Assessment on engineering properties and CO2 emissions of recycled aggregate concrete incorporating waste products as supplements to Portland cement (original) (raw)
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sustainability, 2017
The utilization of traditional supplementary cementitious materials (SCMs) has become more intense in the concrete industry due to their better long-term properties. This research evaluates the fresh and hardened properties of concrete that was developed using a high amount of recycled aggregate (RA) incorporated with sustainable SCMs. Rice husk ash (RHA), palm oil fuel ash (POFA) and palm oil clinker powder (POCP) were used as SCMs at 10%, 20% and 30% cement replacement levels to investigate their positive role in the performance of RA concrete. The results showed that the 10% replacement level of cement by RHA produced the highest strength at all ages tested. Although POFA and POCP were found to negatively affect the strengths at an early age, the hardened properties showed improvement after a relatively long curing time of 90 days. In addition, the targeted compressive strength of 30 MPa was achieved by using SCMs at levels up to 30%. Overall, the sustainable SCMs can reduce the ...
Materials
The increasing volume of waste and the requirements of sustainable development are the reasons for the research on new waste management concepts. The research results presented in this paper show the effect of recycled aggregate on the selected properties of cement concrete. The aggregates obtained from three types of wastes are tested: recycled concrete paving, crushed ceramic bricks, and burnt sewage sludges. The recycled aggregates replaced 25% and 50% of the volume of the fine aggregate. The tested aggregates worsen the concrete mixes’ consistency and decrease, to some extent, the compressive strength of the concrete. However, the tensile splitting strength of the concrete with recycled aggregates is similar to that of the reference concrete. Using recycled aggregates worsens the tightness of the concrete, which manifests itself by increasing water penetration depth. The thermal properties of concrete are slightly affected by the type and content of the recycled aggregate. Consi...
Geoscience Frontiers, 2021
This work examines the environmental and geochemical impact of recycled aggregate concrete production with properties representative for structural applications. The environmental influence of cement content, aggregate production, transportation, and waste landfilling is analysed by undertaking a life cycle assessment and considering a life cycle inventory largely specific for the region. To obtain a detailed insight into the optimum life cycle parameters, a sensitivity study is carried out in which supplementary cementitious materials, different values of natural-to-recycled aggregate content ratio and case-specific transportation distances were considered. The results show that carbon emissions were between 323 and 332 kgCO 2 e per cubic metre of cement only natural aggregate concrete. These values can be reduced by up to 17% by replacing 25% of the cement with fly ash. By contrast, carbon emissions can increase when natural coarse aggregates are replaced by recycled aggregates in proportions of 50% and 100%, and transportation is not included in analysis. However, the concrete with 50% recycled aggregate presented lower increase, only 0.3% and 3.4% for normal and high strength concrete, respectively. In some cases, the relative contribution of transportation to the total carbon emissions increased when cement was replaced by fly ash in proportions of 25%, and case-specific transportation distances were considered. In absolute values, the concrete mixes with 100% recycled aggregates and 25% fly ash had lower carbon emissions than concrete with cement and natural aggregates only. Higher environmental benefits can be obtained when the transportation distances of fly ash are relatively short (15-25 km) and the cement replacement by fly ash is equal or higher than 25%, considering that the mechanical properties are adequate for practical application. The observations from this paper show that recycled aggregate concrete with strength characteristics representative for structural members can have lower carbon emissions than conventional concrete, recommending them as an alternative to achieving global sustainability standards in construction.
IOP Conference Series: Materials Science and Engineering, 2018
Waste and by-product materials have a negative impact on the environment due to the pollution associated with them. The conversion of these materials from useless or harmful to valuable substances by, for example, incorporating them into concrete, can thus be considered to be an issue worthy of consideration in the search to reduce this impact. This study aims to prepare and characterise the ash produced from rice husk wastes to discover the ash's effect when used as a cement replacement in recycled aggregate concrete in the presence of styrene butadiene rubber (SBR). The rice husks were burned in the oven at 550 to 650 ºC for two hours. Afterward, the rice husk ash (RHA) was characterised using X-rays, FT-IR, and grain size analysis tests. Thereafter, four concrete mixes, 0% RHA + 0% SBR, 1% RHA + 1% SBR, 3% RHA + 1% SBR, and 0% RHA + 1% SBR were made. The RHA was used as cement replacement, while the SBR was used as mixing water replacement, with percentages measured by weight for both materials. Crushed clay bricks were employed as coarse aggregate for all mixes. Compressive strength tests were carried out at 7 and 28 days. The X-ray and FT-IR results demonstrate that an amorphous form of silica with good purity was produced from the prepared RHA. For concrete mixes, the results indicate an important enhancement in compressive strength obtained by using RHA.
IRJET, 2021
The aim of this review paper is to investigate the improvement of mechanical properties of concrete by optimal replacement of cement and fine aggregate with ratio of bagasse ash (BA), Rice husk ash (RHA) and waste foundry sand (WFS) in terms of weight, which Portland cement is partially replaced by bagasse ash with Rice husk ash composition and Fine aggregate is partially replaced by waste foundry sand. Some chemical tests are required to show how they react about each other and to check the pozzolanic properties of Materials. Nowadays for emission reduction and high performance concrete production, the scientists are working on pozzolanic properties of materials. In the other case, waste Utilization would be economic and has noteworthy Result in source of global carbon dioxide (CO2) emission, and environmental pollution control. This study finds the influences on behavior of concrete with the partial replacement of cement and fine aggregate at different proportions on the mechanical properties of concrete (compressive strength, flexural strength and tensile strength).
