The ceramic industry is known to generate large amounts of calcined-clay wastes each
year. So far a huge part is used in landfills. Reusing these wastes in concrete could be a
win-win situation. For one hand by solving the ceramic industry waste problem and at the
same time leading to a more sustainable concrete industry by reducing the use of non
renewable resources like cement and aggregates and avoiding environmental problems
related to land filled wastes. This paper examines the feasibility of using ceramic wastes
in concrete. Results show that concrete with 20% cement replacement although it has
minor strength loss possess increase durability performance. Results also shows that
concrete mixtures with ceramic aggregates perform better than the control concrete
mixtures concerning compressive strength and chloride diffusion

Jalali, Said

Pacheco-Torgal, F.

Shahsavandi, Arman

Universidade do Minho: RepositoriUM

WASTES: Solutions, Treatments and Opportunities 1St International Conference  September 12th – 14th 2011   MECHANICAL PROPERTIES AND DURABILITY OF CONCRETE WITH PARTIAL REPLACEMENT OF PORTLAND CEMENT BY CERAMIC WASTES   F.Pacheco Torgal1, A. Shahsavandi2 and S. Jalali3 1 Research Unit C-TAC, University of Minho, Guimarães, torgal@civil.uminho 2 Research Unit C-TAC, University of Minho, Guimarães, arman.sh@civil.uminho 3 Research Unit C-TAC, University of Minho, Guimarães, said@civil.uminho   ABSTRACT The ceramic industry is known to generate large amounts of calcined-clay wastes each year. So far a huge part is used in landfills. Reusing these wastes in concrete could be a win-win situation. For one hand by solving the ceramic industry waste problem and at the same time leading to a more sustainable concrete industry by reducing the use of non renewable resources like cement and aggregates and avoiding environmental problems related to land filled wastes. This paper examines the feasibility of using ceramic wastes in concrete. Results show that concrete with 20% cement replacement although it has minor strength loss possess increase durability performance. Results also shows that concrete mixtures with ceramic aggregates perform better than the control concrete mixtures concerning compressive strength and chloride diffusion.  Keywords: Concrete; ceramic wastes; mechanical properties; durability performance   INTRODUCTION In Europe the amount of wastes in the different production stages of the ceramic industry reaches some 3 to 7% of its global production meaning millions of tons of calcined-clays per year that are just land filled [1]. With increasing restrictions on landfills in European Union area, the cost of deposition will increase and the industries will have to find ways for reusing their wastes. Although the reutilization of ceramic wastes and has been practiced, the amount of wastes reused in that way is still negligible. Hence, the need for its application in other industries is becoming absolutely vital. Construction industry as the end user of almost all the ceramic materials is well posed to solve this environmental problem which is partly its own. The nature of construction industry, especially the concrete industry, is such that ceramic wastes can be used safely with no need for dramatic change in production and application process. On one hand, the cost of deposition of ceramic waste in landfill will be saved and, on the other, raw materials and natural resources will be replaced, thus saving energy and protecting the environment. According to some authors the best way for the construction industry to become a more sustainable one is by using wastes from other industries as building materials [2,3]. The production of cement requires high energy input (850 kcal per kg of clinker) and implies the extraction of large quantities of raw materials from the earth (1,7 tonnes of rock to produce 1 tonne of clinker). On the other hand the production of one tonne of cement generates 0,55 tonnes of chemical CO2 and requires an additional 0,39 tonnes of CO2 in fuel emissions, accounting for a total of 0,94 tonnes of CO2 [4]. Therefore, the replacement of cement in concrete by ceramic wastes represents a tremendous saving of energy and has important environmental benefits. Several authors already confirmed the pozzolanic reactivity of ceramic wastes [5-7], nevertheless, research carried out so far by reusing ceramic wastes in concrete are scarce and do not evaluate concrete durability performance which is a key issue. On the other hand, recent research in the field of reusing ceramic aggregates in concrete are scarce and do not evaluate concrete durability performance [8,9]. Consequently the aim of this research project is the assessment of the properties and durability of of ceramic waste based concrete.   Experimental work Materials and concrete mix design The chemical compositions of ceramic pastes were analysed and results obtained are reported in Table 1. The silica and alumina are the most significant oxides present in the ceramic pastes. The variation of proportion of the silica and alumina is due to the clay used. It should be noted that the red paste shows high proportion of iron oxide responsible for the red colour of the products. Ceramic wastes were crushed with a jaw crusher to make the ceramic aggregate. Thus, by using this system to crush ceramic wastes it is possible obtain coarse aggregates, fine aggregates and ceramic powder that after sieving can be used without additional work and with minimal cost implications.  