Post-thermal performance of concrete containing clamshell

Cement is the most important ingredient in concrete, which acts as a binding material. It is evaluated that cement is the second largest industrial source of CO2 on earth. This demands a partial or full replacement of cement by an environment-friendly material. In this research industrial waste slag from a local Steel Mill, namely Mangla Metals was selected as possible replacement of cement. Some preliminary standard tests conducted on the slag showed its strong chances to be used as pozzolana. Slag used for this study was reduced to the particle size passing through ASTM standard sieve #100. Concrete specimens containing 10% and 20% replacement of cement by slag were prepared. The mechanical properties like compressive, split cylinder tensile and flexure strength were determined as per standard ASTM methods. Tests were conducted at 3, 7 and 28 days of concrete age. Results show a decrease of 14% in compressive strength, 7.5% in tensile strength and 10.5% in flexure strength for 10% replacement vis-í -vis control specimens at 28 days. For 20% replacement, the decrease in compressive, tensile and flexure strength are 25.5%, 29%, 31% respectively. Additionally, ASTM standard strength activity index test with finer slag particles passing through ASTM sieve #200 provided compressive strength more than that of control specimen. Based on the results, it is concluded that the industrial slag has the potential to partially replace the cement if slag is ground to the particles, passing through ASTM sieve #200. This could lead to a huge reduction of cement quantity in concrete and the environmental burden due to deposition of waste slag in landfills.

In this paper, the effect of partial replacement of cement with metakaolin (MK) on the strength properties of oil palm shell (OPS) lightweight concrete was investigated. Generally, 5–20% of partial cement replacement with MK enhanced the compressive, splitting tensile and flexural strengths as well as modulus of elasticity of OPS concrete (OPSC). Though the 28 day compressive strength of the OPSC was found in the range of 39–47 MPa, the highest compressive strength was obtained for the mix with 10% replacement of MK. Similar replacement level of MK was found optimum for both the splitting tensile and flexural strengths. In addition, the strength efficiency of OPSC with MK as partial cement replacement was also investigated and it was found that the increase in the replacement level of MK up to 20% resulted in 49% increase in the strength efficiency for the OPSC.

Effect of nano silica on compressive strength and microstructures of high volume blast furnace slag and high volume blast furnace slag-fly ash blended pastes

Lightweight Aggregate Concrete (LWAC) has emerged as a sustainable alternative to conventional concrete due to its reduced density and improved thermal performance. However, its relatively lower tensile strength and brittle behavior restrict its structural applications. The present study investigates the strength performance and structural efficiency of Glass Fibre Reinforced Lightweight Aggregate Concrete (GFRLWC). Lightweight aggregates were incorporated as partial replacement of conventional coarse aggregates to reduce the density of concrete. Glass fibres were added in controlled proportions to enhance tensile and flexural performance. An experimental program was conducted to evaluate workability, density, compressive strength, split tensile strength, and flexural strength at 7 and 28 days of curing. The results demonstrate that glass fibre addition significantly improves tensile and flexural strength due to crack-bridging action and improved stress transfer within the matrix. Although a slight reduction in workability was observed, the values remained within permissible construction limits. The density reduction confirms the lightweight nature of the developed concrete. Overall, GFRLWC shows balanced mechanical performance and structural suitability for modern sustainable construction practices. Keywords: Lightweight Aggregate Concrete, Glass Fibre, Fibre Reinforcement, Compressive Strength, Flexural Strength, Density Reduction.

Ceramic waste is one of the most active research areas that encompass a number of disciplines including civil engineering and construction materials. Ceramic waste powder is settled by sedimentation and then dumped away which leads to environmental pollution, in addition to forming dust in summer and threatening both agriculture and public health. Therefore, utilization of the ceramic waste powder in various industrial sectors especially the construction, agriculture, glass and paper industries would help to protect the environment. It is most essential to develop eco-friendly concrete from ceramic waste. In this research replacing the (OPC) cement by ceramic waste powder has been studied accordingly in the range of (0, 10, 15, and 20) % by weight of M-30 grade concrete. Concrete mixtures were produced, tested and compared in terms of compressive and tensile strength to the conventional mixture. These tests were carried out to evaluate the mechanical properties for 7 and 28 days. As a result, the CWP cement concretes decreased the workability retention. The values of average hardened concrete density for concrete mixes with CWP cement are higher than the reference mix in 7 days, but lower than the reference mix in 28 days. The maximum value of compressive strengths at 7 and 28 days and tensile strength was achieved at about 5% CWP concrete mix. CWP slowed the compressive strength development especially at early ages. All mixtures with CWP showed good strength development at 28 days. It was observed that all CWP replacement ratios achieved higher compressive strength than characteristic compressive strength which is equal to 30 N/mm2 in 28 days, except the 20% ratio gives 29.72 N/mm2. Test results showed that CWP has potential to be used as an ingredient in concrete mixtures to partially replacing cement. The study showed that concrete mixtures with ceramic waste powder (CWP) had variable performance of the measured properties depending on the replacement level used.

