Influence of Using High Volume Fraction of Silica Fume on Mechanical and Durability Properties of Cement Mortar

The high pollution caused by CO2 emission and the high level of energy consumed during cement manufacturing led the researchers to look for alternative techniques to reduce these environmental effects. One of these techniques includes reducing the content of cement in the mix by replacing it with supplementary cementitious materials such as fly ash, slag, silica fume, and so on. Many previous studies dealt with the utilizing of the high volume of supplementary cementitious materials, such as fly ash and slag. However, limited studies investigated the impact of silica fume on mortar or concrete properties in percentages of more than 30%. Thus, to produce environmentally friendly concrete, this study was performed to investigate the effect of the high replacement level of cement with silica fume on the properties of cement mortar. Six replacement proportions of silica fume (0%, 30%, 40%, 50%, 60% and 70%) were used in this paper. This paper used the flow rate, compressive strength, water absorption, bulk density and volume of permeable voids tests to test the effect of silica fume on different mortar characteristics. The results indicated that the best mixture among all other mixes was found by 50% substitution of silica fume. At this percentage, an enhancement in compressive strength of nearly 83%, 74% and 75% at 7, 28 and 56 days, respectively and an improvement in water absorption resistance by 8% compared to the control mixture were achieved

Future of clay-based construction materials – A review

Sustainability in the manufacture of different construction materials raises many important issues. Nowadays, there is increasing demand for such materials to be produced using environmentally friendly, low energy consuming production methods. This paper presents a review of the current research relating to the use of various production techniques for clay-based construction materials. The techniques which will be reviewed are: blending and stabilising, alkali activation (geopolymerisation) and the use of microwave heating as an innovative sintering, curing and drying method. The advantages and disadvantages of each technique will be discussed. Additionally, a comparison between the environmental and economic aspects of the studied production techniques along with some suggestions to improve the sustainability of different production techniques will be discussed

The Development of a Low Carbon Cementitious Material Produced from Cement, Ground Granulated Blast Furnace Slag and High Calcium Fly Ash

This research represents experimental work for investigation of the influence of utilising Ground Granulated Blast Furnace Slag (GGBS) and High Calcium Fly Ash (HCFA) as a partial replacement for Ordinary Portland Cement (OPC) and produce a low carbon cementitious material with comparable compressive strength to OPC. Firstly, GGBS was used as a partial replacement to OPC to produce a binary blended cementitious material (BBCM); the replacements were 0, 10, 15, 20, 25, 30, 35, 40, 45 and 50% by the dry mass of OPC. The optimum BBCM was mixed with HCFA to produce a ternary blended cementitious material (TBCM). The replacements were 0, 10, 15, 20, 25, 30, 35, 40, 45 and 50% by the dry mass of BBCM. The compressive strength at ages of 7 and 28 days was utilised for assessing the performance of the test specimens in comparison to the reference mixture using 100% OPC as a binder. The results showed that the optimum BBCM was the mix produced from 25% GGBS and 75% OPC with compressive strength of 32.2 MPa at the age of 28 days. In addition, the results of the TBCM have shown that the addition of 10, 15, 20 and 25% of HCFA to the optimum BBCM improved the compressive strength by 22.7, 11.3, 5.2 and 2.1% respectively at 28 days. However, the replacement of optimum BBCM with more than 25% HCFA have showed a gradual drop in the compressive strength in comparison to the control mix. TBCM with 25% HCFA was considered to be the optimum as it showed better compressive strength than the control mix and at the same time reduced the amount of cement to 56%. Reducing the cement content to 56% will contribute to decrease the cost of construction materials, provide better compressive strength and also reduce the CO2 emissions into the atmosphere

Studying the Structural Behaviour of RC Beams with Circular Openings of Different Sizes and Locations Using FE Method