Table 1 - Chemical composition of ceramic pastes Type Si02 Al203 Fe203 Ca0 Mg0 Na20 K20 Ti02 Red paste twice fired ceramic 51.7 18.2 6.1 6.1 2.4 0.2 4.6 0.8 White paste once-fired ceramic 58.0 18.0 1.0 8.3 0.6 0.2 1.2 0.8 White paste for twice -fired ceramic 59.8 18.6 1.7 5.5 3.5 1.6 2.5 0.4 Red paste for stoneware tile 29.1 20.3 7.7 1.2 1.1 0.4 4.2 0.9 White paste for stoneware tile 65.0 21.3 1.3 0.2 0.3 2.5 3.7 0.2 White paste for sanitary ware 65.8 22.2 0.6 0.1 0.1 1.0 3.5 0.3  At laboratory scale the ceramic wastes were grounded with a ball mill with metal balls to obtain ceramic powder. The ceramic powders with a particle size <75µm were chosen for the partial substitution of cement. The coarse aggregate and the coarse sand used in the concrete mixes with cement replacement by ceramic powder were crushed granite aggregates. For the production of concrete samples in phase A, Portland cement, CEM I-32.5, complying with the NP EN 197-1:2001was used along with both natural sand and granite aggregates. The concrete mixes were determined using the Faury method, applying a computer programme [10,11]. A mix design, with characteristic strength fc=25N/mm2 and a target mean strength fm=30 N/mm2 was studied. Four mixes with 20% replacement of cement by ceramic powder were also prepared. Each one is named after the source of the ceramic waste: CB (ceramic bricks); WSTF (White stoneware twice-fired); SW (sanitary ware); WSOF (White stoneware twice-fired). The compositions of the concrete mix used in phase A are described in Table 2.  Table 2-Concrete mix proportions per cubic meter of concrete used in phase A Control mix Concrete mixtures with ceramic wastes Portland Cement 350.0 Kg. Portland Cement 280.0 Kg. Coarse aggregate 1084.0 Kg. Ceramic waste powder 70.0 Kg. Fine sand 135.4 Kg. Coarse aggregate 1084.0 Kg. Coarse sand 564.0 Kg. Fine sand 135.4 Kg. Water 218.5 l Coarse sand 564.0 Kg. W/C 0.6 Water 218.5 l  The equivalent ceramic aggregate concrete for each mix was obtained by replacing the natural aggregates with an equal volume of crushed ceramic, everything else remained the same. To have a direct comparison of concrete made with crushed-ceramic aggregate with conventional concrete, two corresponding mixes were prepared one replacing natural sand by ceramic sand (MCS) and other where coarse granite aggregate where replaced by ceramic coarse aggregate (MCCA). The ceramic aggregates were soaked in water for 24 hr and then air-dried to a saturated surface dry condition before mixing with other ingredients. For the production of concrete samples in phase B, Portland cement, CEM I-42.5, complying with the NP EN 197-1:2001was used. The concrete mixes were determined using the Faury method, applying a computer programme. The compositions of the concrete mix used in phase B are described in Table 3.  Table 3 - Concrete mix proportions per cubic meter of concrete in phase B Materials Control MCS- Mix with ceramic sand MCCA- Mix with ceramic coarse aggregate CEM-II 42,5 350 350 350 Sand 861 - 861 Ceramic sand - 729 - Coarse aggregate 958 958 - Ceramic coarse aggregate - - 820 Water 175 175 175 W/C 0,5 0,5 0,5  Experimental procedures Compressive strength The compressive strength was determinate following the NP EN 12390-3:2003. The specimens were conditioned at a temperature equal to 18 ± 1 ºC cured under water until they have reached the testing ages. Tests were performed on 100x100x100 mm3 specimens. Compressive strength for each mixture was obtained from an average of 3 cubic specimens determined at the age of 7,14, 28, 56 and 90 days of curing.   Durability aging test The aging test performed is composed by twelve cycles; each cycle has 4 steps and one conditioning period (Table 4).   Table 4-Durability aging test phases Principal phase Exposure Temperature Relative Humidity Duration Dry Heat 75±2 ºC 45% 90 min Cold -10±2 ºC --- 90 min Wet Heat 55±2 ºC 95% 90 min Cold -10±2 ºC --- 90 min Conditioning phase Conditioning 23±2 ºC 50% 960 min  The different phases have been selected to simulate dry heat, cold weather and wet heat and cold. Further the rapid change of temperature from 75ºC to –10ºC and then from –10ºC to 55ºC and dropping quickly to –10ºC in each cycle to simulate the thermal shock that concrete can suffer. Following the curing period, all the specimens were weighed and half of the specimens were submitted to twelve cycles of aging 24 hours long each, the remaining specimens were kept in the curing chamber at constant 21ºC. All specimens were subjected to compressive strength test.   RESULTS AND DISCUSSION  Using ceramic powder as partial replacement of cement Compressive strength, The results obtained indicate, as expected, large differences in early curing ages and smaller differences at long curing ages (Fig. 1). The concrete mixture with 20% of CB waste has the highest mechanical performance for all ceramic wastes which means it has higher pozzolanic reactivity. The concrete mixture with WSOF wastes has the worst mechanical performance at early ages, representing 74,8% of control strength for 7 days curing.  0510152025303540450 14 28 42 56 70 84 98Curing daysCompressive strength (MPa)ControlCBWSTFSWWSOF   Figure 1 – Compressive strength at different curing ages.  