Pozzolanic Portland Cement Research Articles

APPLICABILITY OF BITUMINOUS-BASED INHIBITOR AS CORROSION PREVENTION METHOD IN REINFORCED CONCRETE

Corrosion is the most common cause of structural and material degradation in reinforced concrete (RC) constructions. A well-constructed structure protects the embedded steel bar from chloride ions both physically and chemically, which is particularly important for constructions exposed to seawater. Given the significant economic losses caused by corrosion, suitable measures to reduce corrosion in concrete are required. In this study, three-layer of bituminous-based inhibitor was applied to the surface of two steel bars embedded (steel coating) in mortar cement with 3 cm and 5 cm of concrete cover. Portland composite cement (PCC) and Portland pozzolan cement (PPC) was used as a binder material of mortar cement. The cubical mortar cement specimens were fabricated, and exposed to three conditions (e.g., wet condition, dry condition, and dry-wet cycle) until 60 days after 28 days of immersed water curing. The results demonstrated that corrosion prevention employing steel coating techniques by using bituminous-based inhibitor gives superior protection as seen by a higher positive corrosion potential value when compared to non-coating specimens, implying that the coating method may be used to prevent corrosion. This is because the coating process by using bituminous-based inhibitor may prevent ions from entering the reinforcing steel. In all exposure circumstances and with all preventive procedures, a concrete cover with a thickness of 5 cm has a lower corrosion risk, as shown by a higher corrosion potential value, than a concrete cover with a thickness of 3 cm. The larger the thickness of the concrete cover, the more the surrounding ecosystem is protected. The utilization of PPC as binder in concrete maintained the stable corrosion potential value when the coating method applied.

Water-based corrosion inhibitor for prevention and repair of reinforcement in chloride and carbonated environment

This paper explores the influence of 2-aminopyridine (2AP) as water-based migratory corrosion inhibitor (M-CoI) on the corrosion resistance of reinforcing steel bars embedded in ordinary Portland cement and pozzolanic Portland cement concrete subjected to combined chloride and carbonation ingress. Two applications of 2AP are considered i.e., preventive (applied before exposure to aggressive environment) and repair (applied after corrosion initiates). Corrosion performance was assessed using electrochemical techniques and gravimetric mass loss method. The study also examines the impact of 2AP application on chloride ion concentration and carbonation depth of both concrete systems. The compressive strength of each concrete system was also measured to study the impact of M-CoI application on strength properties. Surface condition of hardened concrete and extracted rebar was evaluated by optical microscopy. Results conclude that 2AP effectively retards reinforcement corrosion when used as preventive measure by forming a homogeneous inhibitive layer on steel. However, when used as a repair technique, localised and uniform corrosion was perceived. An attempt has been made to identify the cause of non-performance of 2AP as repair measure. It was concluded that reached concentration of 1 mM was not sufficient to reduce ongoing corrosion due to the accumulation of corrosion products. The influence of the inhibitor on chloride profile and carbonation depth was found to be insignificant. It is concluded that chloride ions initiate the corrosion mechanism, while carbonation exacerbates it, particularly in blended cement concrete. Nonetheless, inhibitor application can provide similar resistance in both concrete systems.

PEMANFAATAN FLY ASH DAN BOTTOM ASH PLTU REMBANG UNTUK PEMBUATAN BETON MENGGUNAKAN SEMEN PPC

The research aims to reduce the amount of coal burning waste of fly ash and bottom ash PLTU Rembang as a substitution of cement and sand in the production of quality concrete K-225 and waterproof using Portland Pozzolan cement. The method was experimented in the laboratory by making 50 samples of 15 x 15 x 15 cm3 test objects for 28 days, 60 days, and water absorption tests. The test objecte was made in 5 variations: normal concrete (without substitution) and 20% bottom ash substitution concrete and fly ash mixture 0%, 5%, 10%, 15%. Strong K-225 pressure occurs at the age of 60 days on bottom ash substituted concrete 20% with fly ash 0%, 5% 10% and 15% respectively of 245 kg/cm2, 254,67 kg/cm2, 250,67 kg/cm2, dan 250,67 kg/cm2. Water absorption of concrete at 28 days of ashes substitution was less than 20% and ashes flew below 0% and 5%, 10% 15% resulted in 4.85%, 5.17%, 5.05%, and 5.18%. The results of the research showed that the concrete made meets the K-225 quality and better absorption than normal concrete.

