Papers by Keyword: Pozzolan

Abstract: The use of huge amounts of concrete has led to an increase in the focus on High Performance Concrete (HPC). This study examined how Waste Paper Pulp Ash (WPPA) pozzolanic qualities affected HPC. WPPA was used to replace PLC at levels of 5, 10, 15 and 20%, respectively. With a characteristic strength of 50N/mm², the COREN Mix Design Manual was followed in the adoption of the concrete mix design. A 150 by 150 by 150 mm concrete cube was cast, and it was cured in water for 7, 28, and 56 days. The X-ray fluorescence (XRF) method was used to ascertain the chemical composition of the WPPA. For fresh concrete, tests for compacting factor and slump were performed; for hardened concrete, tests for density and compressive strength were performed. The concrete gets less workable (stiff) as the proportion increases, according to the workability data. The compressive strength results at 56 days revealed that 5% of WPPA exceeded the 56.56N/mm² design target mean strength, 10% of WPPA met the 50N/mm² designed target mean strength, and 15% and 20% of WPPA fell short of both the designed target mean strength and characteristic strength. SEM analysis showed that up to 5% WPPA maintains a dense microstructure and high strength in concrete, while higher WPPA levels result in increased porosity and reduced mechanical performance. In comparison to traditional HPC, 5% WPPA replacement of PLC would result in concrete that is stronger after a longer curing period.

Abstract: In the study, pozzolanic materials serve as replacements for additives, namely Palm Shell Ash (PSA), Coal Fly Ash (CFA), and Rice Husk Ash (RHA). The purpose of the study is to determine the optimum proportion of additives used in high-performance concrete. The addition of 15% PSA resulted in a strength of 69.227 MPa over a test period of 56 days, while the addition of 15% CFA yielded a strength of 69.369 MPa, and the addition of 5% RHA resulted in a strength of 59.984 MPa. The maximum concrete strength is achieved by adding 15% PSA. Correlation analysis between stress-strain indicates that aggregates exhibit higher strength compared to cement paste, mortar, and concrete, highlighting the relationship between the aggregate, cement paste, mortar components, and concrete as a composite material. Aggregate strength values found to be the highest among concrete, cement paste, and mortar, indicating that cement paste contributes the least to the strength of concrete, followed by mortar as concrete reinforcement. The results suggest that aggregates remain the primary strength component supporting concrete. The finding indicates that the relationship between the basic substances in this study aligns closely with existing theory. Moreover, it suggests that all concrete materials with pozzolan variants can classified as high-quality concrete. The optimum percentage is obtained by adding 15% palm shell ash, resulting in the highest compressive strength compared to counterparts and test objects with other types of pozzolan additions. The relationships between the constituents of concrete demonstrate that aggregates continue to be important contributors to concrete strength, with the cement paste contributing the least. Concrete strength values fall between those of aggregates and those of cement and mortar pastes.

Abstract: Pozzolan is a material that increases the strength of concrete. The pozzolan used in this study is mussel shell powder. The purpose of this study was to find out how MSP substitution affects concrete strength. Mussel shell powder (MSP) contains important levels of calcium oxide and silicon oxide (SiO₂) and used as an alternative to Portland cement (PC) to reduce the amount of PC needed to make concrete will perform. The concrete designed according to the Standard Indonesian Method (SNI) and the slump should be between 75mm and 100mm. As a prototype, he built a concrete cylinder measuring 15 cm x 30 cm. The percentage changes when replacing PC with MSP were 0%, 2%, 4%, 6%, and 8%, respectively, with 0% substitute used as the control mixture. The samples evaluated for compressive and tensile strength after 7 and 28 days, respectively. As a result, in terms of compressive strength, the best replacement level for 28-day-old concrete is 6%, with a strength value of 32.46MPa. This resulted in a 21.98% increase in force compared to control. In contrast, replacing 2% PC with MSP achieved the highest shear strength after 28 days, with a strength value of about 2.584MPa, 10.48% higher than witnessed. The two samples all have slightly different chemical group bonds O-H, CH₂, and C-H. The absorption range of the chemical bond of alkene is 1638.21cm^-1, and group functional C=O of shell concrete of 1638.21cm^-1. The group functional of C=O in the sample, but there is no functional group C in the shell.

Abstract: This paper studies the effect of both perlite and pozzolan powders as cement substituents. First, it addresses the mechanical properties of pozzolanic mortar in the short term, i.e., with a schedule of 7, 14 and 28 days. Next, in order to extend the analysis related to the porosity of the designed mortars, the water absorption is studied. The provided results indicated that the compressive strengths of the pozzolanic mortars were lower than those of the reference mortar. However, among the tested pozzolanic mortars, those containing 10% of perlite displayed superior strengths. Additionally, while the water absorption values for pozzolanic mortars were higher than those of the reference mortar, the inclusion of 10% of perlite in the mortar resulted in lower water absorption compared to the other pozzolanic mortars.

Abstract: Concretes with high fly ash content are within a unified world nomenclature often referred to as HVFAC, resp. high volume fly ash concrete. These concretes are characterized by the percentage of fly ash as an active admixture relative to a cement dose of at least in a ratio of 1:1. The use of these concretes falls into the field of construction with the necessary reduction in the development of hydration heat. In the experiment, long-term monitoring of the development of important mechanical parameters, namely the static modulus of compressive elasticity and compressive strength, was performed. Both monitored parameters play a very important role in the design of buildings, for which construction is HVFAC often used. These parameters were monitored within the carried out research until the time of 360 days. The results of the experiment give an overview of the pozzolanic reaction progress over the in the long-term time horizon and its impact on the concrete parameters monitored. The results clearly show that even after 360 days the development of the strength parameters of these concretes is not stopped.

