HIGH EARLY STRENGTH ALKALI AVTIVATED CLINKERLESS CEMENT

ABSTRACT: Alkali activated Cement binders fly ash /slag /metakaolin or combination thereof has been a topic of extensive research and numerous publications have been made world over on this with studies reported for various alkali activators.

At the authors labs some initial investigations indicated the possibility of high early clinker-less cement/cement binder, further experimentation carried out indicated that the early strengths of alkali activated slag based cement mortars was primarily a function of nature and concentration of the alkali activators used and fineness of the slag used, the effect of curing temperature on the early strengths was not observed to be substantial. Some investigations were also carried out with alkali activated slag +fly ash mix binders to assess the effect on early strengths but use of different fineness of low lime class F fly ash.

The paper discusses the results of these investigations in some details, which include effect of nature and type of alkaline activator, effect of fineness of slag and fly ash used on the early strengths of the clinker - less Cement Mortars.

The paper further discusses the mortar and concrete properties of selected Alkali activated slag/Fly ash cement, in terms of Water permeability, chloride permeability etc and compares the observed properties of concrete with similar grade concrete made with OPC/ PPC and PSC concrete in terms of strength development as well as microstructure development and different hydration products formed at 28 days.

Authors finally concludes that very high early strength cementitious binder could be developed having superior strengths as well as durability properties compared to existing cements in the Indian market.

1.0 Introduction

Alkali activated Cement binders from fly ash /slag /metakaolin or combination thereof has been a topic of extensive research and numerous publications have been made world over on this with studies reported for various alkali activators . Compared with ordinary Portland cement (OPC) and interground slag blended cement , the alkali activated slag (AAS) cements have been reported to have some advantageous properties ,like rapid and high strength development, good durability and high resistance to chemical attack (1-6). The Compressive strength development of granulated slag based alkali activated systems can be enhanced with alkali activators, such as sodium hydroxide or silicate, using different additives like Portland cement, lime, silica fume, fly ash , sodium sulphate etc . The compressive strength reported for alkali activated slag based binders indicates a a good potential to replace the conventional varieties of Portland cements in in concrete (7).

Studies carried out by Shao-Dong et al (8) on alkali activation of ground Granulated blast furnace slag indicated that (i) that the products form by a dissolution and precipitation mechanism during the early stages of reaction, but at later stages the reaction may continue by a solid state mechanism; (ii) regardless of the activator used, the main hydration product is calcium silicate hydrate with low C/S ratio with varying degrees of crystallinity; (iii) a crystalline phase of hydrotalcite type is formed in slags activated with either NaOH or waterglass (sodium silicates ) ; (iv) a crystalline phase of AFm type is also formed in slag activated with NaOH; (v) no hydrates of zeolite group or mica group were formed in slag activated with either NaOH or waterglass solution after wet curing at 20±2 0C up to 15 months or at 80 0C for 14 days. The effect of several factors on the strength of alkali activated slags has been investigated by Shao-Dong et al (9). The

most important factors were found to be: the type of alkaline activator, the mode of adding activator, the dosage of alkali and fineness of slag, SiO2/Na2O ratio (modulus, Ms) when using waterglass solution, curing temperature, liquid/slag or water/slag ratio and additive. The activation of fly ash / slag pastes with NaOH solutions have been studied by Puertas et al (10). The parameters of the process studied were: activator concentration (NaOH 2 and 10 M), curing temperature (25°C and 65°C), and fly ash / slag ratios (100/0, 70/ 30, 50/ 50, 30/ 70, and 0/ 100). The ratio of fly ash / slag and the activator concentration being the dominant factors. Alkali activation of ground granulated blast furnace slag (GGBFS) with sodium silicate gave clinker-free binders , studied by Brough and Atkinson (11), with high strength and early strength development, although with short / cariable setting time. Activation with KOH gave more rapid reaction of slag than for silicate activation. Investigation of alkali activation of Australian slag (AAS) was carried out using sodium silicate, sodium hydroxide, sodium carbonate, sodium phosphate, and combinations of these activators (12). Compressive strengths in the range from 20 to 40 MPa were achieved for the pastes. The most effective activator was liquid sodium silicate. On the basis of this investigation, a sodium silicate solution with a low Na content and Ms =0.75 was recommended for formulation of AAS concrete

