Compressive Strength Test Results Research Articles

Nanosilica Revolution: Unveiling the Impact on Enhancing Performance in Oil and Gas Well Cement

Summary In recent times, numerous oil and gas wells have experienced diverse failures ranging from downhole plug malfunctions to compromised wellbore integrity, resulting in damage to aquifers, loss of assets, and posing significant economic and environmental hazards. The inclusion of nanosilica into oil and gas well cement emerges as a promising solution, demonstrating a positive influence on enhancing mechanical properties, such as compressive strength and durability. This study investigates the impact of nanosilica on the mechanical properties of Class G Portland cement slurry, aiming to enhance its application in the oil and gas industry. The influence of nanosilica on the cement compressive strength behavior of oilwell cementing systems directly set and cured under the condition of 110°C and 2,000 psi is studied. Test results indicate that the cement slurries containing 3% nanosilica experienced compressive strength enhancement by 40% compared with the base sample after 24 hours. The compressive strength test results are corroborated by further evidence from a permeability test as well as microstructure analysis of the set cement. The thermal stability of the set cement samples using thermogravimetry analysis (TGA) concludes that the sample containing 3% nanosilica has the lowest mass loss. Future research should focus on long-term durability studies and comprehensive mechanical property assessments to further validate the benefits of these nanomaterials in real-world conditions.

Sustainable Stabilization of Brown and Green Clays Using Industrial By-products

Background The disposal of industrial by-products and the rising cost of construction materials are critical issues globally, particularly in developing nations such as Jordan. Brown and green clay are considered problematic types of soft clay, as they fail to meet the necessary specifications for use in construction. Objective This study aims to assess the efficiency of Cement Kiln Dust (CKD) and Silica Fume (S.F.) as stabilizing agents for brown and green clays. The research explores how CKD and S.F. can be used as cost-efficient and eco-friendly alternatives to enhance the mechanical properties of soft clays, improving their viability for construction. Methods An experimental approach was used to investigate the impact of CKD and S.F. on brown and green clay stabilization. The study examines the effect of varying CKD and S.F. concentrations on the clays' plasticity, compaction, unconfined compressive strength, and consolidation properties. CKD was tested at four different levels (0%, 5%, 10%, and 15%), as was S.F. (0%, 5%, 10%, and 15%). Results The findings revealed a notable enhancement in the engineering properties and behavior of both brown and green clay, with reductions observed in the plasticity index (P.I.), compression index (Cc), compressive strength (qc), and maximum dry density (γd). Conclusion Adding 15% CKD to brown clay resulted in the most significant improvements after a curing period of 7 days based on the unconfined compressive strength test results.

Study on the leaching behavior of cemented paste backfill containing arsenic trioxide roaster waste

After decades of mining at Giant Mine in Yellowknife, Northwest Territories, a significant amount of arsenic trioxide roaster waste (ATRW), containing around 60% arsenic, was stored underground, posing serious health hazards. This study explored solidification and stabilization of ATRW through its incorporation into cemented paste backfill (CPB). It evaluated the stability of arsenic-bearing compounds and the mechanisms of arsenic trioxide stabilization within CPB. Based on the results of unconfined compressive strength (UCS) tests on CPB samples, certain samples were selected for monolithic tank leaching tests (TLT) and a range of microstructural analyses, including thermogravimetry, X-ray absorption spectroscopy, Fourier-transform infrared spectroscopy, and computed tomography. These tests aimed to examine the leaching behavior of arsenic and the microstructure of the selected CPB samples, and to investigate the relationship between their strength, leaching behavior, and pore characteristics. Findings indicated significant arsenic release from CPB surfaces. Up to 41% of arsenic was leached from the CPB samples, and the leaching of arsenic, calcium, and sulfate showed no signs of stabilizing, suggesting potential long-term leaching risks. The pH levels ranged between 9.2 and 10.0, with the dissolution of ATRW contributing to a decrease in pH. This lower pH inhibited the formation of portlandite, while calcium-silicate-hydrate (C-S-H) gels were identified as the primary hydration product, albeit in limited quantities. Thermogravimetric analysis showed weight losses primarily due to calcite decomposition, while X-ray absorption spectroscopy revealed arsenic was present predominantly in its + 3 oxidation state, with no significant As-Ca bonding observed in high-strength samples. CT scans highlighted a relationship between higher strength and larger pore volumes. The study concluded that while ATRW incorporation in CPB can provide mechanical stability, modifications are necessary to reduce arsenic solubility and mitigate environmental risks.

