Initial Setting Time Research Articles

An in vitro study of a custom-made device for thermoregulation of the mixing slab on the setting properties of zinc oxide eugenol impression paste.

The present study was aimed to investigate the functional relationship between the mixing temperature and properties of a commercially available zinc oxide eugenol impression paste (ZnOE paste). In-vitro study. A custom-made simulated mixing device was indigenously designed to maintain different mixing temperatures, simulating cold, ambient, and hot weather. A commercially available ZnOE paste was mixed according to the manufacturer's instructions in the simulated mixing device at the temperatures ranging from 10°C to 50°C. Initial setting time and consistency were measured according to A. D. A. Specification No. 16 (n = 8). A stainless-steel die having 25, 50, and 75 μm lines was used for surface detail reproduction. Detail reproduction of the stone casts of the impressions was evaluated with a stereomicroscope at 30 magnification (n = 8). The shear bond strength of ZnOE paste to self-cure acrylic tray resin was measured by using the UTM at a crosshead speed of 0.5 mm/min (n = 8). Data were analyzed by using one-way analysis of variance (ANOVA) and Tukey's post hoc tests at a confidence interval of 95% (alpha =0.05). Initial setting time, consistency, and detail reproduction of the ZnOE paste were affected by the mixing temperature (P < 0.001). Mixing ZnOE paste at a lower temperature of 10°C and higher temperatures of 40°C and 50°C resulted in shorter initial setting time, thicker consistency, and poor detail reproduction. However, no significant difference was obtained in the shear bond strength among the different mixing temperatures evaluated (P > 0.05). Based on this in vitro study, it is advisable to perform the manipulation of ZnOE paste at a clinical/laboratory temperature of 30°C for optimum performance. The simulated mixing device used in this study can be an alternative for extreme climatic conditions.

A collaborative scheduling model for production and transportation of ready-mixed concrete.

Ready-mixed-concrete (RMC) is an important green and clean building material which is widely used in modern civil engineering. For the large-scale planar foundations of urban public buildings, huge amounts of RMC need to be continuously delivered to the construction site according to strict time windows, which brings the problem of multi-plants collaborative supply. In this paper, considering transportation capacity, initial setting time, and interrupt pumping time, a collaborative scheduling model for production and transportation of RMC with the objective of minimizing the penalty cost of interruption pumping and vehicle waiting time and fuel consumption cost was established. According to the characteristics of the problem, a double chromosome synchronous evolution genetic algorithm was designed. Finally, the model and algorithm proposed in the paper were verified by data experiments. The computing results showed that in two cases of different scenarios, such as ordinary constructions and emergency constructions, the proposed scheduling model can save 18.6 and 24.8% cost respectively. The scheduling model and algorithm proposed in the paper can be applied directly to improve the operational efficiency of RMC supply chain.

The Effect of a Setting Accelerator on the Physical and Mechanical Properties of a Fast-set White Portland Cement Mixed with Nano-zirconium Oxide.

This study compared the effects of calcium chloride dihydrate (CaCl2.2H2O) on the physical properties and push-out bond strength of white Mineral Trioxide Aggregate (WMTA) and an experimental Malaysian Portland cement mixed with nano-zirconium oxide (nano-ZrO) [(radiopaque Malaysian Portland cement (RMPC). Mineral Trioxide Aggregate (MTA) was the first calcium silicate cement (CSC) introduced in dentistry, but up to date, it is an expensive cement with long setting time and causes tooth discolouration. Although Portland cement has been introduced as a potential substitute to MTA, it still faces some challenges such as long setting time and lack of sufficient radiopacity. Four groups [WMTA, RMPC, fast-set WMTA (FS-WMTA) and fast-set RMPC (FS-RMPC)] were prepared. Initial setting time was evaluated using Vicat apparatus. The pH was measured at seven-day intervals. For discolouration potential, cements were packed in the pulp chamber of 46 extracted maxillary incisors. Spectrophotometric readings were obtained at seven-day intervals, and the rate of colour change (ΔE) was recorded. For the push-out bond strength testing, cements were applied in 48 sectioned root samples, and the test was performed using universal testing machine at crosshead speed of 0.5 mm/min until bond failure. Statistical analysis was done according to the nature of each group of data using SPSS 26. Addition of CaCl2.2H2O decreased the initial setting times of both RMPC and WMTA significantly (p<0.05). The pH values of FS-WMTA and FS-RMPC were comparable to their non-accelerated counterparts ranging from 10 to 12. Discolouration effect was more obviously observed with WMTA and FS-WMTA with time compared to RMPC formulations. Push-out bond strength of the two materials also showed an increase with the addition of the accelerator, however, only FS-WMTA showed statistically significant difference compared to WMTA (p<0.05). The addition of CaCl2.2H2O improves the physical and mechanical properties of the newly formulated RMPC and WMTA. The RMPC formulation overcomes the discolouration potential of WMTA. (EEJ-2022-12-155).

