Mix design and performance evaluation of ultra-high performance concrete (UHPC) with basalt aggregate Li, P.; Yu, Q.; Chung, C.P.; Brouwers, H.J.H.

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1 Mix design and performance evaluation of ultra-high performance concrete (UHPC) with basalt aggregate Li, P.; Yu, Q.; Chung, C.P.; Brouwers, H.J.H. Published in: 6th International Conference on Non-Traditional Cement and Concrete, June 9, 7 Published: //7 Please check the document version of this publication: A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. The final author version and the galley proof are versions of the publication after peer review. The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication Citation for published version (APA): Li, P. P., Yu, Q. L., Chung, C. P., & Brouwers, H. J. H. (7). Mix design and performance evaluation of ultrahigh performance concrete (UHPC) with basalt aggregate. In V. Bilek, Z. Kersner, & Simonova (Eds.), 6th International Conference on Non-Traditional Cement and Concrete, June 9, 7 (pp. -9). Brno, Czech Republic. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal? Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Download date: 9. Oct. 8

2 MIX DESIGN AND PERFORMANCE EVALUATION OF ULTRA-HIGH PERFORMANCE CONCRETE (UHPC) WITH BASALT AGGREGATE P.P. Li, Q.L. Yu, C.P. Chung. H.J.H. Brouwers Abstract In the present research, UHPCs applying coarse basalt aggregate are designed by using the particle packing theory and optimal mineral proportion. The flowability, compressive and flexural strength of paste, the compressive and tensile splitting strength of UHPC were measured and evaluated. Furthermore, the mineralogical composition effect, basalt aggregate size effect and powder content effect were analyzed and discussed. The results show that the optimal proportion of powder is 5% of micro-silica and % of limestone powder by the weight of powder. The coarse basalt aggregate has a limited influence on the mechanical strength of UHPC, which results in a continuous decrease with the increase of maximum size of basalt aggregate. The optimal powder content of UHPC is about 8 kg/m 3 at the maximum size of basalt aggregate of 8 mm in this study. The increase ratios of the compressive and tensile splitting strength of UHPC with different powder amounts by % of steel fiber are between 3% and 9%, 95% and %, respectively. Keywords: Ultra-high Performance Concrete, mix design, performance evaluation, basalt aggregate, powder content Introduction Ultra-High Performance Concrete (UHPC) is a relatively new building material, which has been fabricated since 99s. Compared to conventional concrete, it has superior mechanical strength, durability and impact resistance [ 3]. The UHPC usually can be designed with various raw cementitious components, such as Portland cement, micro-silica, slag, fly ash, limestone powder, nanoparticles, et al. The performance of UHPC greatly depends on the type and proportion of those ingredients [4,5]. The micro-silica can decrease the porosity of UHPC due to the filling and pozzolanic effects, and the optimum content is highly dependent on the waterto-cement ratio [5,6]. As a non-pozzolanic mineral admixture, the limestone powder can improve the fluidity and microstructure of concrete, and has a positive effect on the generation of C-S-H gel [7,8]. Hence, it is of great significance to investigate the mineralogical composition effect and obtain an optimal proportion of different powder before designing the UHPC. To overcome the inherent weakness between coarse aggregate and matrix, and eliminate stress concentration at the contact points between those aggregates, most of Ultra-high Performance Concretes are designed by using only fine aggregates or refined aggregate [,3,4]. However, concrete containing appropriate type and content of coarse aggregate possess some advantages. Ma et al. reported that UHPC with coarse aggregate can reduce the cost, improve the elastic modulus and alter workability more easily [9]. Some researchers presented that an addition of

