Faculty of Engineering and Information Technology Material Science Engineering Graduation Project 2 Alternative concretes, sustainable resources and environmentally friendly products Prepared by Ismael Hamawi Mohammad Kalbonah Supervisor Prof. Hamdallah Bearat This project was submitted in partial fulfillment of the requirements for the degree of Bachelor in Material Engineering July. 2020 I Contents List of Tables .................................................................................................................... III List of Figures ................................................................................................................... IV Abstract .............................................................................................................................. V 1. Introduction ..................................................................................................................... 1 2. Literature review ............................................................................................................. 3 3. Experimental Work ......................................................................................................... 6 3.1 Standard concrete mixture ......................................................................................... 6 3.1.1 Components of Standard mixture ....................................................................... 6 3.1.2 Mechanical testing of standard mixture .............................................................. 6 3.2 Basic material to make concrete................................................................................ 7 3.2.1 Cement (Portland cement) .................................................................................. 7 3.2.2 Aggregate............................................................................................................ 7 3.2.3 Sand .................................................................................................................... 7 3.2.4 Water .................................................................................................................. 8 3.2.5 Super ................................................................................................................... 8 3.3 Waste material and new additive material ................................................................ 8 3.3.1 Iron powder......................................................................................................... 8 3.3.2 Lime .................................................................................................................... 9 3.4 Sample preparation .................................................................................................... 9 3.4.1 Instruments ......................................................................................................... 9 3.4.2 Sieving ................................................................................................................ 9 3.4.3 Mixing process ................................................................................................. 10 3.4.4 Casting process ................................................................................................. 10 3.4.5 Curing ............................................................................................................... 13 3.5 Methodology ........................................................................................................... 14 3.5.1 Test of hardened concrete ................................................................................. 14 3.5.2 Compressive strength ....................................................................................... 14 3.5.2.1 Procedure ................................................................................................ 14 3.5.3 Water adsorption ............................................................................................... 15 3.5.3.1 Procedure ............................................................................................... 15 II 4. Result and dissociation ................................................................................................. 16 5. Conclusion .................................................................................................................... 22 6. Constraints and limitations ........................................................................................... 23 7. References ..................................................................................................................... 24 III List of Tables Table 1: Mass of powder by size ...................................................................................... 10 Table 2: Weigh for each component with iron powder replacement ................................ 