Papers by Keyword: Unconfined Compressive Strength

Abstract: This research explores the feasibility of incorporating dust stone into cement gravel columns to enhance their mechanical properties and sustainability profile. A series of laboratory experiments including unconfined compressive strength (UCS) and permeability tests were carried out. 15 mixture designs were prepared to investigate the effect of stone dust (5-20% of cement and 0, 5, 10, 15, and 20% by weight of highest porous sample) on volume fractions of CG samples on engineering and physical properties of cemented gravel samples, at 7 and 28 days. The findings indicate that the ideal proportion of stone dust is 10%, which significantly enhances the compressibility of the CG mixture while preserving satisfactory permeability. The finding indicates that stone dust is a feasible and efficient additive for improving the performance of cement gravel columns in civil engineering applications. Moreover, stone dust provides sustainability advantages by minimizing waste production and contributing to a circular economy.

Abstract: Bottom ash (BTA), a by-product of coal combustion in electric power plants, is commonly regarded as waste, presenting challenges in its management. Conversely, laterite, typically used in road construction, has become increasingly expensive due to its high quality. This study aims to investigate the mechanical properties of laterite replaced with BTA and cement. The replacement of BTA ranged from 10% to 50% of the dry weight of laterite, with cement contents of 1% and 3% of the dry weight of the laterite-BTA mixture. Experimental tests, including unconfined compressive strength (USC) and splitting tensile strength (STS), were conducted. The results indicate that replacing laterite with BTA and cement enhances strength by 2 to 8 times that of unstabilized laterite, with 20% BTA replacement yielding the highest strengths. This approach not only provides cost-effective road construction materials but also contributes to sustainable practices by conserving natural resources and reducing pollution.

Abstract: This study presents the use of Basic Oxygen Furnace slag (BOFS) as a stabilizer for disilicated waste foundry (DWF) sand and therefore provides an opportunity for high-volume use of waste material for low-cost, low-volume building and construction material. DWF was stabilized with BOFS to 40 %. The effect of composite moisture content, BOFS content, curing time and curing temperature was studied. A 50:50 DWF: BOFS composite cured at 80 °C for 96 h had the highest unconfined compressive strength (UCS) of 7.83 MPa, a 15.5 % water absorption after a 24 h soak with a corresponding 20.5 % reduction in UCS. The green specimen (70:30) was then used to stabilize expansive soil. The formation of hydration products was responsible for the strength gain in the stabilized DWF specimens. It was concluded that BOFS was successful in stabilizing DFS. The stabilised DWF for ASTM C34-13, C129-14a and South African standards (SANS227: 2007).

Abstract: With the rapid development of ferrous metallurgy, the production of iron tailings as waste after beneficiation is increasing. Due to the shortage of natural stone in road construction, iron tailings can be used as an alternative material to natural stone in semi-rigid bases. In order to study the feasibility of application of cement stabilized iron tailings (CSIT) in semi-rigid base, unconfined compressive strength (UCS), indirect tensile strength (ITS) and cyclic freeze-thaw tests were carried out on cement stabilized iron tailings (CSIT). The gradation composition and cement content were selected as influencing factors. The results show that under the condition of the same cement content, the UCS and ITS of CSIT are proportional to the particle size in the mixture. In CSIT with the same gradation, the mechanical properties increase with the increase of cement content; CSM-40(B) has a higher UCS and CSM-40(C) has a higher ITS, the frost resistance coefficient of CSIT increases with the increase of cement content and the tendency of frost resistance coefficient decreases with the increase of cement content. The frost resistanceofCSM-40 (B) is better than that of CSM-40 (C) for the same cement content. Therefore, for the use of iron tailings in CSM, a suitable gradation composition and cement content should be selected.

Abstract: Through a series of experimental studies on the unconfined compressive strength, indirect tensile strength (ITS) and freeze-thaw stability of cylindrical specimens, the feasibility of cement-stabilized iron tailings for semi-rigid bases in road construction is determined.Three variables, including the genesis of the materials from which cement stabilized macadam (CSM) are composed, the granulometric composition of the mineral part and the content of cement, were taken as influencing factors. The experimental study shows that with the increase of cement content, the unconfined compressive strength (UCS) , indirect tensile strength (ITS) and frost resistance all increase. Studies have shown that the content of coarse aggregate affects the strength properties and frost resistance of cement-stabilized macadam materials.

Abstract: Steelmaking industry generates a large volume of by-products that not always can be reintroduced into production processes, such as the steelmaking process itself or the production of cement. This is the case of ladle furnace slag (LFS), whose potential use is limited and usually ends up in landfill. This work investigates the feasibility of using LFS as binder for clayey soils stabilization in substitution of lime. The main parameters evaluated are plasticity index, California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS). The results show that the strength behavior of the mixtures is remarkable, obtaining increases in the CBR index between 8-14 times above unmodified clays. The mechanical performance base on UCS results show improvements of 85 % relative to natural soils three days after mixing. Moreover, if the curing time is up to 90 days, the UCS doubles or triples its value. Depending on the chemical composition of the soils, the performances of the mixtures are different, but in all cases the results are positive and encourage further research for the incorporation of ladle furnace slag as stabilizing agent.