3 coarse aggregate did not reduce or even exhibit a slightly higher compressive strength [,]. With the utilization of coarse aggregate, the autogenous shrinkage was reduced by approximately 4% [4]. Peng et al suggested to use coarse basalt aggregate to improve the penetration impact resistance []. Hence, it is of interest to use the coarse aggregate to design UHPC and study the basalt aggregate size effect. Currently, most UHPCs are designed with a high content of powder, which leads to poor economic benefit and relatively low efficiency [3]. While, on the other hand, a relatively high content of powder is needed to fill the voids between the aggregate to reduce the contact stress concentration and result in a homogenous stress distribution through the matrix. Therefore, it is necessary to research the powder content effect and find an optimal amount for UHPC with coarse aggregate. In the present research, UHPCs applying coarse basalt aggregate are designed by using the particle packing theory and optimal mineral proportion. The mineralogical composition effect, basalt aggregate size effect and powder content effect are analyzed and discussed, by the workability and mechanical strength of paste and UHPC. Experiments. Materials The raw materials used in this study are Portland Cement CEM I 5.5 R (OPC), micro-silica (ms), limestone powder (LP), sand - (S), basalts aggregate (BA), water (W), PCE-type superplasticizers (SP). The steel fibre (SF) (length = 3 mm, diameter =. mm, tensile strength = MPa) is utilized to investigate the reinforcement ratio for UHPC under different powder contents. The dosage of steel fibre is % by the replacement of total volume of mixtures, which is proven to be an appropriate dosage for UHPC for literatures [3,4]. The specific densities of those ingredients are shown in Table. The particle size distributions of the used materials are measured by the sieve and laser diffraction analyses, shown in Figure. Table Specific densities of raw materials Materials OPC ms LP S BA 8- BA others W SP SF Specific density (g/cm ) Cumulative volume (%) CEM I 5.5 R Micro silica Limestone powder Sand - Basalt -3 Basalt -5 Basalt 5-8 Basalt 8- Basalt 8-6 Particle size ( m) Figure : The particle size distribution of raw materials 3

4 . Mix design of mixtures To study the mineralogical composition effect and obtain an optimal proportions of all powders (OPC, ms, LP), the pastes were designed with a water-to-powder ratio of. and SP dosage of.8% by the weight of total powder. The ms and LP were changed from 5% to 5%, % to 3% by the weight of total powder, respectively. The recipes of UHPC is shown in Table. The ms and LP are fixed at 5% and % by mass of powder, respectively, based on the investigation of the mineralogical composition effect. The water-to-powder ration and SP dosage are fixed at. and.% by the weight of powder, respectively. To research the effect of basalt aggregate size on the strength of UHPC, the powder content of UHPC is chosen at 9 kg/m 3. The fraction of the basalt aggregates are calculated by using the modified Andreasen and Andersen model [5]. To investigate the effect of powder content and compactness on the strength of UHPC, the powder contents of UHPC are changed from 9 kg/m 3 to 75 kg/m 3. Table Recipes of UHPC (kg/m 3 ) No. CEM ms LP S BA BA BA BA BA W SP The mixing of mixtures last about 5.5 min (paste), 8 min (UHPC) and min (UHPFRC), respectively, by using a -liter Hobart mixer. The mixing regimes are shown in Figure. OPC+mS+LP 75% W 5% W + SP Start OPC+mS+LP+S 75% W 5% W + SP BA Paste End Start UHPC End OPC+mS+LP+S 75% W 5% W + SP SF BA Start UHPFRC End Mixing time (min) Figure : Mixing regimes for mixtures.3 Testing methods.. Spread flow The spread flow of pastes were measured by using a truncated conical mould (Hägermann cone: height 6 mm, top diameter 7 mm, bottom diameter mm) without jolting, in accordance with EN 5-3: 7 [6]. The flow tests were conducted at room temperature of about ±. 4

