Partial Replacement Of Ordinary Portland Cement Research Articles

Suitability of rapid chloride migration tests for determining the migration coefficient in mortars made from different novel binder types

AbstractThe main cause of corrosion of reinforcing steel, especially in infrastructure structures, is the penetration of chlorides, which can lead to high corrosion rates at the reinforcement steel. A frequently used accelerated test method to evaluate the chloride penetration resistance of concrete and mortars is the rapid chloride migration (RCM) test. The test was initially developed for ordinary Portland cement (OPC) based materials and involves spraying an indicator solution onto split test specimens to determine the penetration depth of the chloride ions. The pore solution compositions of new types of binders differ from OPC‐based materials, which can affect the reaction of the indicator solution. To investigate the suitability of the RCM test, the chloride content in the depth of the color change was determined in mortars made from different types of novel binders. The results show that the test provides reliable results for the binder types with partial replacement of OPC by supplementary cementitious materials. For binder types without OPC, there is a deviation in the migration coefficient due to a differing chloride concentration that triggers the color change.

Service life modelling of carbonated reinforced concrete with supplementary cementitious materials considering early corrosion propagation

The importance of considering corrosion propagation in service life design of carbonated concrete with supplementary cementitious materials (SCMs) has been highlighted by the decline in carbonation resistance caused by partial replacement of ordinary Portland cement (OPC) with SCMs. This study proposes a novel Carbonation-induced Early Corrosion Propagation based Service-life Assessment Model (CECP-SAM) for carbonated SCM concrete, which is characterized by the considerations of semi-carbonation zone and macrocell corrosion in corrosion propagation with an incipient crack as end of service life. Experimental and field data were used to verify CECP-SAM. The effects of exposure conditions, SCM replacements, water/binder ratio, cover thickness, rebar diameter, semi-carbonation zone and macrocell corrosion on service life are presented. Results indicate that the partial replacement of OPC with pulverized fuel ash (PFA) and ground granulated blast furnace slag (GGBS) can significantly decrease service life from 66 years to 8 years and 17 years, respectively. Corrosion propagation can result in a 91% reduction in service life but service life can be extended from less than 20 years to more than 90 years by considering early corrosion propagation. Practical equations are proposed to facilitate performance-based service life design. Prescriptive limits are also provided for service lives of 50 and 100 years.

Numerical Study of Potential Delayed Ettringite Formation in Cemented Nuclear Wasteforms

This paper presents a numerical study to investigate delayed ettringite formation (DEF) that may pose a long-term durability risk by altering the microstructure with consequent swelling leading to cracking. A chemo–thermal model is used to predict the evolution and distribution of temperature and hydration phases in a wide range of blended cements. In particular, the influence of nuclear waste loading, waste package size, and the addition of supplementary cementitious materials (SCMs) on DEF is systematically and numerically investigated. The analyses show that higher amounts of ordinary Portland cement (OPC) and waste loadings result in higher hydration temperatures and consequently increased DEF potential by enhancing sulfoaluminate dissolution and hydrogarnet precipitation. Partial replacement of OPC with SCMs reduced hydration heat and mitigated DEF risks. The analysis indicated that the DEF evolution may be different for waste packages of different sizes due to a shift from sulfate-controlling to aluminate-controlling reactions at high temperatures. Interestingly, higher temperatures did not necessarily induce higher DEF potential due to the excessive precipitation of aluminates in the form of hydrogarnet. This research enriches our understanding of DEF’s complex behavior, providing valuable insights for engineering applications beyond civil engineering, such as nuclear waste conditioning.

