International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), INTERNATIONAL JOURNAL OF CIVIL ENGINEERING ISSN 0976 – 6316(Online), Volume 5, Issue 6, June (2014), pp. 25-36 © IAEME AND TECHNOLOGY (IJCIET) ISSN 0976 – 6308 (Print) ISSN 0976 – 6316(Online) Volume 5, Issue 6, June (2014), pp. 25-36 © IAEME: www.iaeme.com/ijciet.asp Journal Impact Factor (2014): 7.9290 (Calculated by GISI) www.jifactor.com IJCIET ©IAEME CYPRESS TREE EXTRACT AS AN ECO-FRIENDLY ADMIXTURE IN CONCRETE Abraham M. Woldemariam1, 1 Walter O. Oyawa2, Silvester O. Abuodha3 Civil Engineering Department, Basic Science Technology and Innovation, Pan African University, JKUAT, Kenya, 2 Civil, Const. & Env. Engineering Department, Jomo Kenyatta University of Agriculture and Technology (JKUAT), Kenya, 3 Civil Engineering Department, University of Nairobi, Kenya, ABSTRACT In order to get high strength concrete with good rheology, proprietary chemical admixtures are normally added to the concrete during the mixing stage. However, the manufacturing of the chemicals emits toxic gasses like CO2 to the environment which significantly contributes to global warming. The chemicals are also patented products which are imported into developing countries and sold at exorbitant prices. To alleviate this situation, research work was undertaken to determine the suitability of plant extract (cypress extract) as an eco-friendly and economical admixture for concrete. Accordingly, extracts from the bark of cypress tree was prepared by either boiling the bark of the cypress tree in water or by dipping the bark in cold water for some time. Varying dosages of the extracts in water (5%, 10% & 15%) were then used as admixture in the preparation of concrete cubes at constant slump, which were then tested for compressive strength. Results obtained indicate that the use of cypress plant extract delayed the setting time of cement, hence indicating the potential of cypress extract as a concrete retarder in hot climates. It was further determined that at a constant liquid: cement ratio, cypress plant extract increased the workability of the wet concrete mix or vice versa i.e. at a constant slump the cypress plant extract reduced the liquid requirement of the concrete mix. Compressive test results demonstrate that increased dosages of the plant extract in water improved the compressive strength of concrete. In conclusion, the use of cypress plant extract is proved to increase strength at a constant slump, and also increase workability at a constant liquid: cement ratio. Keywords: Cypress Extract, Bio-Admixture, Compressive Strength, Setting Time, Workability. 25 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online), Volume 5, Issue 6, June (2014), pp. 25-36 © IAEME 1. INTRODUCTION Concrete is a mixture of Cement, Sand, Coarse aggregate and water. Concrete is one of the most versatile building materials used in building technology and that can fit any structural shape as required [1, 2].Good characteristics of concrete depend on the quality of the constituent material and the mix proportion of each constituent used. The amount of water required to hydrate the cement in concrete mix ranges from 22 to 25% by weight of cement [3].To obtain high workable concrete, normally much water is used than the required to hydrate the cement. The amount of water used is indirectly related to the strength of concrete. In order to get high strength concrete with good rheology, water reducing (plasticizer) and high range water reducing chemical admixtures are used. However, the manufacturing of the chemicals emits toxic gasses like CO2 to the environment which significantly contributes to global warming. The chemicals are also patented products which are imported into developing countries and sold at exorbitant prices. In addition it is documented that 5% of the world CO2 is contributed from the cement industry [4]. Work done by other researchers show that, Organic admixtures generally improves fresh concrete rheology as well as hardened property. Indeed polysaccharides (polymers) have been used as water reducers, set retarders, anti-washout and water retention agents [5, 6]. Other research work has also shown that bio-admixture from water hyacinth increases both workability and strength of concrete [7]. This research work was undertaken to determine the suitability of plant extract (cypress extract) as an eco-friendly and economical admixture for concrete. 