Accumulated Loss Of Mass Research Articles

Stabilization of waste foundry sand with alkali-activated binder: Mechanical behavior, microstructure and leaching

This study evaluates the stabilization of waste foundry sand (WFS) using an alkali-activated binder (AAB) produced from rice husk ash, hydrated eggshell lime, and sodium hydroxide. Mechanical properties, leaching behavior, and microstructure were assessed. The material’s durability was investigated, and the impact of wetting-drying cycles on mechanical strength and metal leaching was analyzed. The stabilized WFS fulfilled the requirements for unconfined compressive strength (qu) and accumulated loss of mass (ALM), making it suitable for use in pavement layers. Wetting-drying cycles did not significantly affect strength, and leached metal concentrations remained below toxic limits.

Life cycle assessment of soil stabilization using cement and waste additives

Environmental measures show that the effect of global temperature rise goes beyond the natural cycle of the Earth’s environmental system, which affects the social, economical, and health conditions of humanity. In this respect, initially, the UN’s sustainable development goals were adopted where, more recently, a UN net-zero coalition was formed to cut greenhouse gas emissions to as close to zero as possible by 2050 to resist foreseen catastrophic outcomes. As a result of these overwhelming goals and regulations, many nations are setting policies to achieve those targets. Nevertheless, such targets, to the best of our knowledge, have not penetrated well into construction applications. In this study, in addition to the mechanical responses of three different waste additives (bottom ash, marble dust and tire rubber powder to replace cement to stabilize problematic soils, a life-cycle assessment was performed to evaluate environmental impacts. Furthermore, a novel impact-performance approach has been introduced to satisfy safety, performance, and sustainability criteria. In this respect, unconfined compressive strength (UCS), initial stiffness (G0), accumulated loss of mass (ALM) due to wet-dry cycles, and life-cycle analysis (LCA) were performed on artificially cemented (7%, 10%, and 13%) clay specimens, compacted at 1600 and 1800 kg/m3 and cured for 28 days. Further, bottom ash (BA) (10% and 20%), marble dust (MD) (20% and 40%), and tire rubber powder (TRP) (2.5%, 5%, 10%, and 20%) were used to replace the cement, which is known for its great environmental impact. It is reported in this study that 2.5% TRP replacement of cement at low density seems to be the optimum dosage and additive, among others, to provide the best performance (UCS, G0, and ALM). Furthermore, the increase in cement content and density results in a positive contribution to performance indicators and a negative contribution to environmental impact. However, when impact-performance is considered, the opposite was observed, i.e., the rise in cement content, additive content, and density results in favourable contributions.

Using Waste PET Shreds for Soil Stabilization: Efficiency and Durability Assessment

Encountering weak fine-grained soil presents a significant challenge during highway construction. The conventional approach to address this challenge involves incorporating calcium-based stabilizers, particularly cement, for stabilization. However, despite its widespread use, the application of cement for soil stabilization has adverse environmental consequences. Accordingly, finding alternative methods to minimize cement usage has become a prominent area of research, from researchers worldwide. This study evaluates the effectiveness of utilizing discarded polyethylene terephthalate (PET) bottle shreds as soil reinforcement alongside lower cement contents. To this end, soil samples were mixed with varied contents of two grades of shredded PET. The ground PET pellets, which displayed diverse shapes, demonstrated properties resembling fibres. Compacted samples were subjected to CBR to determine optimum PET content. Strength, small-strain stiffness and durability of soils in original state, mixed with cement and PET were measured by a programme of CBR, wetting–drying cycles, and ultrasonic pulse experiments. Findings suggest a 28–91% increase in strength of soil upon its mixing with cement—PET shreds. Substituting cement with cement—PET shred led to a drop in accumulated loss of mass (ALM). In twelve cycles of wetting and drying, the small-strain stiffness initially decreased, but then stabilized at approximately the same value in the subsequent cycles. The porosity to binder ratio was adopted as an index for CBR, ALM and the maximum shear modulus. The latter was finally proposed as a measure for durability.

