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This Study is focused on suitability of industrial wastes in cement stabilized soil. The investigation is based on Unconfined compressive strength (UCS) tests. Experimental work is carried out to compare the UCS of cement stabilized soil specimens with different proportion of industrial wastes like Iron ore tailing, Quarry dust, Fly ash and Bagasse ash. The mix proportion is designed such that clay content is maintained at 10.5% for fine grained soil and density of 17.5 kN/m³. It is observed that the mix comprising industrial wastes and fiber have improved the mechanical properties compared to cement stabilized soil. Fiber addition has improved post peak behavior of soil specimen. The Scanning Electron Microscopy (SEM) microstructure images depict soil particle flocculation, leading to an increase in compressive strength and Energy Dispersive X-ray Spectroscopy (EDS) studies suggest the use of industrial wastes with natural soil helps in strengthening of soil cement stabilization, as well as to minimize the environmental pollution. [ABSTRACT FROM AUTHOR]

There are many environmental problems caused by factory waste. Sugar factory waste, in the form of bagasse ash, and PLTU factory waste, in the form of fly ash, are currently in the spotlight of science studies. This study used waste bagasse and fly ash to substitute Portland cement as the main ingredients for mortar. Baggash and fly ash waste were collected, processed, and then used to replace cement by up to 40% to determine to what extent they could be used in brick masonry work, wall plastering, and masonry paste. Experimental tests were carried out on mortar cube samples measuring 5×5×5 cm, comparing four types of samples consisting of Portland cement, bagasse ash, and fly ash. The compressive strength results were obtained after 28 days. Normal Mortar (MN=11.75 MPa) had higher compressive strength than the substitute mortar types MA (3.23 MPa), MB (3.09 MPa), and MC (2.98) MPa. According to SNI 6882- 2014, MA, MB, and MC mortars can be used as O-type mortar (2.4 MPa). Therefore, they can be applied to wall plastering or walls not bearing loads. [ABSTRACT FROM AUTHOR]

In recent years, nano-sized graphene oxide (GO) has come to the fore as a promising material for enhancing the mechanical and durability performance of cementitious composites. On the other hand, partial substitution of industrial wastes and by-products into cementitious composites attracts the attention of researchers in order to ensure long-term sustainability. In order to combine these two aspects, the main focus of this study is to examine the effect of 0.05% and 0.1% GO-reinforcement on the slump, 7 and 28-day compressive and flexural strength and 28-day rapid chloride permeability test (RCPT) properties of cementitious composites. In this context, mixtures with three different binder combinations, a control, a silica fume (SF) substitution, and a fly ash (FA) substitution, were designed. The results showed that GO-reinforcement reduced the slump values of the mixtures between 5-15 mm, while the 28-day compressive strengths increased in the range of 9.82%-13.61% with 0.05% GO-reinforcement, and in the range of 17.02%-20.68% with 0.1% GO-reinforcement. The 28-day flexural strength of the mixtures increased by about 10% on average as a result of 0.1% GO-reinforcement. According to the RCPT anaylses, it was observed that the chloride permeability of the mixtures decreased up to 18.85% with 0.1% GO-reinforcement. [ABSTRACT FROM AUTHOR]