Effect of Crushed Clay Brick as Partial Replacement of Fine Aggregate in Concrete

The reuse of construction and demolition wastes, especially crushed clay bricks (CCB), represents a major contribution to the environment. Due to the nature of clay bricks, it can be considered as source of fine and coarse aggregate to produce structural concrete. This research has been conducted with the objectives of highlighting the effect of crushed clay brick as partial replacement of fine aggregate in concrete. Compressive strength of concrete made by different partial replacement of fine aggregates were evaluated on (0%,15%, 25%, 30%, 50%, and 75%). To achieve the objectives of this study, the laboratory tests have been performed. The strength of gravels has been investigated by Los Angles Abrasion test according to ASTMC 131. Sieve analysis was performed to determine the particle size distribution. The consistency and fineness test of Cimerwa cement was conducted and results of fineness of cement was 9.165%. Initial setting time was 98 minutes and final setting time was 256 minutes. The compressive strength of concrete was performed and the results at age of 28 days were 31.81Mpa, 29.38Mpa, 27.45Mpa, 24.86Mpa, 17.91Mpa and 15.84Mpa respectively. The percentage reductions for (15%, 25%, 30%, 50% and 75%) was 7.63%, 13.70%, 21.84%, 43.69% and 50.20% respectively. According to IS 456 specified minimum compressive strength of concrete after 28 days of curing is 25N/mm2 for M25 grade of concrete, with the partial replacement of 20%, the resulted compressive strength is 27.45 Mpa.

Monitoramento do período de pega de misturas de concreto com ultrassom

Abstract The setting behavior of concrete mixtures can be indirectly monitored by the penetration resistance test given by ASTM C 403. Arbitrary values of penetration resistance are associated to the initial and final set times. This test is carried out on the previously sieved mortar portion of the concrete mixture, which makes its practical use rare. Alternatively, ultrasound testing can be used to characterize this transition period, since the propagation of ultrasonic waves is greatly affected by the formation of cement hydration products and the extent of microstructure development. In this research, the propagation of ultrasonic waves in fresh concrete during the setting period was studied. In addition to the ultrasonic pulse velocity (UPV), other ultrasonic parameters such as group velocity, parameters related to ultrasonic energy and frequency were monitored during the setting period of various concrete mixes. It was observed that as setting progressed, there was a greater ease of ultrasonic transmission with a continuous increase of wave amplitudes. The results indicated that a combined analysis of the time domain parameters of UPV, group velocity and the time that 10% of energy has propagated (t10) could be used to improve the characterization of the microstructure development regarding the setting behavior of concrete mixtures.

Chemical analysis of mineral trioxide agregate mixed with hyaluronic acids as an accelerant.

Mineral trioxide aggregate (MTA) has many clinical applications in dentistry; the main drawback is the long setting. The main objective is to investigate and compare the chemical effect of using two commercially available hyaluronic acid hydrogels (HA) instead of distilled water for mixing MTA as an accelerant of setting time. Test materials were divided into three groups; Group 1: (control) mixing MTA with distilled water supplied by the manufacturer; Group 2: mixing MTA with a hybrid cooperative complex of high and low molecular weight HA (Profhilo®); Group 3: mixing MTA with High molecular weight / non-cross-linked HA (Jalupro®). Mixing time, and setting time (initial and final) were determined, Fourier-transform infrared spectroscopy, Energy-dispersive X-ray spectroscopy, Field emission Scanning Electron Microscopy, and X-ray diffraction were performed. mixing time, initial, and final setting time for (MTA + HA) groups were significantly different and lower in comparison to the control group (p < 0.05). This study revealed higher expression of calcium silicate hydrate and calcium hydroxide expression with higher Ca release in the MTA + HA group than the control group. commercially available HA demonstrated better chemical properties when used as a mixing medium for MTA. The Mixing and setting time for MTA + HA group were significantly shorter than those of the control group were. Thus, commercially available HA can be used as a mixing medium for MTA.