Effect of harsh environment on ‎cement mortar ‎containing natural pozzolans

This investigation aims to study the effect of the harsh environment on cement mortar containing pumice powder (natural pozzolana) as a partial substitute for ordinary Portland cement (OPC). The harsh environmental conditions applied in this study consisted of seawater supplemented with 5% of sodium sulfate (Na2SO4). Mortar mixtures were produced by replacing 0%, 5%, 10%, and 20% of the OPC mass with natural pozzolana (NP). Mortar samples were treated under two conditions. First, the mortar samples were immersed in tap water. Second, mortar samples are immersed in harsh environmental conditions. In the harsh environment, mortar samples were subjected to 90 cycles of dry-wet, 48-hour drying, and 48-hour wetting over a period of 360 days. Compressive strength, flexural strength, strength loss, change in length, water absorption, and initial surface absorption tests were performed on specimens aged 7, 28, 90, 180, and 360 days. Besides thermogravimetric and microstructure analysis of cement samples that were conducted at a test age of 180 days. The inclusion of NP as a partial replacement of OPC at a rate of 10% improved the results of compressive and flexural strength and achieved the lowest rates of porosity and water absorption of the mortar samples. The inclusion of NP as a partial replacement for OPC reduced the damage caused by the harsh environment.

Stabilization/solidification of heavy metal-contaminated marl soil using a binary system of cement and fuel fly ash.

The stabilization/solidification (S/S) method is one of the most effective remediation techniques for treating contaminated soils. Several stabilizers, mostly the cementitious materials, have been used for the S/S treatment. In this paper, the feasibility of utilizing fuel fly ash (FFA) as a partial replacement of ordinary Portland cement (OPC) for the S/S treatment of marl soil contaminated with heavy metals was investigated. Two industrial waste materials, namely steel and electroplating wastes, were used to synthetically contaminate the marl soil. The stabilizers comprising of OPC and FFA were mixed with the contaminated soil at different dosages ranging from 10 to 40%, by mass, and a total of 48 S/S-treated soil mixtures were prepared. A series of experiments, including density, porosity, permeability, unconfined compressive strength (UCS), and toxicity characteristics leaching procedure (TCLP), were carried out on the soil mixtures to evaluate the efficiency of the proposed S/S treatment. Test results showed that the incorporation of FFA at higher volumes reduced the density and increased the porosity and permeability of the treated mixtures. Although FFA addition resulted in reducing the UCS values by an average of 46%, and this reduction was more significant at higher FFA percentages, the UCS values of all mixtures were more than 0.35 MPa (350 kPa), which passed the minimum requirements set by USEPA. In addition, the metal immobilization ability of the proposed treatment was confirmed by the TCLP analysis. As compared to the negative effect of the contamination of the soil by the electroplating waste, the contamination of the soil by steel waste had a higher negative effect. The results of this study would contribute in selecting an environment-friendly treatment of the contaminated soils using industrial waste materials, such as FFA, as a partial replacement of OPC. Nevertheless, the present study is an initial attempt to explore the possibility of utilizing FFA as a partial replacement of OPC in S/S treatment of marl soil contaminated with heavy metals. It is recommended to conduct another study in future including analysis of the treated soil mixtures using XRD, SEM, and FTIR techniques to better understand the stabilization/solidification mechanism and its implications on the test results.

Effect of manufactured sand, micro silica, and GGBS on properties of high-performance concrete

The most often used building material for engineering constructions is concrete. The rapid urbanization has necessitated the need for High Strength (HS) and High -Performance Concrete (HPC) for specialized constructions, such as high rise/tall structure and other important structures. Greater cement content may be required for concrete with higher performance like strength and durability, but code does not permit it, because higher cement content increases the heat of hydration, which leads to the development of thermal cracks in concrete, reduces its structural performance and damage environment by producing CO2 during production of Ordinary Portland Cement (OPC). This study tries to replace OPC by Micro Silica (MS) and Ground Granulated Blast Furnace Slag (GGBS) by some percentage to find our effect of these materials on properties of concrete HPC.In this work, the influence of Manufactured Sand (M-Sand), Micro Silica (MS) and Ground Granulated Blast Furnace Slag (GGBS) on the mechanical and durability qualities of High - Performance Concrete (HPC) is examined experimentally. Ordinary Portland cement (OPC) is used to create the HPC mixtures and then 40%,45%, 50% by weight of OPC is replaced with GGBS and 2.5% and 5% by weight of OPC is replaced with MS respectively. Additionally, OPC is replaced by 40%GGBS+ 2.5% MS, 40% GGBS+5% MS, 45%GGBS+ 2.5% MS, 45% GGBS+5% MS, and 50%GGBS+ 2.5%MS, 50%GGBS+5% MS. For each percentage replacement workability test, compressive test at the age of 28,56 and 90 days, water permeability test at 28 days and 90 days, Scanning Elector Microscope (SEM) test after 90 days are carried out. The investigative study’s findings showed that partial replacement of OPC with GGBS, MS, and combinations of GGBS and MS produces more consistent outcomes for strength and durability when compared to control mix.

