scholarly journals Strength, Stiffness, and Microstructure of Wood-Ash Stabilized Marine Clay

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 796
Author(s):  
Abdullah Ekinci ◽  
Mohammad Hanafi ◽  
Ertug Aydin

The world’s population is growing at a rapid pace, thus increasing the need for shelter, which, because of increased carbon emissions, is making our planet less habitable. Thus, supplementary cementitious materials (SCMs) are used to reduce the embodied carbon emissions in the building sector. Wood-ash, as a replacement for cement in ground improvement, seems to be a promising material. In this study, we considered the strength, stiffness, and microstructural behavior of marine deposited clays of Cyprus treated with cement and wood-ash as a cement replacement. Since clay is abundant in nature, it could help stabilize waste to improve the mechanical behavior of produced composites. Portland cement (7%, 10%, and 13%) was replaced with various amount of wood-ash (5% and 10%) with two different dry densities (1400 and 1600 kg/m3) and three distinct curing periods (7, 28, and 60 days). Unconfined compressive strength (UCS), direct shear, porosity and pulse velocity tests were performed. Additionally, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy analysis (EDX) were performed for microstructural evaluation of clay–wood-ash–cement mixtures. The results revealed that the replacement of cement with 5% of wood-ash yielded superior performance. The microstructure investigation of wood-ash–cement–clay blends further showed the formation of a densified matrix with stable bonds. Furthermore, the porosity and strength properties (unconfined compressive strength, splitting tensile strength, cohesion (C) and friction angle (ϕ)) of blends have unique relationships with porosity and binder contents, which were further confirmed by other supplementary materials and soils.

Author(s):  
Abdullah Ekinci ◽  
Mohammad Hanafi ◽  
Ertug Aydin

The world’s population is growing at a rapid pace, thus increasing the need for shelter, which, because of increased carbon emissions, is making our planet less inhabitable. Thus, supplementary cementitious materials (SCMs) are used to reduce the embodied carbon emissions in the building sector. Wood ash, as a replacement for cement in soil treatment, seems to be a promising material. In this study, we considered the strength, stiffness, and microstructural behavior of marine clay treated with cement and wood ash as a cement replacement. Since clay is abundant in nature, it could help stabilize waste to improve the mechanical behavior of produced composites. Portland cement (7%, 10%, and 13%) was replaced with various amount of wood ash (5% and 10%) with two different dry densities (1400 and 1600 kg/m3) and three distinct curing periods (7, 28, and 60 days). Unconfined compressive strength, direct shear, porosity, pulse velocity, x-ray diffraction, and scanning electron microscopy tests were performed on selected specimens to evaluate the structural and microstructural effect of clay–wood ash–cement interaction. The results revealed that the replacement of cement with 5% of wood ash yielded superior performance. The microstructure investigation of wood ash–cement–clay blends further showed the formation of a densified matrix with stable bonds. Furthermore, the porosity and strength properties of blends developed unique relationships, which were further confirmed by other supplementary materials and soils.


Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 204
Author(s):  
Yi Han ◽  
Seokhoon Oh ◽  
Xiao-Yong Wang ◽  
Run-Sheng Lin

At present, reducing carbon emissions is an urgent problem that needs to be solved in the cement industry. This study used three mineral admixtures materials: limestone powder (0–10%), metakaolin (0–15%), and fly ash (0–30%). Binary, ternary, and quaternary pastes were prepared, and the specimens’ workability, compressive strength, ultrasonic pulse speed, surface resistivity, and the heat of hydration were studied; X-ray diffraction and attenuated total reflection Fourier transform infrared tests were conducted. In addition, the influence of supplementary cementitious materials on the compressive strength and durability of the blended paste and the sustainable development of the quaternary-blended paste was analyzed. The experimental results are summarized as follows: (1) metakaolin can reduce the workability of cement paste; (2) the addition of alternative materials can promote cement hydration and help improve long-term compressive strength; (3) surface resistivity tests show that adding alternative materials can increase the value of surface resistivity; (4) the quaternary-blended paste can greatly reduce the accumulated heat of hydration; (5) increasing the amount of supplementary cementitious materials can effectively reduce carbon emissions compared with pure cement paste. In summary, the quaternary-blended paste has great advantages in terms of durability and sustainability and has good development prospects.


