Engineering Properties of Wade Sand-Lime- Cement-Phosphogypsum Building Brick Grade MW

International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 – 8958, Volume-2, Issue-4, April 2013 Engineering Properties of Wade Sand-Lime- Cement-Phosphogypsum Building Brick Grade MW Lamia Bouchhima, Mohamed Jamel Rouis, Mohamed Choura Abstract-This study concerns the analysis of wade sand - The PG was treated to be used in the plaster manufacture. It natural hydraulic lime-cement-phosphogypsum (WS-NHL-C-PG) has been found that the PG is suitable for making good solid bricks grade MW. In Tunisia, for several years, a set of quality plaster showing similar proprieties to natural gypsum phosphoric acid production factories have produced a waste plaster [3], [4], [5]. This field is advantageous for the product such as phosphogypsum (PG) in large quantities countries which do not have natural quarries such as Japan (approximately 10 million tons per year). Currently, in Sfax (Center-East of Tunisia), the PG is stored into piles in the vicinity and India. The PG has been sought also to be used in of the factory, by dry or wet process. The storage of PG, even agriculture [6]. It is as effective as the crushed natural though presenting a low radioactivity, causes pollution to the gypsum. However, the quantities used are limited and water table and to the soil (due to the infiltration of acid and moreover the health standards became increasingly heavy metals). After treatment, the Tunisian PG was presented in restrictive. But the most interesting use of the PG is for the the full bricks with different mass percentages of 60, 70 and 80%. cement manufacturing: either by natural gypsum The study involved physical, chemical, mechanical and substitution (about 5%), which will play the role of a set environmental tests on the obtained bricks. retarder [7-8], or to reduce the clinkerization temperature The obtained results showed that WS-NHL-C-PG bricks [9]. The PG was also used in soil stabilization [10]. Finally successfully satisfied the standard requirements of bricks grade MW. Notwithstanding the techno-economic virtues, phosphogypsum PG has been studied to be used in hollow phosphogypsum-based bricks comply with the criteria for blocks [11] and light brick [12]. environmentally friendly products manufactured with industrial In Tunisia, the PG was studied to be used in similar fields. by-product and the manufacturing process is totally energy The most successful application so far is in the manufacture conservative. of cement; by substitution of the gypsum. The obtained product is known under the name of cement ultimo. It Keywords: Phosphogypsum; Full brick grade MW; strength; Durability showed good performances but the used quantity is low [13]-[14]. Moussa et al., (1984) had studied the possibility I. INTRODUCTION of the use of the PG in the embankments [15]. The PG is studied in order to use it like a fill. This study showed a The management of the industrial Phosphogypsum (PG) is behavior to the compaction not similar to that of a soil. environmental problem which concern several countries [1]. Furthermore, the fill showed also a continuous settlement Considering the high produced quantities and the chemical because of the PG solubility. Moreover, Kuryatnyk and composition of waste, this problem is worldwide since the Angulski- Ambroise- Pera (2008) have employed the Gabes phosphoric acid production is all around the world (Florida and Skhira PG to be used as a hydraulic binder. But ‘‘USA”, India, Jordan, Turkey, Morocco, Senegal, etc.). In formation of ettringite led to cracking and strength loss [16]. Tunisia, for several years, a set of phosphoric acid Finally, Sfar et al have explored the PG for a road use [17]- production factories have produced PG in large great [18]. The study proposed the following formulation: 46.5% quantities (approximately 10 million tons per year [2]. of PG, 46.5% of sand and 7% of cement. But this study was Currently, the PG is stored into piles in the vicinity of the conducted in the Tunisian south region, where the rainfall is factory, by dry or wet process. The storage of PG causes the low. pollution of the water table and the soils by acid and heavy In this paper, we start work the treatment of the Tunisian PG metals infiltrations. by adding wade sand and natural hydraulic lime. We deal in Its valorization leads to environmental protection and to the second part with the valorization of PG in full bricks. minimization of the storage costs. Several researchers