The mechanism of activation of a fly ash (no other solid material was used) with highly alkaline solutions is described by Palomo et al (13). These solutions, made with NaOH, KOH, water glass, etc., have the common characteristic of having a very high OH- concentration. The product of the reaction is an amorphous aluminosilicate gel having a structure similar to that of zeolitic precursors. Fernández-Jiménez et al (14) studied the joint influence of a series of factors (specific surface of the slag, curing temperature, activator concentration, and the nature of the alkaline activator) on the development of mechanical strengths in alkaline-activated slag cement mortars.The development of new binders (15), as an alternative to traditional cement, by alkaline activation of industrial by-products (i.e. ground granulated slag and fly ash), However, slag paste activated with SC(sodium carbonate) showed similar setting properties to PC(Portland cement) paste. LSS(Liquid Sodium silicate), SH (sodium hydroxide) and SC activated slag mortar developed 81, 29, and 36 MPa maximum compressive strengths, and 6.8, 3.8, and 5.3 MPa maximum flexural tensile strengths at 28-days.

The paper discusses the results of the investigations carried out at Author’s lab on alkali activated Slag / Fly ash binders , to assess the effect of fineness of slag and fly ash used , the effect of nature and type of alkaline activator on the early strengths of the clinker - less Cement binder mortars .

The paper further discusses the concrete properties of selected Alkali activated slag/Fly ash cement, in terms of Water permeability, chloride permeability etc. and compares the observed properties of concrete properties with similar grade concrete made with OPC/ PPC and PSC, in terms of strength development at 7& 28 days. Microstructure development and different hydration products formed of clinker-less cement concrete are also discussed.

The Authors finally conclude that very high early strength cementitious binder could be made having superior strengths in mortars and concrete as well as durability properties compared to existing cements in the Indian market. The overall aim of the study was to investigate the potential of alkali activated slag / fly ash as a binder in producing Mortar / concrete with different alkaline activators at Ambient Temperature.

2. Experimental: 2.1 Materials and Methods:

Two slags, Ultra Fine Ground Slag (UFGS) and Ground Slag (GS) alone and in combination with Ultra Fine Ground Fly ash (UFGFA) and Fly ash(FA) were used in the present study, slags used had a Glass content of ~92%, the Slags and fly ashes were analyzed for their chemical compositions and Particle size distribution and data is presented in Table-1

Table-1 : Chemical composition and Particle size distribution of Slags and fly ashes %

Oxides SiO2 Al2O3 Fe2O3 CaO MgO LOI Na2O K2O SO3 IR Glass % R45

% Passing 20 µ

UFGS 35.8 19.4 1.0 34 5.8 0.75 0.23 0.54 0.41 0.2 92.3 0 99.2

GS 33.5 17.4 0.8 33.8 7.9 2.1 0.25 0.45 0.71 1.8 92.0 14.2 30.3

UFGFA 56.8 27.2 5.5 1.7 0.4 3.6 0.18 1.86 0.14 73.2 - 0 98.7

FA 63.5 24.8 4.1 3.3 0.6 0.2 0.16 1.17 0.2 86.7 - 37.3 28.8

The alkaline activators investigated were: • Alkali (NaOH) activator solution at lower (1 to 6% ) and higher (7 to 12%) dosage levels. • Alkali silicate activator at three different SiO2/Na2O ratios (High – 2 to 3 , Medium 1.3 to

2.0 and Low - 0.8 to 1.3 ) in solution form , studies were carried out at ambient curing temperature.

2.2 Mortar and Concrete Preparation:

The mortars were prepared with use of three fraction of sand as per Indian standard (Grade I, II and III sand confirming to IS 650 : 1966), machine mixed for 3 minutes at rpm of 140±5 and cast into cube moulds 70.6 mm size, the alkaline activator SiO2/Na2O ratio and alkali solution was added during casting of mortar and concrete. The setting of mortar and concrete was observed to be rapid hence during concrete making, sodium carbonate was added to retard the setting time. After vibration, the samples were cured in the moulds for one day before de-moulding and then cured in water at 27+2°C (curing at Ambient Temperatures) and RH >95% at 1,3,7 & 28 days. The formulation showing higher strengths were considered for concrete testing for M-20 grade of concrete.

2.3 Durability studies on Clinker-less Cement and its comparison with OPC,PPC and PSC :

Durability tests such as RCPT, Water Permeability test, water sorptivity test of Clinker-less cement mortar. The compressive strengths , as well as durability properties of clinker-less cement were compared with OPC,PPC and PSC in terms of both , Mortars and concrete strengths. The morphology & microstructure of the 7 & 28 days hydrated concrete cubes of clinker-less cement were assessed by Scanning Electron Microscope .

