A new type of environment friendly polymer-modified waterproof mortar (PMWM) was developed through adding ethylene vinyl acetate (EVA)/vinyl acetate–vinyl ester of versatic acid (Va–VeoVa) mixture (re-dispersible emulsion powder), mine tailings, quartz sand and additives to the eco-cement, which was prepared by grinding the mixture of steel slag, blast-furnace slag, fly ash and activator. The optimal material proportioning of PMWM was obtained based on the Orthogonal experiment: re-dispersible emulsion powder, 11 wt.%; cement–sand ratio, 1:3.5 (tailings/quartz sand = 1:3); EVA/Va–VeoVa ratio, 1:1; water reducing agent (based on the cement weight), 1.5 wt.%. The product conforms to JC/T 984- 2005 (China professional standard: Polymer–cement waterproof mortar). Some factors influencing the characteristics of the mortar were discussed.
Construction and Building Materials 25 (2011) 2635–2638 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat Preparation and properties of an environment friendly polymer-modified waterproof mortar Zhao Feng-qing ⇑, Li Hao, Liu Shao-jie, Chen Jian-bo Department of Chemical Engineering, Hebei University of Science & Technology, Shijiazhuang 050018, PR China a r t i c l e i n f o Article history: Received 11 October 2010 Received in revised form 27 November 2010 Accepted December 2010 Available online January 2011 Keywords: Waterproof mortar Polymer-modified mortar Eco-cement Tailings a b s t r a c t A new type of environment friendly polymer-modified waterproof mortar (PMWM) was developed through adding ethylene vinyl acetate (EVA)/vinyl acetate–vinyl ester of versatic acid (Va–VeoVa) mixture (re-dispersible emulsion powder), mine tailings, quartz sand and additives to the eco-cement, which was prepared by grinding the mixture of steel slag, blast-furnace slag, fly ash and activator The optimal material proportioning of PMWM was obtained based on the Orthogonal experiment: re-dispersible emulsion powder, 11 wt.%; cement–sand ratio, 1:3.5 (tailings/quartz sand = 1:3); EVA/Va–VeoVa ratio, 1:1; water reducing agent (based on the cement weight), 1.5 wt.% The product conforms to JC/T 9842005 (China professional standard: Polymer–cement waterproof mortar) Some factors influencing the characteristics of the mortar were discussed Ó 2010 Elsevier Ltd All rights reserved Introduction Polymer-modified mortars (PMMs) are widely used building material, which can be used as tile adhesives, frontage coatings, coverings, and as repair materials in road building [1] With the synergistic effect between inorganic and organic materials, some defects of traditional rigid waterproofing material including low flexural strength, low bond strength, poor toughness and easy cracking can be improved Therefore, PMMs has got more and more attentions these years [2–8] PMWM is prepared by adding polymers to the traditional rigid cement mortar to meet waterproofing requirements [9] However, most papers deal only with polymer types and/or the performances of PMAs etc., as for the application of industrial wastes, the reported information is limited With the increasingly deterioration of the globe environment, the focus has been put on resource and energy consumption, carbon dioxide emission and waste utilization [10] Material recycling is expected to be more feasible in the ways that the simplicity of pretreatment, the reduction of energy consumption and environment pollution can be satisfied [11] The aim of this work is to prepare a new type of environment friendly PMWM, in which the cementing material was made from steel slag, granulated blast-furnace slag, fly ash and activator, part of the quartz sand was replaced by iron tailings, an industrial solid waste difficult to reuse As a cement mortar modifier, EVA/Va–VeoVa mixture was used to improve the mechanical properties, construction performance and water resistance of the mortar ⇑ Corresponding author Tel.: +86 31188632239 E-mail address: zhaofq3366@yahoo.com (F.-q Zhao) 0950-0618/$ - see front matter Ó 2010 Elsevier Ltd All rights reserved doi:10.1016/j.conbuildmat.2010.12.012 Experimental 2.1 Materials Eco-cement prepared from slag and steel slag, fly ash and activators was obtained from our previous work [10], and its properties were listed in Table The ordinary Portland cement, Grade 42.5, was produced by Lu Quan Dingxin Cement Co., Ltd The re-dispersible emulsion powders used are commercial EVA and Va– VeoVa The quartz sand is medium coarse sand with fineness modulus 2.3–3.7 Fine tailings (80 lm sieve residue, 17%) was supplied by Cheng De Tongxing Mining Co., Ltd In order to improve the performance of PMWM, de-foaming agent (tributyl phosphate) and water reducing agent (naphthalene sulfonate) produced by Hebei Admixtures Factory were used 2.2 Methods 2.2.1 Preparation and testing of the samples The prepared eco-cement, quartz sand, iron tailings, re-dispersible emulsion powders, additives were mixed to form waterproof mortar, which was then mixed with water to make the test specimens (40 mm  40 mm  160 mm) After molding, the specimens were allowed to cure in the mould for first 24 h The specimens were then kept in the conditions, 20 ± °C and 90 ± 5% relative humidity (RH) for the desired period The mechanical strength, consistency and impermeability test was done according to GB/T 1767 1-1999, JGJ70-90 and DL/T 5126-2001 respectively All the values collected were the average of three separate tests SEM test was done using HITACHI S-570 Scanning Electron Microscope 2.2.2 Orthogonal experiment The Orthogonal array technique was used to obtain optimal proportioning of the mortar Based on our exploratory experiments and other correlative reports, three main factors, the amount of re-dispersible emulsion powder (A), cement/sand ratio (B) and EVA/Va–VeoVa ratio (C) were selected for proportioning optimization Here, the ‘sand’ means the mixture of quartz sand and tailings (tailings/quartz 2636 F.