This paper aims to investigate the structural behaviour of RC beams with circular openings of different sizes and locations modelled using ABAQUS FEM software. Seven RC beams with the dimensions of 1200 mm×150 mm×150 mm were tested under threepoint loading. Group A consists of three RC beams incorporating circular openings with diameters of 40 mm, 55 mm and 65 mm in the shear zone. However, Group B consists of three RC beams incorporating circular openings with diameters of 40 mm, 55 mm and 65 mm in the flexural zone. The final RC beam did not have any openings, to provide a control beam for comparison. The results show that increasing the diameter of the openings increases the maximum deflection and the ultimate failure load decreases relative to the control beam. In the shear zone, the presence of the openings caused an increase in the maximum deflection ranging between 4% and 22% and a decrease in the ultimate failure load of between 26% and 36% compared to the control beam. However, the presence of the openings in the flexural zone caused an increase in the maximum deflection of between 1.5% and 19.7% and a decrease in the ultimate failure load of between 6% and 13% relative to the control beam. In this study, the optimum location for placing circular openings was found to be in the flexural zone of the beam with a diameter of less than 30% of the depth of the beam

The Impact of Rice Husks Ash on Some Mechanical Features of Reactive Powder Concrete with High Sulfate Content in Fine Aggregate

The sulfate issue in fine aggregate grows with time and it is not easy to gain a fine aggregate with sulfates amount within the specifications of Iraqi standard. Internal sulfate attack is regarded as a significant problem in concrete construction in Iraq and the Middle East countries. One of the modern generations in ultra-high performance concrete is Reactive powder Concrete (RPC) that has been prepared for cemented materials using microstructure improvement methods. RPC has gained attention from both academia and engineering fields with extensive applications. This study presents an experimental research on the impact of Rice Husks Ash (RHA) as replacement percentage of cement upon some mechanical features of RPC with high sulfate content in fine aggregate (Three percentages of SO3 = 0.16, 0.5 and 1.2%). Three percentages of RHA (0, 10 and 15%) as a partial substitution of cement weight have been used in this research. The compressive and the flexural strengths have been adopted to attain the impact of adding RHA. The outcomes have showed that the incorporation of RHA has an important influence on the compressive-strength for both with and without internally sulfate attacking. The result has indicated that using 10% of RHA as a partial cement substitution has increased the effectiveness of RPC by its mechanical features (compressive and flexural-strengths) without internal sulfate attacked

Flexural behaviour of reinforced concrete beams with horizontal construction joints

In the present research, ten simply supported reinforced concrete beams having a rectangular cross-section were cast and tested up to failure under the action of two-point loads. Eight of these beams were designed to contain horizontal construction joints (HCJs) of different number and location in the beam while the other two beams had no construction joint which were referred to as reference beams for the sake of comparison of results. All the tested beams had been designed to fail in flexure and had the same amount and type of longitudinal and transverse reinforcement as well as similar concrete properties. The results of this series of tests have indicated that the presence of HCJs in reinforced concrete beams leads to a decrease in its ultimate loads and increase in its ultimate deflection. The values of the recorded ultimate loads ranged between 83% to 98% times that of the reference beam while the ultimate deflection ranged between 102% to 133% times that of the reference beam

Investigating the Mechanical and Durability Performance of Cement Mortar Incorporated Modified Fly Ash and Ground Granulated Blast Furnace Slag as Cement Replacement Materials