had This study scrutinizes the manufacturing process and tests studied the use of PG in various fields. for WS-NHL-C-PG bricks characterization. II. EXPERIMENTAL PROGRAM A. Characteristics of the studied PG The characteristics of a PG depend on its composition and on its manufacturing process and control. Samples are obtained from the PG piles in the vicinity of the factory of Manuscript received on April, 2013. Sfax (Center-East of Tunisia). The studied PG is Lamia bouchhima: Unit of research environmental geotechnique and civil materials, Institute of the engineers of Sfax, Tunisia. characterized through its granularity, grains density, Mohamed jamel rouis: professor in civil engineering, : Unit of research radioactivity and chemical composition. environmental geotechnique and civil materials, Institute of the engineers 2.1.1 Particule size of Sfax, Tunisia. Mohamed choura: Assist.prof. Unit of research environmental Fig. 1 presents the granulometric curve of the studied PG. geotechnique and civil materials, Institute of the engineers of Sfax, Tunisia. The granular distribution of PG is obtained by laser diffraction (laser granulometry). This figure shows that the 43  Engineering Properties of Wade Sand-Lime-Cement-Phosphogypsum Building Brick Grade MW studied PG appears like fine sand, of a granulometry lower B. Characteristics of the wade sand than 250 µm. The granular distribution of PG depends on Granularity the quality and the reaction of the time of the phosphate Fig. 2 presents the granulometric curve of the wade sand. attack. The test allowed calculating the Coefficient of The granular distribution of wade sand was obtained by dry Uniformity (Cu) and the Coefficient of Conformity (Cc). sieving. The Cc (resp. Cu) was evaluated at 1.14 (resp. 3.11). Fig. 2 shows also a suitable uniform granulometry, consequently, it gives an optimum compactness which influences the strength, mainly in compression. Grains density The real densities of the grains were determined by the pycnometer method. The studied ridded wade sand presented a density of about 2630 kg/m3. This value is higher than the one for phosphogypsum. C. Mix proportion The mix proportions of phosphogypsum wade sand (WS), lime and cement (cement HRS 42.5) for bricks are given in table II. Fig. 1. Granulometric curve of the studied Tunisian PG. The optimization of the mixes is based on the results of the evolution of pH of Phosphogypsum- wade sand-lime The Cc (resp. Cu) was evaluated at 8 (resp. 3.125). Fig. 1 mixtures. Fig. 3 show that the wade sand-mix increased shows also a suitable uniform granulometry, consequently, it slightly the pH without reaching neutralization. Therefore, a gives an optimum compactness which influences the small adding lime is necessary.Fig.4 shows the evolution of strength, mainly in compression. The PG is considered to pH values with adding natural hydraulic lime. These results have a fine granulometry which is similar to sand. The indicate that the adding of lime has allowed the Tunisian PG presents a percentage of fines of about 80% neutralization of Phosphogypsum- wade sand mixtures. [17]-[18]. Besides, treatment with 3% lime has contributed to the use of higher percentage of Phosphogypsum (up to 60%). This Grains density minor amount of lime (3%) was chosen due to the fact that the PG plays the part of grease-remover. The use of higher The real densities of the grains were determined by the percentage of phosphogypsum allows an economical gain on pycnometer method, by using water saturated with gypsum. the price of brick (nowadays, the PG is free). Actually, the The studied PG presents a density of about 2300 kg/m3. use of PG would resolve the problem of its storage.These This value is the same as for the natural gypsum (2320 Phosphogypsum-wade sand-lime mixtures would facilitate kg/m3). This value is also close to that indicated for the basic cementitious reactions, the formation of CSH Brazilian PG (2308 kg/m3) [19]. But this density is lower compounds and, therefore, the best opportunities for than the one of the Turkish PG (2890 kg/m3) [20]. Theses development as a building material.Shrinkage cracking and high values are explained by a strong presence of impurities. spalling are major weaknesses in phosphogypsum-based Chemical composition bricks. Shrinkage cracking can be minimized by keeping the water content of binder as low as possible. Hence, in the The chemical analyses, most relevant to the prospect use in present study, a low slump mix was used to limit the commercial