5 .. Mechanical strength The fresh pastes were casted into plastic moulds (4 4 6 mm 3 ) and steel cubic moulds ( mm 3 ), respectively. While, the fresh UHPCs were casted into steel cubic moulds ( mm 3 ). All samples were covered with plastic film to prevent the moisture loss. They were demoulded approximately 4 h after casting and then cured in water under room temperature of ±. The compressive and flexural strength of paste samples were tested after 7 days and 8 days, based on EN 39-3: 9 [7] and EN 96-: 5 [8], respectively. The compressive and tensile splitting strength of UHPC samples were measured after 8 days, based on EN 39-3: 9 [7] and EN 39-6: 9 [9]. 3 Results and discussion 3. Mineralogical composition effect Different mineral admixtures process different water demand based on their different chemical and physical characteristics, which result in a great influence on the fluidity of concrete. Figure 3 shows the spread flow of pastes incorporating different content of micro-silica and limestone powder. With the increase of micro-silica content, the spread flow decreases continuously, which indicates the water demand of micro-silica is much larger than that of cement. The maximum decrease occurs at the limestone powder content of %, from 9 mm to.4 mm. The reason is that the micro-silica with very fine particle sizes absorb much superplasticizer on the surface [] and decreases the amount of lubricating water available within the inter particle voids. While, the increasing addition of limestone powder improves the fluidity greatly, especially at the micro-silica content of 5%, changed from.4 mm to 7.4 mm. The limestone is more like a spherical shape and smooth surface, which can provide lubricating effect. Furthermore, the less water demand of limestone powder than that of cement contributes to release more free water, and then improves the fluidity of cementitious pastes. The spread flow can be classified into 6 levels (in Figure 3), the content of micro-silica should be less than % and limestone powder should be more than %, to obtain the first level (35 4 mm) () 3 d (mm) Figure 3: spread flow of pastes (a) 7 days 3 f (b) 8 days Figure 4: Flexural strength of pastes f 7 The flexural and compressive strength of pastes are depicted in Figure 4 and Figure 5. A relatively low content of micro-silica and limestone powder tends to improve both flexural and compressive strength, especially for the 7 days strength. A too high content (more than 5%) of micro-silica results in negative effect on strength of UHPC, attributed to dispersion problems and agglomeration of particles, which is similar to nano-silica []. A higher content (more than %) of limestone powder decreases the strength of paste due to less pozzolanic reaction and weaker bonding force. However, it is important to notice that the 8 days strength of pastes are only slightly reduced or even slightly improved at a higher content of micro-silica and limestone powder. The pozzolanic reaction of micro-silica with calcium hydroxide forms more 5 3 5

6 C-S-H gel and fills the remaining voids at final stages, which refines the microstructure and improves mechanical properties []. Furthermore, an appropriate limestone powder amount has a positive effect on the generation of C-S-H gel [7,8]. The compressive strength of pastes with micro-silica less than 5% is also measured to find the optimum content of micro-silica. To summary, the optimal proportion of powders is 5% of micro-silica and % of limestone powder by mass of total powder, which will be used in the following mix design of UHPC (a) 7 days 3 4 c (b) 8 days c 4 3 Compressive strength Figure 5: Compressive strength of pastes % % 7d, LP=% 8d, LP=% (c) LP=% 3. Basalt aggregate size effect Figure 6 presents the compressive and tensile splitting strength of UHPC versus the maximum size of basalt after 7 days and 8 days. The results show that the 7 days compressive strength of UHPCs do not have obvious difference, at around of MPa, while the tensile splitting strength of UHPCs have a linear decrease from 9. MPa to 6. MPa. After 8 days, the compressive strength has a liner decrease trend from 44 MPa to 3 MPa, while the tensile splitting strength shows a slight decrease from 9.8 MPa to 8.3 MPa and then keeps stable up to the maximum size of basalt of 6 mm. The decrease tendency of strength caused by the bigger basalt aggregate probably contributed by weaker interfacial transition zone between the aggregate and paste, and stress concentration at the contact points between those aggregates. However, the decrease degrees by basalt aggregate size effect are limited, which is similar to other researches []. Other researches even shows that the addition of the coarse aggregate exhibit a slightly higher compressive strength []. It can be concluded that it is possible and reasonable to add coarse aggregate into UHPC. Compressive strength c day 8-day Max size of basalt (mm) (a) Tensile splitting strength t day 8-day Max size of basalt (mm) (b) Figure 6: Strength of UHPC with different max size of basalts 3.3 Powder content effect Figure 7 shows the 8-day strength of UHPC with different powder contents using basalt aggregate with the maximum particle size of 8 mm. Figure 8 depicts the PSDs of the target line (optimum curve calculated from the modified Andreasen and Andersen model [5]) and

