Effect of polymer cement modifiers on mechanical and physical properties of polymer-modified mortar using recycled artificial marble waste fine aggregate

Various polymer-modified mortars using recycled artificial marble waste fine aggregate (AMWFA) were prepared and investigated for the purpose of feasibility of recycling. Styrene–butadiene rubber (SBR) latex and polyacrylic ester (PAE) emulsion were employed as polymer modifier, and compared each other. The replacement ratio of AMWFA was also changed to investigate the effect of it on physical properties. Adding polymer cement modifier into mortar reduced water–cement ratio, and PAE was the more effective polymer cement modifier to reduce water–cement ratio than SBR. PAE emulsion-modified mortar increased the air content entrained as the proportion of PAE was increased. There was little difference in water absorption between SBR latex and PAE emulsion. The compressive strength decreased in the presence of polymer cement modifiers compared to that of no polymer cement modifiers, but the compressive strength of 20% of polymer–cement ratio was higher than that of 10%. After the hot water resistance test, both compressive strength and flexural strength were decreased.

Available online at www.sciencedirect.com Journal of Industrial and Engineering Chemistry 14 (2008) 265–271 www.elsevier.com/locate/jiec Effect of polymer cement modifiers on mechanical and physical properties of polymer-modified mortar using recycled artificial marble waste fine aggregate Eui-Hwan Hwang *, Young Soo Ko, Jong-Ki Jeon Department of Chemical Engineering, Kongju National University, 275 Budae-dong, Cheonan, Chungnam-do 330-717, Republic of Korea Received 29 October 2007; accepted 11 November 2007 Abstract Various polymer-modified mortars using recycled artificial marble waste fine aggregate (AMWFA) were prepared and investigated for the purpose of feasibility of recycling Styrene–butadiene rubber (SBR) latex and polyacrylic ester (PAE) emulsion were employed as polymer modifier, and compared each other The replacement ratio of AMWFA was also changed to investigate the effect of it on physical properties Adding polymer cement modifier into mortar reduced water–cement ratio, and PAE was the more effective polymer cement modifier to reduce water–cement ratio than SBR PAE emulsion-modified mortar increased the air content entrained as the proportion of PAE was increased There was little difference in water absorption between SBR latex and PAE emulsion The compressive strength decreased in the presence of polymer cement modifiers compared to that of no polymer cement modifiers, but the compressive strength of 20% of polymer–cement ratio was higher than that of 10% After the hot water resistance test, both compressive strength and flexural strength were decreased # 2007 The Korean Society of Industrial and Engineering Chemistry Published by Elsevier B.V All rights reserved Keywords: Polymer cement modifier; Polymer-modified mortar; Recycling; Recycled waste material Introduction It has been significantly important to develop the technology to treat or recycle the waste from organic materials such as plastics, vehicle tires, and artificial marble due to the enormous production of them as the industry and economy of the world are growing [1–3] There have been several ways to treat the wastes such as landfill, incineration, chemical recycling, material recycling and the utilization of energy from combustion [4–12] Most methods excluding material recycling are known to have critical limitations in economic, technical and environmental manners [10,13–15] Material recycling is expected to be more feasible in a way that the simplicity of pretreatment, and the reduction of energy consumption and environment pollution can be satisfied [1,10,14,16] A recent trend and preference of the interior decoration or housing construction material is known to be of higher quality * Corresponding author E-mail address: ehhwang@kongju.ac.kr (E.-H Hwang) and more ornamental than the past, making use of a huge amount of acrylic artificial marble as construction material Consequently, this links to the huge amount of waste artificial marble, causing the environmental issue in our society Furthermore, the waste artificial marble is categorized and treated as industrial wastes It means it should be disposed or burned to destroy, resulting in the air pollution and environmental pollution [13,14] The importance of how to recycle or reuse waste artificial marble became an important technological issue recently, and a countermeasure was usage of the waste artificial marble as an aggregate in the production of mortar [17] However, the recycling of waste artificial marble could cause lowering of the performance or mechanical properties of the final mortar [17] An organic polymer or resin, so-called polymer modifier is expected to overcome the problems described above because the polymer-modifier is well known to offer to the final mortar the improvement of higher strength, durability, good resistance to corrosion, and strong resistance to damage from freeze-thaw cycles [18–28] In this study the polymer-modified mortars using recycled artificial marble waste fine aggregate (AMWFA) were 1226-086X/$ – see front matter # 2007 The Korean Society of Industrial and Engineering Chemistry Published by Elsevier B.V All rights reserved doi:10.1016/j.jiec.2007.11.002 266 E.