11 Table 3: Weigh for each component with lime powder replacement ............................... 11 Table 4: New mixing present by replace the cement by iron powder ............................. 12 Table 5: New mixing present by adding iron powder....................................................... 12 Table 6: Compression strength after 7 days ...................................................................... 16 Table 7: Compression strength after 28 days .................................................................... 17 Table 8: Water absorption ................................................................................................. 18 Table 9: Compression test after 7 and 14 days ................................................................. 19 Table 10: Compression test for new mixes after 7 and 14 days ....................................... 20 Table 11: Water absorption for best result ........................................................................ 21 IV List of Figures Figure 1: Cement powder, Figure 2: Main concrete component ........................................ 7 Figure 3: Sieve gradient, Figure 4: Result of screening...................................................... 8 Figure 5: Lime sample ........................................................................................................ 9 Figure 6: Curing mold ....................................................................................................... 10 Figure 7: Setting and molding........................................................................................... 10 Figure 8: Setting for 24 hours ........................................................................................... 13 Figure 9: Demolding ......................................................................................................... 13 Figure 10: Curing in water path for 7 days ....................................................................... 13 Figure 11: Compression machine ..................................................................................... 14 Figure 12: Compression strength after 7 days .................................................................. 16 Figure 13: Compressive strength after 28 days................................................................. 17 Figure 14: Water absorption for all samples after 28 days ............................................... 18 Figure 15: Compressive test after 7 and 14 days .............................................................. 19 Figure 16: Compression test for new mixes after 7 and 14 days ...................................... 20 Figure 17: Water absorption for best result ...................................................................... 21 V Abstract In this project, we added hydrated lime and waste iron powder with a few percentages instead of cement as in the proportions shown (3%, 5%,7%, 10%,13% and 15%). The samples were mixed with electrical machine by mixing dry component of cement, sand, aggregate, hydrated lime and iron powder for four minutes to become a homogenous mix. Then water is added to initiate the reaction. After mixing the components with water, the mix was cast in molds to take its shape, before curing it in water path and testing it. After making and curing cubes of concrete for 7 and 28-days testing was applied to specimens. This was to determine the compressive strength and water absorption to evaluate the effect of lime and waste iron powder on the concrete absorption and compression strength. We found that adding 5% of lime and 7% of iron powder give the best results. It enhances the compression strength for 7% of Fe powder added to cement, the compressive strength improves from 29.8 MPa to 37.8 MPa, and water absorption change from 4.89% to 2.56%. For lime it enhances the compression strength at 5% of replacement from 19.6 to 25MPa, but the water absorption increased from 7.22% to 7.31%. 1 1. Introduction Ordinary Portland cement (OPC) is widely used all over the world, but not without environmental impact. In fact, it contributes about 8% of the global man-made CO2. This is the second highest source after the energy sector. Cement industry contributes either to this emission directly by releasing CO2 from the decomposition of calcium carbonate, which is the main ingredient for OPC manufacture, or indirectly through the production of energy needed for this manufacture. Therefore, reducing the amount of OPC used for concrete preparation is a milestone in reducing the overall production of CO2 as a greenhouse gas. In this project, we shall explore new concrete admixtures by attempting to replace OPC partially replacement binders used are lime and iron powder. We are particularly interested in adding powdered solid waste materials such as iron to construction materials to determine the impact of these wastes on the properties of construction