Mechanical and environmental behavior of waste foundry sand stabilized with alkali-activated sugar cane bagasse ash-eggshell lime binder

This study evaluated the stabilization of waste foundry sand (WFS) with an alkali-activated binder (AAB) produced from sugar cane bagasse ash, hydrated eggshell lime, and sodium hydroxide. WFS-Portland cement (PC) mixtures entailed a control group. Strength, stiffness, accumulated loss of mass (ALM), microstructure, and leaching of metals were evaluated. WFS-AAB showed mechanical results similar or superior to WFS-PC, reaching 9.8 MPa after 28 days at 40 °C. Specimens with higher strengths showed higher initial stiffness, ALM around 7 %, and more homogeneous and compact matrices. N-ASH gel were identified in WFS-AAB. WFS-AAB mixtures encapsulated Cd, Cr, Mn, Pb, and Zn from wastes.

Low plasticity clay stabilized with cement and zeolite: An experimental and environmental impact study

To mitigate environmental issues caused by conventional binders and gain superior geotechnical properties, pozzolanic materials can be considered for soil stabilization purposes. Herein, the effectiveness of zeolite for enhanced treatment of cement-stabilized clay was studied by measuring pH, maximum dry unit weight (MDUW), optimum moisture content (OMC), unconfined compressive strength (UCS), and accumulated loss of mass (ALM), as well as carrying out scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. Then, the life cycle assessment (LCA) analyses were conducted to evaluate the potential environmental impacts of cement and zeolite production and their use as stabilizing agents in clayey soil. The soil was stabilized by 2, 4, 6, and 8% cement contents and 0, 15, 30, 45 and 60% cement replacements with zeolite. Furthermore, 56-day curing time was considered to assure accomplishment of hydration and pozzolanic reactions. Besides, samples were exposed to up to 8 wetting-drying cycles to evaluate durability-based parameters. The environmental impacts of the combination of cement, zeolite, and clay for constructing a one-kilometer pavement subgrade in terms of greenhouse gas (GHG) emissions and energy consumption in production, transportation, and execution were studied using LCA. Finally, Al2O3, SiO2, and CaO components were discussed to react with one another and to participate in the chemical reactions as the active composition (AC). UCS results indicated that up to 15% cement content replacement with zeolite, strength increased whereas it reduced thereafter. UCS and ALM were observed to decrease and increase during wetting-drying cycles, respectively. The efficacy of optimum zeolite percentage was more noticeable in higher cement percentages, both in terms of mechanical and durability tests. LCA confirmed that the efficiency of energy consumption and GHG emissions reduced with increasing zeolite. Also, for the samples containing zeolite and cement, the porosity parameter (n)/AC was nominated as a key controlling parameter for determining the UCS, ALM, consumed energy, and the produced CO2. Regarding the experimental program and LCA, the use of zeolite instead of cement is highly recommended both in terms of moisture changes, mechanical properties and environmental aspects.

Lime–Ground Glass–Sodium Hydroxide as an Enhanced Sustainable Binder Stabilizing Silica Sand

Ordinary portland cement (OPC) has been extensively used for decades to improve the engineering properties of a variety of soils. However, the environmental issues related to the production of OPC have created an urgent need to develop and use alternative binders such as alkali-activated cements (AAC). Thus, this work assesses the mechanical performance of a sandy soil amended with an AAC composed of ground waste glass (GWG), carbide lime (CL), and sodium hydroxide (NaOH). The effect of key factors, such as the presence of a NaOH solution, the dry unit weight, and the amount of binder were evaluated on the unconfined compressive strength (qu), initial shear modulus (G0), and accumulated loss of mass (ALM) of compacted sand-binder specimens cured for 7 days. When analyzing the curves that correlated the mechanical behavior of the blends (qu, G0, and ALM) with the η/Biv index, the results show that the alkaline solution has a significant positive influence on the mechanical response of the tested specimens. The improved mechanical performance of the alkali-activated treatments was associated with the formation of a blend of C─ S─ H and (C,N)─ S─ H cementitious compounds coexisting in the same cementitious matrix (alkaline hybrid cement), of heterogeneous structure and composition, and characterized by developing in greater quantity than those produced from a pozzolanic reaction.