-H Hwang et al / Journal of Industrial and Engineering Chemistry 14 (2008) 265–271 Table Physical properties of polymer cement modifiers Type Specific gravity (20 8C) Viscosity (20 8C, cP) pH (20 8C) Total solids (wt%) SBR PAE 1.020 1.054 171 28 9.2 8.8 49.1 54.2 investigated in detail with two different polymer-modifiers to overcome the drawbacks like losing mechanical properties of the mortar using AMWFA Styrene–butadiene rubber (SBR) latex and polyacrylic ester (PAE) emulsion were employed as polymer modifier, and compared each other The effect of replacement ratio of AMWFA on the physical properties and mechanical properties were also investigated and reported in this article specimen so that the flow values of final mortar were fixed at 170 Ỉ mm following KS F 2476 The specimens were prepared using the mold in the dimension of 40 mm  40 mm  160 mm Those were cured in a humid condition at 20 Ỉ 8C and 90% of relative humidity for days, cured again in water at 20 8C for days, and then cured in air at 20 Æ 8C and 60 Æ 10% of relative humidity for 21 days in a thermo-hygrostat consecutively [29,30] 2.3 Test of air content, unit weight and flow value The air content and unit weight of fresh polymer-modified mortars were tested in accordance with JIS A 1174 and flow value of fresh polymer-modified mortars was tested in accordance with KS L 2476 2.4 Test of hot water resistance and pore diameter distribution Experimental 2.1 Materials Conventional Portland cement (OPC, type 1) and standard sand were used throughout this study Waste artificial marble fine aggregate was acquired from the production process of acrylic artificial marble, and it was crushed to get the fine aggregate SBR and PAE were purchased and utilized in the form of latex and emulsion, respectively without any further treatment Table shows the physical properties of two polymer cement modifiers 2.2 Preparation of specimens The contents of polymer modifiers in polymer–cement mixture were 0, 10 and 20 wt% as shown in Tables and The replacement ratios of AMWFA for the sand were 0, 25, 50, 75 and 100% Water–cement ratio was adjusted specimen by Specimens were cured in water at 90 8C for 28 days, and then were measured for compressive and flexural strengths The pore distribution was measured with mercury porosimeter for the particle from specimen which had particle diameter of 2.5– mm after washed with acetone and dried for 48 h Results and discussion 3.1 Variation of water–cement ratio As shown in Fig 1, water–cement ratio was increased as the replacement ratio of AMWFA in mortar increased without polymer modifier However, adding polymer modifier into mortar reduced water–cement ratio significantly In case of SBR latex and PAE emulsion, the content of 20 wt% results in decrease in water–cement ratio by 28% and 55%, respectively, meaning PAE was the more effective polymer modifier to reduce water–cement ratio in this mortar system than SBR Table Mix proportion of SBR polymer-modified mortars containing artificial marble waste fine aggregate Cement:(sand + AMWFA) (by weight) AMWFA/ (AMWFA + sand) (wt%) 1:3.00 1:2.75 1:2.50 1:2.25 1:2.00 25 50 75 100 1:3.00 1:2.75 1:2.50 1:2.25 1:2.00 1:3.00 1:2.75 1:2.50 1:2.25 1:2.00 W/C ratio (%) Unit weight (g/ml) Air content (%) Flow value 70.1 73.6 77.3 79.8 82.6 1.961 1.709 1.541 1.434 1.364 8.5 14.9 16.4 18.0 19.5 170 168 165 173 169 25 50 75 100 10 61.6 67.3 71.0 75.1 77.3 1.605 1.479 1.395 1.291 1.151 24.6 25.0 25.0 25.6 26.2 168 169 168 170 175 25 50 75 100 20 42.3 48.5 49.5 50.0 51.0 1.577 1.384 1.199 1.115 1.053 26.1 29.6 31.5 32.7 34.2 174 165 175 175 170 AMWFA: artificial marble waste fine aggregate P/C ratio (wt%) E.-H Hwang et al / Journal of Industrial and Engineering Chemistry 14 (2008) 265–271 267 Table Mix proportion of PAE polymer-modified mortars containing artificial marble waste fine aggregate Cement:(sand + AMWFA) (by weight) AMWFA/ (AMWFA + sand) (wt%) 1:3.00 1:2.75 1:2.50 1:2.25 1:2.00 25 50 75 100 1:3.00 1:2.75 1:2.50 1:2.25 1:2.00 1:3.00 1:2.75 1:2.50 1:2.25 1:2.00 P/C ratio (wt%) W/C ratio (%) Unit weight (g/ml) Air content (%) Flow value 70.1 73.6 77.3 79.8 82.6 1.961 1.709 1.541 1.434 1.364 8.5 14.9 16.4 18.0 19.5 170 168 165 173 169 25 50 75 100 10 44.4 36.2 37.8 40.3 41.7 1.531 1.328 1.195 1.120 1.034 31.6 37.3 40.4 41.5 42.0 170 175 166 175 173 25 50 75 100 20 34.2 21.2 22.3 23.6 24.9 1.510 1.325 1.218 1.106 1.020 33.2 38.7 41.2 42.2 43.1 171 165 168 172 174 The water absorption of cement paste in AMWFA could be a reason for the increase in water–cement ratio with higher replacement ratio Polymer modifier is known to improve flowability, water resistance, and ball-bearing effect due to the better dispersion of antifoaming agent and air-entrainment during forming admixture [29], resulting in the decrease in water–cement ratio for the mortar with polymer-modifier PAE emulsion is more air-entrainment