materials. In addition, we shall focus on the behavior of the resulting binders and concretes with respect to water such as hydrophilic or hydrophobic reactions, water absorption. Permeability of concrete will be studies as function of porosity and sealing effects of certain additives. Another characteristic of concrete is its ability and capacity to fix carbon dioxide that will be explored, too. All final products shall be tested for their mechanical properties such as compressive and abrasion (friction) resistance. Concrete is a composite material made of a mix of cement, water, sand, gravel. Some other material (additives) can be added to obtain certain properties, that harden into a super strong building material. The properties of the final product depend on the relative proportions of these components. So different mixes have different properties. For instance, for compression strength, every material in concrete has a special contribution. First, cement is a fine powder material that one pound of contains 150 billion grains. Mixed with water, cement creates a paste that binds with sand, aggregate and reinforcing steel as it hardens. 2 Second, sand and aggregate (gravel), have a significant impact on the properties of the concrete as they form a mass of concrete, modify strength and stability. Third, additive powdered or liquid material added to fresh concrete in small amounts to increase the durability of concrete, to control setting time or hardening. Concrete additive thus have different functions, depending on what to achieve. There are two type of it, chemical additive reduce the cost of construction, modify properties of hardened concrete, ensure quality of concrete during mixing, transporting, placing and curing, mineral additives make mixtures more economical, reduce permeability, increase strength, and influence other concrete properties. Advantage of concrete • The component of cement is available and cheap • Concrete strength can be controlled by different the component • The concrete is very durable • Easy to form to any shape due to fluidity property • Fire resistance concrete • Concrete is insulator • Concrete can withstand forces of wind and water • Sound proofing material • Can add different type of additives to enhance its property Disadvantage of concrete • The shrinkage of concrete which causes cracking • Low tensile strength, and it is a brittle material • Concrete has a porous structure • Concrete contains low soluble salts, which affect its properties. 3 2. Literature review Sand could be replaced by different type of waste material to enhance the property of fresh and hardening concrete such as workability, strength, compressive and tensile strength. Krikar and Ibrahim [1] conducted a study on iron waste as a partial replacement of sand in concrete. The aim was to assess the possibility of adding iron waste as fine aggregate in different proportions (6%, 12%, 18%, 24%, and 30%) to enhance the strength of concrete. The mixing design was (1, 2.12, 2.37) to give 33MPa of compressive strength after 28 days of curing without any replacement of sand. Compressive strength and flexural tensile strength tests were conducted to determine the influence of iron waste on the strength of concrete. After mixing the concrete with different parentage showed that the best proportion is 12% replacement of sand with iron waste (15% more compressive strength and flexural tensile in 28 days than normal concrete). Ghannam et al. [2] found that granite powder (GP) and iron powder (IP) are industrial byproduct that are generated from granite polishing and milling industry. It is a hazardous material to human health because they are airborne and can be easily inhaled. This study was conducted on waste granite and iron powder and the possibility to use it as a replacement of sand in concrete with these proportions (5%, 10%, and 20%) by weight and to observe the effects on compressive and flexural strength compared to other ratios. For (GP) it was observed that 10% replacement of sand was the most effective one and it enhances the compressive and flexural strength by 30% compared to normal concrete. It was observed that substitution of up to 20% weight of sand by (IP) replacement the result was an increase in compressive and flexural strength. Concrete mix that contained (GP and IP) showed good workability and fluidity similar to normal concrete mixes. Largean el al. [3] studied the effect of (Fe2O3) on compressive strength, tensile strength, workability and porosity. Portland cement was partially replaced by (1.5%, 2.5%,3.5% and 5%) by weight of ferric oxide, respectively. They observed that the compressive strength was enhanced at 2.5%. However tensile strength was enhanced at 1.5%. The workability has decreased with the increase in the amount of ferric oxide, while the 4 porosity has slightly decreased at 2.5% of sand replacement it decreased