The great increase of carbon emission and waste generation has been a major threat to sustainable constructions and buildings. To address this, magnesium oxysulfate cement (MOSC) has recently been introduced as a green and sustainable alternative of Portland cement with lower carbon footprints. This article investigated the binding capability of MOSC with multi-source industrial and forestry wastes by mechanical experiments. 18 samples with waste dosage of 0–70 wt% substituting MgO were prepared and cured for 90d. Multi-source solid wastes improved the flexural strength up to 57.05% and reduced the compressive strength by 3.44% at least. The maximum displacement and absorbed energy before fracture were increased by 63%∼226% and 79%∼274% under flexural loads; the energy absorption capacity under compressive loads reduced by 6.75%∼30%. Six indexes were defined to compare the effects based on both Index Ranking method and Targeted Index Value method. Four samples exhibiting outstanding mechanical strength and low brittleness were found by substituting 40%∼65% mass of MgO. The optimal sample consisting of 20 wt% poplar powder, 20 wt% fly ash, 20 wt% ground slag and 5 wt% bamboo powders as MgO' mass had flexural and compressive strength of 17 MPa and 76 MPa, respectively. Mechanism of wastes' effects on MOSC was discussed by microscopic experiments. The economic and environmental benefits as well as potential application of the optimal composite were discussed. These findings will contribute to the development of more sustainable cement products and improve the utilization of multi-source solid wastes. [Display omitted] • Multi-source industrial and forestry wastes were added into MOSC to prepare new composites. • Flexural strength of MOSC were improved by 57% with outstanding fracture resistance. • Optimal composite containing 65% wastes as MgO' mass had flexural and compressive strength of 17 MPa and 76 MPa. • The cost and benefits of optimal composites were discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chemical compositions of SCM sourced from agricultural waste indicates that they are more pozzolanic than cementitious hence their blends with SCMs sourced from industrial waste provides a sustainable use. • Pozzolanic activities of SCMs provide viable solutions to durability in terms of ASR and chloride sulphate action while cementitious activities exhibit structural performance. • It is shown that ground granular base slag and Pulverised fuel ash reduces the risk of poor compressive strength when used as SCMs by at least 2% and at most 75%. Supplementary cementitious materials (SCM) are alternative to the conventional cement and have been studied by so many authors owing to the high carbon content of cement. The use of SCM is significant in addressing challenges of carbon emission and its impact on the 2050 carbon reduction RoadMap. Available studies shows that SCM obtained from both industrial and agricultural wastes presents significant variability in performance as cement dosage in concrete increases. The first aim of this study is to map and synthesize the available evidence from literatures to support this variability. The second objective is to provide statistical evidence from available literatures of certain SCM that enhance the structural performance of low carbon concrete in terms of compressive strength. From the results, trend of findings from literatures on the use of SCM shows a surge in research for cement replacement occurring over the last decade with optimal performance for industrial waste SCM shown to be limiting at 40% cement replacement while that from agricultural waste occurs at 10% cement replacement. Data were sourced from Scopus database and selected from peer review journals of both primary and secondary studies on cement replacement materials. 728 published articles were obtained from the search using four strings namely,'Recent cement* replacement and cementitious materials", ''Recent supplementary cementitious materials', ''Eco-friendly and cementitious materials" and ''Low carbon intensive cement replacement materials'. Meta-analysis is carried out on the selected articles having quantitative data to synthesise some of the result of the published articles to examine the impact of Ground granular base slag and Pulverized Fuel Ash cement on concrete strength development as cement replacement. It is shown that Ground granular base slag, Pulverized Fuel Ash and Metakaolin improve and enhance the eco friendliness of the concrete. From the results, optimal percentage of cement replacement is a gap which remains unresolved due to mineralogy and reactivity of the SCMs and would provide the solution for the desired green concrete optimization. It is shown with statistical evidence from meta -analysis that ground granular base slag and Pulverised fuel ash decreases the effect of low compressive strength by at least 2% to about 75% which is considered in our opinion as effective to enhance the sustainability of concrete. [ABSTRACT FROM AUTHOR]

• The use of CDP reduced water demand and increased the setting time of paste blends. • CDP improved the early strength of concrete, contributing positively to industrial waste recycling. • Mortar mixtures incorporating up to 50% CDP exhibited comparable 28-day compressive strength to the control mixture. • CDP type and curing procedure have no significant effect on the 28-day strength of concrete. This study evaluated the strength development in hyperalkalized concrete mixtures incorporating cement waste-derived Portlandite (CDP), synthesized from two variants of cement kiln dust (CKD). The source CKDs (coded CKD1 and CKD2) and synthesized CDPs (coded CDP1 and CDP2) were characterized physically and mineralogically, after which the CDPs were used as cement replacement, from 0 to 60 %, in the mortar phase of a base concrete mixture at w/b of 0.5 and 0.425. After in-mold curing, the mortar mixtures were subjected to 12 h of accelerated carbonation curing (ACC), and then moist–cured until 28 days. The strength development and alkalinity of mortar mixtures were investigated using the strength activity factor (SAF) and pH analysis, respectively. The incorporation of more alkaline and fine-grained CKD1 (D50 = 14.74 µm) was found to increase the water demand and setting time of CKD-cement paste blends, compared with the coarse-grained CKD2 (D50 = 27.51 µm). Additionally, the use of CDP reduced water demand but increased the setting time of paste blends. Further, the incorporation of CDP increased the early-age compressive strength of mortar, but its effect diminished as the mixtures matured, with SAF reduction of over 50 % in most cases. Finally, CDP1 mixtures exhibited about 30 % higher early–age compressive strength than CDP2 counterparts but the difference evened out at a later age, with the studied mixtures exhibiting 28-day compressive strengths varying between 23 and 54 MPa. [ABSTRACT FROM AUTHOR]