-q Zhao et al / Construction and Building Materials 25 (2011) 2635–2638 Table Performances of the eco-cement 80 lm sieve residue/% Setting time/(h:min) Initial setting Final setting 3d 28 d 3d 28 d 2.0 1:38 3:25 5.55 7.55 22.5 53.2 Flexural strength/ MPa Compressive strength/ MPa Factors Re-dispersible emulsion powder/wt.% (A) Cement/sand ratio (B) EVA/Va–Veo Va ratio (C) 12 16 1:3 1:4 1:5 1:3 1:1 3:1 sand = 1:3) The de-foaming agent and water reducer was 0.2 wt.% and 0.5 wt.% respectively (based on the amount of cementing material) The factors and levels were shown in Table Results and discussion 3.1 Intuitive analysis of the Orthogonal experiment Considering the cost of raw materials, the composition of mortar is further optimized by slightly reducing the amount of re-dispersible emulsion powder (A) and cement–sand ratio (B) while the performance of the mortar keeps excellent The adjusted optimized factor and level combination was A20 B10 C2, i.e., re-dispersible emulsion powder, 11 wt.%; cement–sand ratio, 1:3.5; EVA/Va–VeoVa ratio, 1:1 The results were summarized in Table It can be found that, all the specifications, including 28 d C/F ratio and impermeability pressure (i.e impervious strength), meet the requirement of JC/T 984-2005 Table Response data collected from the experiments Qualified 28 d strength of mortar A B C Compressive Flexural Mean Mean Mean 1 2 3 3.5 2.6 2.9 3 3.433 2.833 2.733 3 3.133 2.933 2.933 30.3 28.4 23.4 26.6 22.5 22.0 25.7 22.4 22.1 7.1 8.8 7.7 9.3 8.5 9.0 8.0 8.1 7.6 Range 0.9 0.7 0.2 Cementing material is the main factor influencing the mortar’s strength and structure In general, the ordinary Portland cement (OPC) can be used But the eco-cement will has higher economic and environmental benefits The PMWM using OPC and ecocement with the same material ratio (polymer–cement, 11 wt.%; sand–cement ratio, 1:3.5; EVA/Va–VeoVa ratio, 3:1) were prepared The results were listed in Table It can be found that the 28 d C/F ratio of the mortar prepared using eco-cement is lower than that prepared using OPC Their anti-permeability strength values are almost the same Besides, the eco-cement is of superiority in cost, resources consumption and carbon emissions The aggregate is comprised of tailings and quartz sand The experiment showed that tailings/sand ratio has marked effect on the mortar’s performances in a certain range See Figs and (The amount of re-dispersible emulsion powder is wt.%, sand– cement ratio, 1:3.5, EVA/Va–VeoVa ratio is 3:1.) It was showed that both the compressive strength and impervious strength decrease with an increase in tailings/sand ratio The decrease of the Table Results of the validation test 3.2 Further optimization and properties of the product 28.1 3.4 Effect of tailing’s content on the mortar’s performances Table shows the results of the Orthogonal experiment We use the 28 d compressive strength, flexural strength and their ratio (C/ F ratio) as the objective The range analysis showed that the cement–sand ratio and redispersible emulsion powder have significant effect on the 28 d C/F ratio The influence of EVA/Va–VeoVa ratio is relatively less Considering the 28 d compressive and flexural strength value, the to be optimized result is A2B1C2, i.e re-dispersible emulsion powder, 12 wt.%; cement–sand ratio, 1:3; EVA/Va–VeoVa ratio, 1:1 Experiment number Soundness 3.3 Comparison of PMWM prepared by OPC and eco-cement Table Factors and levels of Orthogonal experiment Levels Water requirement of normal consistency/ml C/F ratio 4.3 3.2 3.0 2.9 2.6 2.4 3.2 2.8 2.9 Specifications JC/T 984-2005 This work Appearance Setting time Uniform, no lumps Initial setting, P45 Final setting, 612 h P1.0 P1.5 P24.0 Uniform, no lumps 60 P8.0 63.0 P1.0 P1.2 No cracking and spalling No cracking and spalling No cracking and spalling 10.1 2.8 1.3 1.8 No cracking and spalling No cracking and spalling No cracking and spalling 60.15 0.05 Impermeability pressure/MPa Compressive strength/ MPa Flexural strength/MPa C/F ratio Bond strength/MPa 7d 28 d 28 d 28 d 28 d 7d 28 d Alkaline resistance (Ca(OH)2 saturated solution, 168 h) Heat resistance:100 °C, h Freeze–thaw cycle(À15 °C $ +20 °C, 25 times) Shrinkage h 15 1.3 1.8 28.4 Table Performances of mortars prepared using different cementing materials Cement type 28 d compressive strength/MPa 28 d C/F ratio Eco-cement OPC 27.9 29.1 2.8 3.7 Impervious strength/ MPa 7d 28 d 1.3 1.3 1.6 1.5 F.