Abstract: The worldwide supply constraints and the anticipated high demand for sodium silicate as well as environmental issues associated with the use of sodium silicate has given dawn to the need to opt for alternative activating solutions such as alkali-hydroxides. The current study mainly focuses on the evaluation of mechanical and chemical properties of Granulated Blast Furnace Slag (GGBFS) Binder-Spend Foundry Sand (SFS) based material toward the development of a durable material for building applications. Activated GGBFS was synthesized using a NaOH solution as the sole GGBFS activator. Uniaxial compressive strength (UCS) tests were conducted on the GGBFS-SFS based specimens to investigate the influence of varying amount of GGBFS binder (15 %- 45 %) cured at 80°C. Results showed that the specimen consisting of 45% GGBFS and 55% SFS at a solid to liquid of 0.17 yielded the high UCS equivalent to 11.07MPa. Increase in UCS has been attributed to the presence of calcium silicate hydrate phase confirmed by XRD analysis. In conclusion, GGBFS-based binder waste foundry-based material sand can be considered as a promising and efficacious building material as per ASTM C34-13, C129-14a and South African standard (SANS227: 2007).

Abstract: High content of organic matter and fibre within peat results in a high degree of porosity; causing peat to have low bearing capacity. This study focuses on the application of nylon fibre as reinforcing material with fly ash as the chemical stabilizer to enhance the strength of the peat. The standard proctor tests were conducted to obtain the optimum moisture content (OMC) for all samples in which these OMC is then used for sample preparation of both the Unconfined Compressive Strength (UCS) tests and the California Bearing Ratio (CBR) tests. Samples for this study were categorized into control samples and modified samples for comparison purposes. Additives that were being used in this study are 5% cement, 5% nylon fibre and 10%, 15%, and 20% fly ash. For UCS test, the samples were cured for 7, 14, 28 and 56 days, whereas only 7 days of curing for CBR test. Throughout the study, improvements of strength were observed where sample added with 5% cement, 5% nylon fibre and 10% fly ash recorded the highest compressive strength value, of 123.71 kN/m2. As for CBR test, all samples exceeded the minimum requirement of 12% CBR value for subgrade design recommended by JKR Malaysia with the highest CBR value obtained from samples added with 5% cement and 10% fly ash. The CBR values were 43.85% and 43.70% for unsoaked and soaked condition, respectively.

Abstract: This research investigated the compressive strength of cemented soils admixed with saturated granular activated carbon (GAC). The saturated GAC was obtained from the water filtration system. A series of unconfined compressive strength was performed on both compacted soil-cement specimens and compacted soil-GAC-cement specimens with GAC content of 30 percent. All specimens were prepared by compaction with energy equivalent to the modified Proctor test. The results from modified Proctor tests showed that the maximum dry unit weight and the optimum moisture content of soil-GAC sample was less than those of soil sample. From the unconfined compression tests, there was tiny development of strength for both types of specimens with cement content of 1 percent throughout the curing period of 28 days. For both types of specimens with cement content of 2 and 3 percent, the significant development of strength occurred after curing for 3 days. The strength of specimens typically increased with increasing cement content. Generally, the strength of compacted soil-GAC-cement specimens was less than that of compacted soil- cement specimens. It was also observed that the relationships between normalized compressive strength ratio and curing period was unique for the specimens with the same cement content.

Abstract: Enzyme induced calcite precipitation (EICP) or biocementation has rapidly evolved in the last decade as an environmentally friendly ground improvement technique. In EICP, plant-derived urease enzyme is used to trigger the hydrolysis of urea in the presence of calcium ions to produce calcium carbonate (CaCO₃) precipitate within the soil matrix. Despite the advancement in soil improvement technology via biocementation, there are still concerns about the fate of the ammonium produced as one of the by-products. Therefore, this study performed an experimental investigation to ascertain that using palm oil fuel ash (POFA) might reduce the amount of ammonia produced as a result of biocementation. The soil was mixed with POFA at different percentages (1, 2, 3, 4 and 5%) by dry weight of the soil. The effectiveness of the treatment process was evaluated by conducting the unconfined compressive strength (UCS) and the ammonium removal efficiency. Results show that the strength and ammonium removal efficiency of the biocemented soil decreased and increased, respectively, with an increase in the percentage of POFA. The highest UCS of 161 kPa was obtained at 3% POFA content, while the lowest concentration of ammonium of 0.71 mg/L was at 5% POFA content.