than SBR latex, suggesting that PAE emulsion is more effective to reduce water–cement ratio in mortar 3.2 Air content and unit weight case that the AMWFA replace ratio was 50%, the air content of SBR-modified mortar were 16.4, 25.0 and 31.5 for the SBR proportion of 0, 10 and 20%, respectively, whereas those PAEmodified mortar were 16.4, 40.4, and 41.2% for the PAE proportion of 0, 10 and 20% The change in the unit weight of the fresh mortars was dependent on the replacement ratio of AMWFA as shown in Fig Regardless of the absence and presence of polymer cement modifier, the unit weight decreased significantly with increasing the replacement ratio of AMWFA It should be considered that the specific gravity of AMWFA is lower than that of standard sand and that the presence of polymer cement modifier increased the air content entrained Fig exhibits the change in air contents in the fresh polymer-modified mortar in a function of the replacement ratio of AMWFA SBR latex-modified mortar increase air content entrained as the proportion of SBR latex was increased from to 20 wt%, whereas PAE emulsion showed no significant difference in air content entrained between 10 and 20 wt% In Water absorption was measured after the curing steps described in Section There was little difference in water absorption between SBR latex and PAE emulsion as shown in Fig Variation of water–cement ratios vs replacement ratios of artificial marble waste fine aggregate Fig Variation of air contents vs contents of artificial marble waste fine aggregate 3.3 Water absorption 268 E.-H Hwang et al / Journal of Industrial and Engineering Chemistry 14 (2008) 265–271 Fig Variation of unit weight ratios vs contents of artificial marble waste fine aggregate Fig Compressive strengths of polymer-modified mortars vs contents of artificial marble waste fine aggregate increased significantly in the presence of polymer cement modifiers, whereas it decreased as the replacement ratio increased The improvement of flexural strength is linked to the nature of polymer that is known to be flexible than cement hydrate and other inorganic materials [29] The flexural strength of SBR-modified mortar with 20% of polymer–cement ratio was about 47% higher than that of no polymer modification at the replacement ratio of AMWFA of 50% 3.5 Mechanical strength after hot water resistance test Fig Variation of water absorption vs contents of artificial marble waste fine aggregate (before hot water immersion) Fig 4, and it was decreased drastically at 20% of polymer– cement ratio for both SBR and PAE, resulting from a very good water-resistant bond between the polymer cement modifier and the cement components AMWFA having the property of high water absorption resulted in higher water absorption with higher replacement ratios As shown in Fig 7, the compressive strength after immersing the specimen in hot water of 90 8C was lower than it was before the immersion The compressive strength was lowered significantly after the hot water resistance test, suggesting that the deterioration or decomposition of polymer cement modifier at high temperature causes the change in strength There was little difference between SBR latex and PAE emulsion in hot water resistance, but as the replacement ratio of AMFWA increased, the compressive strength decreased The increase rate of compressive strength of 20% 3.4 Mechanical strength Compressive strengths and flexural strengths were measured and summarized in Figs and 6, respectively The compressive strength decreased in the presence of polymer cement modifier compared to that of no polymer cement modifiers, but the compressive strength of 20% of polymer–cement ratio was higher than that of 10% The polymer-modified mortar has cement hydrate–cement hydrate bond and cement hydrate– polymer bond [29] Cement hydrate–polymer bonds are weaker in compressive strength than cement hydrate–cement hydrate bonds However, the higher proportion of polymer modifier, the higher sealing effect is shown, resulting in the improvement of compressive strength The flexural strengths of mortar Fig Flexural strengths of polymer-modified mortars vs contents of artificial marble waste fine aggregate E.-H Hwang et al / Journal of Industrial and Engineering Chemistry 14 (2008) 265–271 Fig Compressive strengths of polymer-modified mortars vs contents of artificial marble waste fine aggregate (—: before hot water immersion, : after hot water immersion) Fig Flexural strengths of polymer-modified mortars vs contents of artificial marble waste fine aggregate (—: before hot water immersion, : after hot water immersion) 269 Fig Comparison of total pore volume vs contents of artificial marble waste fine aggregate before/after hot water immersion test (PAE polymer–cement ratio: 20 wt%) Fig 10 Comparison of bulk density vs contents of artificial marble waste fine aggregate before/after hot water immersion test (PAE polymer–cement ratio: 20 wt%) of polymer–cement ratio had a lower value than that of 10% for both SBR and PAE, resulting from the higher proportion of polymer which was deteriorated or decomposed at high temperature The flexural strength was