The process of cement manufacturing produces a huge amount of carbon dioxide (CO2). The utilization of alternative waste materials from various industrial processes as a partial substitution to cement is encouraged due to environmental and specific technical requirements. This strategy will have the potential to reduce cost of cement, conserve energy, and reduce waste volumes. Therefore, the aim of this research is to investigate effect of the replacement of cement with modified fly ash (MFA) and ground granulated blast furnace slag (GGBS) to reach 80% total replacement on mechanical and durability performance of cement mortar. Normal consistency, the initial and final setting times, compressive strength and electrical resistivity of all the ternary mixtures were determined and compared with the control binder. Compressive strength and electrical resistivity were tested at various curing ages of 3, 7, 14, and 28 days. Test results revealed that the normal consistency of the ternary mixtures increased with increasing the GGBS and MFA content, while the initial and final setting time decreased compared to that of control mixture. The results also showed that the compressive strength of all the ternary blends mortars were lower at early and later ages in comparison with control mortar. The reductions in the compressive strengths of the ternary mixtures T40, T60 and T80 compared to the control mixture were approximately 16%, 29% and 37%, respectively at 28 days. The surface electrical resistivity of ternary blends mixtures was higher than the control mixture at all curing ages. The use of GGBS and MFA in the production of cement mortar and concrete can significantly help in reducing the CO2 emissions of the cement industry and reduce the overall cost of cement

Behaviour of moment resisting reinforced concrete frames subjected to column removal scenario

Researchers awarded a considerable attention to progressive collapse analysis in recent years to avoid the partial or entire failure of structures. General Service Administration guidelines (GSA) established the base to deal with such catastrophic failure. For multi-story building, these guidelines proposed column removal scenario in which one or more columns in different locations should be removed from a structure. Then, the response of entire structure with the column omitted should sustain the loading applied ensuring no global failure occurred. In this paper, three-dimensional reinforced concrete (RC) frame is constructed and analyzed using the commercial program SAP2000. Non-linear static analysis is employed to obtain Demand Capacity Ratios (DCR) for beams and the displacement of joint connecting beams to column in the selected frame. The response of moment resisting RC frame under column removal scenario is presented and discussed in terms of strength and displacements in critical locations in RC frame to evaluate the strength of such frame against progressive collapse

Towards Net Zero Carbon Economy: Improving the Sustainability of Existing Industrial Infrastructures in the UK

To comply with the new net zero greenhouse gas emissions (GHGs) target set by the United Kingdom government by 2050, different sectors including the industrial sector are required to take action to achieve this target. Improving the building envelope and production of clean energy on site are among the activities that should be considered by businesses to reduce their carbon emissions. This research analysis the current energy performance and carbon dioxide (CO2) emissions of an industrial building in Liverpool, UK utilizing the Integrated Environmental Solutions Virtual Environment (IESVE) software modeling. Then it has proposed some methods for improving the current performance and reduce the carbon footprint of the building. The results indicated that the installation of wall and floor insulation could decrease the energy usage and CO2 emissions of the building by about 56.39%. Additionally, the production of clean energy on site using solar photovoltaic (PV) panels could reduce the annual CO2 emissions by up to 16%. Furthermore, this research provided some figures about offsetting the rest of CO2 emissions using different international offsetting schemes to achieve carbon neutrality of the building

Users, Planners, and Governments Perspectives: A Public Survey on Autonomous Vehicles Future Advancements

Autonomous vehicles (AVs) are expected to change driving perspectives once they are available in the markets. This type of vehicle has received substantial attention lately from media and researchers. This technology is still under rapid advancements, and further research studies are needed to address the potential outcomes, opportunities, and challenges. The fuel system of the AVs is expected to be electrical; therefore, this study addresses the current status of electric vehicles (EVs), including charging time, charging type, and driving range. The study also discusses the barriers that may hindrance the transformation to AVs from the users, planners, and government perspectives. These barriers include the current charging stations of EVs, which provide 2kW power. These stations can be insufficient for the AVs since these cars are expected to utilize advanced sensors and computers. The authors also propose comprehensive recommendations that could facilitate the so-called transformation of EVs to AVs and AVs' associated marketing. The authors found out that conducting a survey is essential to observe the public perception, and marketing and communication plans are essential to educating the public regarding AVs’ features and advantages. Also, a collaboration between auto manufacturers and planners is critical to the success of these vehicles. Finally, a public survey which consisted of 95 participants were conducted to examine the general perspective as surveys are necessary to assist planners, governments and automakers for their future movement toward a sustainable transportation system