Mechanical behaviour of dredging waste in the port of Rio Grande by adding stabilizing agents

ABSTRACT The Port of Rio Grande demands periodic maintenance dredging processes in the access channel of the port complex. These large volumes of dredging waste disposal in the ocean cause environmental and social problems in this region. One possible solution to reduce the impact is onshore disposal, but the sediment has a low support capacity and high compressibility. So, the present paper evaluates the mechanical behavior of dredging waste improved with chemical agents (chemical: pozzolanic Portland cement) and compounds (physical + chemical: fine sand + pozzolanic Portland cement). The results show that the stabilized material reaches compressibility resistance ranging from 400 to 1600 kPa depending on the dosage proposed. A good correlation was observed between the compression resistance results and cement agents’ porosity-volume content. The stabilizing agents using a composite material (sand + Portland cement) achieved better results. The results show that adding stabilizing agents is a satisfactory option to improve the mechanical behavior of dredging waste.

Strategi Pemasaran Dalam Mempertahankan Citra Merek Dan Perilaku Konsumen Terhadap Pembelian Produk PT.Semen Indonesia (Persero) Tbk.

Indonesia's cement industry plays a pivotal role in economic and infrastructural development. PT Semen Indonesia (Persero) Tbk stands out as a leading company in this sector, boasting renowned brands like Semen Gresik, Semen Padang, and Semen Tonasa, producing various types of cement, including Pozzolan Portland Cement (PPC) and Ordinary Portland Cement (OPC). Competing with other major cement players like PT Indocement Tunggal Prakarsa Tbk and PT Holcim Indonesia Tbk, PT Semen Indonesia remains a significant force.This study aims to formulate marketing strategies focusing on maintaining the company's longstanding positive image and influencing consumer behavior towards purchasing its products. Key aspects explored include product quality, pricing, corporate image, customer service, innovation, sustainability, promotion, and socio-cultural factors. Understanding consumer behavior is vital, considering their interest in cement products with a strong brand image, factoring in aspects such as quality, pricing, corporate image, customer service, innovation, sustainability, promotion, and socio-cultural elements. Research findings are expected to provide in-depth insights into PT Semen Indonesia's ability to comprehend and respond to consumer preferences effectively. This understanding will serve as a foundation for formulating smarter and more relevant marketing strategies, aiding the company in maintaining and increasing market share, while reinforcing its image as a leading provider of building solutions in Indonesia. in Indonesia.

Study on energy use and carbon emission from manufacturing of OPC and blended cements in India.

The demand for production of cements is ever increasing to meet the infrastructure development globally. The energy and emission factors available for cements in most of the life cycle assessment (LCA) databases may not exactly suit for all the geographical locations. The main challenge in Indian scenario is the absence of database for LCA study. This study attempts to develop the energy and emission factors for the manufacturing of cements in Indian context. In the present study, five different cement manufacturing plants located in north, south, east, west and central zones of India are considered to assess the energy dissipation and carbon dioxide emission involved during the production of ordinary Portland cement (OPC). Most of the data is collected from the field, so that the energy and emission factors determined will be suitable for the zonal study. The study is then extended to assess the energy consumption and carbon dioxide emission for three blended cements, viz. Portland Pozzolan cement (PPC), Portland slag cement (PSC) and composite cement (CC) with permissible known replacement levels of fly ash, granulated blast furnace slag and both fly ash and slag, respectively. The average energy use and carbon emission is found to be on higher side in India by 15.14% and 12.64%, respectively, compared to other countries in manufacturing of cements. An average energy consumption in manufacturing of PPC, PSC and CC is found to be respectively 24.5%, 35.3% and 43.13% less compared to that of OPC. The CO2 emission intensity for OPC is found to vary between 893 and 940kg/tonne of cement from five different zones, and an average of respectively 24.8%, 40.97% and 47.18% lower CO2 emission was observed from PPC, PSC and CC compared to OPC. From the inventory results, CC has proven to be a more sustainable cement with low energy consumption and lower CO2 emission compared to other cements.