Enhancing concrete pavement performance using refuse derived fuel fly ash as a sustainable cementitious material

ABSTRACT The utilization of waste materials in concrete is becoming increasingly important for sustainability in construction. This research investigated the mechanical performance and environmental safety of concretes containing Refuse Derived Fuel fly ash (RDF FA), a waste product from waste incineration plants. The innovative mix design strategically used RDF FA as both cement replacement and cementitious addition in concrete. Compressive and flexural strength test results showed that RDF FA addition increased both compressive and flexural strengths, while RDF FA replacement decreased strengths (< 28 days cured) compared to those of traditional cement concrete. Microstructural and mineralogical analyses revealed dense C–S-H formation in RDF FA added samples, indicating improved hydration. In contrast, RDF FA replacement reduced cementitious products and hindered hydration. RDF FA’s high SiO2 content and favourable SiO2/CaO ratio enhanced pozzolanic reaction in RDF FA added samples, further improving strength development. Leaching test results demonstrated that heavy metal concentrations in RDF FA-modified concretes remained within environmental protection limits. Thus, with proper mix design, RDF FA has the potential to be a sustainable supplement for concrete, reducing industrial waste and natural resource use. This work provides an approach to balance enhanced concrete performance with environmental safety when using RDF FA.

Experimental Study on Optimization of Consolidation Parameters of Silty Clay Based on Response Surface Methodology: A Case Study on the Protection and Restoration of the Ming and Qing Dynasty Hangzhou Seawall Site

The preservation of the ancient seawall site is a focal point and challenge in the protection of historical relics along Hangzhou’s Grand Canal in China. This endeavor holds significant historical and contemporary value in uncovering and perpetuating Hangzhou’s cultural heritage. Researchers investigating the Linping section of the seawall site aimed to address soil site deterioration by selecting environmentally friendly alkali-activated slag cementitious materials and applying the response surface method (RSM) to conduct solidification experiments on the seawall soil. Researchers used the results of unconfined compressive strength tests and microscopic electron microscopy analysis, considering the comprehensive performance of soil solidification mechanisms and mechanical properties, to establish a least-squares regression fitting model to optimize the solidification material process parameters. The experimental results indicate that the optimal mass ratio of lime, gypsum, and slag for achieving the best solidification process parameters for the seawall soil, with a 28-day curing period, is 1:1.9:6.2. This ratio was subsequently applied to the restoration and reconstruction of the seawall site, with parts of the restored seawall exhibited in a museum to promote the sustainable conservation of urban cultural heritage. This study provides theoretical support and practical guidance for the protection and restoration of soil sites.