Strength, durability, and microstructure of geopolymers based on recycled-glass powder waste and dolomitic lime for soil stabilization

Glass waste in soil stabilization is a promising use as a precursor of forming geopolymers and avoid its discard in landfills as well as decreasing the consumption of traditional binders like lime and cement. Thus, the impact of low, intermediate, and high contents of recycled-glass powder (GP) waste on soil behavior was evaluated by determining the unconfined compressive strength (qu), splitting tensile strength (qt), and durability against wetting/drying cycles (W-D) for the long-term. GP contents were defined as 5%, 15%, and 30% by weight, and a fixed percentage of 5% for lime was selected to ensure the pozzolanic activity of blends based on the pH criterion of optimum lime content. The results indicated improvement in the microstructure and the mechanical properties (qu and qt) of soil-GP-dolomitic lime compacted blends with increasing GP contents, as well as decreases in the accumulated loss of mass (ALM). All of these results were dependent on a novel index given by the ratio of the porosity η to the sum of the percentages of GP and lime in volumetric terms (volumetric binder content Biv), or η/Biv. None of the blends may be used for subbase applications after 7 days of curing time, but all of them are suitable for engineering earthworks after 90 days of curing time.

Suitability of fly ash and cement for fabrication of compressed stabilized earth blocks

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.

Evaluation of the long-term performance of stabilized sandy soil using binary mixtures: A micro- and macro-level approach

The growing trend towards cement production for civil engineering applications has caused many environmental concerns, which can be addressed by the partial or total replacement of cement in civil construction projects. In the current study, the effect of partial cement replacement with zeolite (Z) on the behavior of poor-graded sandy soil was evaluated by means of a series of unconfined compression, durability (wetting-drying cycles), and undrained triaxial (CU) tests, as well as SEM and XRD analyses, and considering curing times ranging from 3 to 90 days. Based on the results, the incorporation of zeolite up to 30% cement replacement in the cemented sand increased the unconfined compressive strength (UCS) and reduced the accumulated loss of mass (ALM), and, hence, enhanced the strength and durability. However, the higher adoption of zeolite decreased the UCS and durability. Therefore, 30% of zeolite replacement was the optimum state. Moreover, the key parameter of active composition (AC) was successfully employed to estimate the UCS and ALM through a power relationship. The triaxial test results proved that the addition of zeolite led to an increase in the peak and residual shear strengths (qmax and qres) and axial strains at qmax (ϵf), and improved the ductility of the samples by reducing the brittle index (IB). It also enhanced the other properties, including stiffness (E50), friction angle (ϕ), and cohesion (C). Ultimately, the SEM and XRD analyses confirmed that the inclusion of zeolite in the cemented sand resulted in the formation of more ettringite crystals and calcium silicate hydrate (C–S–H), which led to higher strength. Finally, it was concluded that zeolite could effectively supplant part of the cement in sand stabilization for geotechnical applications.

Ground waste glass–carbide lime as a sustainable binder stabilising three different silica sands

Waste glass is a solid residue usually available near urban centres, where it is discarded after being used as a container for one of several products. Carbide lime (CL) is a by-product of the manufacture of acetylene gas. The present research evaluates the potential of combining these two wastes as a possible hydraulic cement to enhance the behaviour of sands. Pozzolanic reactions occur between silica in its amorphous phases (found in GG) and Ca++(present in CL) in an alkaline environment. The effect of the amount of GG, the CL content and the porosity of the blend on the strength, stiffness and durability of compacted sand–GG–CL mixes is quantified for three distinct sands. An original parameter, termed the porosity/binder index (η/Biv), can be used to normalise the behaviour of the unconfined compressive strength (qu), the shear modulus at small strains (G0) and the accumulated loss of mass (ALM) of the compacted mixes, considering GG + CL as the binder. Results have shown unique normalised tendencies for qu, G0and ALM with η/Bivfor the three studied compacted sand–GG–CL blends, even though each sand has a distinct grain size distribution.