Abstract: This work shows the results carried out by mixtures of Portland cement mortars with twoadditions: ash brick ovens (CELU) which acting as pozzolan, and ground expanded perlite (PEM)as filler. The objective of this research is to determine whether by adding a pozzolan and fillermixtures base Portland cement is possible to increase physical and mechanical behavior. There were3 mixtures: the control and 2 more: one with substitution of 7% CELU, and other with 7% CELU+5%PEM respectively, carrying out tests of normal consistency, setting, fluency, simple compression,indirect tension, ultrasonic pulse velocity and electrical resistivity at the ages of 3, 7, 14, 28 and 120days. The results were favorable in the mixture that incorporates both materials (CELU+PEM).

Abstract: The use of dehydrated fibres of cactus, Opuntia ficus-indica (FN), and starch (corn starch,Zea Mays (MZ)) as partial substitutes for the total mass of Portland Cement (CP) in the making ofmortar, aims at modifying its physical and mechanical properties, reducing the amount of cementand the CO2 emission. Four mixtures of CP mortar were designed incorporating a superplasticizeradditive with a water/cement weight ratio of 0.68. To compare the results, there was a controlmortar; two mixtures with partial substitutions using fibres of FN, 0.5 and 1.5% (in weight of CP)respectively; and a substituted mixture with 2% of corn starch plus 0.5% of cactus fibre (MZ - FN).The test age was 180 days. The specimens were subjected to an accelerated attack of sodiumsulphate, quantifying the electric resistivity (ER) and the ultrasonic pulse velocity (UPV). Theresults indicate that the substitution of the materials, remarkably densify the cement matrix, whichresults in the improvement of the physical properties and the durability.

Abstract: Applications of agricultural by-product as substitute for non-renewable material in cement production are desirable in stimulating socio-economic development. In this study, Rice Husk Ash (RHA) blended cement was produced by replacing 5%, 7%, 11.25%, 15%, 20.25% and 25% by weight of Ordinary Portland Cement (OPC) clinker with RHA. The cement without RHA serves as the control. The chemical compositions of RHA, OPC-clinker and the blended cements were determined using X-ray fluorescence analyzer. The physical characteristics of RHA blended cements that were considered are fineness, soundness, consistency, initial and final setting times and compressive strength at 2, 7, 28, 56 and 90 curing ages. The results showed that RHA is a suitable material for use as a pozzolan as it satisfied the minimum requirement by having the sum of SiO₂, Al₂O₃ and Fe₂O₃ of more than 70%. Incorporation of RHA led to an increase in the composition of SiO₂ and reduction in that of CaO. An increase in RHA content showed a decrease in compressive strength at early ages and slightly increase at a later age (90 days). The blended cement produced with lower levels of RHA replacement conforms to standard specifications specified in BS EN 197-1:2000, NIS 439:2000 and ASTM C 150-02. The minimum Strength Activated Index (SAI) of 75% at the age of 28 days of curing as specified by ASTM C 618 was satisfied by RHA replacement of up to 15%. It was concluded that blended cement with the maximum of 15% RHA content is suitable for use for structural purposes.

Abstract: Cement is currently the most versatile and widely used material in construction. However, the high carbon emissions and energy consumption associated with the manufacture of cement remains a serious concern. bagasse ash (BA) is a secondary waste product of bagasse-fired power generation. This study investigated the use of BA as a replacement for cement as a means of reducing the environmental impact of concrete-based construction. At 28 days, we measured the water absorption of cement mortar specimens as well as the compressive strength at room-temperature and after heating. Experiments were conducted involving the replacement of various proportions of cement using BA and fly ash (FA), followed by a comparison of the physical properties. Our test results demonstrate the applicability of BA in the production of cement mortar mixtures with high water-binder ratios. It was found that the water-binder ratio determines the optimal proportion of BA when used as a replacement for cement, wherein a higher water-binder ratio means that more of the cement can be replaced with BA. In compressive strength respect, the optimal cement replacement with BA was 15 % to 25 %, whereas the optimal cement replacement with FA was 20 %. BA was shown to have a more pronounced effect in reducing water absorption in cement mortar specimens with high water-binder ratios (0.55 to 0.65). The compactness of specimens with lower water absorption enables them to retain more of their initial compressive strength following exposure to high temperatures.

Abstract: Using high temperature fly ash for his pozzolan properties to cement composite production is known a few years ago. New ways combustion of fossil fuels also creates a new type of fly ash, named fluidized bed combustion fly ash. However, this fly ash has same pozzolan properties as has high temperature fly ash, this type is not using for production of cement composites. Fluidized bed combustion fly ash has highly variable chemical composition but usually it has a higher amount of free CaO together with sulphates. This higher amounts of free CaO after mixing of fluidized bed combustion fly ash with water to some extent becomes an activator for the beginning of the pozzolanic reaction, during which is consumed the extinguished CaO. If there is also present high temperature fly ash in cement composite, it could be accelerated his pozzolanic reaction in the same manner using a fluidized bed combustion fly ash. In this experiment was tested a synergy effect in the use of fluidized bed combustion fly ash with high temperature fly ash as an additive. The experiment was carried out on cement pastes that have been studied in particular the progress of hydration processes, pointing to a possible acceleration of pozzolanic reactions of both types of fly ash.