Shrinkage behaviour of self-compacting concrete with a high volume of fly ash and slag experimental tests and analytical assessment

This study assesses the effectiveness of the high-volume replacement of Ordinary Portland cement (OPC) by non-clinker binders in terms of shrinkage behaviour. Fly ash (FA) or granulated blast furnace slag (GBFS) was used as a partial replacement for OPC at 60% by volume of the paste in self-compacting concrete (SCC). SCC having both FA (30%) and GBFS (30%), as well as SCC only with OPC, were also investigated. In all tested self-compacting concretes, the volume of the paste, which determines the shrinkage strains, was preserved. The shrinkage behaviour of SCCs was tested in shrinkage drains, bending drains and shrinkage rings. The total effect of autogenous and drying shrinkage under different drying conditions, also with the additional heating of the concrete samples was analysed. The strains were registered in the early stage of concrete curing, directly after mixing all concrete components, as well as in the later period, up to 28 days. The results indicate that the applied high volume of supplementary cementitious materials in self-compacting concrete (SCC) significantly reduces the shrinkage strains in comparison to SCC only made of OPC. Simultaneously, fly ash replacement is found as the most effective in reducing the free shrinkage of self-compacting concrete. The registered shrinkage development also shows the significant role and the level of very early shrinkage, which decided the values of 28-day strains. In the analytical part, the results from three used testing devices were compared with each other to confirm the effect of the non-clinker components on the shrinkage behaviour. Additionally, the results have been related to the Eurocode 2 and ACI shrinkage models, as well as the method for calculation of the differences in the shrinkage strains between the bottom and top surface of the sample based on measurements in the bending drain was presented.

Spalling mitigation techniques for high-performance concrete at elevated temperature

High-performance concrete (HPC) is highly susceptible to temperature-induced spalling, which unveils severe damage of HPC structural members. Therefore, this research work is aimed at developing spalling mitigation techniques for HPC and experimentally assessing spalling behaviour at transient heating conditions up to 1000 °C for a 4-hour fire resistance rating. A total of four HPC mixes were comprised for spalling behaviour evaluation, in which Mix H1 was designed only using main binder ordinary Portland cement (OPC), whereas Mix-H2, Mix-H3, and Mix-H4 were designed by partial replacement of OPC with three different supplementary cementitious materials (SCMs), i.e., fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBS) one at a time as a binary composite system. Polypropylene (PP) fibres and steel (ST) fibres one at a time from a range of 0.00, 0.62, 1.24, 1.86, and 2.48 kg/m3 and ST fibres range of 0.00,12.43, 24.87, 37.30, and 49.74 kg/m3 were incorporated into HPC mixes for evaluating spalling mitigation behaviour at elevated temperature. For each HPC mix, a total of three standard cylindrical specimens (100 mm diameter × 200 mm height) were exposed to transit temperature 1000 °C for up to 4 h to assess spalling behaviour. It is observed that Mix-H1 content only OPC does not reveal any severe damage and spalling behaviour, whereas Mix-H2, Mix-H3, and Mix-H4 comprising SCMs revealed very severe damage and spalling behaviour. This result indicates that the highly dense microstructure with a highly durable HPC matrix using SCMs does not allow any moisture movement/migration from the inherent concrete binding matrix to the outer exposed surface of cylinder specimens and resulting in explosive-type spalling of HPC. However, using 1.86 kg/m3 of PP fibres and 37.30 kg/m3 of ST fibres in HPC binary systems has a positive impact on mitigating spalling of HPC at elevated temperatures.