2. MATERIALS METHODS 2.1 Materials 2.1.1 Plant Extract The plant extract used as an admixture was prepared by boiling cypress bark in water and soaking it in cold water. For the first case, bark of cypress was cut in to very small pieces and then 1kg of the bark was boiled with four litter of water for two hours under pressure. From successive boiling an average of 700ml/kg was obtained. For the later one, bark of cypress tree was cut in to small pieces and then 1kg of the bark was soaked in 1litter of water for 24 hours. After 24 hours it was shaken vigorously for 5 minutes and an average of 900ml/kg of extract was obtained. The elemental analysis for boiled plant extract was done by X-ray florescence and the results are shown in the table 1. Table 1: Chemical concentration in ppm or µg/g Element Bark of Cypress Extract Element Bark of Cypress Extract Potassium (K) 576 ±14 Copper(Cu) 0.070 ±0.007 Calcium (Ca) 102 ±3 Zink(Zn) 0.428 ±0.017 Titanium (Ti) 0.199 ±0.014 Arsenic(As) <0.01 Vanadium(V) 0.201 ±0.020 Bromine(Br) 1.26 ±0.04 Chromium(Cr) 0.241 ±0.014 Rubidium(Rb) 1.49 ±0.05 Manganese (Mn) 15.3 ±0.50 Strontium(Sr) 1.62 ±0.04 Iron(Fe) 2.72 ±0.09 Yttrium(Y) 0.074 ±0.006 Nickel <0.10 26 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online), Volume 5, Issue 6, June (2014), pp. 25-36 © IAEME The elemental analysis shows the extract was not toxic to human body. The level of bromine, rubidium, arsenic and nickel are insignificant as compared their toxic level. 2.1.2 Cement The cement used was Ordinary Portland cement (OPC) of grade 42.5. It was manufactured by Bamburi cement Ltd, Kenya. The product conforms to European Norm EN 197 cement speciation and has its composition contains of 95-100% clinker and 0-5% minor additional constituents by mass. It was produced by inter-grinding Portland Cement Clinker with a controlled amount of limestone and a strength enhancing additive. 2.1.3 Fine Aggregate Locally available river sand was used. The aggregate was graded through sieving and curve plotting according to BS 812:1992. The physical properties of fine aggregate were done based on their respective BS standard: The specific gravity (BS 812-102:1995), Bulk density (BS 812-2:1995), water absorption(BS 813-2:1995)and moisture content(BS 812-109:1990).The sieve analysis result show5mm (99.5%), 2.36mm (98.5%), 1.18mm (86.75%) ,0.6mm (58.25%), 0.3mm (23.75%) and 0.15(4%) passing BS sieve and was in zone II grading. The fine aggregate has the following properties: fineness modules of 3.3, specific gravity of 2.62, Bulk density of 1470kg/m3, water absorption of 8.63% and moisture content of 8.1%. 2.1.4 Course Aggregate The course aggregate used for this research was crushed stone obtained from Juja. According to BS 812:1992 requirement for 20mm nominal size, percentage by mass passing BS sieve was 37.5mm (100%), 20mm (90-100%), 10mm (30-60%) and 5mm (0-10%). The course aggregate was graded as 37.5mm (100%), 20mm (99.6%), 10mm (40%) and 5mm (9%) passing BS sieve. The course aggregate properties were done based on their respective BS code and have the following properties: Specific gravity (BS 812:1992) of 2.76, of Bulk Density (BS 812-2: 1995) of 1420 kg/m3, Water Absorption (BS 813-2:1995) of 2.7% and Moisture Content (BS 812-109:1990) of 2.2%. 2.1.5 Water The water used for concrete mix and curing the specimen was the water available in the laboratory form the tap. The water was clean, and the one used for home consumption and other activities in Jomo Kenyatta University of Agriculture and Technology (JKUAT). 2.2 Methodology 2.2.1 Concrete Mix For this research the prescribed mix ratios were used. The mix ratios are Mix-I (1: 1.5: 3) and Mix-II (1: 2:4) for cement: sand: coarse aggregate, and for each of the mix ratios two different slumps were used, namely 30mm and 50mm. 2.2.2 Standard consistency and setting time of cement The consistency of cement was determined by vicat apparatus based on BS EN 196-3:1995. A 400g of cement and a quantity of water with in a range of (105-135g) was mixed on a non-porous tray by two trawls. The cement consistency mold was filled immediately with the cement paste and the surface was smoothed. The plunger was lowered to touch the surface of cement paste and allowed to sink with in 4minutes