CHARACTERISTICS OF FLY ASH-BASED GEOPOLYMER MORTAR WITH VARIATION OF TYPES AND DOSAGES OF ADMIXTURE AND CURING SYSTEMS

Geopolymer concrete is the concrete of the future because, in its manufacture, it does not cause environmental problems; instead, it can prevent air pollution and environmental pollution. Geopolymer concrete has several advantages: suitable mechanical properties, high early strength, stable heat, and fire resistance. In the mixture, fly ash, a silicate and aluminum source, is reacted with an alkaline solution as an activator to make a polymerization reaction. To carry out the polymerization reaction, it is necessary to use Sodium Hydroxide or NaOH, which has strong basic properties as an alkaline reactant, and sodium silicate or Na2SiO3 as a catalyst.This study aims to determine the effect of using admixture on the compressive strength of 50x50x50 mm geopolymer mortar cubes. This study's ratio of the alkaline solution was 1/1, while the balance between fly ash/solution was 60/40. Planning a mixture of mortar composition, namely fine aggregate/paste of 65/35. The admixture used is Sikament LN and Sika Viscocrete 1050 HE with a curing system that is humid temperature and at room temperature. Sikament LN content is 0,3%, 1%, 1,5%, and 2% by weight of fly ash, while the Sika Viscocrete 1050 HE content is 0,8%, 1%, 1,5% and 2% by weight of fly ash. Mortar compressive strength test was carried out at 7 days, 14 days, and 28 days.In this study, the optimum grade for each use of admixture in geopolymer mortar was Sikament LN 0,3% and Sika Viscocrete 1050 HE 0,8% at humid temperature curing, which produced the highest compressive strength of 37,65 MPa and 21,26 MPa at 28 days of age. Increasing the percentage level of the amount of admixture used decreases the results of the mortar compressive strength test. The curing system shows that the mortar with the humid temperature curing system produces a higher compressive strength compared to the room temperature curing system. Keywords: Geopolymer, Fly ash, Admixture, Curing System

PENGARUH PEMANFAATAN AIR KELAPA SEBAGAI BAHAN SUBSTITUSI CAMPURAN BETON PRACETAK METODE SELF COMPACTING CONCRETE (SCC)

Concrete mixtures are usually made with drinking water or pure water. However, if we are in a difficult condition to get clean water, we must try to use additional materials or waste around us. This is also a difficulty in the construction industry; one of the challenges is how to develop new ideas, such as high-quality and durable concrete (sustainability), from existing materials, such as coconut water. The data collection strategy for this study is laboratory-based. Given that the variables studied in this study include the composition of coconut water used to determine the quality of the concrete mixture, its compressive strength, and its comparison with ordinary water. The compressive strength of self-compacting concrete (SCC) made with 100% coconut water varies. The average compressive strength of SCC concrete with 100% coconut water is 41 kg/cm2 after 3 days, 88.67 kg/cm2 after 7 days, 242.67 kg/cm2 after 14 days, and 364 kg/cm2 after 21 and 28 days. 550.67 kg/cm2. The results of the normal compressive strength test showed growth; the average compressive strength was 284 kg/cm2 at 3 days, 511 kg/cm2 at 7 days, and 1386 kg/cm2 at 14 days. 21 days = 2226; 28 days equals 3098.67.

Pemanfaatan Abu Cangkang Kopi Sebagai Substitusi Semen Untuk Bahan Beton Ringan Menggunakan Bahan Tambah Sikament NN

The chemical reaction of cement and water produces compounds that are alkaline and react with various acids so that they can reduce the quality of concrete. To minimize this effect, pozzolanic materials need to be added. Organic pozzolan materials such as coffee shell ash waste can be used as material for making lightweight foam concrete which can be applied to non-structural buildings such as lightweight bricks. This research was conducted to see the effect of coffee shell ash substitution for cement on the properties of fresh concrete and the mechanical properties of lightweight foam concrete and to find the most optimal substitution composition for coffee shell ash for cement as well as lightweight foam concrete with FAS 0.5. Substitution of coffee shell ash for cement weight was carried out with variations of 0% BBN, 5% BBAAK1, 10% BBAAK2, and 15% BBAAK3 using 1% superplasticizer additive. The test object used is a cylinder with dimensions of 15 cm x 30 cm. The number of test objects used was 24 pieces. Tests for compressive strength and split tensile strength were carried out at the age of 28 days. The results of compressive strength tests carried out at 28 days for the lightweight foam concrete variations BBN, BBAAK 1, BBAAK 2 and BBAAK 3 were respectively 15.29 MPa, 12.21 MPa, 18.29 MPa and 19.52 MPa. The greater showing variation in the percentage of coffee shell ash substitution used, the greater the resulting compressive strength and split tensile strength values. This is because Sikament NN also plays a role in increasing the compressive strength of concrete