Utilization of textile and tannery sludges in cement mortar

The aim of this study is to investigate the characteristics of Textile ETP and Tannery sludges and strength characteristics of cement-sludge mortar. The textile Effluent Treatment Plant (ETP) and tannery sludges have the potential to become a serious environmental burden for Bangladesh in the future because of their high rate of generation, with a very limited safe disposal option. On the other hand, day by day the demand and price of cement are increasing. This study was devoted to evaluate the technical feasibility of utilizing textile ETP and tannery sludges in cement mortar both as separate and mixed modes. An attempt was taken to replace 5%, 10%, 15% and 20% by weight of cement in mortar with textile ETP and tannery sludges both as a separate and mixed modes. To evaluate the characteristics of the textile ETP and tannery sludges, the pH, moisture content, organic matter content, chemical composition (XRF), TCLP (Heavy Metal) tests were studied. The initial and final setting time, compressive strength, tensile strength, and water absorption of mortar by partial replacement of cement by textile ETP and tannery sludges both as separate and mixed modes were studied to evaluate the properties of cement-sludge mortar. It was found that the textile ETP and tannery sludges both as separate and mixed modes can be a replacement of cement up to 10% in cement mortar and can be used for the purposes of S-type of mortar. The textile ETP sludge as a separate and mixed modes of the sludges can be a replacement of cement up to 20% and can be used for the purposes of N-type of mortar.

Influence of Nickel in water on properties of Ordinary Portland Cement Concrete

The study is aimed at investigating the effect of presence of Nickel in water on setting times and compressive strength of cement concrete. In the present study, the effect of Nickel (Ni) on setting time and compressive strength of cement is assessed under laboratory conditions. The research programme included tests of setting times and Mechanical strengths up to 28 days. In this research, the cement concrete cubes were cast with deionised water and deionised water containing the Nickel ions at various concentrations. The concentrations of Nickel (Ni) tested for different samples are 10, 50, 100, 500, 1000, 2000, 3000, 4000 and 5000 mg/L. The experimental results show that the presence of Nickel in deionised water accelerate both initial and final setting times up to 2000 mg/L. Nickel in deionised water up to 2000 mg/L there is a nominal change in compressive strength at early age (3-day). Beyond 2000 mg/L there is a significant change in the compressive strength at early ages as well as 28-day. Comparison of the Nickel with those of control mix levels reveal that the presence of Nickel increases the compressive strength. The rate of increase in compressive strength is with increase in concentration of Nickel.

Influence of alkaline activator solution ratio on the properties of biomass fly ash-based alkali-activated materials

This study explored the use of untreated high-carbon biomass fly ash (BFA) and less alkaline Na2CO3 as an activator to create alkali-activated materials (AAM). This article investigated how the Na2CO3/Na2SiO3 (SC/SS) ratio of the alkaline activator solution (AAS) influenced the setting time, structural development and physical-mechanical properties of BFA-based AAM pastes that were cured at room temperature. With an increase in the SC/SS ratio, AAM pastes’ initial and final setting times shorten, respectively. The AAM sample with the lowest density and ultrasonic pulse velocity (UPV) value also has the maximum water absorption. The compressive strength of AAM samples dropped after 7 days of curing while the SC/SS ratio increased. Nevertheless, after 28 days of curing, the compressive strength of AAM samples rose with a rising SC/SS ratio. The results for density, water absorption, and UPV were corroborated by the scanning electron microscope (SEM) analyses, which demonstrated that when the SC/SS ratio rises, the structure of the samples gets denser and more homogeneous, in line with the increased compressive strength of the samples.

Rheological behaviour, setting time, compressive strength and microstructure of mortar incorporating supplementary cementitious materials and nano-silica.