3. Results and Discussions:

3.1 : Compressive Strengths of Mortar with UFGS and GS with Alkaline activator at various SiO2/Na2O Ratio Mortar cubes were prepared with UGFS and GS with Alkali- silicate Activator at three SiO2/Na2O ratio- Low Medium and High and the data generated is graphically shown in Fig. 1 & 2.

Fig.1: Mortar Strengths with UFGS with Alkaline Activator at SiO2/Na2O Ratio – Low, Medium and High

Fig.2:Mortar Strengths with GS with Alkaline Activator at SiO2/Na2O Ratio – Low, Medium and High

It is observed that : • 1 day strength of 87 MPa and 28 days strength of 153 MPa could be achieved with use of

Ultra fine ground slag(UFGS) and Alkaline activator with SiO2/Na2O ratio –Medium . At higher SiO2/Na2O ratio, the strengths are comparatively lower at 1 & 28 days(68 & 120 MPa), whereas for low SiO2/Na2O ratio the strengths are marginally lower ( 1 & 28 days – 81 & 148 MPa) when compared with SiO2/Na2O ratio –Medium.

• The strengths of Mortar having Ground Slag (GS) are comparatively lower than UFGS and this observation also corroborates with the findings of Wang et al (9), that compressive strengths are a function of fineness of slag used.

• With GS with SiO2/Na2O ratio –Medium 1 day strength of 38 MPa and 28 days strength of 86 MPa could be achieved and SiO2/Na2O ratio – low shows marginally lower strengths (34 & 83 MPa at 1 & 28 days) , whereas SiO2/Na2O ratio – high shows lower strengths of 25 & 78MPa at 1 & 28 days.

Considering best mortar strengths achieved with use of Alkaline activator with SiO2/Na2O ratio –Medium, this ratio was considered for further studies.

3.2 Compressive Strengths of Mortar with UFGS and GS with Alkali activator (NaOH solution ) at Low & High Concentration:

Mortar cubes were cast with high and low alkali concentration with UFGS and GS and the Compressive strength data is presented in Fig.3 & 4

• The 1 and 28 days compressive strengths of UFGS with higher alkali concentration are 34 & 62 MPa as compared with 23 & 41 MPa with use of Lower alkali concentration (Fig.3),

• With use of comparatively coarser slag(GS), the 1 and 28 days strengths are at 15 & 32 MPa,

At the Lower alkali concentration : • Lower strength development was observed of 11 MPa and 19 MPa at 1 & 28 days (Fig.4)

The studies thus indicate that :

• Higher Alkali (NaOH) concentration is suitable for strength development . • Within Alkali-silicate activator the SiO2/Na2O ratio –Medium shows the highest mortar

strengths with use of UFGS. Considering higher mortar strengths achieved with use of Higher Alkali (NaOH) concentration, and Medium Na2O/SiO2, these combinations were considered for further studies.

Fig.3:Mortar Strength with UTGS with Alkali activator at Low and High Concentration

Fig.4: Mortar Strength with GS with Alkali activator at Low and High Concentration

3.3 Compressive Strengths of Mortar with UFGS + UFGFA (60:40) , UFGS+FA (60:40) and GS+UFGFA (60:40)& GS + FA (60:40) with alkali silicate activator at SiO2/Na2O ratio-Medium

With such higher strengths achieved with use of UFGS and GS with Alkaline activator at SiO2/Na2O ratio-Medium, it was decided to check the impact this alkaline activator with use of UFGS in combination with fly ash at two fineness levels (Ultra fine Ground Fly ash –UFGFA and Fly ash – FA) at 60:40 ratio of slag to fly ash and were compared SiO2/Na2O ratio-Medium and the data generated is illustrated in Fig. 5&6

As from the Fig.5, • with use of UFGS and UFGFA at 60:40 ratio with the alkali silicate activator (medium)

shows 1 and 28 days of 68 and 107MPa. • Use of UFGS and FA at 60:40 ratio shows marginal decrease in 1 & 28 days strength of

67 & 104 MPa respectively • With use of GS and UFGFA (60:40) & GS with FA (60:40) with the alkali silicate

activator shows 1 day strength of 26 and 25 MPa and 28 days strength of 67 & 65 MPa. The studies indicate that : With the use of 40% fly ash of varying fineness there upto 28 days, the dominating effect on strength development is mainly use of ultra fine ground slag

3.4 Compressive Strengths of Mortar with UFGS + UFGFA (60:40) , UFGS+FA (60:40) and GS+UFGFA (60:40)& GS + FA (60:40) with high alkali (NaOH) concentration .