Behaviour of cement-stabilised silty sands subjected to harsh environmental conditions

This work evaluated the effect of three distinct amounts of fines, Portland cement and dry unit weights on the accumulated loss of mass (ALM), maximum shear modulus at small strains (G0) and tensile strength (qt) of stabilised sands subjected to wetting–drying cycles. Tensile strength test results showed that addition of fines to sand stabilised with cement increased its tensile strength, irrespective of the dry unit weight (γd) and cement content in the mixture. Increasing the amount of fines in compacted cement-stabilised silty sand specimens subjected to wetting–drying cycles reduced the ALM and increased the G0 and qt of the mixtures. This may be due to the fact that specimens with larger amounts of fines have more contact points among the particles, which provides better opportunities for the cement to develop more efficient bonds within the soil fabric, thus improving its mechanical performance. An increase in the cement content and γd of the compacted cement-stabilised silty sand specimens reduced their ALM and increased G0 after each one of the 12 wetting–drying cycles. The G0 and qt of cement-stabilised silty sand specimens with fines increased up to the sixth cycle, remaining practically constant after that, when these specimens were subjected to wetting–drying cycles.

Short- and long-term effects of sodium chloride on strength and durability of coal fly ash stabilized with carbide lime

The research presented aims to quantify the influence of the curing period (t), dry unit weight (γd), lime amount (L), and the addition of sodium chloride (NaCl) on the short- and long-term behaviors of coal fly ash – carbide lime blends. Strength and wet–dry durability tests were carried out for differing values of porosity (η), L, and curing time (t) on mixtures that either contained small amounts of NaCl or contained none. Addition of NaCl to the mixtures resulted in significant increase in early strength gain when compared to specimens without NaCl, which demand longer curing periods to reach similar strength values. The addition of NaCl to coal fly ash – carbide lime blends reduced the accumulated loss of mass (ALM) after 12 wet–dry brushing cycles for specimens at early stages of curing (about 50% for 7 days). Equivalence in the unconfined compressive strength (qu) and ALM(after 12 wet–dry cycles) between the specimens with and without NaCl is achieved in the long term. Finally, a variance analysis performed regarding qu and ALM results yielded that the order of importance of the controllable factors changed from t, NaCl addition, γd, and L for strength to γd, t, NaCl addition, and L for ALM(after 12 wet–dry cycles).

The effects of curing time and temperature on stiffness, strength and durability of sand-environment friendly binder blends

Agricultural-industrial wastes, like rice-husk ash (RHA) and carbide lime (CL), have great potential applications in such earthworks as the stabilization of slopes and pavement layers and the spread footings and bed of pipelines, particularly in the regions near where the waste is produced. Present research evaluates the potential use of RHA mixed with CL as a binder, improving strength, stiffness and durability properties of a uniform sand. Two different curing temperatures, 23 °C and 40 °C, and curing periods, 7 and 28 days, of compacted sand-RHA-CL blends (distinct dry unit weights and contents of RHA and CL) were evaluated to determine the importance of these changes on the reactions between the materials. The experimental program aims to assess the following parameters: initial shear modulus (G0), unconfined compressive strength (qu), and accumulated loss of mass (ALM). Studies have been carried out to quantify these parameters as a function of a novel index called porosity/volumetric binder content (η/Biv). The results showed higher values of G0 and qu, as well as a small rate of ALM with reduction of porosity and with rise of the environment friendly binder content. The latter is achieved either by increasing eith the RHA or the CL content. The curing temperature acts as a catalyser, accelerating the pozzolanic reactions between RHA and CL. Longer curing periods also benefit reactions between materials by enhancing their geotechnical properties. An analysis of variance (ANOVA) was carried and the results showed the dry unit weight, RHA content and curing type are significantly effect the strength results. It was also possible to verify that curing for 28 days at 23 °C and for 7 days at 40 °C are statistically equivalent in terms of strength. The G0 results after weathering cycles tended to decrease in specimens at a 40 °C curing temperature and increase in specimens at a 23 °C curing temperature.