For 28 days curing that concrete mixture has almost 80% of the control strength index. However, for 90 days curing the compressive strength activity index of the WSOF mixture reaches 90,4%.For long curing ages concrete mixtures with 20% cement replacement has minor the strength loss. Since higher curing temperatures increase the rate of pozzolanic activity pre-fabrication industry may be an ideal way to their employment. This is because higher curing temperatures are used in concrete pre-fabrication for accelerated demoulding.  Durability performance As for the durability aging test (Fig.2), results indicate that all mixtures without exception have higher durability performance which confirms the positive impact of the ceramic additions.   43464952Control CB WSTF SW WSOFConcrete mixDurability aging test - Compressive strength before and after  Figure 2 – Compressive strength: Before and after the durability aging test  Using ceramic aggregates replacing traditional aggregates Compressive strength The results obtained (Fig. 3) indicate that the strength is higher for concrete with both replacements coarse ceramic aggregate (MCCA) and ceramic sand (MCS) than control concrete with traditional aggregates.   01020304050600 14 28 42 56 70 84 98Curing daysCompressive strength (MPa)ControlMCSMCCA   Figure 3 – Compressive strength  This behaviour is opposite to the one obtained by others using low percentage crushed brick aggregates [12,13]. One explanation for that may be due to the fact that they used brick aggregates with a water absorption level between 16% and 19%, which is much higher than the water absorption of the ceramic aggregates used in the present investigation. Another explanation relates to the fact that ceramic aggregates are used in a pre-saturated state they can provide water for cement hydration. Nevertheless, the strength performance is higher for concrete mixtures with ceramic sand beyond 14 days curing. As for concrete mixtures with coarse ceramic aggregate a maximum strength level is attained at 28 days curing.   Durability performance As for the durability aging test (Fig.4) compressive strength reduction is higher for ceramic based concrete.   3843485358Control MCS MCCAConcrete mixDurability aging test - Compressive strength before and after Figure 4 – Compressive strength: Before and after the durability aging test  Nevertheless, compressive strength after the aging test is still higher in ceramic based concrete. Therefore, the replacement of traditional sand in concrete by ceramic sand represents important environmental benefits. Avoids the extraction of large quantities of raw materials from the earth, avoid energy costs and also landfill problems.   CONCLUSIONS Results show that concrete with ceramic waste powder although has minor strength loss possess increase durability performance. Results also show that replacement of traditional sand by ceramic sand is a good option because does not imply strength loss and has superior durability performance. As for the replacement of traditional coarse aggregates by ceramic coarse aggregates, the results are promising but require further investigations.   References [1] M. Fernandes, A. Sousa, A. Dias, Environmental impact and emissions trade. Ceramic industry. A case study. Portuguese Association of Ceramic Industry APICER (2004) [2] P. K. Metha, Reducing the environment impact of concrete. Concrete can be durable and environmentally friendly. Concr Inter 10 (2001) [3] C. Meyer, The greening of the concrete industry. Construction and Building Materials (2009) [4] E. Gartner, EIndustrially interesting approaches to low-CO2 cements. Cem Concr Res 34 (2004) 1489-1498. [5] F. Puertas, I. Garcia-Diaz, A. Barba, M. Gazulla, M. Palacios, M. Gomez, S.Martinez-Ramirez, Ceramic wastes as alternative raw materials for Portland cement clinker production. Cem Concr Compos 30 (2008) 798-805. [6] A. Naceri, M. Hamina, Use of waste brick as a partial replacement of cement in mortar. Waste Manag 29 (2009) 2378-2384. [7] A. Lavat, M. Trezza, M. Poggi, Characterization of ceramic roof tile wastes as pozzolanic admixture. Waste Manag  29 (2009) 1666-1674. [8] H. Binici, Effect of crushed ceramic and basaltic pumice as fine aggregates on concrete mortar properties. Constr Build Mat 21 (2007) pp.1291-1197. [9] P. Cachim, Mechanical properties of brick aggregate concrete. Constr Build Mat 23 (2009) pp.1292-1297. [10] J. Faury, Beton. Influence de ses constituents inerts. Regles á adopter pour sa meilheure composition. Sa confection et son transport sur les chantier. 3rd ed. Paris, Dunod (1958). [11] J. Lourenço, J. Coutinho, Automatic calculations for concrete mix selection. Faury and Bolomey methods. Technical documents, Coimbra (1986) [12] J. de Brito, A.Pereira, J. Correia, J.- Mechanical behaviour of non-structural concrete made with recycled ceramic aggregates. Cem Concr Compos 27 (2005) 429-433. [13] J. Khatib, Properties of concrete incorporating fine recycled aggregate. Cem Concr Res 35 (2005) 763-769.   

Mechanical properties and durability of concrete with partial replacement of Portland cement by ceramic wastes

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Mechanical properties and durability of concrete with partial replacement of Portland cement by ceramic wastes

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