from 26.72% to 21.3%. Ismail el al. [4] was found presented a summary of works conducted by other researchers or organizations. For example, he quoted from Dryden Aqua Company that tiny glass particles could be used as filtration media for purifying water. The colored glass (green or amber) have been ground into particles of less than a tenth of a millimeter, during this process a net negative electrical charge will be left on the particles surfaces, which enables them to attract grays. A second effect can occur in filters made from colored glass grains. Those filters can split oxygen molecules into single highly reactive oxygen, which is responsible for drawing microbes to the surface of the grains and killing them. Wartman el al. [5] Glass is an indeterminate material with high silica content (SiO2), 72% of waste glass when crush to very fine powder (600 micron) reacts with alkali in cement & cementations product that help to contribute to the strength development. When glass is crunched to small scale it has a cementation property. Abdallah el al. [6] conducted a study on the effect on concrete when sand is replaced by powdered glass, to see the effect of using crushed waste glass as fine aggregate replacement, to study compression, slump and water absorption, Replacement percentages were (0%, 5%, 15%, 20%) by weight of sand, the compression was enhanced by 5.28% when adding 20% of waste glass and the amount of water absorption decrease when increase the amount of waste glass, the value of slump will decrease with increase in glass added. Taha el al. [7] state that replacement of course aggregate by crushed glass will effect the mechanical properties, due to lower adhesion and bonding strength between cement past and glass aggregate, due to smooth surface of aggregate. Song, Ha-Won el al. [8] studies the effect of carbonation of concrete, During carbonation process they observed the CO2 reacts with CaO and convert to CaCO3, Due to this reaction the voids are filled because the volume of product CaCO3 is lager than that of CaO particle, this decreases the permeability of concrete due to change in porosity. 5 TEPFERS [9] states that today it is possible in production to reach concrete compressive strength of up to 150 MPa, In laboratory Aalborg Cement, Denmark they have reached 300 MPa and French researchers have reached 800 MPa, in that case they have hardened the concrete at 200C and under pressure, It can be supposed that they have succeeded to reduce the gel and contraction porosity by pressing atoms with thermo vibrations into the micro pores of the structure, Basically they have applied nanotechnology for achieving this, The concrete technology is about to reduce the porosity of the concrete, In this way the concrete becomes both stronger and more environment resistant. 6 3. Experimental Work 3.1 Standard concrete mixture The selected composition of the concrete in this study is B300 (1, 1.9, 2.7) kg and 90%w/c ratio. The main reason to select this composition is that it is the most popular in Palestine, it contains the main materials of concrete cement, sand, aggregate and water 3.1.1 Components of Standard mixture 1. Cement 3000 g 2. Sand 5700 g 3. Aggregate (18-25) 5100 g 4. Aggregate (7-17) 2700 g 5. Aggregate (1-6) 1800 g 6. Total Aggregate 9700 g 7. Water Cement ratio (w/c) 55% 8. Super (G7) 60 g 3.1.2 Mechanical testing of standard mixture I. Compression at 7 days 22.2 (MPa) II. Compression at 14 days 29.8 (MPa) III. Water adsorption 4.90% 7 3.2 Basic material to make concrete 3.2.1 Cement (Portland cement) Cement acts as a binder material that holds sand and aggregate to each other to give the final strength when it hardens. The cement in its wet form should coat the individual pieces of aggregate. Cement is approximately 10 to 15 %; more cement means that the spaces between aggregates are better filled. Consequently, more cement added, stronger concrete, the type of cement used is (42.5N) as shown in figure, the component of cement as Figure (2) Figure 1: Cement powder Figure 2: Main concrete component 3.2.2 Aggregate Gravel or a coarse aggregate increases the failure strength of concrete. Makes concrete solid hard mass, and reduce the cost of concrete because coarse aggregate constitutes large part of the volume of finished concrete. In our project we are using three types of coarse aggregates: medium (18-25) 5.1 kg , small (7-17) 2.7 kg and very small (1-6) 1.8 kg. 3.2.3 Sand Sand helps to make concrete free from voids, and helps to provide homogeneity to some extent. It helps in increasing the strength of concrete. 8 3.2.4 Water Water is responsible for the reactions of cement phases or in the process called “setting”. Therefore, the strength of concrete depends on the water /cement ratio. More water is added than what chemical reactions require. The excessive water evaporates from cement glue and leaves pores behind, which weaken the concrete. More excessive water means higher water/cement ratio, results in weaker concrete. 