• Fly ash-cement stabilized CSEBs are assessed in terms of compressive, split tensile, flexural and shear strength. • Inclusion of fly ash is effective to reduce the cement content significantly. • Inclusion of FA ≥ 20% with 5% and 7% cement satisfies the strength requirements. • Fly ash is effective in reducing the accumulated loss of mass. • Life cycle analysis suggest that CSEBs are superior to conventional fired clay bricks. Fly ash is a common industrial waste that requires a proper disposal which otherwise will have a detrimental effect on the environment. As such, utilization of fly ash in producing Compressed Stabilized Earth Blocks (CSEB) can provide suitable means to promote sustainability. Work herein focuses on investigating the performance of CSEBs stabilized with cement and fly ash (FA) as an alternative to traditional construction materials, like Fired Clay Bricks (FCB). Strength characteristics of CSEBs have been evaluated in terms of compressive, split tensile, flexural and shear strength. For durability, accumulated loss of mass due to cyclic drying-wetting test, wet strengths, submersion and efflorescence test have been performed. For this study, 270 CSEBs and 192 cylindrical samples are prepared with 0–10% cement and 0–30% FA (All the percentages are by dry mass of soil taken). Addition of 10–30% FA along with cement increases the compressive strength, flexural strength and split tensile strength by different magnitudes depending on the cement content used. Inclusion of FA ≥ 20% with 5% and 7% cement satisfies the strength criterion suggested by different standards. Moreover, FA was effective in reducing the cement content in the mix without sacrificing the strength. Cyclic drying-wetting test shows that with the increase of the amount of FA with cement, accumulated loss of mass reduces, which is in agreement with the observation of microstructural analyses. Strength retention of the samples after cyclic drying-wetting test ranged within 51–88%, showing the durable performance of cement-FA stabilized earth. Results of triaxial test indicate that FA improves the peak deviatoric stress-strain and failure stress-strain irrespective of cement content and confining stress. With the addition of 0–30% FA with 5% and 7% cement, the cohesion parameter varies within 159–315 kPa, and the angle of internal friction varies within 38.1–57.1°, indicating an improved shear response of cement-FA stabilized mixes. Life Cycle Analysis (LCA) shows that considering energy consumption, Global Warming Potential (GWP) and other environmental impacts, CSEBs are superior to the traditional FCBs. [ABSTRACT FROM AUTHOR]

Modification of a cement matrix using additives and admixtures has been a common practice for many years. The use of some mineral additives as substitutes for the cement, e.g., the siliceous fly ashes (FAs), has a positive effect on reducing the energy used in cement production. On the other hand, such activities may have negative effects due to the lowering of strength parameters of composites in early stages of curing. In order to solve this problem, over the last few years, thanks to the patented "seedings" technology, a branch of industry connected with the production of admixtures that accelerate the binding process has developed significantly. Therefore, the paper presents the results of research aimed at analyzing the parameters of FA cement matrix with the nanoadmixture containing the nanometric C-S-H seeds (nanoadmixture (NA)). By using the modern NA, an attempt was made to neutralize the negative influence of the used industrial waste on the structure of the cement matrix in the early stages of its curing. The paper presents the results of strength tests for the FA cement pastes modified by NA in seven test periods, i.e., after 8, 12, 24 and 72 h, and 7, 14 and 28 days. Additionally, hydration heat tests were carried out on the analyzed material in the first 24 hours of curing. [ABSTRACT FROM AUTHOR]

• Potential of industrial waste fly ash (FA) is studied along with cement for producing earth blocks. • Compressive strength, deformation characteristics, shear behavior, and durability of CSEBs are studied. • Effect of curing time, influence of FA-cement on density and porosity are analyzed. • 6–10% Cement and 20–30% FA provides satisfactory CSEBs in terms of strength and durability. This study is aimed at utilizing industrial waste Fly ash (FA) in combination with cement for production of environment friendly and economically viable Compressed Stabilized Earth Blocks (CSEBs). CSEBs are prepared with four cement contents (4%, 6%, 8% and 10%) and four FA contents (0%, 10%, 20%, 30%) and its performance are assessed in terms of strength and durability. Strength was measured using unconfined compression test, and consolidated undrained (CU) triaxial test; and durability was assessed in terms of water absorption test, wet compressive strength test, and accumulated loss of mass (ALM). Unconfined compression test shows that with the increase of cement, strength of the blocks increases for a definite FA content, however, for a fixed amount of cement, strength increases with addition of certain amount of FA, which is defined as the optimum FA content beyond which strength begins to drop. For 4% and 6% cement, optimum FA content was found 10%, for 8% cement, 20% FA was found to be the optimum content, whereas for 10% cement the optimum FA content is 30%. Deformation characteristics of CSEBs with different cement-FA combinations are analyzed in terms of stress-strain response and modulus of elasticity. Addition of proper amount of FA is found to improve modulus of elasticity, peak and failure strain response for a definite cement content. Moreover, microstructural investigation is carried out to investigate the arrangement of soil matrix for different contents of stabilizers. Optimum content of cement-FA obtained from unconfined compressive strength provide wet-to-dry strength ratio >0.33 which is an indicator of better durability performance. CU triaxial test results show that at a confining stress of 200 kPa and 300 kPa, maximum stress ratio and secant modulus occurs at a mix composition of 8% cement and 20% fly ash, which was considered optimum from compressive strength test scheme. Finally, test results were compared with the specifications of various existing standards and it can be concluded that with addition of optimum amount of cement-FA, CSEBs with acceptable strength and durability response can be produced. [ABSTRACT FROM AUTHOR]