Dimensional And Mechanical Deviation Of Paving Block Type Rectangular From Several Manufacturers In Semarang City

The non-uniformity of paving block quality can result in uneven pavement, which in turn can increase the risk of traffic accidents. This study aims to determine the quality of compressive strength of paving block type Holland from several manufacturers in Semarang City area both manually and massively. As well as knowing why the physical dimensions of paving block type Holland from several producers in Semarang City are not uniform. This research was conducted by taking samples in the paving block manufacturing industry around the city of Semarang. The discussion in this study only covers the type of holland paving block in Semarang City from 4 producers namely CV Waringin Putih Banyumanik Semarang, PT Alam Daya Sakti, Anugerah Block, and Putra Alam Sari. All paving block products tested met or exceeded the minimum value of compressive strength specified in SNI 03- 0691-1998. This indicates that these products have an adequate ability to withstand the given compressive load. The compressive strength test results show that the lowest value was recorded for Anugrah Block at 17.21 MPa, while the highest value was achieved by PT Alam Daya Sakti with 20.112 MPa. The non-uniformity of the physical dimensions of Holland type paving from several producers in Semarang City can be influenced by several factors, including different production processes between producers, the use of different raw materials, and differences in the arrangement of machines or production equipment.

Penggunaan Abu Sekam Kopi dan Ordinary Portland Cement terhadap Kuat Tekan Beton Normal

Cement is one of the binders which is commonly used as a concrete-forming material. Currently, there is a lot of coffee husk waste in Takengon, Central Aceh Regency, which contains silica. The basis of using coffee husk ash and OPC cement as an adhesive on the normal compressive strength of concrete. This study aims to determine the influence of using coffee husk ash and OPC cement as an adhesive on the compressive strength of normal concrete at a percentage of 5%, 10% and 15%. The research specimen is cylindrical shape with 15 cm diameter and 30 cm height. The test was carried out at the age of 7 and 28 days by using a compressive strength testing machine. The method of making the specimen is in accordance with the SNI 7656-2012 standard. It is found from the results in the laboratory, coffee husk ash obtains silicate compounds (SiO2) 29.11%, magnesium oxide (MgO) 4.92%, calcium oxide (Cao) 5.33%, ferrioxide (Fe2O3) 4.25% and aluminum oxide (Al2O3). The average compressive strength test results of 7-day old concrete at the percentage of 5% coffee husk ash mixture was 20.21 MPa, at 10% was 20.03 MPa and at 15% was 17,25 MPa. The average compressive strength of concrete at 28 days of age with 5% coffee husk ash mixture is 20.27 MPa at 10% coffee husk ash mixture percentage 19.70 MPa and 15% coffee husk ash mixture 15.46 MPa. Comparison of the results of the compressive strength test for concrete at 7 and 28 days was higher for concrete at 7 days. The results of the different compressive strength tests between the ages of the concrete are caused by the high percentage of coffee husk ash mixture where the higher the coffee husk ash percentage, the weaker the adhesion to the concrete. The percentages of coffee husk ash and OPC cement that meet the design compressive strength of 20 MPa are at 5% and 10% respectively.

Development of Geopolymer/Activated Carbon Composite Mortar from PLTU Paiton Fly Ash with the Addition of Sidoarjo Mud Waste