brick making, are undertaken on the PG. The shrinkage. results of these analyses are presented in Table I. The PG is primarily (about 77%) made up of calcium sulfate (CaSO4). The remaining components are present at low percentage. It should be noted that the pH of PG samples are around 2.9, indicating a high acidity of the PG. 100 cum.. pasing(%) Table I. Chemical composition of phosphogypsum 90 Elements (%) 80 CaO 32.8 70 SO3 44.4 60 P2O5 1.69 50 F 0.55 40 SiO2 1.37 30 Fe2O3 0.03 20 Al2O3 0.11 10 MgO 0.07 0 Ignition loss at 22.3 diameter (mm) 0.01 0.1 1 10 1000°C Fig 2. Granulometric curve of the waded sand. 44  International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 – 8958, Volume-2, Issue-4, April 2013 8 14 7 13 12 6 11 0%C pH 5 pH 10 3%C 4 9 4%C 8 5%C 3 7 7.5%C 2 10%C 6 0 50 100 150 0 50 100 Phosphogypsum (%) riddled wade sand (%) Fig.5. pH phosphogypsum-wade sand-lime-cement mixtures Fig.3. pH phosphogypsum-wade sand mixtures versus versus cement proportioning crushing sand proportioning D. Manufacturing process The water contents of Phosphogypsum-wade sand-lime mixtures were fixed to 4 %. Bricks produced with more than Mixing of raw materials 4 % showed cracks after fabrication due to excessive water. A mixer, as shown in appendix figure A-1, is used for All the formulations phosphogypsum-wade sand-lime mixing materials. The dry phosphogypsum is sieved through presents white spots on the brick surface. To solve this 1 mm sieve. The weighed quantity of phosphogypsum, wade problem, minor amounts of cement HRS 42.5 (3 to 10%) sand, lime and cement are first thoroughly mixed in dry state was introduced. The optimum composition of for a period of 10 minutes to uniform blending. The required phosphogypsum-wade sand-lime-cement mixes is based on water is then gradually added and the mixing continued for the results of the evolution of pH. Fig. 5 shows that the pH another 5 min. increases very slightly with the addition of 3 and 4% cement. A significant rise in pH is remarkable from 5% Preparation of bricks cement. Besides, the pH shows a significant rise for mixtures which contain 3% CHN, 5 to 10% cement, 60 to All full bricks were made on a bench model, semiautomatic 80% phosphogypsum and the rest is that of wade sand. press having a capacity of 25 tons, as shown in appendix Mixtures containing 3% CHN, 5 to 10% cement, less than figure A-2, to produce bricks of 0.051×0.095×0.203 m in 60% of phosphogypsum and the rest wade sand, shows a size under a static compaction of 27MPa. The following very slight increase of pH. Thus the percentages are set to operations are performed to produce one brick: 3% CHN, 5, 7.5 and 10 of cement, 60 to 80% a. The material at the preset constituent proportions is fed phosphogypsum and the rest is that of wade sand. The mix into the mold. proportions of phosphogypsum, wade sand (WS), lime and b. The material fully occupies the space available in the cement (cement HRS 42.5) for bricks are given in table 2. mold (volumetric fill). At this point, the top surface is The mix proportions are given in terms of dry weights of the trimmed and the supply material is impeded. ingredients. c. The press ram compacts the material in the mold and immediately after, is raised. d. The crick having a capacity of 5 tons fully extends to 2% NHL 3%NHL extrude the brick. Table II. Mix proportions of WS-NHL-C-PG full bricks 14 Constituant materials (Weight %) Mix 12 désignation Phosphogypsum Sand Cement Lime 10 (WS) M-1 60 32 5 3 8 M-2 60 29.5 7.5 3 pH 6 M-3 60 27 10 3 M-4 70 22 5 3 4 M-5 70 19.5 7.5 3 2 M-6 70 17 10 3 0 M-7 80 12 5 3 M-8 80 9.5 7.5 3 0 50 100 150 M-9 80 7 10 3 Phosphogypsum (%) E. Method of curing All bricks were dried to the free air for a period of 28, 56 Fig.4. pH phosphogypsum-sand mixtures versus natural and 90 days. The durability of phosphogypsum-based bricks hydraulic lime (NHL) proportioning was investigated by submersion in cold and boiling water. 