Influence of limestone calcined clay cement on properties of 3D printed concrete for sustainable construction

The research on emerging digital construction techniques, particularly the 3D concrete printing of cement-based materials, is imperative owing to the several economic, environmental, and societal benefits it offers over conventional cast-in-place concrete. In this study, limestone calcined clay cement (LC3) was utilised for 3D printed concrete (3DPC) production towards sustainable composite infrastructure by replacing up to 50% of ordinary Portland cement (OPC) with limestone and calcined clay (LC2). The fresh, rheological, and hardened mechanical properties of fibre-reinforced 3DPC were investigated. Six different 3DPC mixes were made for these purposes: the control (no LC2), four mixes with 1.0, 0.91, 0.8, and 0.6% superplasticiser (SP) dosages, and the last mix without micro-synthetic polypropylene fibre. Findings revealed that achieving a slump of less than 10 mm and a slump flow between 140 and 160 mm as required by relevant standards (ASTM C1437 & C230/C230 M) is crucial in obtaining an extrudable 3D concrete mixture. A finite flow value and satisfactory rheological properties are achieved in mixes C (with 0.6 SP), D (0.8 SP), and Dadj (0.91 SP) to produce a feasible 3D printable cement-based concrete mixture. Test results validated the promise of LC2 as a partial replacement for OPC in digital concrete depending on the testing orientations of the printed samples. Buildability performance using a gantry-type 3D printer was conducted and the significant orthotropic phenomenon was indicated in the compressive properties of printed samples. The presence of fibres toughened the cylindrical strength perpendicular to the layer-interface-plane and enhanced the bearing load in tension and flexure, thereby making the direction 1 (D1) interfacial flexural/tensile bearing capacity comparable to cast-in-situ 3DPC samples.

Investigation into the Effect of Rice Husk Ash in Partial Replacement of Cement in Concrete

The purpose of this study was to investigate the properties of Rice Husk Ash (RHA) as a partial cement replacement material in concrete production based on analysis of its contribution to strength in comparison with Ordinary Portland Cement (OPC). The analysis was focused on: the chemical properties of RHA, workability, density, compressive strength, and tensile strength of concrete. The RHA was obtained from Mwea, Kirinyaga County, Kenya and burned in a kiln to produce white ash which was tested. Chemical analysis to determine the pozzolanic properties of RHA was done using the Gravimetric method, Flame Photometry and Atomic Absorption Spectroscopy while particle size distribution of RHA was carried out using sieve analysis and hydrometer analysis. Concrete mixes with different ratios of OPC to RHA binder were cast into cuboid and cylindrical samples. The binder was made by replacing OPC with RHA at intervals of 10% by mass to a maximum of 50% replacement. A binder, sand, and ballast ratio of 1:1.5:3 were maintained with a constant water-cement ratio of 0.6. The cast samples were subjected to water curing on the third day at room temperature. Workability tests were performed on fresh concrete while compressive strength tests and tensile strength tests were performed on hardened concrete in all the mixes. The results were compared with OPC concrete. Results indicated that Kenyan RHA has high silica, alumina, and iron oxide content of about 92%. The workability slightly improves with 10% partial replacement of OPC with RHA but decreases with further addition of RHA. It was also deduced that the optimal binder mix was 10% partial replacement of OPC with RHA however the compressive strength was lower than the OPC concrete by 2.3%. The tensile strength of concrete increased with the addition of RHA up to an optimum of 10%.