7 designed curves of UHPC mixtures. It should be pointed out that 75 kg/m 3 is the optimal content of powder and best compactness can be obtained based the packing model, while the worst compactness occurs at the powder content of 9 kg/m 3. The results indicate that with the increase of powder content at the maximum size of basalt aggregate of 8 mm, the compressive strength of UHPC first increases and then decreases, reaching the maximum value of 4 MPa at the powder content of 8 kg/m 3. While, the tensile splitting strength only has a slight fluctuation between 8.3 MPa and 9. MPa. The optimal powder content occurs at moderate value, rather than the highest content or optimal content for compactness. It indicates that the optimized mix design of UHPC with coarse basalt aggregate should incorporate an appropriate powder content to fill into the gaps between aggregate and avoid a poor compactness. The powder content has a similar effect on mechanical strength with and without % steel fiber. The increase ratios of compressive strength of UHPCs are very limited, changing between 3% and 9%. While, the increase ratios of tensile splitting strength are very considerable due to the bridging effect of steel fiber [3], during the range from 95% and %. Compressive strength c without fiber % steel fiber Powder content (kg/m 3 ) (a) Tensile splitting strength t without fiber % steel fiber Powder content (kg/m 3 ) (b) Figure 7: 8-day strength of UHPC with different powder contents Cumulative volume (%) Target line L, 8-9 L, 8-85 L3, 8-8 L4, 8-75 Particle size ( m) Figure 8: PSDs of the target and designed curve of UHPC mixtures 4 Conclusion This article presents a mix design of UHPC with coarse basalt aggregates and investigates the mineralogical composition effect, basalts aggregate size effect and powder content effect on the performance of UHPC. Based on the obtained results, the following conclusions can be drawn: The replacement of cement by limestone powder can improve the workability, while the addition of micro-silica decreases the workability. The optimal proportion of powders is 5% of micro-silica and % of limestone powder by mass of the total powder, by considering the flowability and mechanical strength of pastes. 7

8 The coarse basalt aggregate results in a decrease of mechanical strength, but the decrease degrees are limited. With the increase of particle size of basalt aggregate, both compressive and tensile splitting strengths tend to decrease. The optimized mix design of UHPC with coarse basalt aggregate should incorporate an appropriate powder content to fill the voids between aggregate and avoid a poor compactness. The optimal powder content is about 8 kg/m 3 at the max size of basalt aggregate of 8 mm in this study. The increase ratios of compressive and tensile splitting strength of UHPC with different powder amount by % of steel fiber are between 3% and 9%, 95% and %, respectively. Acknowledgements This research was carried out under the funding of China Scholarship Council and Eindhoven University of Technology. Furthermore, the authors wish to express their gratitude to the following sponsors of the Building Materials research group at TU Eindhoven: Rijkswaterstaat Grote Projecten en Onderhoud; Graniet-Import Benelux; Kijlstra Betonmortel; Struyk Verwo; Attero; Enci; Rijkswaterstaat Zee en Delta-District Noord; Van Gansewinkel Minerals; BTE; V.d. Bosch Beton; Selor; GMB; Icopal; BN International; Eltomation, Knuaf Gips; Hess AAC Systems; Kronos; Joma; CRH Europe Sustainable Concrete Centre; Cement & Beton Centrum; Heros; Inashco; Keim; Sirius International; Boskalis; NNERGY; Millvision; Sappi and Studio Roex (in chronological order of joining). References [] P. Richard, M. Cheyrezy, Composition of reactive powder concretes, Cem. Concr. Res. 5 (995) 5 5. [] W. Wang, J. Liu, F. Agostini, C. a. Davy, F. Skoczylas, D. Corvez, Durability of an Ultra High Performance Fiber Reinforced Concrete (UHPFRC) under progressive aging, Cem. Concr. Res. 55 (4) 3. [3] R. Yu, L. van Beers, P. Spiesz, H.J.H. Brouwers, Impact resistance of a sustainable Ultra- High Performance Fibre Reinforced Concrete (UHPFRC) under pendulum impact loadings, Constr. Build. Mater. 7 (6) 3 5. [4] D.Y. Yoo, N. Banthia, Mechanical properties of ultra-high-performance fiber-reinforced concrete: A review, Cem. Concr. Compos. 73 (6) [5] D. Wang, C. Shi, Z. Wu, J. Xiao, Z. Huang, Z. Fang, A review on ultra high performance concrete: Part I. Raw materials and mixture design, Constr. Build. Mater. 96 (5) [6] C. Shi, D. Wang, L. Wu, Z. Wu, The hydration and microstructure of ultra high-strength concrete with cement silica fume slag binder, Cem. Concr. Compos. 6 (5) [7] M. Nehdi, S. Mindess, P.C. Aïtcin, Optimization of high strength limestone filler cement mortars, Cem. Concr. Res. 6 (996) [8] W. Zhu, J.C. Gibbs, Use of different limestone and chalk powders in self-compacting concrete, Cem. Concr. Res. 35 (5) [9] J. Ma, M. Orgass, F. Dehn, D. Schmidt, N. V. Tue, Comparative Investigations on Ultra- High Performance Concrete with or without Coarse Aggregates, Proc. Int. Symp. Ultra High Perform. Concr. Kassel. (4) 5. [] S. Collepardi, L. Coppola, R. Troli, M. Collepardi, Mechanical properties of modified reactive powder concrete, ACI Spec. Publ. 73 (997). [] K. Wille, A.E. Naman, G.J. Parra-Montesinos, Ultra-High Performance Concrete with 8