Comparison of Physical Properties and Strength of Geopolymer Mortar with White Soil Substitution and Mortar with Portland Pozzolan Cement under Corrosive Seawater Conditions

Construction also causes environmental pollution due to excessive cement production, so an alternative to cement is needed. Geopolymer is considered an alternative material to replace cement. This research compares three variations of mortar (PPC, geopolymer, and geopolymer with white soil) in a seawater environment. Research in the laboratory with 5x5x5 cm mortar specimens and test parameters for porosity, compressive and direct tensile strength, density, and absorption has been carried out. Microstructure due to immersion effect was also carried out but only on MGT15 mortar. The results showed that the PPC mortar had the highest compressive and tensile strength among the three variations, namely 27.80 MPa and 2.540 MPa at 28 days of age, the most negligible porosity and absorption were 1.124% and 76 gram/100cm2, and increased density after immersion. However, when immersing for 56 days, the decrease in strength reached 21%, while geopolymer mortar tended to be stable and even increased to 19%. Microstructure tests in the form of SEM and EDX on MGT15 showed the effect of seawater immersion, such as the presence of cracks, ettringite, and bad reactions. Soaking in seawater caused a decrease in some mortar strength supporting compounds and the appearance of 0.3% free chloride at 28 days of immersion.

Clayshale Stabilization using Portland Pozzolan Cement Type II to Increase the Shear Strength of Soil

Clayshale soil was found 5 meters below ground level in the Hambalang area. The fragility of clay shale soil results in clay shale soil being rarely used in construction needs. The physical condition of clayshale is not optimal when it is dry and also when it is mixed with water. This research is carried out so that the cohesion value and shear strength in the clayshale is close to perfection with the stabilization process. Disturbed sampling was carried out in the Hambalang area, providing that the granules passed the 4mm filter. Tests carried out to obtain soil parameters include physical properties testing and mechanical properties testing. Based on the results of laboratory tests, the original clayshale soil has a plasticity index (IP) value of 27.07%, so clayshale soil included CL (Clay-Low plasticity) according to the USCS category. The use of Portland pozzolan cement in this study is because it has high resistance to salts and sulfuric acid. Mixing of PPC cement test materials was carried out to determine the optimal cohesion value and shear strength by mixing 5%,8%, and 11% of clayshale weight per sample. The addition of cement variations can increase the specific gravity value of the soil and the optimum moisture content, but it can reduce the dry weight value of the soil and the value of the plasticity index on clayshale soils. The cohesion values and soil shear strength obtained after Triaxial UU testing on samples with the addition of Portland pozzolan cement (PPC) increased; however, the increase that occurred was varied and significant at the time of the PPC cement mixture.

Identification of patterns of strength formation of concrete using cement Portland Pozzolan (PPC) and waste tire powder in the condition of seawater curing

According to the national standard body in Indonesia, the compressive strength of 20 MPa concrete is medium quality concrete. Medium-strength concrete is usually used for floors, light construction, houses, warehouse factories, and sidewalks. The use of medium-strength concrete is very broad, it is necessary to continuously conduct research to produce new innovations. Previous research on the utilization of waste rubber tires has been carried out. Research on the development of concrete with the use of waste tire rubber powder is very interesting to do considering the waste of used tires that continues to increase along with the increase in the number of motorized vehicles in Indonesia. Portland Cement (OPC) and Portland Pozzolan Cement (PPC) are the two types that will be used in this research to see its effect on concrete with waste rubber powder. These two cements also have different corrosion resistance. And seawater is one of the triggers of high concrete corrosion. Research on the development of concrete with the use of waste tire rubber powder is very interesting to do considering the waste of used tires that continues to increase along with the increase in the number of motorized vehicles in Indonesia. Portland Cement (OPC) and Portland Pozzolan Cement (PPC) are the two types that will be used in this research to see its effect on concrete with waste rubber powder. These two cements also have different corrosion resistance. And seawater is one of the triggers of high concrete corrosion. This study aims to analyze how the compressive strength of PPC concrete compares with OPC and the addition of used tire powder under seawater treatment conditions. Six concrete variants were made and then tested for compressive strength. The compressive strength values of variants 1 to 6 were obtained as 20.78 MPa, 18.26 MPa, 19.56 MPa, 16.58 MPa, 13.03 MPa. The results show that tile powder is not effective in increasing construction strength, but the use of PPC cement is more effective than the use of OPC in improving construction, especially for cement use in buildings close to sea water