measured after immersing the specimen in hot water of 90 8C, and shown in Fig The rate of decrease in flexural strength was similar between PAE-modified mortar and SBR-modification As the replacement ratio of WCFA increased, the flexural strength as well as compressive strength decreased The flexural strength is closely affected by the bonding strength of polymer itself and an overall improvement in cement hydrate–aggregate bond [29,30–33], and the hot water resistance test leads to the weakening of this bonding due to the deterioration or decomposition of polymer [29,34] 3.6 Pore volume and density The pore volumes of the specimen before and after hot water resistance test were measured as depicted in Fig Fig 11 Comparison of average pore diameter vs contents of artificial marble waste fine aggregate before/after hot water immersion test (PAE polymer– cement ratio: 20 wt%) 270 E.-H Hwang et al / Journal of Industrial and Engineering Chemistry 14 (2008) 265–271 The total pore volume increased as the replacement ratio of AMWFA increased significantly, resulting from that the higher the amount of AMWFA, the higher the amount of air entrained during the mixing process The reason for the significant decrease of total pore volume after the hot water resistance test could be the progress of hydration reaction of cement paste The decrease of total pore volume is also closely linked to the slight increase in the density of the specimen after the hot water resistance test as shown in Fig 10 AMWFA had lower density than the standard sand, suggesting the higher replacement ratio caused the lower density value It was shown in Fig 11 that the average pore diameter is in the range of 0.10–0.14 mm, meaning it consisted of mainly macro-pores regardless of the presence of AMWFA The higher replacement ratio of AMWFA caused increase in pore diameter The larger entraining air content due to the higher AMWFA content could cause a slight increase in the pore diameter Fig 12 SEM photographs of the specimens having the replacement ratio of AMWFA of 50% prior to (a–e) and after (f and g) the hot water resistance test: (a) polymer cement modifier = 0%; (b) SBR polymer cement modifier = 10%; (c) SBR polymer cement modifier = 20%; (d) PAE polymer cement modifier = 10%; (e) PAE polymer cement modifier = 20%; (f) SBR polymer cement modifier = 10%; (g) PAE polymer cement modifier = 10% E.-H Hwang et al / Journal of Industrial and Engineering Chemistry 14 (2008) 265–271 However, there was little difference in the average pore diameter between different proportions of AMWFA after the hot water resistance test 3.7 Microstructure of the mortars The microstructures of two specimens having SBR or PAE polymer cement modifier of 10% and 20% with the replacement ratio of AMWFA of 50% were observed by SEM prior to and after the hot water resistance test (10% of polymer cement modifier only), and shown in Fig 12 In the presence of polymer cement modifier, the components of mortar, cement hydrate, AMWFA and polymer cement modifier were shown to stick to each other, and present in the same co-matrix phase [29,35,36] The remarkable shrinkage of polymer cement modifiers in the mortar could be observed with the specimens after the hot water resistance test due to the thermal degradation and deterioration of polymer cement modifiers Conclusions The effect of the type of polymer cement modifier in the mortar using AMWFA was investigated and can be summarized as follows (1) Adding polymer modifier into mortar reduced water– cement ratio significantly PAE was the more effective polymer modifier to reduce water–cement ratio in this mortar system than SBR (2) PAE emulsion-modified mortar increased the air content entrained as the proportion of PAE was increased (3) There was little difference in water absorption between SBR latex and PAE emulsion and it was decreased drastically at 20% of polymer–cement ratio for both SBR and PAE (4) The compressive strengths decreased in the presence of polymer cement modifiers compared to that of no polymer cement modifiers, but the compressive strength of 20% of polymer–cement ratio was higher than that of 10% (5) After the hot water resistance test, both compressive strength and flexural strength were decreased Acknowledgements This study was supported by Ministry of Commerce, Industry & Energy (MCIE) and Regional Innovation Center for New Materials by Recycling (RIC/NMR) at Kongju National University and here we would like to appreciate their supports References [1] [2] [3] [4] [5] [6] H.K Lee, H.S Kim, J Korean Ind Eng Chem 14 (2003) 622 W.I Kim, H.j Kim, I.K Hong, J 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vs contents of artificial marble waste fine aggregate increased significantly... absorption between SBR latex and PAE emulsion as shown in Fig Variation of water cement ratios vs replacement ratios of artificial marble waste fine aggregate Fig Variation of air contents vs contents... strengths of polymer- modified mortars vs contents of artificial marble waste fine aggregate (—: before hot water immersion, : after hot water immersion) Fig Flexural strengths of polymer- modified mortars