3.2.5 Super super plasticizers help to improve workability by maintaining the fluidity in concrete by releasing the water (from flock) which is entrapped during initial mixing. Retarders slows down the setting of concrete for example hydration process will take place slowly. 3.3 Waste material and new additive material As disposal of iron wastes, by-products is a major problem in today’s world due to limited landfill space as well as its escalating prices for disposal, utilization of these wastes in concrete will not only provide economy but also help in reducing disposal problems. We have used different waste materials in our project 3.3.1 Iron powder We use a waste iron powder that is produced from grinding and cutting metals. The size of iron powder used varies from (30 and 60 micron). as shown in Figures 3 and 4. Properties of iron powder: • Reacts with CO2. • High strength and high hardness. • Improve the wear resistance. Figure 3: Sieve gradient Figure 4: Result of screening 9 3.3.2 Lime Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca(OH)2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed, or slaked with water. It has many names including hydrated lime. It protects other metals from corrosion such as iron and steel by raising the pH and passivating their surface. Limewater turns milky in the presence of carbon dioxide due to formation of calcium carbonate, a process called carbonation Ca(OH)2 + CO2 → CaCO3 + H2O Figure 5: Lime sample 3.4 Sample preparation 3.4.1 Instruments Our project involves the preparation of concrete specimens that have a specified aggregate, cement, sand and new additive. The specimens were prepared and tested using many instruments, which must be always ready in advance to carry out the specimen mixing and test it, So, in this section, the instruments, are presented in sequence starting from the beginning to the end of test, as following scoop handle, digital balance, steel trays, water path, concrete molds, compression testing machine and furnace. 3.4.2 Sieving Sieving is the process where the materials are separated into different particle size levels using a set of sieves. In this project sieving was used to separate iron powder. The size levels resulted ranges between 4.75 mm and 150 microns. The electrical shaker used to enhance sieving process. The set of sieves are placed on the shaker by order containing the material. They are electrically shacked separating the material to deferent particle size fractions, This process saved time and provided the potential of more accurate sieving. 10 By use iron powder of 3.45 kg the distribution of mass was as shown in table Table 1: Mass of powder by size Size of powder (mic) Mass in (g) 700 587 450 1760 300 837 150 266 3.4.3 Mixing process 1. It was carried out by electrical mixing machine; The materials were weighed occurring to this mixing design relative to cement (1, 1.9, 2.7). For our study the cement=3kg sand=5.7kg aggregate=9.6 kg using electrical balance. The dry component (cement, sand, aggregate) of each mixture were initially mixed for 2 to 4 minutes until achieving a homogenous mix. 2. The water was added to other component, the concrete is mixed with all component in the mixer for at least three to four more minutes. 3.4.4 Casting process 3. The molds were cleaned and coated with oil to prevent adhesion of concrete before casting Figure 6: Curing mold 4. The concrete was placed in molds. Figure 7: Setting and molding 11 5. The experiment work starts by cast cube for mix without any replacement of (iron powder and lime) these cubes are our reference to compare other product with. 6. The iron powder and lime were added as partial replacement of cement in these percentages (0%, 3%, 5%, 7% 10%, 13%, 15%) with constant water cement ratio at project one we used from 0.9% to 1.1% and we fixed it in project two to be 55%. Table 2: Weigh for each component with iron powder replacement Cement(kg) Iron powder(kg) Sand(kg) Aggregate(g) Water cement ratio Mix 0% 1.250 0 2.9 5 0.9 Mix 5% 1.187 0.0625 2.9 5 0.9 Mix 10% 1.125 0.125 2.9 5 0.9 Mix 15% 1.063 0.187 2.9 5 0.9 Table 3: Weigh for each component with lime powder replacement Cement (kg) Hydrated lime (kg) Sand (kg) Aggregate (kg) Water cement ratio Mix 0% 1.250 0 2.9 5 0.9 Mix 5% 1.187 0.0625 2.9 5 0.9 Mix 10% 1.125 0.125 2.9 5 1 Mix 15% 1.063 0.187 2.9 5 1.1 12 Table 4: New mixing present by replace the cement by iron powder Cement (kg) Iron powder (kg) Sand (kg) Aggregate (kg) Water cement ratio Super to cement ratio Mix 0% 3 0 5.7 9.6 0.55 0.02 Mix 3% 2.91 0.09 5.7 9.6 0.55 0.02 Mix 5% 2.85 0.15 5.7 9.6 0.55 0.02 Mix 7% 2.79 0.21 5.7 9.6 0.55 0.02 Mix 10% 2.7 0.3 5.7 9.6 0.55 0.02 Mix 13% 2.61 0.39 5.7 9.6 0.55 0.02 Mix 15% 2.55 0.45 5.7 9.6 0.55 0.02 Table 5: New mixing present by adding iron powder Cement (kg) Iron powder (kg) Sand (kg) Aggregate (kg) Water cement ratio Super to cement ratio Mix 0% 3 0 5.7 9.6 0.55 0.02 Mix 3% 3 0.09 5.7 9.6 0.55 0.02 Mix 5% 3 0.15 5.7 9.6 0.55 0.02 Mix 7% 3 0.21 5.7 9.6 0.55 0.02 Mix 10% 3 0.3 5.7 9.6 0.55 0.02 7. The samples were shake for approximately 30 seconds to fill the void and to achieve good dispersion of course and fine material, as the cement slurry appeared on the top surface of the mold. 13 8. The top surfaces of the molds were leveled to make uniform and a label of information was added to each sample. Figure 8: Setting for 24 hours 9. The samples were left in the iron mold for the first 24 hours at ambient condition. 