Studi Perbandingan Sifat Mekanik Mortar PPC dan Mortar Geopolimer dengan Aktivator NaOH pada Rendaman Air Laut

Using Portland pozzolan cement (PPC) is considered suitable for infrastructure in the sea area because it has a high resistance to salt and sulfate but still produces carbon dioxide gas emissions that can damage the environment. Environmentally friendly materials that can completely replace cement are geopolymer materials. This study compared the mechanical properties of PPC mortar and geopolymer mortar with and without white soil under seawater bath conditions. The test object is a 5x5x5 cm mortar cube with fly ash, white soil, sand, water, alkaline activator NaOH 8M, and PPC cement. Mortar variations include PPC mortar, geopolymer mortar without white soil substitution (TTP), and 15% white soil substitution mortar (TP15%). Tests include compressive strength, tensile strength, porosity, density, and absorption for all three variations. Microstructure testing of the influence of the bath is carried out on the TP15% mortar. The test results showed that PPC mortar has better resistance compared to both variations of geopolymer mortar in terms of its compressive and tensile strength at a bath life of 28 days, namely 32,427 MPa and 2,318 MPa, while the geopolymer mortar produced maximum compressive and tensile strength values of 14,373 MPa and 0.993 MPa. TTP mortar has better resistance than TP15% mortar. Microstructure testing showed mortar with baths had a denser matrix.

The Influence of Pulverized Fuel Ash (PFA) on the Thermal and Transport Properties of Foamed Concrete

The incorporation of materials derived from industrial waste presents a viable avenue for mitigating the exorbitant production expenses associated with building materials, while concurrently ameliorating the deleterious ecological ramifications of said waste. The utilization of pulverized fuel ash (PFA), an industrial residue resulting from the combustion of powdered coal in an electricity-generating facility, as a substitute for cement in the composition of concrete, is a viable option owing to its inherent pozzolanic properties. The present study endeavours to investigate the potential of Partially-Fumed Ash (PFA) as a viable substitute for cement in the production of foamed concrete (FC). The thermal and transport properties were meticulously assessed, with a particular focus on thermal conductivity, thermal diffusivity, specific heat capacity, water absorption, and porosity. A series of experiments have been undertaken wherein varying proportions of Portland Pozzolan Cement have been substituted for PFA, specifically at levels of 10%, 20%, 30%, 40%, and 50% by weight. The findings suggest a prospective application of PFA in the manufacturing of FC. The utilization of PFA (Pulverised Fuel Ash) assumes a pivotal role in enhancing the thermal conductivity, thermal diffusivity, specific heat capacity, water absorption, and porosity of FC. Therefore, it can be inferred that the utilization of PFA holds promising potential in the production of cost-effective, lightweight construction materials, while simultaneously mitigating the adverse environmental consequences.