KnE engineering, 2020
This study investigates the possible effects of incorporating different industry wastes during manufacturing of concrete, with percentages ranging from 0% to 30%, and assesses the influence of these combinations (mineral additions and recycled aggregates) on the properties of a recycled concrete comprised of these two main constituents products. Recycled concrete samples with different combinations of mineral additions at various dosages were used to determine these properties in the fresh and hardened states. The "Design-expert" methodology was used to analyse the results after 7, 14 and 28 days, identifying correlations and the effects of the different variables. The results obtained showed the advantageous effect of incorporating the pozzolana and slag into the concrete mixture at dosages of 15% and 30%, they also demonstrated the low optimal percentage of marble fillers of 5%. These findings suggest that replacing clinker with industrial waste could limit the dust and CO 2 emissions into the atmosphere during concrete manufacture, offering environmental advantages as well as conserving the natural resources of aggregate recovery from C&D wastes.
The aim of this review paper is to investigate the improvement of mechanical properties of concrete by optimal replacement of cement and fine aggregate with ratio of bagasse ash (BA), Rice husk ash (RHA) and waste foundry sand (WFS) in terms of weight, which Portland cement is partially replaced by bagasse ash with Rice husk ash composition and Fine aggregate is partially replaced by waste foundry sand. Some chemical tests are required to show how they react about each other and to check the pozzolanic properties of Materials. Nowadays for emission reduction and high performance concrete production, the scientists are working on pozzolanic properties of materials. In the other case, waste Utilization would be economic and has noteworthy Result in source of global carbon dioxide (CO2) emission, and environmental pollution control. This study finds the influences on behavior of concrete with the partial replacement of cement and fine aggregate at different proportions on the mechanical properties of concrete (compressive strength, flexural strength and tensile strength).
Sustainability
The search for new alternative materials for employment in the construction industry is necessary for more sustainable development. The construction demolition waste (CDW), as well as by-products generated by initiatives, such as slag, fly ash (FA), palm oil fuel ash (POFA), metakaolin (MK), silica fume (SF), and rice husk ash (RHA), are objects of studies in several segments of the civil construction sector. The addition of these wastes to the materials currently used to produce concrete and mortar can be one of the significant efforts to achieve more sustainable construction. The use of these wastes in the construction sector can bring considerable benefits in terms of costs, energy efficiency, and environmental and ecological benefits. Over the years, many types of research have been developed aiming at the possibility of a practical use of CDW as an aggregate and industrial by-product (FA, POFA, MK, SF, RHA) as pozzolans. Based on recent studies, this paper reviews the current s...
8th International Conference on Structural Engineering and Construction Management, 2017, 2017
Conventionally the concrete production is highly energy intensive and one of the main sources of greenhouse gas emissions in the World. The high strength concrete (HSC) is a trendy and effective solution for many structural applications. This concrete is particularly beneficial in compression members as it can endure higher stresses. In general the HSC requires the higher cement content and quality aggregates to achieve designated strength. However this process adds to the economy of the HSC production. Therefore replacement of supplementary cementitious materials and aggregates in HSC could lead to economical and sustainable manufacturing. Thus, the objective of this research is to investigate the effect of partial replacement of untreated rice husk ash (RHA) together with recycled coarse aggregate (RCA) on the engineering properties of HSC. Sixteen various mix propositions were examined by replacing the cement and natural coarse aggregates by RHA and RCA respectively to investigate the compressive and tensile strengths. Further the influences of untreated RHA and RCA on other engineering properties including air-entrainment, modulus of elasticity, workability were examined. Replacement of RCA up to 100 % did not significantly alter the strength properties of HSC. The addition of RHA up to 20% has reduce the compressive and tensile strength by only 10%.
Engineering Behavior of Concrete with Recycled Aggregate
MATEC Web of Conferences, 2016
Concrete is extensively used as construction materials in Malaysia. Concrete contributes suitable feature for construction industry for instance durability, adequate compressive strength, fire resistance, availability and is economic as compared to other construction materials. Depletion of natural resources and disposal of construction and demolition waste remarkably claim environmental threat. In this paper, the engineering behavior, durability, and concrete microstructure of recycled concrete aggregates (RCA) on short-term concrete properties were investigated. The studied concrete at design mix proportion of 1:0.55:2.14:2.61 (weight of cement :coarse aggregates :sand :water) used to obtain medium-high compressive strength with 20%, 50%, and 100% of RCA. Results show that for the same water/cement ratio, RCA replacement up to 50% still achieved the targeted compressive strength of 25 MPa at 28 curing days. Addition, at similar RCA replacement, the highest carbonation depth value was found at 1.03 mm which could be attributed to the pozzolanic reaction, thus led to lower carbonation resistance. Scanning electron microscopy microstructure shows that the RCA surface was porous and covered with loose particles. Moreover, the interfacial transition zone was composed of numerous small pores, micro cracks, and fissures that surround the mortar matrix. On the basis of the obtained results, recommendable mineral admixtures of RCA are necessary to enhance the quality of concrete construction.