45  Engineering Properties of Wade Sand-Lime-Cement-Phosphogypsum Building Brick Grade MW F. Testing of bricks absorption of bricks decreased with the increase cement and Compressive strength, density, water absorption, saturation phosphogypsum contents was deduced. Moreover, the coefficient and leaching tests of bricks from different mixes values obtained were favorable when compared with those of phosphogypsum, wade sand, lime and cement with of clay bricks (0 to 30%) [23]. available mixing water content were determined. The 24-h cold water absorption of each unit of a random Compressive strength of the units was determined according sample of five WS-NHL-C-PG bricks exceeds 8%. So, the to ASTM C67 [21]. Test bricks, as shown in appendix figure saturation coefficient requirement does apply [24]. A-2, consist of a half brick with full height and width. The water absorption by 5 hours boiling test The absorption qualities of bricks are taken as a part of the The Water absorption after 24 hours in cold water+5hours in acceptance measurement of the material durability. ASTM boiling water is shown in table IV. The fact that water specification C67 describes a method by which absorption absorption of bricks increased after 5hour boiling was of building clay brick can be measured. First, the samples noticed. The 24- hour submergence alone will not fill all the are immersed for 24 hours in cold water. The amount of pores spaces in a brick, so more will be filled during the water absorbed is then recorded as a percentage of the total boiling stage. weight of the dry unit. After the cold water immersion, the Besides, the results show that the water absorption of unit is immersed in boiling water for 5 hours. Again the phosphogypsum-based bricks is less than the maximum amount of absorption is recorded as a percentage of the total limit for clay building brick grade MW (moderate weight of the dry unit. The ratio of these two immersions is weathering) set by ASTM (22%). the cold water/boiling water ratio, or saturation coefficient. The test specimens were consisted of half bricks. Five The saturation coefficient specimens were tested. In order to determine the density of each brick, dry bricks The saturation coefficient of those bricks is shown in table IV. This ratio is the proportion of total pore space that is were weighed accurately and their volumes were measured. easily filled with moisture. Since only a part of the total pore The leaching tests had been performed according to the space of the brick is naturally filled with water in place, it is French Norm NF EN 12457-3 [22] at an ambient thus known that the room for expansion exists during temperature (20 ± 5°C). The specimens (three different freezing, without disrupting the wade sand-lime-cement- samples for each mix-design) were crushed and an amount phosphogypsum body. This is the reason why this property of 0.175 kg was taken to be analyzed. The distilled water becomes a partial measure of durability. The saturation was added to obtain a liquid/solid ratio of 10 l/kg. coefficient of phosphogypsum-based bricks is less than the The compressive phosphogypsum-based bricks were tested maximum limit for clay building brick grade MW set by after 28, 56 and 90 days of treatment. Water absorption, (0.88). Therefore WS-NHL-C-PG bricks have moderate saturation coefficient, density and leaching test were resistance to damage by freezing when wet. determined on bricks tested after 28 days of casting. Table IV. Physical characteristics of WS-NHL-C-PG full bricks III. TEST RESULTS AND DISCUSSION Mix Water Water Saturation A. Dry density designation absorption absorption coefficient after 24 hr after 24 hr The densities of WS-NHL-C-PG full bricks are shown in cold water cold water table III. These densities range from 1598 to 1834 kg/m3. (%) +5hr Therefore the WS-NHL-C-PG full bricks have high density. boiling Table III. Dry densities (kg/m3) of WS-NHL-C-PG full (%) bricks Mix désignation Dry densities (kg/m3) M1 19.71 22.4 0.88 M2 18.23 21.2 0.86 M1 1598 M3 16.88 20.1 0.84 M2 1631 M4 18.7 21.5 0.87 M3 1660 M5 17.25 20.3 0.85 M4 1615 M6 16.1 19.4 0.83 M5 1638 M7 17.74 20.63 0.86 M6 1652.5 M8 16.29 19.4 0.84 M7 1731 M9 15.04 18.35 0.82 M8 1753 C. Mechanical properties of studied bricks M9 1834 The results, obtained as an average of measurements performed on three specimens, are shown in Figs. 6-8. For all the studied cases, the compressive strength of the 90 days B. Water absorption and saturation coefficient of studied cured full bricks was higher than 17.2 MPa which is the bricks minimum strength of building brick grade MW [24]. The 24-h cold water absorption According to literature sources, recommended wet compressive strength values of bricks and blocks are quite The water absorption is a principal factor for the durability wide ranging, varying from country to country and from an of the product and its behavior to natural environment. author to another. The experimental values obtained here, Table IV presents the results of the water absorption for the however, can be well compared with most current brick and selected percentages of the bricks. The fact that the water block standards. Some recommended minimum values are: 46  International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 – 8958, Volume-2, Issue-4, April 2013 1.2 and 2.8 MPa [23]. Cement and lime as a source of 20 reactive silica and alumina are given to silicate and 10% 19.5 Cement aluminates hydrates, which are responsible for the development of compressive strength. 