2021 ◽  
Vol 13 (19) ◽  
pp. 10605
Author(s):  
Mohammed A. Abed ◽  
Bassam A. Tayeh ◽  
B. H. Abu Bakar ◽  
Rita Nemes

The increasing demand for eco-efficient concrete puts pressure on the industry to innovate new alternatives for its constituent materials. Coarse recycled concrete aggregates (RA) and supplementary cementitious materials (SCMs) are considered promising substitutes for coarse natural aggregates (NA) and cement, respectively. Using destructive and non-destructive testing methods, the present work aims to evaluate the effect of RA and different types of waste SCMs on the long-term performance of self-compacting high-performance concrete (SCHPC). Twenty-one mixes that were prepared with a 0.35 water-to-binder ratio were tested for their compressive strength, surface hardness, and ultrasonic pulse velocity. These tests were conducted over a two-year period at ambient temperature and again after exposure to up to 150 freeze–thaw cycles. Study findings demonstrated the possibility of developing eco-efficient SCHPC mixes using RA and waste SCMs. In addition, correlations have been introduced for predicting the compressive strength of SCHPC.


2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Ali Ateş

Soil stabilization has been widely used as an alternative to substitute the lack of suitable material on site. The use of nontraditional chemical stabilizers in soil improvement is growing daily. In this study a laboratory experiment was conducted to evaluate the effects of waterborne polymer on unconfined compression strength and to study the effect of cement grout on pre-venting of liquefiable sandy soils. The laboratory tests were performed including grain size of sandy soil, unit weight, ultrasonic pulse velocity, and unconfined compressive strength test. The sand and various amounts of polymer (1%, 2%, 3%, and 4%) and cement (10%, 20%, 30%, and 40%) were mixed with all of them into dough using mechanical kneader in laboratory conditions. Grouting experiment is performed with a cylindrical mould of  mm. The samples were subjected to unconfined compression tests to determine their strength after 7 and 14 days of curing. The results of the tests indicated that the waterborne polymer significantly improved the unconfined compression strength of sandy soils which have susceptibility of liquefaction.


2021 ◽  
Author(s):  
Eethar Thanon Dawood ◽  
Marwa Saadi Mhmood

AbstractA quaternary supplementary cementitious materials as partial replacement of ordinary Portland cement decreases CO2 emission. This paper has investigated the properties of mortars made from different quaternary blends of wood ash, steel slag powder and glass powder with ordinary Portland cement at different replacement levels of 0, 24, 25, and 30% by weight of the binder. The blended mortar mixtures tested for flow, compressive strength and density. The results showed that the flow of mortars is decreased with the combined use of steel slag powder, glass powder, and wood ash compared with control mix. Compressive strength reduced with the combination of steel slag powder, glass powder and wood ash but this reduction effects is acceptable especially at 24% replacement contain super-plasticizer compared with the ecological benefit.


2020 ◽  
Vol 10 (10) ◽  
pp. 3511
Author(s):  
Abdul Qudoos ◽  
Ehsanullah Kakar ◽  
Atta ur Rehman ◽  
In Kyu Jeon ◽  
Hong Gi Kim

The worldwide production of cement is growing every year due to its increased use in the construction. Cement production is affiliated with an environmental concern as it contributes to the CO2 emissions. It is imperative to reduce the cement production by incorporating supplementary cementitious materials in the cement composites. In this research study, wheat straw ash (WSA) was used as an alternate of ordinary Portland cement. The ash was ground separately with a ball mill and a disintegrator mill as well as with a combination of both to enhance its pozzolanic efficiency. Mortar and paste specimens were made by substituting cement with WSA (20% by weight). Ash specimens were examined in terms of particle size distribution, X-ray diffraction, and X-ray fluorescence analyses. The performance of the ash specimens in cement composites was examined via compressive and flexural strengths, and ultrasonic pulse velocity (UPV) tests. Isothermal calorimetric, thermogravimetric analyses (TGA), mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM) were also employed on the specimens. The results revealed that the particle size of the wheat straw ash specimens significantly reduced and specific surface area enhanced when ground with a combination of both milling techniques. Cement composites made with this type of ash demonstrated improved mechanical and physical properties, accelerated hydration reaction at the early ages, reduce calcium hydroxide content at the later ages, and densified microstructure.