Abstract Cement production produces CO2 gas emissions that are harmful to the environment, so the manufacture of geopolymers can be done to substitute cement. Geopolymers are mineral chemical compounds or mixtures thereof consisting of repeating chemical units, such as silica-oxide. This research aims to make geopolymer mortar made from fly ash waste and Sidoarjo Lapindo mud composites with activated carbon to increase compressive strength, reduce moisture and increase CO2 absorption. Broadly speaking, the stages of this research began with preparing tools and materials to make geopolymer mortar, then mix design between fly ash, Sidoarjo lapindo sludge, and activated carbon with the addition of alkali activator, as well as fine aggregate in the form of Lumajang sand, which was then cured at 7, 14, and 28 days. Furthermore, characterization tests carried out for geopolymer mortar are SEM and XRD and testing compressive strength, water absorption, and CO2 absorption. The compressive strength test results showed that of all sample variations, the F100 variation had the highest compressive strength with a value of 17.57 MPa after curing for 28 days. The compressive strength of each sample variation increases with the longer curing time, except for the L100 variation. While in the additive variation group, the compressive strength of the F75C15L10 variation is the highest with a value of 17.43 MPa. In the water absorption test based on the carbon additive variation, it can be seen that the longer the curing time, the higher the water absorption.

The Influence of Diatomite Addition on the Properties of Geopolymers Based on Fly Ash and Metakaolin.

Geopolymer materials, considered to be an alternative to Portland cement-based concretes, can be produced from various types of waste aluminosilicate raw materials. This article presents the results of research related to the use of diatomite as an additive in geopolymers. The results of testing geopolymer composites with 1%, 3%, and 5% additions of diatomite with a grain size of 0-0.063 mm after and without thermal treatment were presented. This article presents the physical properties of the diatomite additive, the morphology of diatomite particles SEMs, thermal analysis, and compressive strength test results. In this research, diatomite was treated as a substitute for both fly ash and metakaolin (replaced in amounts of 1 and 3%) and as a substitute for sand introduced as a filler (in this case, 5% of diatomite was added). As a result of this research, it was found that the addition of diatomite instead of the main geopolymerization precursors in amounts of 1 and 3% had a negative impact on the strength properties of geopolymers, as the compressive strength was reduced by up to 28%. The introduction of crushed diatomite instead of sand in an amount of 5% contributed to an increase in strength of up to 24%.

Assessment of meta-schist as a novel sustainable resource for Portland cement manufacturing

In this study, the use of meta-schist as an alternative to sand–clay in preparing cement raw mixtures was investigated for the first time. To produce the highest quality Portland cement clinker by examining the mineral and chemical properties of meta-schists, two different raw meal samples were prepared, utilising conventional cement clay as a baseline sample ((PC)Ref) and the other with meta-schist ((PC)MSC). The effects of both raw mixtures on burnability tests and reactivity were evaluated based on the unreacted lime content in samples after they had been sintered at 1200, 1300, 1350, 1400 and 1450°C. The porosity amount, distribution, grain structure of silicate phase crystals, and equivalent crystal diameters and amounts of meta-schist clinker phases (C3S, C2S, C3A and C4AF) examined by polarising optical microscope showed that they are suitable for the production of PC. The hydration products of the cement mortars were determined by scanning electron microscopy and energy-dispersive X-ray analysis at 2, 7 and 28 days. In addition, the compressive strength test results of (PC)MSC and (PC)Ref mortars after 28 days of curing ranged between 57 and 55.5 MPa, and the cement produced was classified as CEM I 42.5R.

Experimental investigation of sandy soil stabilization using chitosan biopolymer

The performance of an environmentally friendly biopolymer synthesised from secondary resources to overcome the wind erosion of sandy soil was investigated in this study. The study employed a multi-scale approach to investigate the mechanical, erosional, and hydraulic properties of sandy soil. At the macroscale, experimental techniques such as unconfined and triaxial compression tests, permeability measurements, contact angle assessments, and wind tunnel experiments were utilized to characterize the bulk behavior of the soil. Concurrently, molecular dynamics (MD) simulations were conducted at the nanoscale to predict surface mechanical characteristics and elucidate chemical interactions at the molecular level. Results show that when the outer surface of the sandy particles is coated with a sparse concentration of biopolymer, the sandy aerosol inhibitory performance is significant even under extreme storm conditions reaching speeds of 140 km/h of storms. The study on the impact of biopolymer content, curing time, and curing conditions revealed that the addition of chitosan biopolymer has the ability to enhance the bonding between particles and significantly enhance the mechanical properties of sandy soil. The atomic insight from molecular dynamics reveals huge entanglement between sandy particles and biopolymer by Van der Waals interaction. The results of the Unconfined Compressive Strength test indicate that chitosan enhances the compressive strength of sand by up to 320 kPa. Additionally, the triaxial test demonstrated that the application of chitosan led to a 34.2 kPa improvement in the cohesion of sand. Furthermore, analysis of the permeability test results revealed a decrease in the hydraulic conductivity coefficient from 1.6 × 10^-6 m/s to 5.7 × 10^-7 m/s, representing a reduction of approximately 35 %.