The setting time of the paste and the rheological properties and microstructure of the mortar after replacing OPC cement with silica fume (SF), fly ash cenosphere (FAC) and nano-silica are studied as a reference for shotcrete applications. The suggested contents of SF, FAC and nano-silica are around 5-7.5%, higher than 20% and 1-3%, respectively, to meet the initial setting time specification. Viscosity and yield stress of mortar are highly dependent on water/cement ratio and paste/sand ratio. At the higher water/cement ratio, viscosity is more based on the paste itself. For SF of 2.5-10%, viscosity and yield stress increase, and the flowability of the mixture decreases. For FAC of 5-25%, viscosity and yield stress increase with a lower rate than SF, and flowability increases at 5% and then decreases as FAC content increases, which, however, is at the same level as the control. When SF and FAC are both added, a tortuous behavior of viscosity is shown. As nano-silica is further added, significant increases in viscosity and yield stress are shown. The compressive strengths of mortar with different supplementary cementitious materials (SCMs) at early ages are close. The difference in compressive strength after 28 days of standard curing is significant. The SF5-FAC15 group exhibits the largest increase in strength for 32.82%. At the age of 2.5 h, the macropore areas distribution of SF5-FAC25-NS1.5 test groups were 31.96%, indicating the lowest macropore area distribution. The secondary hydration reaction of supplementary cementitious materials (SCMs) continuously generates products that fill the pores, and the ultrafine filling effect of nanomaterials improves the compactness of the mortar microstructure and reduces the macropore area distribution. The mercury intrusion test results of the SF5-FAC25-NS1.5 group show that the pores are concentrated within the range of 0.01 to 0.05 μm, and the most probable pore size is significantly smaller than that of the CTR group. As the overall replacement level of SCMs increases, the diffraction peak of calcium hydroxide gradually weakens.

Potential of Local Clay for the Development of Limestone Calcined Clay Cement in East Java

Limestone Calcined Clay Cement (LC3) offers an innovative and sustainable alternative to traditional binders, utilizing calcined clay and limestone as partial substitutes for Ordinary Portland Cement (OPC) clinker. This study investigated the potential of local clays found in East Java, Indonesia, for LC3 production. Clay samples from three sites in East Java, with pure kaolin as a benchmark, were assessed. A formulation with 50% OPC clinker substitution was employed, integrating limestone powder, calcined clay, and gypsum. The clays underwent drying, grinding, sieving, and calcination at both 700°C and 800°C. For comparison, a sample of local Trass, typically used in Portland Composite Cement, was also evaluated. Compared to OPC, the LC3 samples exhibited reduced workability and a faster initial setting time. However, the LC3 mortar displayed commendable compressive strength, achieving a Strength Activity Index exceeding 75% at 28 days. The calcination temperature influenced the ultimate strength, especially in specimens with a higher kaolin concentration. One of the local clays, sourced from Trenggalek, with a kaolinite content of 49%, achieved a compressive strength of 43 MPa at 28 days. This value closely parallels the strengths of both OPC (49 MPa) and the metakaolin (42 MPa) mixtures.

The performance evaluation of protection barriers in bacterial self-healing mortar

The early age microcracking is a significant problem in concrete structures resulting in increased permeability and decreased durability. The previous work showed thatSporasarcina pasteuriicells immobilized on natural minerals such as bentonite, diatomaceous earth, sepiolite, and pumice effectively remediated early-age microcracks in the cementitious systems by triggering microbial-induced calcite precipitation (MICP). This promising approach can solve early-age shrinkage cracking in cementitious systems. Therefore, it is essential to assess the impact of self-healing additives on drying shrinkage. This study investigates the influence of mineral-based biological additives on the drying shrinkage capacity of cement-based mortar and the possible self-healing of cracks if any occur. To achieve this goal, the free shrinkage in control (containing only minerals) and bacterial (containing bio-based additive) samples were measured based on ASTM 596-18 norms. Moreover, the performance assessment of developed self-healing additives was done by determining compressive strength and initial setting time of bacterial self-healing mortar.

Development of New Composites Using Industrial by Products

In this paper thesis describes an experimental investigation of magnesium based cement mortar which consists of fly ash, magnesium oxide (MgO), magnesium Phosphate (MgPO4) and Phosphate tailings. This magnesia based cements are emerged as a viable alternative to Portland cement, with both technical and sustainability advantages. This study aims to use the mixture of cement, fly ash and magnesia. The major drawback of delayed setting time can be eliminated with the use of magnesia based cement. Hence, in this study different admixtures such as magnesium oxide, magnesium phosphate, phosphate tailings are attempted. Initial and final setting time of plain cement, fly ash cement and magnesia based cement are determined and found that the small dosage of magnesium compound reduced the setting time. Further, magnesia based cements are reported to be used along with sea water without much negative effect. In view of all these, this study proposed a magnesia based cement as an alternative for conventional Portland cement. Industrial wastes such as fly ash, and phosphate tailings are used in this study.