Sustainable Use of Recycled Asphalt Pavement in Soil Stabilization

This study addresses unused recycled asphalt pavement (RAP) incorporated into sedimentary soil from the Guabirotuba Formation in Curitiba, Southern Brazil. Different percentages of RAP, ranging from 0% to 80% by weight, were mixed with the pure soil, with and without the addition of pozzolanic Portland cement. Tests were conducted to evaluate the mixtures' compaction properties, mechanical strength, and expansion after curing for up to 28 days. The results showed that adding RAP improved the mixtures' unconfined compressive strength (qu) and splitting tensile strength (qt). Up to 60% RAP, the qu increased by 260 kPa, and the qt increased by 340 kPa compared to the pure soil. The California Bearing Ratio (CBR) tests demonstrated an 18.62% improvement when 80% RAP was added to the untreated soil. In addition, the RAP also reduced the expansion of the compacted blends, with values decreasing from 1.19% to 0.88% with 80% RAP replacement. The expansion value was further reduced to 0.86% when the cement was added. The cement-soil-RAP compacted blends showed suitability for subgrade reinforcement, meeting the criteria of expansion <1% and CBR> 2%. Additionally, 3% cement and 40% RAP mixtures were suitable as a sub-base layer, with expansion <1% and CBR > 20%. The results provide valuable insights into utilizing RAP as an alternative material in soil improvement techniques employing the novelty porosity-to-cement index. Doi: 10.28991/CEJ-2023-09-09-016 Full Text: PDF

Mechanical, durability and microstructural characteristics of Portland pozzolan cement (PPC) produced with high volume pumice: Green, cleaner and sustainable cement development

Nowadays, it is frequently preferred to use pozzolans instead of clinker to reduce the CO2 emissions that increase with cement production. Because in the future, the release of artificial pozzolans, such as fly ash and blast furnace slag, will decrease. Therefore, the demand for natural pozzolanic cement will increase. This study aimed to produce Portland Pozzolan Cement (PPC) by using pumice instead of clinker up to 40%. The Chemical, physical, mechanical, durability, microstructure, and carbon footprint characteristics of PPCs were investigated experimentally. As the pumice volume in the PPCs increased, the CaO/SiO2 ratio and specific gravity decreased. Due to the hygroscopic moisture of the pumice, its grindability has become difficult. While the 40 µm sieve residue of PPCs ranges from 0.8 to 1.7%, the sieve residue ratio generally increases as the pumice volume increases. The porous structure of pumice led to an increase in Blaine fineness as the replacement ratio increased. The Blaine fineness of PPCs containing 40% pumice rose by about 20% more than the reference cement. The consistency water of PCs varies between 29 and 36%. As the water consistency increased, the setting time of the pastes was prolonged. Initial setting times of PPCs are between 150 and 220 min. If the CaO/SiO2 ratio decreased with the pumice volume, the compression strength of the mortars decreased. While the 28-day compression strength of PPC containing 10% pumice was measured as 36.2 MPa, this value was measured as 21.6 MPa for PPC containing 40% pumice. As the pumice volume increased, the mortars' drying shrinkage and sulfate-induced expansion values decreased significantly. According to the sustainability analysis, the CO2 emissions of cement vary between 518 and 880 kg CO2/t. By using pumice instead of clinker, CO2 emissions of cement can be reduced. In SEM examinations, it was determined that pumice concentrated the microstructure. As a result, it has been determined that eco-friendly cement can be obtained by using 10% and 20% pumice in PPC production.

Effects of acid attack and cassava flour dosage on the interfacial transition zone thickness, durability and mechanical characteristics of high-strength (HS) concrete

Due to its higher porosity, the interfacial transition zone (ITZ), that is, the zone between the hardened cement paste (HCP) and the aggregate, is the weakest point in concrete. It is less resistant to cracking than both HCP and aggregate, and microcracks begin in this zone when the load is applied and propagates into the mass of concrete. The goal of this research is to investigate how various dosages of cassava flour (CF) addition affect the ITZ and how this is related to the mechanical properties of concrete, including its resistance to sulfuric acid. CF is added as a percentage of Portland pozzolanic cement (PPC) used as a binder, with dosages of 1, 2, 3, 4, and 5%. The morphology of CF and PPC was studied using x-ray diffraction (XRD) and x-ray fluorescent (XRF) techniques. Changes in the thickness of the ITZ were observed using a scanning electron microscope (SEM). The effect of sulfuric acid was observed by immersing samples of concrete in a 2% sulfuric acid solution. The results show that adding CF up to 3% progressively reduced the thickness of ITZ and improved the densification of concrete. As more CF was added, the ITZ began to widen again, but even at 5% CF addition, the thickness of the ITZ remained well below that of the control. The workability of fresh concrete decreased with an increase in CF dosage, but CF addition increased the compressive, tensile, and flexural strengths of hardened concrete. The greatest compression resistance was achieved at a 3% cassava flour addition level, which was 83.8 MPa after 180 days of curing and 8.9 MPa, 4.7 MPa for flexural and splitting strengths, respectively, after 90 days of curing. All the concrete samples containing CF had lower strengths than the control after immersion in sulfuric acid, with the concrete with 3% CF performing better than the others. The research concludes that CF used as an additive to concrete in dosages up to 5% improves the ITZ zone, leading to improved mechanical properties. However, resistance to sulfuric acid attacks is reduced. In all tests, it has been shown that a CF dosage of 3% gives the best results.

