and proving the interference effect of additives on the hydration of the cement silicate phase.

Novel method of ancient pottery analysis based on radioactive isotope ratios: a pilot study

The proposed method has been applied to a multi-phased settlement complex and pottery manufacturing centre in Ostrowite in northern Poland. In this study the radioactive isotope ratios method has been applied to a set of ceramic pottery specimens from the same multi-layered archaeological site and probably produced from local raw material. The pilot radiometric research was based on: 24 Neolithic (5200–5000 BCE), 21 Early Iron Age (800–600 BCE), 4 Roman Period (100–400 CE), and 13 Middle Ages (1030–1320 CE) pottery fragments, and also 8 samples of local clay (glacial till) and 3 burned clay samples. The method shows the similarities within the ceramic material used to manufacture the pottery. The variations in the quantitative and qualitative compositions of the basic products (clay, silt, loam, sand, ash and organic admixtures) used in the preparation of the ceramic paste change the isotopic composition and activity ratios. Pottery from each ceramic manufacturing centre, based on the specific composition of the raw materials, have characteristic isotope ratios. Radioactive isotope ratios as fingerprints of ancient ceramic manufacturing centres have not yet been applied as an archaeometric method. In this study two isotope ratios have been selected and applied: 40K/228Ac and 226Ra/208Tl. All analysis have been done using gamma spectrometry system, with quality and quantity analysis of the spectrums. Low-background passive shield was used for obtain improvement of results quality. The pilot study confirms the grouping of isotope ratio results for each sample type, even in terms of similarities with the base clay material collected in this region.

Influence of Sticky Rice and Jaggery Sugar Addition on Lime Mortar

Lime mortar has many advantages, yet its durability properties are the most remarkable, making it very useful in building preservation. Traditional mortar for conservation and restoration work contains lime, which guarantees that the fresh mortar is applied to the underlying layer, increases its setting time, and gives adequate workability. This research aims to determine the durability performance, mechanical properties, and optimum percentage of organic admixtures to be used in lime mortar. Five mix proportions and one control lime mortar mix were prepared. Mixes with jaggery sugar and sticky rice with weight proportions of 3%, 6%, 9%, 12%, and 15% were compared with the control lime mortar mix. The results show that 9% sticky rice lime mortar achieved the highest performance in terms of mechanical and durability properties.