Cement is importance as one of the strategic construction of any civilization depends, and its paramount significance in the construction of building, roads, bridges and infrastructure, which requires the use of cement with special specification and thus the use of polymers as additives to increase the compressive, flexural and tensile strength of the cement used in construction. Cement producing can possibility with high specification and for multiple uses, some studies be carried out on the use of some available additives in small quantities so as to give the cement high desirable specification in terms of color, compressive strength, tensile and permeability compared to ordinary cement. This research aims to know the extent to which some of the physical and mechanical properties of cement mortar, such as compressive strength, flexural and tensile strength, are improved upon weight substitution of specific polymeric materials with high efficiency, such as, silica fume .styrene-butadiene, styrene- acrylic in low weight ratio so that it does not add a high economic cost to the production of therequired concrete .for specific uses and sheds light on the effect of different temperatures on the properties where studied in this study . The study showed that the addition of polymeric materials (Glenium 51, silica fume, styrene –butadiene) with different weight ratio of cement weight at 20°C led to obtaining the highest compressive strength, flexural and tensile strength at the optimum level to the development and improvement of properties. Mechanical and physical cement mortar compared to the reference cement free of additives .As for the use of styrene –acrylic, it had a negative effect and led to a decrease in the compressive and tensile strength .especially in the later ages compared to the reference cement. The optimum ratio of Glenium51 was added to the optimum ratio of each material separately and the mixture was added to the cement mortar at different temperatures( 7, 20, 55 )°C .The effect of additives on the properties of the cement mortar was studied. Also, a mixture (Glenium51, silica fume, styrene-butadiene, styrene-acrylic) was added in the optimum proportions for each material to the cement mortar at different temperatures, and this addition led to increase on compressive, flexural and tensile strength at all temperatures compared with reference cement. Silica fume, styrene-butadiene rubber and styrene acrylic were added separately to the cement mortar without Glenium51, then a mixture of silica fume, styrene-butadiene, and styrene-acrylic was added to the cement mortar .The results showed that the compressive, flexural and tensile strength of cement mortar increase while styrene acrylic decrease these properties when compared with the reference mixture.In addition, the study showed the effect of temperature to the properties of added polymers with cement mortar, All experiments were performed at different temperatures (The temperature which Iraq's climate is exposed under natural conditions.All experiments were conducted at different temperatures (7, 20, 55)°C respectively, to show the effect of degrees on cement compressive strength, which the degree7 represents in winter, 20 in spring and autumn, and 55 in summer.

This research is funded by African Union Commission (AUC) and Japan International Cooperation Agency (JICA) Abstract Although concrete has good qualities that make it suitable for a wide range of applications in the construction industry, it also has undesirable properties; one of which is its low tensile strength. Numerous studies are being carried out to improve the undesirable features of concrete by using substitute materials such as industrial, manufacturing, agricultural as well as domestic wastes. In Africa, there is a pressing need for reusing and recycling waste materials. Following the extensive use of concrete in the vast construction industry, the incorporation of wastes like Polyethylene Terephthalate (PET) bottles and fly ash to improve its quality is a sensible intervention. PET bottles, used for packaging of beverages, and fly ash, generated during the combustion of coal, are causing severe environmental degradation. This study evaluated the effects of using PET fibres and fly ash on the performance of concrete. PET fibres with an aspect ratio of 50 (100mm length and 2mm width) were incorporated in the concrete mix at percentages of 0.5, 1.0 and 1.5% by weight of cement. On the other hand, fly ash was introduced as a cement replacement at percentages of 20, 22.5, 25, 27.5 and 30% by weight of cement. The performance of the modified concrete was evaluated based on workability, compressive strength, and splitting tensile strength. The combination of 1.5% PET fibres and 27.5% fly ash resulted in 33.45% tensile strength improvements, while keeping the workability and compressive strength unaffected. Keywords: Concrete, polyethylene terephthalate; fly ash; ordinary Portland cement; aggregates; workability; compressive strength; splitting tensile strength; aspect ratio DOI : 10.7176/CER/11-6-05 Publication date :July 31 st 2019