2019 ◽  
Vol 26 (1) ◽  
pp. 449-464 ◽  
Author(s):  
Mifeng Gou ◽  
Longfei Zhou ◽  
Nathalene Wei Ying Then

AbstractOne of the advantages of cement and the cement concrete industry in sustainability is the ability to utilize large amounts of industrial solid wastes such as fly ash and ground granulated blast furnace slag. Tailings are solid wastes of the ore beneficiation process in the extractive industry and are available in huge amounts in some countries. This paper reviews the potential utilization of tailings as a replacement for fine aggregates, as supplementary cementitious materials (SCMs) in mortar or concrete, and in the production of cement clinker. It was shown in previous research that while tailings had been used as a replacement for both fine aggregate and cement, the workability of mortar or concrete reduced. Also, at a constant water to cement ratio, the compressive strength of concrete increased with the tailings as fine aggregate. However, the compressive strength of concrete decreased as the replacement content of the tailings as SCMs increased, even whentailings were ground into smaller particles. Not much research has been dedicated to the durability of concrete with tailings, but it is beneficial for heavy metals in tailings to stabilize/solidify in concrete. The clinker can be produced by using the tailings, even if the tailings have a low SiO2 content. As a result, the utilization of tailings in cement and concrete will be good for the environment both in the solid waste processing and virgin materials using in the construction industry.


Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4248
Author(s):  
Xingxing Li ◽  
Ying Ma ◽  
Xiaodong Shen ◽  
Ya Zhong ◽  
Yuwei Li

The utilization of coral waste is an economical way of using concrete in coastal and offshore constructions. Coral waste with more than 96% CaCO3 can be ground to fines and combined with supplementary cementitious materials (SCMs) such as fly ash, silica fume, granulated blast furnace slag in replacing Portland cement to promote the properties of cement concrete. The effects of coral sand powder (CSP) compared to limestone powder (LSP) blended with SCMs on hydration and microstructure of mortar were investigated. The result shows CSP has higher activity than LSP when participating in the chemical reaction. The chemical effect among CSP, SCMs, and ordinary Portland cement (OPC) results in the appearance of the third hydration peak, facilitating the production of carboaluminate. CSP-SCMs mortar has smaller interconnected pores on account of the porous character of CSP as well as the filler and chemical effect. The dilution effect of CSP leads to the reduction of compressive strength of OPC-CSP and OPC-CSP-SCMs mortars. The synergic effects of CSP with slag and silica fume facilitate the development of compressive strength and lead to a compacted isolation and transfer zone (ITZ) in mortar.


2015 ◽  
Vol 52 (11) ◽  
pp. 1699-1713 ◽  
Author(s):  
G.H. Cai ◽  
Y.J. Du ◽  
S.Y. Liu ◽  
D.N. Singh

Soil electrical resistivity has been used quite extensively for assessing mechanical properties of chemically treated soils in the recent past. One of the most innovative applications of this technique could be in the field of ground improvement wherein carbonated reactive magnesia (MgO) is employed for treating soils. With this in view, a systematic study that targets the application of electrical resistivity to correlate physical and strength characteristics of the carbonated reactive MgO-admixed silty soil is initiated, and its details are presented in this manuscript. To achieve this, reactive MgO-admixed soils were carbonized by exposing them to CO2 for different durations, and subsequently their electrical resistivity and unconfined compressive strength were measured. In this context, the role of a parameter, the ratio of the initial water content of the virgin soil to reactive MgO content (designated as w0/c), has been highlighted. It has also been demonstrated that w0/c is able to correlate, uniquely and precisely, with the physicochemical parameters of the soils (viz., unit weight, water content at failure, porosity, degree of saturation, and soil pH), electrical resistivity, and unconfined compressive strength at various carbonation times. In addition, microstructural properties have been obtained from the X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry analyses. These properties have been used to substantiate the findings related to the carbonation of the reactive MgO-admixed soils.


Author(s):  
Olusola Emmanuel Babalola ◽  
Paul O. Awoyera

Supplementary cementitious materials are most needed to enhance a sustainable development in poor communities. It is pertinent to investigate the suitability of such alternative materials for construction. The present study evaluates the strength characteristics of concrete made with varied proportion of Cordia millenii ash blended with Portland cement. Chemical composition of Cordia millenii and the setting time when blended with cement was determined. Other laboratory tests performed on Cordia millenii blended cement include: sieve analysis and specific gravity. Five replacement percentages of Cordia millenii (5%, 10%, 15%, and 20%) were blended with cement in concrete. Control specimens were also produced with only cement. Tests to determine the workability, air entrained, bulk density and compressive strength properties of the concrete were also conducted. Results obtained revealed that optimum Cordia millenii mix is 10%, which yielded the highest density and compressive strength in the concrete.


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