Experiments were carried out with use of UFGS+UFGFA at 60:40 ratio and UFGS+FA at 60:40 ratio with use of Higher Alkali (NaOH) concentration and the Mortar strengths were compared with UFGS with higher Alkali ( Fig.7& 8 ).

Fig.5: Compressive Strengths of Mortar with UFGS +UFGFA (60:40) & UFGS +FA (60:40) at SiO2/Na2O Ratio – Medium

Fig.6: Compressive Strengths of Mortar with GS +UFGFA (60:40) & GS+FA (60:40) at SiO2/Na2O Ratio – Medium

Fig.7: Compressive Strengths of Mortar with UFGS + UFGFA (60:40) & UFGS+FA (60:40) with Alkali activator at High Concentration

Fig.8: Compressive Strengths of Mortar with GS + UFGFA (60:40) &GS+ FA (60:40) with Alkali activator at High Concentration

• UFGFA+ UFGS gives the highest 1- Day strength of 45 MPa and 57 MPa at 28 days, could be due to use of ultrafine ground fly ash usage.( Fig.7)

• UFGS + FA shows lower strengths. 3.5 Concrete Properties of Clinker-less cement and Comparison with Concrete Properties of OPC,PPC and PSC

Alkali silicate activator at SiO2/Na2O ratio-Medium has shown better compressive strength development at all ages as compared to higher alkali (NaOH) concentration at the two fineness levels of slags as well as the combination with the fine and coarser fly ash , based on Mortar performance , Concrete studies were carried out with UFGS and GS + FA (showing higher and lower strengths) with Alkali silicate activator at SiO2/Na2O ratio-Medium, 2% of soda ash was added to delay the setting time of concrete and make it workable The mix design used for concrete (M-20) is shown in Table-3 and the Mortar properties of OPC,PPC and PSC used are shown in Fig.9 . A Comparison of OPC,PPC and PSC Concrete strength with the compressive strengths of Concrete made with UFGS & GS+FA ( 60:40) with alkali silicate Activator (Medium) are depicted in Fig.10

Fig.10 : Comparison of OPC,PPC and PSC Concrete strength with the concrete made with of UFGS & GS with FA ( 60:40) with alkali silicate Activator (Medium)

Fig.9: Mortar strengths of OPC,PPC,PSC

Table 3: Mix Proportions of concrete studies (M20 Mix Design)

Mix Design

OPC / PPC/PSC

UFGS with SiO₂/ Na₂O

Ratio Medium

GS with FA at SiO₂/ Na₂O

Ratio Medium

Cement (kg/m3) 350

UFGS (kg/m3) - 350 -

GS (kg/m3) - - 210

FA (kg/m3) - - 140

W/C ratio - -

Alkaline Activator with SiO2/Na2O ratio-Medium (lts)

- 5.25 5.25

Sodium Carbonate added (%)

- 2 2

20 mm (Kg) 625.0 625.0 625.0

10 mm (Kg) 616.0 616.0 616.0

Fine Aggregate (Kg) 666.0 666.0 666.0

• UFGS with Alkali-silicate activator SiO₂/ Na₂O Ratio-Medium , shows very high concrete compressive strength of 52 MPa at 1 day , with 79 MPa at 28 days and could be used for higher grades of concrete.

• The Concrete strengths of GS +FA (60:40) with Alkali silicate activator SiO₂/ Na₂O - Ratio-Medium , shows comparable strengths at 1 day while at 3,7& 28 days strengths the strengths are much higher than corresponding concretes strengths of OPC,PPC and PSC.