Influence of graphene oxide properties, superplasticiser type, and dispersion technique on mechanical performance of graphene oxide-added concrete

The incorporation of Graphene Oxide (GO) nanomaterial into concrete has gained significant attention due to its potential to enhance mechanical and durability properties. The addition of GO to concrete creates considerable changes in the morphology of the concrete matrix, creating a densified microstructure. Critical parameters significantly affect these microstructural enhancements and, consequently, the final performance in GO-added concrete. These parameters include GO material properties, superplasticiser (PS) type, and dispersion techniques. Therefore, this study investigates the influence of GO on the mechanical performance of concrete, focusing on these critical factors. Unlike existing studies concentrating on a single parameter's effect, this research comprehensively compares how these parameters impact GO-added concrete. Two commercially available GO types (GO-A and GO-B) and two PS types (PS-A and PS-B) are utilised. At the same time, three commonly used mixing techniques, such as mechanical, high-speed, and ultrasonic mixing techniques, are considered for GO dispersion. GO-A is added to concrete in percentages ranging from 0.02% to 0.14% by weight of cement (bwoc), while GO-B ranges from 0.04% to 0.20% bwoc. Based on compressive strength test results, the optimum GO dosages are 0.08% for GO-A and 0.12% for GO-B. The highest strength results are achieved for GO-B added concrete with PS-A addition and following the ultrasonic dispersion method, highlighting these parameters as optimal for maximising GO-added concrete performance. The optimum concrete mix exhibits 33%, 24%, 25%, and 30% increments for compressive strength, indirect tensile strength, flexural strength, and elastic modulus properties at 28 days. This paper provides a deep theoretical explanation of the effects of GO material properties, dispersion techniques, and PS type on GO-added concrete performance. The findings provide valuable insights into selecting suitable parameters for optimising the mechanical properties of GO-added concrete, contributing to the advancement and effectiveness of construction materials.

Testing the effect of UHPFRC jacket thickness and steel fiber volume fraction on NSC‐UHPFRC column compressive behavior

AbstractSeveral efficient applications of ultrahigh‐performance fiber‐reinforced concrete (UHPFRC). Among them are UHPFRC jackets utilized for strengthening or permanent formworks of the steel reinforcing normal strength concrete (NSC) columns since UHPFRC jackets could enhance the compressive strength and other properties of the NSC column. However, the efficiency of a UHPFRC jacket simultaneously depends on its thickness and the added steel fiber volume fraction. The paper aims to explore the interaction effect of UHPFRC jacket thickness and steel fiber volume fraction on the behavior of UHPFRC jackets confining the NSC core under compressive load. The circular ultrahigh performance concrete jacket filled inside with the normal strength concrete, named NSC‐UHPFRC column specimen, is tested under loading on the NSC core. UHPFRC jacket thickness of 18‐49 mm with three adding steel fiber volume fractions was conducted for the experimental study. The investigation and analysis of the effect of the UHPFRC jacket and the steel fiber volume fraction on compression behaviors of NSC‐UHPFRC columns proceeded after the compressive strength test results were validated using Richart's model. This comprised a review of various parameters such as specimen failure pattern, stress–strain relationship, and ductile indices. The Weibull distribution was employed to explain the interaction effect on the variation in the experimental results. Finally, an interaction model was proposed and used to discuss the interaction effect of UHPFRC jacket thickness and steel fiber volume fraction and the optimum condition of the compressive strength of the NSC‐UHPFRC columns.