Eco-Sustainable Recycling of Cement Kiln Dust (CKD) and Copper Tailings (CT) in the Cemented Paste Backfill

Cement global demand shows continued growth and a significant increase in the production volume, which may negatively impact the non-renewable natural resources and the environment, which is incompatible with sustainability goals. Cement kiln dust (CKD) is a primary concern associated with clinker manufacturing as a waste byproduct. Similarly, the mining industry produces copper tailing as unwanted material while beneficiating the ore, creating environmental problems due to difficulty in managing worldwide generated quantities that reach billions of metric tons. This study investigated the beneficial utilization of cement kiln dust and copper tailing as undesirable wastes in industrial applications through underground mines’ cemented paste backfill (CPB). Sixty different mixtures were prepared with three types of CKD collected from various cement manufacturers and were accordingly used with a proportion of 5, 10, and 15% to partially replace ordinary Portland cement (OPC) and pozzolan Portland cement (PPC) binders, represented in hundreds of CPB samples. The hardened specimens were subjected to density, uniaxial compressive strength (UCS), and axial deformation measurements to evaluate the physical and mechanical properties at curing up to 90 days. Meanwhile, X-ray powder diffraction (XRD) was extensively applied to chemically investigate the hydration products of CPB-hardened mixtures. Moreover, we developed a UCS predictive model applying two techniques: multiple variables regression analysis and artificial neural network (ANN). The results showed that the tricalcium silicate (Alite) and dicalcium silicate (Belite) phases form C-S-H upon hydrations and provide high strength in the binary mixtures. Meanwhile, the CKD’s lime saturation factor (LSF) governed the strength value in the ternary mixtures that utilized copper tailings. That makes CKD practical in the CPB mixture when partially replacing the OPC and PPC binders, with a proportion of up to 15%. In addition, the ANN technique’s predictive model exhibited a significant positive correlation with excellent statistical parameters that achieved 0.995, 0.065, and 0.911 for R2, RMSE, and MAE, respectively.

Daya Tahan Mortar Geopolimer dan Mortar Semen Portland Pozzolan (PPC) terhadap Larutan Asam Sulfat

The manufacture of cement is often criticized to produce high CO2 emission to environment. Reducing cement in construction is believed to be the solution for better environment. Portland pozzolan cement (PPC) is known as a more environmentally friendly cement which substitutes some portion of cement clinkers with pozzolanic materials such as fly ash. Another material which is considered as green material is Geopolymer. The purpose of this study is to investigate the durability of mortars made of PPC and geopolymer in the corrosive environment. The geopolymer mortar was made of fly ash with 25% white soil substitution, and also 8M NaOH and Na2SiO3 as activators. The corrosive condition was simulated by Sulfuric Acid solution (H2SO4) with a pH of 4. The durability of the two types of mortar was investigated by testing their compressive strength, direct tensile strength, porosity, density and the changes of mass and physical shapes after immersion. The results show that the immersion of the mortars in a solution of pH 4 sulfuric acid does not make any major effects on the performance of the PPC mortar. However, the performance of geopolymer mortar with 25% white soil substitution decreases after being immersed in sulfuric acid solution.

Research corrosion of cements with a new hydraulic additive

Based on the above studies, the following conclusions can be made: The introduction of hydraulic additives into Portland cements increases their sulfate resistance, especially when cements have higher C3A content. Cements with 30% tuffite give better strength than those with 20% tuffite. The least aggressive for pozzolanic Portland cements are 5% Na2SO4 solution, the most aggressive is 3% MgSO4 solution, in which cements with hydraulic additives were more resistant than pure Portland cements, which is in agreement with the data of other researchers. For sulfate-resistant pozzolanic Portland cement maximum C3A content in the original Portland cement can be increased up to 8%.