Durability, strength, and stiffness of compacted gold tailings – cement mixes

Compaction and Portland cement addition are amongst promising ground improvement procedures for enhancing the mechanical properties of gold tailings. The present investigation intends to compute the impact of Portland cement content and dry density on the properties (durability, stiffness, and strength) of compacted gold tailings – cement mixes. Its main significant addition to knowledge is the quantification of accumulated loss of mass (ALM) after wetting–drying cycles, shear modulus at small strains, and unconfined compressive strength (qu) as a function of the porosity/cement index. In addition, the existence of an exclusive relation connecting ALM divided by the number of wetting–drying cycles and porosity/cement index is revealed empirically. This broadens the applicability of such an index by demonstrating that it controls not only mechanical but also endurance performance of compacted gold tailings – Portland cement mixes.

Sodium chloride as a catalyser for crushed reclaimed asphalt pavement – Fly ash – Carbide lime blends

Abstract Reclaimed asphalt pavement (RAP) is the name given to reused pavement materials comprising asphalt and aggregates. Recycled RAP is almost always returned back into the roadway structure in some form, usually incorporated as a stabilized aggregate in base or subbase construction. To produce a stabilized base or subbase aggregate, RAP must also be crushed and screened, then blended with one or more stabilization reagents so that the blended material, when compacted, will gain strength. The aim of this study is to evaluate the impact of sodium chloride (NaCl) on the compressive strength and the accumulated loss of mass (ALM) after wetting–drying cycles on a mixture of crushed RAP with fly ash (FA) and carbide lime (L) (both industrial residues). Stabilization was carried out considering blends of 75% RAP and 25% FA. The moulding points considered three different dry unit weights [18.5 kN/m3 (maximum dry density at modified energy Proctor) and two below 18.0 kN/m3 and 17.0 kN/m3], optimum mixture content at 9.0% and three different lime percentages (3.0%, 5.0% and 7.0%), as well as a 7-day curing period. The results indicate that adding 1.0% NaCl to the crushed RAP-FA-lime blends almost doubles strength for a 7-day curing period and reduces the ALM by an average of 50% in durability tests.

Compacted clay-industrial wastes blends: Long term performance under extreme freeze-thaw and wet-dry conditions

The use of industrial wastes (coal fly ash and carbide lime) is appropriate procedure to enhance the long-term performance of clays under extreme freeze-thaw and wet-dry conditions. This investigation assesses the impact of lime content (L) and dry unit weight (γd) on the durability and long-term performance of compacted clay-fly ash-carbide lime mixes. It defines the accumulated loss of mass (ALM) after freeze-thaw and wet-dry cycles as a function of the porosity/lime index. Results have shown that compacted clay-fly ash-carbide lime blends under wet-dry cycles presented better performance that when submitted to freeze-thaw cycles. Specimens were statically compacted in 3 stratums to reach required dry unit weights in the interior of cylindrical moulds, stipulating in each case the dry weight of solids to the volume of the specimen moulded. Moulding moisture content (w) of all specimens was 29%. In addition, the existence of mathematical equations connecting accumulated loss of mass divided by the number of freeze-thaw (and wet-dry) cycles and porosity/lime index, as well as with unconfined compressive strength is revealed empirically. This broadens the applicability of such index by demonstrating it controls not only mechanical but also long term performance of compacted clay-industrial wastes mixes.

Durability and strength of fiber-reinforced compacted gold tailings-cement blends

In order to investigate techniques to support mine tailings use as earthwork material, the improvement of mechanical properties of gold tailings through compaction, insertion of fibers and cement is studied. Present investigation intends to assess the impact of Portland cement content and dry density, as well as fiber insertion in the enhancement of durability and strength of compacted gold tailings-cement mixes. This manuscript advances in understanding the parameters that control durability and strength of fiber-reinforced compacted gold tailings-cement blends. Its main significant addition to knowledge is quantifying the accumulated loss of mass (ALM) of fiber-reinforced compacted gold tailings-cement blends after wet/dry cycles and unconfined compressive strength (qu) as a function of the porosity/cement index. In addition, the existence of exclusive relations connecting accumulated loss of mass divided by the number of wetting/drying cycles and porosity/cement index is empirically revealed for the studied materials. This broadens the applicability of such index by demonstrating it controls not only mechanical but also endurance performance of fiber-reinforced compacted gold tailings-Portland cement mixes.