Properties of Laterized Concrete Incorporating Sawdust Ash as A Partial Replacement for Cement

Ordinary Portland cement (OPC), the main binder in concrete, is the most expensive component and the major contributor to the embodied carbon of the composite. This necessitates alternative eco-friendly materials such as waste, with comparative binding properties as a part replacement for OPC to have economic and sustainable concrete production with minimal hazardous impact on the environment. This study uses Sawdust Ash (SDA) which is a waste product of the wood milling industry, to replace some proportion of OPC in concrete. To further reduce the cost and negative environmental impact of concrete, laterite was used to replace river sand, and fresh and hardened properties were investigated. The fresh property evaluated in this study is the slump, while the hardened properties investigated are the density and compressive strength. This study showed the viability of successfully incorporating SDA as a partial replacement of OPC and laterite soil to replace the conventional fine aggregate. An acceptable slump and compressive strength can be achieved using 10% SDA and 45% laterite as partial replacement of OPC and river sand, respectively.

Experimental Investigation on Concrete Using Agricultural Waste Ash-A Review

The present study is aim to develop a high strength concrete bye using mineral admixtures of bamboo leaf ash and pawpaw leaf ash. In order to check the compatibility, physical and chemical properties of materials are studied. This aims to provide a comprehensive review of recent trends incorporating biomass ashes from agricultural waste in ordinary Portland cement(OPC).The material properties of different leaf ashes and their effect on fresh and hardened concrete properties are review. Partial replacement of OPC with by products, such as bamboo leaf ash, pawpaw leaf ash. Partial replacement of OPC with by products, such as bamboo leaf ash, pawpaw leaf ash. It will also contribute to the effort of achieving zero waste technology and sustainable development.

Bermuda grass ash as a sustainable cementing material in concrete for ethiopian construction industry

The general constituent materials of concrete are a binding material, fine aggregate, coarse aggregate and water. Ordinary portland cement (OPC) is the common form of binding material used in concrete which acts as a bonding material for the fine and coarse aggregate. However as OPC is a major contributor of CO2 creating several environmental issues, researchers are now are keen to find out alternative cementing materials which can partially or fully replace OPC in concrete. This research paper presents the suitability of Bermuda Grass Ash (BGA) which is abundantly available in Ethiopia as an alternative cementing material in concrete. For this research work C-25 grade of concrete has been used. Physical and chemical properties of BGA were studied to initially identify the suitability of this material as a cementing material. Further the mechanical and durability properties of concrete with BGA as a cementing material was studied. Concrete test specimens with different percentages of BGA (0%, 5%, 10%, 15% and 20%) as a partial replacement of OPC were prepared and tested for their mechanical and durability properties at 28 days of curing. Workability test was conducted as part of the fresh properties of concrete and at hardened state, the density, compressive strength, abrasion resistance and water absorption of concrete were studied. The test results showed that, BGA when used as a partial replacement of cement upto 10%, the strength limit of concrete remains within that of C25 grade concrete (26.62 MPa). Inclusion of BGA as a cementing material helped in enhancing different durability aspects of concrete. Hence it can be concluded that optimum uses of BGA as a cementing material in concrete can be a sustainable approach for construction industry in Ethiopia.

Performance of GGBS Cement Concrete under Natural Carbonation and Accelerated Carbonation Exposure

One of the primary problems related to reinforced concrete structures is carbonation of concrete. In many cases, depth of carbonation on reinforced concrete structures is used to evaluate concrete service life. Factors that can substantially affect carbonation resistance of concrete are temperature, relative humidity, cement composition, concentration of external aggressive agents, quality of concrete, and depth of concrete cover. This paper investigates the effect of varying the proportions of blended Portland cement (ordinary Portland cement (OPC) and ground granulated blast-furnace slag (GGBS)) on mechanical and microstructural properties of concrete exposed to two different CO2 exposure conditions. Concrete cubes cast with OPC, and various percentages of GGBS (0%, 30%, 50%, and 70%) were subjected to natural (indoor) and accelerated carbonation exposure. The aim of this paper is to present the research findings and authenticate the literature results of carbonation by using GGBS cement in partial replacement of OPC. The concretes with OPC are compared to concretes with various percentages of GGBS, to assess the carbonation depth as well as rate of carbonation of GGBS-based concretes, under both accelerated carbonation and natural carbonation exposure conditions. Even though GGBS cement increases the carbonation depth, the results are not the same with different GGBS replacement percentages. A correlation is made between concrete samples exposed to 15 ± 2% carbon dioxide (CO2) concentration and those exposed to natural CO2 concentration. The results reveal that the products formed by carbonation are similar under both exposure conditions. The experimental tests also revealed that GGBS cement concrete has a lower carbonation resistance than OPC concrete, due to the consumption of portlandite by the pozzolanic reaction. The combination of 70% OPC and 30% GGBS behaved well enough with respect to accelerated carbonation exposure, the depth of carbonation being roughly equivalent to that of control group (100% OPC). The results also show that rate of carbonation becomes more sensitive as the percentage of GGBS replacement increases (binder ratio), rather than duration of curing. Concretes exposed to natural carbonation (indoor) achieved lower carbonation rates than those exposed to accelerated carbonation.