10. After that they were removed from mold Figure 9: Demolding 3.4.5 Curing The specimens were placed in a water tank for 7 days to let the reaction take its place. Figure 10: Curing in water path for 7 days 14 3.5 Methodology 3.5.1 Test of hardened concrete There are two type of testing of hardened concrete, These are destructive and non- destructive tests. The destructive tests are compressive strength, flexural strength and tensile strength. Nondestructive test are water absorption, porosity, dry density and alkali silica test. 3.5.2 Compressive strength This test is made to determine the amount of load that concrete can hold without any fracture, Waiting for 7 days to take the first specimens force with this percent range (60- 70) % of the total strength and waiting 28 days to take the final specimens strength. Figure 11: Compression machine 3.5.2.1 Procedure 1. The samples were curried for 7 days in water and left to dry before testing it. 2. The compression machine was cleaned from any contamination. 3. Cross section areas were measured for samples (unit should be in mm2). and the weight of each sample was taken 4. The sample was placed in the middle of surface of the machine, to distribute the load on all the sample sides. 5. The piston was modified to be in touch with sample. 6. The machine was started to applied load on the sample. 15 7. The compression load was increased: By turning pressure-increasing valve clockwise, adjust the pressure on piston so that it matches concrete compression strength value. Apply the load gradually without shock. 8. The sample was fractured at its maximum load. 9. The absorbed load was recorded for all sample. 10. The compressive strength was calculated for all samples. 𝒄𝒐𝒎𝒑𝒓𝒆𝒔𝒊𝒐𝒏 𝒔𝒕𝒓𝒆𝒏𝒈𝒕𝒉 = 𝒂𝒑𝒑𝒍𝒊𝒆𝒅 𝒍𝒂𝒐𝒅 𝒂𝒓𝒆𝒂 = 𝒖𝒍𝒕𝒊𝒎𝒂𝒕𝒆 𝒍𝒐𝒂𝒅 (𝑵) 𝒎𝒎𝟐 3.5.3 Water adsorption The test is needed to measure the percentage of water absorbed by the concrete samples, and the porosity can be determined by this test too. 3.5.3.1 Procedure 1. After curing of samples in water for 7 days, as concrete takes final strength and after 28 days as the reaction stops, this test was repeated. 2. Concrete samples were placed in oven for 7 hours at 110C, the weight of samples was taken this process called dry concrete. 3. The sample were put in the water path for 48 hours. 4. Digital balance was use for weighting the samples according to the percentage of their size and masses after take from water path this process called is concrete wet. 5. Water absorption was calculated using this equation. 𝑤𝑎𝑡𝑒𝑟 𝑎𝑏𝑠𝑜𝑟𝑝𝑡𝑖𝑜𝑛 = 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑤𝑒𝑡 𝑠𝑎𝑚𝑝𝑙𝑒 − 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑑𝑟𝑦 𝑠𝑎𝑚𝑝𝑙𝑒 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑑𝑟𝑦 𝑠𝑎𝑚𝑝𝑙𝑒 ∗ 100% 16 4. Result and dissociation Table 6: Compression strength after 7 days Sample Weight of sample (g) 7days compressive test (KNa) 7 days compressive test (MPa) Standard 2261 126 12.6 5%lime 2364 186 18.6 10%lime 2010 50 5 15%lime 2071 57 5.7 5%Fe 2359 146 14.6 10%Fe 2329 118 11.8 15%Fe 2291 116 11.6 Figure 12: Compression strength after 7 days 17 Table 7: Compressive strength after 28 days Sample Weight of sample (g) 28 days compressive test (KNa) 28 days compressive test (MPa) Standard 2166 196 19.6 5%lime 2198 250 25 10%lime 1953 130 13 15%lime 2063 64 6.4 5%Fe 2228 212 21.2 10%Fe 2187 170 17 15%Fe 2194 164 16.4 Figure 13: Compressive strength after 28 days 18 Table 8: Water absorption Weight of dry sample Weight of wet sample Water absorption % Standard 2156 2324 7.228% Lime 5% 2160 2318 7.314% Lime 10% 1835 2050 11.700% Lime 15% 2015 2253 10.918% Fe 5% 2161 2313 7.030% Fe 10% 2190 2350 7.305% Fe 15% 2160 2338 8.240% Figure 14: Water absorption for all samples after 28 days 19 ➢ Our new result for using new mixing design in this experiment we replace the cement by iron power Table 9: Compression test after 7 and 14 days Sample Weight of sample 7 days compression test (MPa) 14 days compression test Standard 2378 22.2 29.8 Fe 3% 2254 21.8 28 Fe 5% 2409 20.4 27.4 Fe 7% 2335 18.5 25.2 Fe 10% 2408 16.7 21.4 Fe 13% 2484 14 19.8 Fe 15% 2409 11.6 16 Figure 15: Compressive test after 7 and 14 days 0 5 10 15 20 25 30 35 Standard Fe 3% Fe 5% Fe 7% Fe 10% Fe 13% Fe 