Physical Properties of Different Brands of Cement Manufactured in KPK, Pakistan: A Case Study

One of the key elements affecting structural concrete's strength and longevity is the cement's quality. In Pakistan, large amounts of cement are utilized in construction projects. This study appraised some physical properties of five brands of Portland cement bought from cement industries in KPK. Cement brands are investigated, including Cherat cement, Askary cement, Luckey cement, Kohat +, and Bestway cement. The composition of the cement has been recorded from the cement bags. Each initial setting time, normal consistency, final setting time, fineness, and compressive strength cement samples (collected as bags from the market) have been tested in the laboratory at three days, seven days, 14 days, and 28 days per ASTM standards. Amongst these various cement brands in KPK, we aim to investigate the best cement brands taking into consideration the above all physical test and then test these brands after three months. Taking time as a factor, the best cement quality is to be found. According to the fineness of cement, Cherat cement is found to be the best amongst all five brands of cement when tested initially, while lucky and Kohat were the least in fineness properties. Consistency tests were performed for all brands of fresh types of cement, and Cherat and Kohat have more consistency, while Askary has the least consistency. Initial and Final setting time tests were performed for all brands, and Cherat cement was found to have the more initial and final setting time, while Kohat and Askary had the least setting time. In the case of the compressive strength test, Cherat cement was found to be the greater strength, while lucky had the least compressive strength. For seven days curing. For 28 days curing Cherat cement was the best one having greater strength, while Askary had the least strength among all. All the cement brands were tested the same way after three months of age, which shows that all five brands crossed the ranges for each test. Still, it has been observed that the decrease in the fineness is small for Cherat compared to all other brands while in case of compressive strength, the decrease in Cherat is greater than all other brands.

Optimization of the Injection and Physical Properties of Sulfoaluminate Cement via the In Situ Polymerization of Acrylamide

Deep coal mining requires grouting to reinforce the coal rock walls. The conventional polymer-modified cement-based grouting materials have improved toughness but poor fluidity. The purpose of this paper was to improve the injectability of grout. The preconditions were that the physical properties of the stones are not obviously damaged and the mechanical properties are optimized. The acrylamide monomer was incorporated into the sulfoaluminate cement-based grouting material system. The effects of the in situ polymerization modification of the acrylamide on the paste properties and stone body strength were investigated. The results showed that the acrylamide mixed with the sulfoaluminate cement could increase the fluidity of the grouting material, prolong the paste setting time, and improve the flexural strength of the stone body. Compared with the blank group, the 500 mL efflux time of the 1006 mud viscometer in the 35% AM (acrylamide) dosing group decreased from 51 s to 41 s, the initial setting time increased from 15 min to 98 min, and the flexural strength at three days increased by 202.8%. The compressive stress–strain of the stone body gradually changed from brittle to ductile damage as the acrylamide dosing increased. Based on the microscopic analysis, a composite structure model of the inorganic skeleton of the flexible polyacrylamide network of toughened AFt (ettringite) was built in this paper. A mechanical study of the compressive stress–strain characteristics of the stone body was performed. It was concluded that the acrylamide in situ polymerization-modified sulfoaluminate cement-based grouting material is suitable for coal rock wall grouting reinforcement.

Preparation of architectural 3D printing material with a solid waste-derived sulfoaluminate matrix: A high-value conversion of solid waste

The preparation and development of eco-friendly building materials have emerged as feasible options for large-scale solid waste management. This research prepared a high-performance three-dimensional (3D) printing material and printed building components using the two-stage conversion of solid waste. In the first transition process, a sulphoaluminate cementitious material was produced by calcination at 1270 ℃ using industrial solid waste, including municipal solid waste incineration fly ash, flue-gas desulfurization gypsum, and aluminum ash. Then, four admixtures, namely, water-reducing agent, sodium gluconate, dispersible latex powder, and hydroxypropyl methylcellulose, were selected to improve its performance and achieve a further transition of solid waste. The effect of admixtures, standard sand, and fiber on the properties of cementitious materials was studied. It was found that the addition of appropriate proportion admixtures increased the fluidity, extended the initial setting time, and controlled the decrease of compressive strength of the materials. A 1:1 ratio of cementitious material to standard sand with a fiber length of 12 mm, generated a high-performance sulfoaluminate-based cementitious material suitable for the preparation of 3D building components. The material has a fluidity of 188 mm, an initial setting time of 53 min, one-day compressive strength of 37.8 MPa, and one-day flexural strength of 7.6 MPa. Therefore, utilizing solid waste through this two-stage transition to prepare 3D printing materials has significant economic benefits, providing valuable ideas for large-scale solid waste treatment.