Determining the Ultrasonic Pulse Velocity (UPV) of Cement Mortar with Partial Replacement of OPC with CKD and SF

A significant number of researches pointed to the serious environmental and health effects of the Ordinary Portland Cement (OPC), including the harmful emissions and alkaline wastewaters. Therefore, the development of eco-friendly alternatives for the OPC is one of the priorities of nowadays studies. However, the suggested eco-friendly alternatives to the OPC might possess negative influences on the properties of the concrete. This research aims at investigating the applicability of by-product materials, such as cement kiln dust (CKD) and silica fume (SF), as an alternative to OPC in the cement mortars. The mortar specimens were mixed with 0 to70% CKD with SF (equal values) as a partial replacement for cement. The hardening samples have been tested by the UPV test at ages 1 week to 4 weeks. The results indicated that high ratios of CKD and SF replacements result in a slight decrease in the pulse velocity of specimens, while small replacement ratios show improvement in these properties. Time of curing is very important in improving the properties of the hardening mortars. Using a small amount of CKD and SF (20-30%) could improve the durability of cement mortars and it seems to be reasonable value in mixers.

Assessment of the long-term leaching characteristics of cement-slag stabilized/solidified contaminated sediment

The use of stabilized/solidified (S/S) soils and sediments as sustainable construction materials is a global concern due to the potential risk of contaminant leaching including potentially toxic elements. The long-term leachability of four metals (Zn, Pb, Cd and As) in sediments mixed with OPC (Ordinary Portland Cement) and OPC/GGBS (Ground Granulated Blast Furnace Slag) binders were investigated through a combination of tank leaching tests and kinetic leaching models, with varying ranges of curing ages and ambient pH. The leaching data revealed that both binder compositions offer an excellent immobilization capacity for the four metals, while their releases are strongly pH-dependent and are a complex function of curing time. The partial replacement of OPC by GGBS is more effective for fixing Zn and As at pH of 1, Pb at pH of 7, Zn and Pb at pH of 10. Controlling leaching mechanisms and leachability indices were determined using nonlinear regression analysis and kinetic leaching models. The first-order diffusion model (FRDM) was the most applicable model for describing the leaching characteristics of these metals under the investigated cases, the leaching rate is controlled by surface wash-off initially and then by diffusion. The leachability indices indicate that the cement-slag S/S sediment can be regarded as an environmentally sustainable material with potential beneficial uses in construction.

EFFECTS OF USING SEAWATER IN THE MIXING AND CURING OF CONCRETE

The U.N. evaluates that in 2050 the world population will increase about three point five billion, mostly in evolving countries that have underwent potable water crises. Furthermore, over half of the world population will unable to provide sufficient amounts of drinking water. Consequently, it is absolutely crucial to study ways to save freshwater. The use of seawater, which accounts for 97 percent of all the water present on Earth, is very essential. This thesis studies the use of seawater instead of freshwater in the mixing and curing of structural concrete in order to reduce future water shortage and aid in the evolution of concrete technology. Concrete mixed and cured with seawater is studied in terms of fresh and hardened properties. Results include an expected early accelerated rate of gain in compressive strength and presumably no direct effect on the rate of corrosion of reinforcement when compared to concrete mixed and cured with freshwater. Also, the type of concrete’s effect was studied by using ordinary Portland cement (OPC) and by partial replacement of OPC with Blast-Furnace Slag Cement (BFSC).