• Fly ash, silica fume, rice husk ash, GGBS and metakaolin were incorporated in mortars. • Cement content was minimized in geopolymer mortars by 80 to 100% by using alkali-activated GGBS. • Compressive strength was improved by activating FA and GGBS with AS of NaOH and Na 2 SiO 3 with AS/ binder ratio = 0.25 in mortars. • The proposed AS of NaOH and Na 2 SiO 3 failed to activate each of silica fume, rice husk ash and metakaolin. Cement industry is one of the industries that contribute to global warming by emitting tons of carbon dioxide. On the other hand, there are lots of industrial wastes that are piling up daily. Therefore, minimizing the use of cement and reducing its negative impact on the environment is our scope. This paper targets to study the effect of alkali-activated pozzolanic materials used as partial or full substitution of cement in mortars cured at ambient temperature. Fly ash, silica fume, rice husk ash, metakaolin, as well as ground granulated blast-furnace slag were incorporated in mortars as cement substitute by ratios varied from 10% to 100% by weight of cement. Alkaline solution of sodium hydroxide and sodium silicate was utilized as activator with activation solution to binder ratio varies from 0.25 to 0.5. Besides, the ratio of sodium silicate to sodium hydroxide was kept 2:1 throughout the study. The results showed the potential of producing high early strength eco-friendly mortars using alkali-activated fly ash and slag as cement substitutions with ratios of 80% and 100% respectively, which is promising for sustainable construction. [ABSTRACT FROM AUTHOR]

• Suitability of CSEB stabilized with cement and fly ash is assessed in terms of strength and durability. • Inclusion of fly ash is effective in reducing the cement content significantly. • Optimum fly ash content is 15% for 5–7% cement content. • Fly ash is effective in reducing water absorption capacity. • Fly ash and cement stabilized CSEBs are more suitable compared to fired clay bricks from economic standpoint. For saving natural resources, reducing pollution and increasing energy efficiency, Compressed Stabilized Earth Block (CSEB) can serve as a suitable alternative to conventional Fired Clay Brick (FCB). In this study, suitability of industrial waste, Fly Ash (FA) is assessed along with cement as stabilizers for producing CSEBs with coarse grained soil. Different combination of cement and FA (5–10% cement and 5–25% FA; by weight of dry soil) was considered to prepare CSEBs for finding the optimum mix composition in terms of strength, durability, deformation characteristics and cost effectiveness. Furthermore, strength and durability test results are compared to the design criteria reported in Indian Standard, Sri Lankan Standard, Standard Australia, British Standard and Malaysian Standard for assessing its viability as construction material. With the increase in cement content, strength of the blocks gradually increases; however, at a definite cement content, addition of FA increases strength up to a certain limit and then begins to drop. Inclusion of 7–8% cement and 15–20% FA is found to provide adequate dry compressive strength (>5 MPa), wet-to-dry compressive strength (>0.33) and enough durability in terms of water absorption (<20%) as recommended by British Standard and Standards Australia. The behavior of the CSEBs were also analyzed through microstructural investigation, where SEM images were taken to ascertain the morphologic and anatomic changes that occurred at different fly ash contents. At a definite cement content, with the increase of FA, peak strain and failure strain increase; thereby indicating an improved straining capacity of the blocks due to inclusion of FA. Moreover, modulus of elasticity improves with increasing amount of cement and FA for both dry and wet state. Furthermore, economic analysis of a typical house constructed with CSEBs and FCBs was performed and compared with literature. Considering all the parameters it can be concluded that CSEBs prepared with cement and fly ash as stabilizers can be used as a sustainable construction material. [ABSTRACT FROM AUTHOR]

• Alkali-activated fly ash cements incorporating soda residue were prepared by compaction. • Compressive strength and water absorption were investigated. • Microscale characteristics of alkali-activated cements at 90d were probed through SEM-EDS, XRD and FTIR. Alkali-activated material, a new eco-friendly alternative to conventional cement binders, has been produced using alumino-silicate material and alkaline activator. Those alumino-silicate material can be formulated by adding natural minerals, waste and /or industrial by-products. This study investigates the mechanical and microstructural properties of alkali-activated cement synthesized from fly ash and soda residue activated by NaOH. The mineralogy phases, microstructure and product compositions were characterized by SEM-EDS, XRD and FTIR. The study reveals that product gels are identified as the coexistence of hydration and polymerization gels containing Ca and Na, which show glassy microstructures in X-ray patterns. The results provide experimental basis for the scientific utilization of SR to an industrial scale. [ABSTRACT FROM AUTHOR]