-q Zhao et al / Construction and Building Materials 25 (2011) 2635–2638 2637 28d compressive strength/MPa 35 30 25 20 15 10 0:4 1:3 1:1 3:1 4:0 tailings-sand ratio Fig SEM photograph of ordinary cement mortar Fig Effect of the tailings/quartz sand ratio on the 28 d compressive strength 28d impervious strength/MPa 1.8 1.6 1.4 1.2 0.8 0.6 0.4 0.2 Fig SEM photograph of PMWM 0:4 1:3 1:1 3:1 4:0 tailings-sand ratio Fig Effect of the tailings/quartz sand ratio on the 28 d impervious strength compressive strength is slight when the ratio is lower than 1:1 However, it decreases sharply after that The compressive strength is only 10 MPa when quartz sand was totally replaced by tailings The impervious strength increases slightly when the tailings/sand ratio is below 1:3 Further increasing the tailings/sand ratio will decrease the impervious strength The value will be less than 1.5 MPa when the ratio is over 1:1 Controlling the tailings/sand ratio below 1:1, the performance of PMWM can meet the requirements and significantly reduce the cost together by many membrane-like substances and form a dense network structure Some of the membrane-like substances are across the pores, while others are through the pores The pore size becomes smaller through this bridging and filling effect In addition, the polymer can fill the pores in the mortar due to its good fluidity and film-forming characteristics It will make the interfacial transition zone of cement-aggregate become more compact and thus the mortar’s permeability resistance and water resistance are improved The network membranous structure formed by the polymer can also increase the paste’s toughness and flexural strength Conclusions 3.5 Microstructure SEM is an effective means to study material’s internal morphology In order to observe the polymer morphology in the hardened polymer-modified mortar paste more clearly, the samples were eroded with dilute nitric acid or hydrochloric acid for a short time [12] The results were showed in Figs and It can be seen from Fig that the morphology of ordinary cement mortar is multiphase aggregate There are large numbers of pores and needle-like crystals in the structure These pores lie mainly in the interfacial transition zone of cement-aggregate in a separate state The spatial distribution of these pores will affect the properties of cement mortar such as mechanical strength, water resistance, impermeability and freezing–thawing characteristics Fig is the morphology of PMWM It can be clearly seen that the SEM micrograph changes significantly compared with ordinary cement mortar The acicular crystals are bonded In order to utilize solid waste and reduce the environmental impact, eco-cement and tailings were used in PMWM With relatively higher flexural strength, the eco-cement, which is made from steel slag, granulated blast-furnace slag and fly, can replace the ordinary Portland cement in the preparation of PMWM with lower C/F ratio Fine tailings can partly replace the quartz sand while the product’s performances not decrease significantly Thus the product prepared possesses environment friendly characteristics and relatively lower cost The Orthogonal experimental results showed that cement–sand ratio is the most significant factor to the performance of PMWM, followed by the amount of re-dispersible emulsion powder and EVA/Va–VeoVa ratio EVA/Va–VeoVa mixture (re-dispersible emulsion powder) is suitable for the product, and contributes the improvement in mechanical properties and impermeability of the mortar, which was conformed and characterized by SEM photograph of mortar paste The water resistance 2638 F.-q Zhao et al / Construction and Building Materials 25 (2011) 2635–2638 of the product was characterized by impervious strength, which was proved to be excellent References [1] Reis JML Mechanical characterization of polymer mortars exposed to degradation solutions Constr Build Mater 2009(23):3328–31 [2] Joachim Schulze, Otmar Killermann Long-term performance of re-dispersible powders in mortars Cem Concr 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Zhao Feng-qing, Ni Wen Activated fly ash/slag blended cement Resour Conserv Recycl 2007(52):303–13 [11] Eui-Hwan Hwang, Young Soo Ko Comparison of mechanical and physical properties of SBR-polymer modified mortars using recycled waste materials J Ind Eng Chem 2008(14):644–50 [12] Qi Xu, Pei-Ming Wang Physical properties of styrene–butadiene emulsion modified cement mortar used for repair of bridge surface J Build Mater 2001;4(2):143–7 [in Chinese] ... in mechanical properties and impermeability of the mortar, which was conformed and characterized by SEM photograph of mortar paste The water resistance 2638 F.-q Zhao et al / Construction and Building... than 1.5 MPa when the ratio is over 1:1 Controlling the tailings/sand ratio below 1:1, the performance of PMWM can meet the requirements and significantly reduce the cost together by many membrane-like... blast-furnace slag and fly, can replace the ordinary Portland cement in the preparation of PMWM with lower C/F ratio Fine tailings can partly replace the quartz sand while the product’s performances not