form the time of water added to cement. The test was repeated for different water contents within the range of (105g-135g) until it was found to produce a distance between plunger and base plate of 6±1mm. The quantity of cement and water used for setting time 27 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online), Volume 5, Issue 6, June (2014), pp. 25-36 © IAEME were 400g and the quantity water obtained from consistency test respectively. The penetration was measured for 10min time interval for 0 - 4mm and 5min for 4 - 6±1mm penetration. For the cement past containing plant extract the same procedure was followed for both consistency and setting time. 2.2.3 Workability The workability of concrete was measured by both slump and flow table test. For the first case, the slump was measured and recorded using a truncated cone with base diameter of 300mm, top diameter of 200mm and a height of 300mm based on BS 1881-102:1983. For the later one, the flow or workability of mortar was determined by measuring the mean diameter of the test sample (BS EN 1015-3). 2.2.4 Compressive strength 150x150x150mm steel molds were used for casting concrete cubes. A total of 144 cubes were cast i.e. 36 cubes without plant extract as control and 108 cubes containing plant extract at dosages of 5, 10 and 15% in water , according to BS EN 12390-1:2000. The mixes were compacted with a vibrator in two layers. Within 16-28 hours the cubes were de-molded and cured in water at a temperature of 20 ±50C until the testing age as it is prescribed in BS EN 12390-2:2000 i.e. 7, 14 and 28 day. The cubes were tested based on BS EN 12390-3: 2002 by placing and aligning each specimen between the lower and upper platens of the test machine and loading appropriately. The load was applied at a rate of 0.2 MPa/s until failure. 3 RESULTS AND DISCUSSION 3.2 The Effect on Setting Time of Cement Table 2 describes the effect of plant extract on consistency and setting time. The plant extract has reduced the consistency of cement due to its viscous nature. The plant extract has also delayed the setting time of cement, possibly due to its ability to delay hydration process of cement. Cement contains compounds responsible for setting, early age strength and longtime strength. Tricalcium aluminate (3CaO•Al2O3) and tetracalcium aluminoferrite (4CaO•Al2O3•Fe2O3) are Compounds in cement that react with water and make cement to set very fast [8]. Tricalcium silicate (3CaO•SiO2) and dicalcium silicate (2CaO•SiO2) are also compounds responsible for setting and strength of concrete through time. When cement react with water (Cat-ions (Ca2+) from cement and anions (OH) from water), calcium hydrate gel (3CaO2·SiO2·H2O) calcium hydroxide (Ca (OH)2) are formed [9]. Plant extract has anions to link up with cat-ions, and polysaccharides have a carboxyl group. Since plant extract contains polysaccharides it has a carboxyl group that can be coupled with Ca2+ions on the surface of cement particles. In addition C3A (3CaO•Al2O3) react rapidly to form calcium aluminate hydrate if there is insufficient sulfate in solution [10]. The plant extract was engaged in complex formation with calcium crosslinking, and may be decrease the large amount of heat liberated by Tricalcium aluminate (3CaO•Al2O3) to delay the setting time. In hot areas concrete sets very fast thus reducing the time available for handling and placing the concrete. Hot weather may also result in early age shrinkage, leading to cracking and decreased durability of the concrete. So the boiled cypress bark plant extract can be used as a retarder in hot areas. 28 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online), Volume 5, Issue 6, June (2014), pp. 25-36 © IAEME Table 2: The Effect of Plant Extract on setting time of Cement Plant extract Consistency Initial setting time, Final setting time, added, % % min. min. 0 32 128 193 5 31 186 303 10 30 197 291 15 30 212 315 3.3 The Effect on Workability of Concrete From the flow table test, it was observed that at constant liquid to cement ratio, plant extract additions improved concrete workability as shown in Figure 1. The plant extract was able to increase the viscosity of mix and retain water. It was demonstrated in other research that, starch and starch derivatives are capable of reducing the amount of free water and increasing viscosity [11, 