3.6 Microstructure of the 28 Days hydrated Concrete:

The Micro-structural changes at 7 & 28 days hydrated Clinker-less cement concrete of UFGS with Alkali-silicate activator SiO₂/ Na₂O Ratio-Medium .is shown in Fig.11 (a),(b),(c) & (d), whereas microstructure at 7 & 28 days hydrated Clinker-less cement concrete of GS + FA at 60:40 ratio with Alkali-silicate activator SiO₂/ Na₂O Ratio-Medium is depicted in Fig.12 (a),(b),(c), (d), (e) & (f). • Clinker less cement – UFGS with Alkaline Activator SiO₂/ Na₂O Ratio-Medium at 7 days

shows porosity as well as compact aggregate matrix interface (Fig.11a & 11c) whereas at 28 days more compacted structure at aggregate – Cement Paste Matrix interface is observed with significantly reduced porosity (Fig.11b & 11d)

• Clinker less cement – GS + FA (60:40) with Alkali-silicate activator SiO₂/ Na₂O Ratio-Medium at 7 days shows porosity with un hydrated slag and fly ash grains ( Fig. 12a,12c & 12e) whereas at 28 days microstructure with reduced porosity and partially reacted / hydrated slag and fly ash (Fig.12b,12d& 12f)

7 & 28 Days hydrated concrete Microstructure of Clinker - less cement Concrete ( UFGS with Alkali-silicate activator SiO₂/ Na₂O Ratio-Medium )

Fig.11a: 7 days hydrated Clinker-less Cement Concrete showing porous microstructure

Fig.11b: 28 days hydrated Concrete showing compacted Microstructure structure with decreased Porosity

Fig.11c: 7 days hydrated Clinker-less cement concrete showing compact Aggregate – CPM interface

Fig.11d: 28 days hydrated Clinker- less Cement Concrete showing strong Compacted Aggregate – CPM interface

7 & 28 Days hydrated Concrete Microstructure of Clinker less cement Concrete ( GS + FA) (60:40) Alkali-silicate Activator SiO₂/ Na₂O with Ratio-Medium

4. Durability Studies on the Clinker – less Cement Concrete

4.1 Rapid Chloride Penetration Test:

The results of Rapid Chloride Penetration Test (ASTM C 1202 – 07) carried out for comparative durability testing with respect to chloride penetration for 28 days concrete and the results are graphically illustrated in Fig.13:

Sr. No Charge Passed (Coulombs) Chloride Ion Permeability 1 >4000 High 2 2000-4000 Moderate 3 1000-2000 Low 4 100-1000 Very Low 5 <100 Negligible

Fig.13 : RCPT values of OPC,PPC,PSC and Clinker-less cement Concrete

Fig.12a: 7 days hydrated Clinker less cement concrete showing porosity

Fig.12b: 28 days hydrated Clinker- less cement Concrete showing reduced porosity

Fig.12c: 7 days hydrated Clinker less cement Concrete showing un-reacted slag grains

Fig.12d: 28 days hydrated Clinker less cement concrete showing partially reacted slag grains

Fig.12e: 7 days hydrated Clinker less cement concrete showing Un-reacted fly ash grains

Fig.12f: 28 days hydrated Clinker less cement concrete showing flyash grains reaction during hydration

The test results indicate that the concrete made from Clinker-less cement (UFGS with Alkaline Activator SiO₂/ Na₂O Ratio-Medium ) shows lowest and almost negligible RCPT value (negligible permeation of chlorides ) indicating very dense and compact structure followed by GS with FA with Alkaline Activator SiO₂/ Na₂O Ratio-Medium as compared the concretes made from PSC,PPC and OPC

4.2 Water Permeability: The permeability of concrete is related to durability of concrete in terms of its resistance against progressive determination under exposure to sever climatic conditions and leaching due to prolonged seepage of water. The permeability is measured in terms of depth of penetration of hardened concrete cube after 28 days of curing at certain water pressure by Water permeability test (DIN – 1048 Part V). The test results are graphically depicted in Fig. 14 Results illustrate that the Concrete made with , Clinker less cements especially UFGS with Alkaline Activator SiO₂/ Na₂O Ratio-Medium shows the lowest permeability, followed by GS with FA with Alkaline Activator SiO₂/ Na₂O Ratio-Medium, compared with M20 concrete made from PSC and PPC. OPC 4.3 Water Sorptivity:

Water sorptivity test confirms to ASTM C 1585- 13 for hydraulic cement concretes. The sorptivity is determined by capillary rise absorption of water by concrete by measuring increase in mass of specimen resulting from absorption of water. The exposed surface of specimen is immersed in water at standard relative humidity to induce consistent moisture condition. Fig. 15 shows decrease in absorption of water at 28 days as compared to 7 days., with lowest water absorption in Concrete of UFGS with Alkali- silicate Activator & GS with FA with Alkali-silicate Activator when compared with OPC,PPC and PSC concrete