Roles of recycled fine aggregate and carbonated recycled fine aggregate in alkali-activated slag and glass powder mortar

Alkali-activated materials have attracted a lot of research interest due to the advantage of less CO2 emission than ordinary Portland cement (OPC) systems. The use of recycled aggregate or carbonated recycled aggregate in new concrete is considered a good way to solve the problem of construction and demolition waste. This study aims to investigate the influences of recycled fine aggregate (RFA) and carbonated RFA (CRFA) on the properties of alkali-activated slag and glass powder mortar (AASGM). The macro properties (compressive strength, workability, setting time, and shrinkage) and microstructural properties of AASGMs prepared with RFA/CRFA were evaluated. The hydration evolutions of AASGMs and the reactions between RFA/CRFA and sodium silicate were investigated to explore the reaction mechanisms of AASGM with RFA/CRFA. The results showed that with the increase in RFA content from 0 % to 100 %, the flow value of AASGM decreased from 240 mm to 145 mm, the initial setting time was shortened by 44 %, the 7 days autogenous shrinkage decreased by 82 %, the 25 days drying shrinkage decreased by 31 %, and the 28 days compressive strength firstly increased (RFA content ≤ 50 %) and then decreased. On the contrary, with the increase in CRFA content from 0 % to 100 %, the flow value of AASGM increased from 240 mm to 270 mm, the final setting time increased by 37 %, and the compressive strength decreased by 97 %. The roles of RFA and CRFA in AASGM were different from their roles in OPC-based materials. That was because the calcium hydroxide in RFA could react with sodium silicate (SS) and increase the concentration of alkali, which accelerated the polymerization reaction of AASGM. However, the calcium carbonate and silica gel in CRFA reacted with SS and reduced the concentration of alkali, and thus the polymerization reaction of AASGM was decelerated.

Does the ultrasonic activation of calcium silicate-based sealers affect their physicochemical properties?

This study aimed to evaluate the influence of ultrasonic activation (UA) on the physicochemical properties of hydraulic calcium silicate-based sealers. Nine experimental conditions were created based on the hydraulic calcium silicate-based sealers (Bio-C Sealer, Sealer Plus BC and Bio Root RCS) and the ultrasonic activation (no activation [NA], 10 seconds, and 20 seconds). Then the experimental groups were BC-NA, BC-10, BC-20, SPBC-NA, SPBC-10, SPBC-20, BR-NA, BR-10, and BR-20. Activation was performed with an ultrasonic insert 20/.01. The mold for the physicochemical analysis was filled and evaluated according to the ANSI/ADA specification nº. 57: initial and final setting time, flow, radiopacity and solubility. Tests were also performed to evaluate pH and calcium ion release with experimental periods of 1, 24, 72, and 168 hours with a pH meter and colorimetric spectrophotometer. Data were analyzed by one-way analysis of variance and post-hoc Tukey tests. The significance level was set at 5%. The time of UA progressively delayed the initial setting time for all hydraulic calcium silicate-based sealers (p < 0.05). Twenty seconds of UA increased the mean flow values of Sealer Plus BC and Bio-C Sealer compared to NA (p < 0.05). UA did not influence the radiopacity and solubility of the tested sealers (p > 0.05). UA for 20 seconds enhanced the pH levels and the calcium ion release of Sealer Plus BC and Bio-C Sealer at 168h (p < 0.05). UA for twenty seconds interferes with some physicochemical properties of hydraulic calcium silicate-based sealers.

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

Performance of SCC Concrete with Additional Materials of Rice Husk Ash

Concrete with high ductility, workable, high strength, easy to flow without compaction, and durable is a concrete need in the future. Concrete with this quality, one of which is to make self-compacting concrete (SCC). This paper reports performance of self compacting concrete (SCC) containing rice hush ash. Rice husk ash is waste from burning rice husks. The purpose of this study was to determine the performance of SCC concrete with the addition of rice husk ash. SCC specimens were made using rice husk ash (RHA) and SCC without rice husk ash (NRHA). The specimens were made with water cement ratio 0.30. Superplastisizer used is a type Naptha 511P. The result indicated that the workability of SCC containing rice hush ash (RHA) more workable compare SCC without rice hush ash (NRHA). The initial setting time of SCC with rice hush ash more slowly compare SCC without rice hush ash. The compressive strength, flexural strength, and tensile strength of SCC RHA mor higher compare SCC without RHA (NRHA). The tensile strength value of RHA and without RHA concrete meets the tensile strength requirements of RSNI T-12-2004.