15% M P a Compressive test after 7 and 14 days 7 days compression test (MPa) 14 days compression test 20 ➢ Our new result for using new mixing design in this experiment we added the iron powder to cement. Table 10: Compression test for new mixes after 7 and 14 days Sample Weight of sample 7 days compression test 14 days compression test Standard 2264 22.2 29.1 Fe 3% 2329 23.7 30.6 Fe 5% 2352 24.9 34.4 Fe 7% 2410 27.4 37.8 Fe 10% 2465 26 34.2 Figure 16: Compression test for new mixes after 7 and 14 days 0 5 10 15 20 25 30 35 40 Standard Fe 3% Fe 5% Fe 7% Fe 10% M P a Compression test for new mixes after 7 and 14 days 7 days compression test 14 days compression test 21 ➢ Water absorption of best result of compression strength which is adding iron powder to cement Table 11: Water absorption for best result Sample Weight of dry sample Weight of wet sample absorption test (%) Standard 2257 2368 4.89% Fe 3% 2307 2398 3.97% Fe 5% 2365 2453 3.70% Fe 7% 2474 2538 2.56% Fe 10% 2314 2394 3.47% Figure 17: Water absorption for best result • The best value of add iron powder to cement was 7% of weight of cement and we get the best compression strength and water absorption, and we get if we remove cement and replace it with iron powder the strength and most property will decrease. Standard ; 4.89% Fe 3%; 3.97% Fe 5% ; 3.70% Fe 7% ; 2.56% Fe 10% ; 3.47% 0.00% 1.00% 2.00% 3.00% 4.00% 5.00% 6.00% Standard Fe 3% Fe 5% Fe 7% Fe 10% Water absorption for best result 22 5. Conclusion Our standard sample was 22.2MPa after 7day of compression test and 29.8 MPa at 14 days and water absorption 4.89%. So we will compare all the results with it, Some samples that contain different additives enhance the compression strength and other additive reduce it, We make our sample with added Fe powder in these percentages (3%,5%,7%,13%, 10%, 15%), The best result was observed is for lime 5% which is 18.6 MPa at 7 days and 25MPa at 28 day but the water absorption has increases which is 7.3%, For Fe 7% the compression strength at 7 days was 27.4 MPa and 37.8 MPa at 14 days, After taking results from the water absorption test, the difference between them was measured, and then we could calculate the percentage of water absorption, We have noticed that at 7% the absorption of water was reduced by 50%, then above 7% the water absorption started to increase, this is actually good, because at high percentage of iron powder in concrete, the strength is lower, because even the concrete contents are weakly connected to each other. 23 6. Constraints and limitations Unfortunately, we faced many obstacles in this semester; it began with the illness of the lab director which delayed our working in the lab and preparation and testing of samples until the Civil Engineering Department have hired a new lab director. After working for a week, we faced another obstacle which was the covid-19 pandemic that led to the lock down of the university. All our efforts were in vain because we couldn’t test the samples and have the results until we started our work again in June. But we couldn’t complete our work on the samples because of the lack of time and the renewed lock down of the university in June because covide-19. 24 7. References [1] Krikar M-Gharrib Noori, Hawkar Hashim Ibrahim, Mechanical properties of concrete using iron waste as a partial replacement of sand, Eurasian Journal of Science & Engineering ISSN 2414-5629 (Print), May 26, 2018,(205-215). [2] Ghannam S, Najm H, Vasconez R. Experimental study of concrete made with granite and iron powders as partial replacement of sand. Sustainable Materials and Technologies. 2016 Sep 1; 9:1-9. [3] Largeau, Moussa Anan, Raphael Mutuku, and Joseph Thuo. "Effect of Iron Powder (Fe2O3) on Strength, Workability, and Porosity of the Binary Blended Concrete, Open Journal of Civil Engineering: October 31, 2018, (8), (411-425). [4] Ismail, Zainab Z., and Enas A. Al-Hashmi. "Recycling of waste glass as a partial replacement for fine aggregate in concrete." Waste management 29.2 (2009): 655- 659. [5] Wartman, Joseph, Dennis G. Grubb, and A. S. M. Nasim. "Select engineering characteristics of crushed glass." Journal of Materials in Civil Engineering 16.6 (2004): 526-539. [6] Abdallah, Sadoon, and Mizi Fan. "Characteristics of concrete with waste glass as fine aggregate replacement." International Journal of Engineering and Technical Research (IJETR) 2.6 (2014): 11-17. [7] Taha, Bashar, and Ghassan Nounu. "Properties of concrete contains mixed colour waste recycled glass as sand and cement replacement." Construction and Building Materials 22.5 (2008): 713-720. [8] Song, Ha-Won, and Seung-Jun Kwon. "Permeability characteristics of carbonated concrete considering capillary pore structure." Cement and Concrete Research 37.6 (2007): 909-915. [9] Tepfers RA. Concrete technology–porosity is decisive. Befestigungstechnik, Bewehrungstechnik und... II. ibidem-Verlag. 2012.