12]. Soft wood plant bark contains lignin (40-45%), polysaccharide (30-48%) [13]. Starch is also a polysaccharide that can be found in plant extract. In addition of increasing the slump, the extract retained water and reduced the fast flow of water or acted as viscous enhancing admixture. Workability increased linearly for the added extract up to 5% and thereafter remained almost constant after 5%. Figure 2-6 shows the amount of liquid reduced to get constant slumps of 30 & 50mm when using plant extract admixture. In Figure 2&3 for Mix-I, the average amount of liquid reduced for slump 30&50mm were 1.5% & 1.7% by weight ratio of cement or 3.0% &3.4% of the water used for control respectively. The same is true for figure 4-5 and water was reduced by 1.55% & 1.55% by weight ratio of cement or 2.54% &2.46% of the water used for their respective control. Figure 2&6 shows the amount of liquid reduced to get constant slump for the same mix when using boiled and water soaked cypress extract respectively. The water soaked extract was not effective in reducing the water demand as compared to the boiled extract. Water soaked extract reduced the water demand in average of 0.69% by weight ratio of cement or 1.39% of the water used for control. As compared to water soaked extract, the boiled one reduced the water demand by double. The plasticizing properties of the admixture resulted in decreased mix water demand. Figure 2-6 also shows indirectly the plant extract was improving the workability of concrete. Workability Workability (%) 70 65 60 Extract From Bark of Cypress Tree 55 50 0 5 10 15 20 % of Plant Extract Added Figure 1: The Effect of Boiled Cypress Bark Extract on Workability 29 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online), Volume 5, Issue 6, June (2014), pp. 25-36 © IAEME Amount of water in gm/1000gm of cement The Effect Boiled Cypress Extract on Water Usage for mix-I and slump 30mm Water Used 600 500 Water Reduced by % of Extract added 400 % Plant Extract added 300 200 Water used + Extract added 100 0 0 5 10 15 Water removed by the same amount of extract added 20 % Plant Extract added Figure 2: The Effect on Water usage for Mix-I & slump 30mm Amount of water in gm/1000gm of cement The Effect Boiled Cypress Extract on Water Usage for Mix-I and slimp of Water Used 50mm 600 500 400 Water Reduced by % of Extract added 300 % Plant Extract added 200 Water used + Extract added 100 0 0 5 10 15 % Plant Extract added 20 Water removed by the same amount of extract added Amount of water in gm/1000gm of cement Figure 3: The Effect on Water usage for Mix-I & slump 50mm The Effect of boiled Cypress Extract on Water Usage for mix-II (1:2:4) & slump 30mm Water Used 700 600 Water Reduced by % of Extract added 500 400 % Plant Extract added 300 200 Water used + Extract added 100 0 0 5 10 15 % Plant Extract added 20 Water removed by the same amount of extract added Figure 4: The Effect on Water usage for Mix-II& slump 30mm 30 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online), Volume 5, Issue 6, June (2014), pp. 25-36 © IAEME Amount of water in gm/1000gm of cement The Effect of Boiled Cypress Extract on Water Usage for mix-II (1:2:4) & slump 50mm Water Used 700 600 Water Reduced by % of Extract added 500 400 % Plant Extract added 300 200 Water used + Extract added 100 0 0 5 10 15 % Plant Extract added 20 Water removed by the same amount of extract added Figure 5: The Effect on Water usage for Mix-II& slump 50mm Amount of water in gm/1000gm of cement The Effect of water Soaked Cypress Extract on Water Usage for mix 1:1.5:3 and slump 30mm Water Used 600 500 400 Water Reduced by % of Extract added 300 % Plant Extract added 200 Water used + Extract added 100 0 0 5 10 15 20 Water removed and the same amount of extract added % Plant Extract added Figure 6: The Effect of Water soaked Extract on Water usage for Mix-I & slump 30mm 3.4 The Effect of Plant Extract on Compressive Strength of Concrete The compressive strength of concrete was done for both plant extract (boiled and water soaked), two different mixes, two different slumps and different percentage of dosage. The compressive strength was measured after 7, 14 and 28 days. Based on the compressive strength test results, as the percentage of boiled plant extract increased from 0 to 15%, the compressive strength also increased while for water soaked