9 Compressive Strength Exceeding 5 MPa (ksi) : A Simpler Way, ACI Mater. J. 8 () [] Y. Peng, H. Wu, Q. Fang, J.Z. Liu, Z.M. Gong, Impact resistance of basalt aggregated UHP-SFRC/fabric composite panel against small caliber arm, Int. J. Impact Eng. 88 (6) 3. [3] R. Yu, P. Spiesz, H.J.H. Brouwers, Effect of nano-silica on the hydration and microstructure development of Ultra-High Performance Concrete (UHPC) with a low binder amount, Constr. Build. Mater. 65 (4) 4 5. [4] L. Soufeiani, S.N. Raman, M.Z. Bin Jumaat, U.J. Alengaram, G. Ghadyani, P. Mendis, Influences of the volume fraction and shape of steel fibers on fiber-reinforced concrete subjected to dynamic loading A review, Eng. Struct. 4 (6) [5] R. Yu, P. Spiesz, H.J.H. Brouwers, Mix design and properties assessment of Ultra-High Performance Fibre Reinforced Concrete (UHPFRC), Cem. Concr. Res. 56 (4) [6] EN-5-3, Methods of test for mortar for masonry - Part 3: Determination of consistence of fresh mortar (by flow table), Br. Stand. Institution-BSI CEN Eur. Comm. Stand. (7). [7] EN 39-3, Testing hardened concrete Part - 3: Compressive strength of test specimens, Br. Stand. Institution-BSI CEN Eur. Comm. Stand. (9). [8] EN-96-, Methods of testing cement - Part : Determination of strength., Br. Stand. Institution-BSI CEN Eur. Comm. Stand. (5). [9] EN 39-6, Testing hardened concrete - Part 6: Tensile splitting strength of test specimens, Br. Stand. Institution-BSI CEN Eur. Comm. Stand. 3 (9) [] C. Schröfl, M. Gruber, J. Plank, Preferential adsorption of polycarboxylate superplasticizers on cement and silica fume in ultra-high performance concrete (UHPC), Cem. Concr. Res. 4 () [] P. Hosseini, A. Booshehrian, A. Madari, Developing concrete recycling strategies by utilization of nano-sio particles, Waste and Biomass Valorization. () [] G. Quercia, G. Hüsken, H.J.H. Brouwers, Water demand of amorphous nano silica and its impact on the workability of cement paste, Cem. Concr. Res. 4 () [3] R. Madandoust, M.M. Ranjbar, R. Ghavidel, S. Fatemeh Shahabi, Assessment of factors influencing mechanical properties of steel fiber reinforced self-compacting concrete, Mater. Des. 83 (5) P.P. Li, Ph.D. student, Department of the Built Environment, Eindhoven University of Technology, P.O. Box 53, 56 MB Eindhoven, The Netherlands tel , p.li@tue.nl Q.L. Yu, Dr., Department of the Built Environment, Eindhoven University of Technology, P.O. Box 53, 56 MB Eindhoven, The Netherlands tel , q.yu@bwk.tue.nl C.P. Chung, Master student, Department of the Built Environment, Eindhoven University of Technology, P.O. Box 53, 56 MB Eindhoven, The Netherlands tel , c.chung@student.tue.nl H.J.H. Brouwers, Prof., Department of the Built Environment, Eindhoven University of Technology, P.O. Box 53, 56 MB Eindhoven, The Netherlands tel , jos.brouwers@tue.nl 9