Assessment of packing, flowability, hydration kinetics, and strength of blended cements with illitic calcined shale

The effects of two illitic calcined shales as supplementary cementitious materials (SCMs) on the performance of ordinary Portland cement (OPC)-based pastes and mortars were investigated. The packing density of blended cement pastes and mortars were predicted with compressible packing model (CPM). The water film thickness (WFT) and flowability were calculated and measured. Early hydration was described by calorimetric curves and the hydration microstructure was identified by X-ray diffraction (XRD), differential thermal analysis (DSC/TG), and pore size distribution (MIP). The compressive strength was tested at 2, 7, 28, and 90 days. The results showed that the partial replacement of OPC by illitic calcined shale decreased the packing density and the flowability of cement pastes but this does not occur for standard mortars. For blended cements, the hydration products were similar to that corresponding to OPC, the pozzolanic reaction contributed from 28 days to the densifying of solid structure and it was also noticed the pore size refinement that improved the compressive strength at later age.

Physico Mechanical Properties of Bricks Manufactured using Cement Kiln Dust

the actual increase in global industrial production and manufacturing, produces a continuous increase in amount of industrial waste and continues to emit an all-time high amount of air pollutants and greenhouse gas emissions. To fight and mitigate these phenomena, proper Waste Management became the pillar of most environmental strategies worldwide. By reduction of consumption, re-use of goods and recycling of products, waste management aims to preserve the resources and to protect the environment. The Cement industry is one of the most important industrial sectors for society development; however it also has significant negative environmental impacts due to its emissions and production of waste. Cement kiln dust (CKD) is an industrial waste or by product which results from cement manufacturing. CKD is fine grained, solid, highly alkaline particulate material chiefly composed of oxidized, anhydrous, micron-sized particles collected from electrostatic precipitators during the production of cement clinker. This research examines the effects of using large amounts of CKD to replace the cement content in the fabrication of solid cement bricks. It is triggered by the quadruple objectives of reducing the amount of cement consumption, disposing efficiently of its industrial waste and producing economic bricks with safe strength. The purpose of this paper is to assess the properties of solid cement bricks containing different amounts of CKD. Cement bricks produced using different amounts of CKD were tested to find their properties and final comparison has been made to identify the effect of using different CKD/Cement ratio on the performance of bricks compared to the reference specimen produced using cement only with no CKD. For the brick mixes, Ordinary Portland cement (OPC), with two cement content of 200kg/m3 and 250kg/m3 were used throughout this investigation. The physical properties; unit weight, water absorption and mechanical properties; compressive strength, flexural strength, of the produced bricks were determined. Results showed that partial replacement of OPC with CKD reduces the brick compressive strength by 18% to 23% for CKD/OPC ratio of 30% and by 36% for CKD/OPC ratio of 50% and in all cases the strength remains largely higher than the standard limit for load bearing bricks.

Sugarcane bagasse and rice husk ash pozzolans: Cement strength and corrosion effects when using saltwater

The production of ordinary Portland cement (OPC) contributes to the release of harmful greenhouse gases. In an effort to reduce these emissions, this study explores biomass materials to evaluate their use as partial replacements for ordinary Portland cement. Rice husk and sugarcane bagasse are agricultural waste products and large amounts of these are currently landfilled, making them inexpensive and available. When combusted at high temperatures they form rice husk ash and sugarcane bagasse ash with pozzolanic characteristics. The high silicon dioxide levels in these products make them good options to use as partial replacement for OPC. Replacement with 20% rice husk ash or 10% sugarcane bagasse ash give similar compressive strength and corrosion resistance for hardened cement paste samples compared to control OPC samples, if appropriate amounts of plasticizer are used. Porosity as measured by water adsorption trended higher with increased water to cement ratio due to replacement of cement with pozzolan, since water to binder ratio remained constant at 0.45:1. This study used saltwater in the mix, to investigate the use of a resource that requires less energy use in ocean-bordering areas.