extract, the compressive strength increased for 5% and decreased onwards. The boiled plant extract acted as a plasticizer by reducing the water demand and increasing the strength of concrete. Figure 7-8 and Table 3 shows, the compressive strength of concrete for mix-I with two different slumps (30 &50mm). The 28 days test result show, the percentage variations between the conventional concrete (control) and concrete with 15% of boiled extract were 13.8 & 15% for slump of 30 and 50mm respectively or 15% dosage of plant extract increased the compressive strength by 5.5 & 6 Mpa for slump of 30 and 50mm respectively as compared to the control. Boiled plant extract was effective in improving the strength of concrete as the slump increases from 30 to 50mm. Figure 9 and table 4 shows, the effect of water soaked plant extract on compressive strength of concrete. 5% dosage of the plant extract has increased the compressive strength by 4% as compared to the control and meanwhile the compressive strength was decreased for 10 and 15% plant extract dosage. 31 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online), Volume 5, Issue 6, June (2014), pp. 25-36 © IAEME Figure 10-11 and table 5 shows, the compressive strength of concrete for mix-II with slumps of 30 &50mm. The 28 days test result show, the percentage variations between the conventional concrete (control) and concrete with 15% of boiled extract added were 10.45 and 17% for slump of 30 and 50mm respectively as compared to the control. Figure 8a and 8b shows 28 day compressive strength for slump 30&50mm. Addition of plant extract for slump 50mm resulted much increased strength as compared the control for slump of 30mm. The compressive strength of control for 30mm slump was greater than that of 50mm slump by 6.5%. However, the addition of plant extract to get 50mm slump increased the compressive strength by 2, 4.7 & 8.4% for 5, 10 & 15% dosage respectively as compared to the control for slump of 30mm. The boiled plant extract increased the compressive strength comparable to super plasticizers. Researched conducted on supper plasticizer like Sulphonated naphthalene polymer, aqueous solution of (anionic formaldehyde-polycondensate, naphthaline sulphonic acid and sodium salt), lignosulphonate and sulphonated naphthalene formaldehyde increased the compressive strength by 5.5, 4.73, 4.03 and 4.45 Mpa respectively [14]. Comparably the boiled plant extract has also increased the compressive strength for mix-I by 5.5 and 6 Mpa for slump of 30 and 50mm respectively. And also for mix-II of slump of 30 and 50mm, the compressive strength increased by 3.5 and 5 Mpa. So the plant extract has chains that react with Ca2+ to give calcium silicate hydrate gel which increases the strength of concrete. Super plasticizer has a carboxyl chain [9]. Carboxyl group and other chains present in plant extract increased the strength of concrete by increasing calcium hydrate gel and decreasing calcium hydroxide content. The durability of concrete is an actual issue linked to sustainable development considerations. The cypress extract is increasing the strength of concrete and it can have a positive effect on durability of concrete. Researches done on ancient structure show, in ancient time extract from herbs were used in construction with lime [11]. Still some of the structures are standing and proved its durability for centuries. So it is evident to say plant extract has a positive effect on durability of concrete. Table 3: Compressive Strength of concrete for Mix-I The Effect of Boiled Plant Extract from Bark of Cypress Tree on Concrete Compressive Strength Mix-I: 1:1.5:3 28 Day comp 7 Day Compressive 14 Day Compressive % age Strength Strength Plant Extract Load Strength Load Strength Load Strength Slump added (KN) (MPa) (KN) (MPa) (KN) (MPa) (mm) 893.081 39.692 0% 603.536 26.824 805.109 35.783 30* 938.227 41.670 5% 658.873 29.328 822.628 36.561 977.762 43.456 10% 704.835 31.326 865.396 38.461 15% 762.556 0% 568.432 5% 605.692 10% 620.767 15% 619.822 *The slump margin is ±2 33.891 896.339 39.837 1016.331 45.170 25.263 26.92 27.59 27.548 748.447 787.005 801.592 822.682 33.265 34.978 35.626 36.564 838.365 911.086 934.946 968.249 32 37.260 40.492 41.553 43.033 50* International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online), Volume 5, Issue 6, June (2014), pp. 25-36 © IAEME Strength of concrete for Cypress Extract added Comp. Strength, MPa 50 45 40 35 30 25 20 15 10 5 0 7 Day for slump 30mm 14 Day for slump 30mm 7 day for slump 50mm 14 day for slump 50mm 28 Day for slump 30mm 0% 5% 10% 15% Plant Extract added 20% 28 Days for slump 50mm Figure 7: The Effect on Compressive Strength of Concrete for Mix--I. 28 days Comp. Strength for Mix Mix-I 46 Comp. Strength, MPa Comp. Strength, MPa 28 Days Comp. Strength for Mix-I Mix 44 42 28 Days for slump of 30mm 40 38 36 44 42 40 28 Days for slump 50mm 38 36 34 0% 5% 10% 15% Plant Extract added (b) 0% 5% 10% 15% Plant Extract added (a) Figure 8: Plant Extract Effect on Comp. Strength of Mix-I, I, (a) slump 30mm and (b) slump 50mm Table 4: Compressive strength of concrete for water soaked Extract (Mix (Mix-I) Water soaked Plant Extract from Bark of Cypress Tree Mix-I: 1:1.5:3 7 Day Compressive Strength % age Plant Extract added Load (KN) Strength (MPa) 0% 603.536 5% 10% 14 Day Compressive Strength 28 Day Compressive Load (KN) Strength (MPa) Load (KN) Strength (MPa) 26.824 805.109 35.783 616.335 27.392 801.382 35.617 893.081 928.958 39.692 41.287 601.275 26.723 808.860 35.949 889.143 39.517 15% 588.187 26.142 *The slump margin is ±2 792.289 33.879 882.862 39.238 33 Slump, mm 30* 45 40 35 30 25 20 15 10 5 0 Comp. Strength for Mix-I ( Water soaked) 28 Days for Slump of 30mm 14 Days for slump of 30mm 7 Day for slump of 30mm 0% 5% 10% 15% Plant Extract added (c) 20% Comp. Strength, Mpa Comp. Strength, Mpa International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online), Volume 5, Issue 6, June (2014), pp. 25-36 © IAEME 45 40 35 30 25 20 15 10 5 0 28 Days Comp. Strength for Mix-I ( Water soaked) 28 Days for Slump of 30mm 0% 5% 10% 15% Plant Extract added (d) Figure 9: Effect of water soaked Plant Extract on Comp. strength for Mix-I Table 5: Compressive Strength of concrete for Mix-II The Effect of Boiled Plant Extract from Bark of Cypress Tree on Concrete Compressive Strength Mix-II: 1:2:4 7 Day Compressive 14 Day Compressive 28 Day comp % age Strength Strength Plant Extract Strength Strength Load Strength Slump Load (KN) Load (KN) added (MPa) (MPa) (KN) (MPa) (mm) 0% 486.286 21.613 634.286 28.190 757.043 33.646 30* 5% 544.418 24.196 623.685 29.073 767.095 34.093 10% 567.071 25.203 705.253 31.344 792.753 35.233 15% 576.162 25.607 752.743 33.455 836.147 37.162 0% 441.148 19.606 593.67 26.385 683.348 30.371 50* 5% 472.872 21.016 645.086 28.671 715.313 31.792 10% 479.595 21.315 634.445 28.197 766.246 34.055 15% 498.174 22.141 622.27 27.656 799.616 35.538 *The slump margin is ±2 Strength of concrete for Cypress Extract added 40 7 Day for slump 30mm Comp. Strength, MPa 35 30 14 Day for slump 30mm 25 20 7 day for slump 50mm 15 14 day for slump 50mm 10 5 28 Day for slump 30mm 0 0% 5% 10% 15% 20% 28 Day for slump 50mm Plant Extract added Figure 10: The Effect on Compressive Strength of Concrete for Mix-II 34 38 37 36 35 34 33 32 31 28 Days Comp. Strength for Mix-II 28 Days Comp. Strength for Mix-II Comp. Strength, MPa Comp. Strength, MPa International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online), Volume 5, Issue 6, June (2014), pp. 25-36 © IAEME 28 Days for slump of 30mm 0% 5% 10% 15% Plant Extract added (e) 36 35 34 33 32 31 30 29 28 27 28 Days for slump of 50mm 0% 5% 10% 15% Plant Extract added (f) Figure 11: Plant Extract Effect on Comp. Strength of Mix-II, (e) slump 30mm and (f) slump 50m 4 CONCLUSIONS Based on the experiments carried out and the results on the effect of plants extracts on the properties of fresh and hardened concrete, the following conclusions are made: a) The addition of plant extract increased the setting time of concrete and hence the plant extract can be used as a retarder in hot climate. b) The plant extract increased the workability of concrete at constant liquid to cement ratio, hence fresh concrete properties are improved by the use of cypress plant extract. c) The plant extract increased the strength of concrete at constant slump; hence hardened concrete properties are improved by the use of cypress plant extract. d) The ways of extraction has also an effect on the optimum dosage of the extract. It was determined that the boiled plant extract significantly improves the property of concrete as compared to cold extraction in cold water. 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