Aims: In this study, the mechanical characterization of no-fines concrete solutions is addressed experimentally, with the purpose of possibly increasing their strength by using silica fume and embedded fibers (steel and nylon fibers) as possible efficient reinforcement. Background: Due to competition between developed and advanced countries, the contemporary construction sector is currently experiencing a shortage of fundamental building materials. In this regard, no-fines concrete is becoming increasingly popular, and it has been proven in the literature that it can offer some advantages as an economic and lightweight solution compared to conventional concrete. However, experiments and investigations are still needed to investigate the potential mechanical advantages for its efficient use in buildings, given that the major limitation compared to normal concrete is represented by limited strength. Objective: The primary objective of the present study is to assess the mechanical strength of no-fines concrete samples in which steel fibers, nylon fibers, and partial cement replacement with silica fume are used. For this purpose, no-fines concrete specimens are produced with fixed mix proportions of 1:6 cement-aggregate (c-a) ratio, various coarse aggregate gradations ((20-10) mm and (10-5) mm), and fixed w/c ratio (0.42). Methods: The experiments are carried out on cubes, cylinders and prisms of concrete samples with various aggregate solutions. The nominal length of both types of fibers is fixed at 20 mm. Steel fibers with 1 mm in diameter and nylon fibers with 0.3 mm, 0.4 mm, 0.5 mm, or 0.6 mm diameters, respectively, are taken into account to explore their effects on compressive strength, split tensile strength, and flexural strength. Results: The presented experimental results showed various mechanical advantages, such as increased compressive, splitting tensile and flexural strength parameters, for most of the examined samples. Nylon fibers, in particular, proved to significantly increase compressive, splitting tensile, and flexural strength values, compared to normal concrete, with additional benefits compared to steel fibers (for the examined arrangements and configurations). Conclusion: Overall, the examined compositions and mixtures of silica fume-based no-fines concrete samples encourage further investigations for the optimization of these solutions. In this regard, in addition to mechanical capacities, further key parameters (such as weight, cost, impact on concrete microstructure, etc.) will be taken into account.

This work presents the results of investigation conducted to assess the suitability of polyvinyl waste powder (PWP) as partial replacement of cement in the production of concrete.B Up to 50% by weight of cement was replaced with PWP at interval of 10%. The parameters investigated are: the chemical composition of polyvinyl waste powder (PWP) and the setting times of cement-polyvinyl paste. Also investigated in concrete containing polyvinyl powder were: workability, density, compressive strength, and tensile strength. The results showed that polyvinyl waste powder (PWP) has a pozzolanic effect by the consideration of strength activity index, and higher compressive strength than the control specimens for replacement level up to 20%, and up to 30% cement resulted in higher splitting strength. Further inclusion of polyvinyl waste powder (PWP) increased the setting times of cement-PWP paste, and resulted in a reduction in concrete workability as the replacement value of cement with PWP increased. From these results, it can be concluded that polyvinyl waste powder (PWP) is suitable as partial replacement of cement at the replacement levels considered in the current investigation. http://dx.doi.org/10.4314/njt.v33i4.11

Rice husk ash (RHA) possesses high pozzolanic activities and very suitable as partial replacement of cement in concrete. This paper presents a comparative study on use of RHA as partial replacement of cement in concrete specimens. Review of the researches on physical, mechanical and structural properties of concrete containing RHA as partial replacement of ordinary Portland cement was included in this paper. Simultaneously, concrete specimens were tested with different percentages of RHA as replacement of cement content and with different w/c ratio. Compressive strength, flexural strength, tensile strength and slump test were carried out to evaluate the appropriateness of using RHA in concrete. The replacement of cement by RHA in structural concrete represents a good alternative in as economical as strength consideration of concrete, even without any kind of processing and found environmental benefits related to the disposal of waste. Review of researches shows that RHA-used concrete can resist chloride penetration more than normal ordinary Portland cement concrete.

This study aims to get the maximum compressive strength with high quality in determining the effect of partial replacement of cement with bentonite to the compressive strength of concrete. This study was conducted by testing the chemical composition of the bentonite by using the method of Atomic Absorption Spectrometry (AAS) and Gravimetry that refers to the ASTM 618- 03. For testing the compressive strength of concrete it was used the age variation to assess the compressive strength of concrete using 10% of bentonite as the partial replacement for cement. There were 18 samples consisting of three cylindrical concrete samples in each age variation (the diameter was 150 mm and the height was 300 mm) and the testing was conducted at the age of 3, 7, 14, 21, 28 and 56 days. The results showed that the test of bentonite chemical composition in the Chemistry Analytical Laboratory of Gadjahmada University met the requirements of pozolan chemical. The highest compressive strength at the age of 56 days and at 28 days the lowest compressive strength were 49.454 MPa and 37.119 MPa respectively. The percentage of the optimum increase of concrete obtained at the age of 28 days to 56 days was 33.23%. Moreover the addition of bentonite gives the effect to the workability so that the value of the slump was lower than the that in the planning. Keywords: Bentonite, Compressive strength, Slump