Analysing the Effect of Cassava Flour as a Mixture on the Physical, Mechanical, and Durability Properties of High-Strength Concrete

The availability, cost, and environmental impact of chemical admixtures are reduced when natural substitute materials are incorporated into the concrete as an admixture. This paper outlines the findings of a study that looked at the physical characteristics of fresh and hardened concrete made with Portland pozzolanic cement CEM II/B-P blended with cassava flour up to 5% by weight of cement. A low water/binder ratio of 0.35 was used together with a carboxylate-based superplasticizing admixture to produce high strength. In fresh-state concrete, the initial and final setting times, soundness, and consistency were found to increase with increased cassava flour content, whereas the compacting factor and slump were observed to decrease. In the hardened state, compressive strengths were determined at 3, 7, 14, 28, 56, and 90 days, while split tensile and flexural strengths were investigated at 28 days. Similarly, dry density and porosity were also investigated at 28 days. Water absorption was also studied as a potential indicator of durability in hardened concrete. Scanning electron microscopy characterization of cassava flour revealed porous particles of irregular shape. On the other hand, X-ray diffraction imaging showed that the primary chemicals in cassava flour are silicon dioxide (50%), calcium oxide (17%), and aluminium oxide (7%). All of the mixes that incorporated cassava flour were stronger than the control mix, with the 3% cassava flour combination producing the best results. Doi: 10.28991/CEJ-2022-08-12-015 Full Text: PDF

Use of Ground Calcium Carbonate for Self-compacting Concrete Development based on Various Water Content and Binder Compositions

Objective: The development of a Self-Compacting Concrete (SCC) mixture requires a different composition compared to normal vibrated concrete. This experimental study was designed to propose a modification of the concrete mix design formula to produce an SCC mix that meets the specified requirements for both fresh and hardened concrete using Ground Calcium Carbonate (GCC) as local fine powder material. Methods: The research was carried out with a targeted compressive strength between 30 and 60 MPa. The materials that were used in this research were fine natural aggregate, crushed stone as a coarse aggregate with a maximum size of 19 mm, Portland pozzolan cement (PPC), GCC, freshwater, and high-range water reducer. The properties of fresh concrete were tested using the slump-flow test method, while the compressive strength test was carried out on 50 standard cylinders after 28 days of curing with water immersion. Results: Test results indicated that the compressive strength and fresh properties of SCC significantly depend on the water content, the water/cement ratio, the volume ratio between water to the total binder, and the weight ratio between the GCC and Portland cement. Conclusion: Furthermore, using the experimental data based on varied water content and binder compositions produces equations with a good fit for SCC mix design in the compressive strength range between 30 MPa to 60 MPa.

Study of the effect of pozzolanic Portland cement-basic oxygen furnace slag on the mechanical properties of roller compacted concrete

ABSTRACT Due to the presence of free lime (FL) in slag and its lack of reaction with concrete components, concrete containing slag reduces strength. Pozzolanic Portland cement (PPC) in the presence of moisture and normal heat during chemical reactions with lime (calcium hydroxide) generates stable calcium silicates that have adhesion properties. By using PPC instead of Portland cement type I in roller compacted concrete (RCC) containing basic oxygen furnace slag (BOFS), it is possible to determine the mechanical properties of RCC due to the reaction between the FL in BOFS and PPC. Therefore, this study aims to investigate the effect of PPC on the mechanical properties of RCC containing BOFS. For this purpose, specimens are made with various cement content values (225-400 kg/m3), various BOFS content values (0-50%) and with the optimum moisture. The properties examined in this paper are compressive strength, indirect tensile strength, and static modulus of elasticity tests. The results show that the use of PPC is effective in compensating the negative impact of using BOFS and providing the minimum specified mechanical properties. Also, the proportion of consumption of PPC with BOFS value is determined for the possibility of maximum reaction between FL and pozzolan in cement.