Influence of Aging Time on Compressive Strength of Silica Fume Reinforced High Strength Concrete Composite

The goal of this study is to gather a High Strength Concrete (HSC) composite reinforced by silica fume and superplasticizers. Specimens are Cured by water and tested after aging time of 3, 7, 28 days. Specimens are cubes of 150 and 200 mm and 150x300mm cylinder. The aim is to get mean strength of 80- 85 MPa, and determination of physical properties of the materials used, which are basic components of the High Strength Concrete (HSC) composites. After designing mix proportions, according to design requirements some adjustments were done. Both fresh and hardened properties of the specimens were tested under standard condition (curing schemes, setting time, comp.str. etc). Compressive strength test results were gathered and compared with the requirements.

REVIEW OF THE EFFECT OF INDUSTRIAL WASTE ON SELF COMPACTING CONCRETE

Self-Compacting Concrete (SCC) is an innovation in concrete technology used in building elements with dense and complex reinforcement frameworks. SCC is characterized by its high fluidity and the ability to self-compact without the use of vibrators. Superplasticizer is one of the components applied in the production of SCC. The use of superplasticizer aims to reduce water consumption, accelerate the setting time, improve concrete workability, and also make the concrete impermeable.&#x0D; As time progresses, industrial waste continues to increase, highlighting the importance of recycling industrial waste. The purpose of this research is to investigate the influence of industrial waste as a substitute material for fine aggregates on the workability and compressive strength of SCC. This study is the result of a literature review obtained by examining various sources including books, proceedings, as well as international and national journals.&#x0D; The results of this literature study involve the use of industrial waste materials such as recycled glass, granite waste, nickel slag, and copper slag as substitutes for fine aggregates. The results of the workability and compressive strength of SCC are influenced by the characteristics of each industrial waste used. This indicates an improvement in the flowability (slump flow) with an increasing percentage of industrial waste, ranging from 0% to 60%, in the concrete composition.&#x0D; Compressive strength test results indicate that the optimal percentage of industrial waste addition in the concrete composition lies between 20% and 40%."

Investigation of the effect of flexural strength test damage on compressive strength of construction materials

Concrete, the principal material of the construction sector, has been the subject of many scientific researches for decades. As a result of these investigations, new scientific information has been obtained on the weak points of cement-based products, especially concrete, their behaviour under load, etc. In light of this information, it is recommended that some test methods specified in international standards be revised. In this study, the effect of damage caused by flexural strength test performed on samples prepared with mortar prisms, of dimensions 160 mm x 40 mm x 40 mm within the scope of EN 13813, EN 13888, EN 13279-1, EN 197-1, TS 13566 and TS 13687 standards, on the results of compressive strength test performed on the broken samples was investigated. In the final analysis, some improvement suggestions have been made in the test methods in question.

Investigation on strength characteristics of fly ash treated dredged marine clay with various pore water salinities

This study investigated the strength characteristics of dredged marine clays treated with fly ash with varying porewater salinities. A series of laboratory tests were conducted on fly ash-treated dredged marine clay specimens with various salinities and curing times. In the direct shear tests, observed patterns revealed a consistent initial rapid increase in shear stress with the increase of horizontal displacement, followed by either a gradual decline or stabilization after reaching the peak shear stress. The variation curve consistently positioned the lower salinity or longer curing time above the higher salinity or shorter curing time. Furthermore, the shear strength at a given vertical stress consistently decreases with increasing salinity while ascending with increasing curing time. This indicated that curing time positively influences shear strength development, while the presence of salt negatively affects it. Both strength parameters cohesion and friction angle exhibited growth trends with increased curing time but displayed a decline as salinity increased from 0% to 6%. Unconfined compressive strength test results showed a strain-softening behavior for all tested specimens. The compressive strength demonstrated a declining trend with rising salinity, with a more pronounced decrease observed within the initial 7d compared to the less significant change between 7d and 28d.