The cement industry is one of the most polluting industries globally, due to the high amount of CO2 emissions generated during production. Improving the sustainability of cement production is thus vital. Waste paper is also a big problem for many societies, especially in developed countries, where the use of board and paper increases almost every day. This work examines the possibility of using incinerated waste paper ash (IWPA) and non-incinerated waste paper (NIWP) as a partial replacement for cement (by weight) in mortar mixtures. For non-incinerated waste paper, the tested replacement levels were 1%, 1.5%, 2.5% and 3.5%, while for incinerated waste paper, the replacement levels were 2.5%, 5%, 7.5%, and 10%. An additional mix without any replacement was also cast for comparison purposes. The fresh and hardened properties of mortar were assessed using flow rate, compressive strength, direct tensile strength, water absorption, and dry density tests, and two test ages (7 and 28 days) were considered for the compressive and tensile strength tests, though water absorption and density tests were undertaken at 28 days only. The results showed that the presence of waste paper (incinerated or non-incinerated) reduced the flow rate of fresh mortar as compared with the reference mix. It was also found that, for the NIWP mixtures, 1% replacement of cement was the most efficient percentage; this increased the compressive strength by 16% and the direct tensile strength by 19% at 28 days of age. For the IWPA mixes, the results showed that the best replacement ratio was 5%, where the compressive strength and direct tensile strength were improved by 10% and 11% at 28 days, respectively. These 1% NIWP and 5% IWPA mixtures gave similar water absorption of 7% to the reference mix.

This research showed the results of experiments effect use of oil palm fibre (OPF) from oil palm industry as partial replacement for ordinary Portland cement. Research on the reuse of waste materials in the concrete industry has been quite intensive in the past decade. The objective of this research is to identify the Effect of oil palm fibre as a partial cement replacement in the production of concrete. After the treatment, the economical ways to dispose of it is by using landfill method. But due to a limited landfill site in Malaysia and it is the temporary solution for the disposal of the waste, it becomes a problem to Malaysia and the number of the oil palm fibre keeping increase year by year because of the population increase year by year too. The results showed that oil palm fibre (OPF) greatly improved the compressive and flexural strength of concrete. The rate of water absorption of oil palm fibre (OPF) concrete was reduced as oil palm fibre filled up the existing voids, making it more impermeable. However, the compressive strength of the oil palm fibre concrete decreases gradually when the amount of oil palm fibre (OPF) increased. It can be concluded that the optimum percentage of oil palm fibre as a partial cement replacement is 10%. In this direction, an experimental investigation of ultrasonic pulse velocity, carbonation test, compressive strength, flexural strength and water absorption was undertaken to use oil palm fiber and admixtures as partial replacement for cement in concrete.

This research showed the results of experiments evaluating the use of empty fruit bunch ash (EFBA) from the oil palm industry as partial replacement for ordinary Portland cement. Research on the reuse of waste materials in the concrete industry has been quite intensive in the past decade. The objective of this research is to identify the performance of EFBA as a partial cement replacement in the production of concrete. EFBA of various amounts, namely 5%, 10%, 15% and 20% by volume, was added as a replacement for ordinary Portland cement. The results showed that EFBA concrete greatly improved the compressive and flexural strength of concrete. The rate of water absorption of EFBA concrete was reduced as EFBA filled up the existing voids, making it more impermeable. However, the compressive strength of the EFBA concrete decreases gradually when the amount of EFBA increased. It can be concluded that the optimum percentage of EFBA as a partial cement replacement is 15%. In this direction, an experimental investigation of ultrasonic pulse velocity, carbonation test, compressive strength, flexural strength and water absorption was undertaken to test the performance of EFBA and admixtures as partial replacement for cement in concrete.KeywordsEmpty fruit bunch ashAdmixtureStrength and durability concerete properties

Palm oil is used to produce cooking oil and its waste is called palm oil fuel ash (POFA). POFA is one of the wastes that have same chemical properties as cement, which is silica and calcium oxide. Demand for cement used in concrete was high. The cement is not suitable for a sustainable environment as cement industry is the primary producers of carbon dioxide (CO2). The aim of this study is to investigate water absorption on various molarity of treated POFA in 10% of replacement of cement in concrete and to study the effect of optimum molarity of treated POFA towards the compressive strength with 10% replacement of cement in concrete. POFA was treated in the environmental laboratory by using various molarity of sulphuric acid, H2SO4. Then, the treated POFA has been partially replaced by cement of 10% in order to cast a concrete mix on 50 × 50 × 50 mm mould. The cubes samples were being produced to test the compressive strength and water absorption by following the British Standard to check the effect of the treatment of the POFA. From the result obtained, concrete with partially replacement of cement by using POFA treated 5M of sulphuric acid is the optimum value that gets from the compressive strength test and achieved the design strength which is M30. The values for the 5M treated POFA and ordinary portland cement (OPC) were compared and the result is 44.77 and 47.26 N/mm2, respectively. The higher the molarity of the sulphuric acid, the lower the compressive strength achieved.