19 Compressive strength (MPa) 7.5% These Figures also shows increase in the compressive 18.5 18 5% strength with the phosphogypsum and cement additions. This result confirms the water absorption test outcome, 17.5 where it has been indicated that the addition of 17 phosphogypsum produces a decrease in the internal pore 16.5 size. Thus, the brick becomes less porous causing an 16 increase in the mechanical strength. 15.5 WS-NHL-C-PG bricks are found to be conforming to 15 physical requirements of clay or shale building brick grade MW (moderate weathering), bricks intended for use where 20 40 60 80 100 moderate resistance to cyclic freezing damage is permissible Curing period or where the brick may be damp but not saturated with water when freezing occurs [24]. Therefore, WS-NHL-C-PG Fig.7 Compressive strength of WS-NHL-C-PG full bricks bricks can replace the clay or shale brick grade MW. (phosphogypsum=80%) D. Leaching tests Table V. Leaching test results, in mg/kg for L/S = 10 l/kg The average values of the leaching test are presented in Mix designation Elements Table V. The concentrations of the selected metal species, i.e., Cd, Cu, Zn, Ni, Pb, and Cr, for all mix-design, were Cr Ni Zn Pb Cu Cd M1 0.063 0.058 N 0.064 0.17 0.067 well below the regulatory limits. Thus, this result indicates M2 0.057 0.045 N 0.053 0.15 0.055 that PG amended brick specimens can be considered as non M3 0.05 0.039 N 0.035 0.09 0.043 hazardous materials. M4 0.055 0.046 N 0.06 0.12 0.053 18.5 10% M5 0.046 0.04 N 0.05 0.09 0.046 M6 N 0.035 N 0.03 0.063 0.037 Cement 18 7.5% M7 0.043 0.04 N 0.05 0.09 0.04 M8 0.035 0.035 N 0.045 0.055 0.02 Compressive strength (MPa) 17.5 5% M9 N 0.03 N 0.027 0.03 0.01 17 Limit values 4 0.4 4 0.5 2 0.04 acceptable as inert 16.5 Limit values 50 10 50 10 50 1 16 acceptable as non hazardous 15.5 IV. CONCLUSION 15 Based on the experimental investigation reported in this 20 40 60 80 100 paper, following conclusions are drawn: Curing period (1) Unique possibility exists for the utilization of phosphogypsum in producing bricks in the proximity of phosphoric acid fertilizer industries Fig.6 Compressive strength of WS-NHL-C-PG full bricks (2) The WS-NHL-C-PG bricks have sufficient strength (phosphogypsum=60%) and have potential as a replacement for conventional 19.5 full clay bricks grade MW. 10% 19 (3) Phosphogypsum has more pronounced binding action Cement 18.5 than Wade sand. Compressive strength (MPa) 7.5% 18 (4) The increase of the percentages of PG and cement 5% 17.5 resulted in inecrease in the mechanical strengths of 17 bricks. (5) Cementations binder with 80% phosphogypsum 16.5 content shows low water absorption and better 16 compressive strength and thus is suitable for use in 15.5 construction industry. WS-NHL-C-PG bricks with 5% 15 cement can be delivered after 56 days of manufacturing.WS-NHL-C-PG bricks with more than 20 40 60 80 100 7.5% cement can be delivered to the construction site Curing period after 28 days of manufacturing. This is can reduce the cost of storing the bricks. (6) When subjected to a boiling test, the cementations Fig.7. Compressive strength of WS-NHL-C-PG full bricks binder which gave low water absorption after 24 hours (phosphogypsum=70%) in cold water and better compressive strength exhibited a low saturation coefficient. 47  Engineering Properties of Wade Sand-Lime-Cement-Phosphogypsum Building Brick Grade MW APPENDIX Fig.A-1. A mixer The mixer was used for mixing materials. This type of mixer Fig.A-3. Compressive strength test of the units is suitable for mixing dry and lean mixes. The size of test specimen is full height and width, and approximately one-half of a brick in length. The specimen is centered under spherical upper bearing block. The introduction of an eccentric load, if the specimen is not carefully centered, can result in a lower apparent compressive strength for the test specimen. Therefore, the specimens were carefully centered. REFERENCES [1] Rutherford PM, Dudas MI, Samek RA. Envir nmental impacts of phosphogypum. Sci Total Environ. 149 199(4).pp.1–38. 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