Fig. 14 : Water Permeability of Concretes made with OPC,PPC, PSC and Clinker-less Cement(DIN 1048 Part V )

Fig. 15 : Water Sorptivity of OPC,PPC, PSC and Clinker-less Cement

Conclusions:

• Clinker-less cement / binders can be manufactured at Ambient temperatures with use of slag/ fly ash and alkali silicate activator / alkali (NaOH)

• Mortar Strengths of clinker-less cements are similar or better than OPC/PPC /PSC available in the market and depending upon fineness of slag used, highest strengths (150 MPa) could be achieved at 28 days

• Amongst the three levels of Alkali-silicate Activator used, SiO₂/Na₂O Ratio-Medium shows the best strengths development in Ultrafine Ground slag (UFGS) mortars and concrete and with Alkali (NaOH) of high concentration .

• Concrete performance of Clinker-less cement is much superior than the available OPC,PPC and PSC in the market with much improved durability properties

• Depending upon the requirement of early strengths, Clinker-less cement / binder can be tailor made by optimizing fineness of slag /slag + fly ash proportions with alkali-silicate activator of Medium concentration .

• The properties and performance of the clinker – less Cement is governed by fineness and reactivity of ground granulated slag as also on the concentration of the alkaline activator

Further studies need to be carried out related to concrete performance with different aggregates, later age strength development characteristics , durability aspects and leachability aspects of the clinker-less cement concrete . References: 1. B. Talling and J. Brandstetr, 3rd ICFSSNC, Trondheim, SPl14-74,2, 15 19-46( 1989). 2. S.D. Wang, Mag. Concr. Res., 43(154), 29-35(1991). 3. X.C. Pu, CC. Gan, SD. Wang and C.H. Yang, Reports of research on alkali-activated slag cement and concrete; Chongqing Inst. of Archit. and Eng., China, 1988, 6. 4. R. Andersson, H-E Gram, J. Malolepszy and J. Deja, Alkali-activated slag; Swedish Cem. Cont. Res. Inst., 104~s Stockholm, 1988. 5. V.D. Glukhovsky, G.S. Rostovskaja and G.V. Rumyna, 7th ICCC, Paris, III, V164-Vl68(1980). 6. V.D. Glukhovsky, Silic. Ind., 48( lo), 197-200( 1983). 7. A Preliminary Study on the Alkali Activation of Ground Granulated Blast –Furnace Slag “E. Douglas and J. Brandstetr” Cement and Concrete Research, Vol. 20, pp. 746-756, 1990. 8. “Hydration Products of Alkali Activated Slag Cement”, Shao-Dong Wang and Karen L. Scrivener , Cement and Concrete Research, Vol. 25, No. 3, pp. 561-571.1995 9. “Factors Affecting the Strength of Alkali-Activated Slag”, Shao-Dong Wang, Karen L. Scrivener and P.L. Pratt, Cement and Concrete Research,V ol.2 4, No. 6,p p. 1033-1043, 1994. 10. “Alkali-activated fly ash/slag cement Strength behaviour and hydration products”, F. Puertas, S.

Martonez-Ramorez, S. Alonso, T. Vazquez, Cement and Concrete Research 30 (2000) 1625- 1632 11. “Sodium silicate-based, alkali-activated slag mortars Part I. Strength, hydration and microstructure”,

A.R. Brough, A. Atkinson, Cement and Concrete Research 32 (2002) 865–879. 12. “Alkali activation of Australian slag cements”, Tatiana Bakharev, Jay Gnananandan Sanjayan, Yi-

Bing Cheng, Cement and Concrete Research 29 (1999) 113–120. 13. “Alkali-activated fly ashes- A cement for the future”, A. Palomo, M.W. Grutzeck, M.T. Blanco,

Cement and Concrete Research 29 (1999) 1323–1329. 14. Alkali-activated slag mortars-Mechanical strength behavior”, A. Fernández-Jiménez, J.G. Palomb, F.

Puertas, Cement and Concrete Research 29 (1999) 1313–1321 15. “Influence of activator on the strength and drying shrinkage of alkali-activated slag mortar”, Cengiz

Duran Atis, Cahit Bilim, O¨ zlem C, elik, Okan Karahan, Construction and Building Materials 23 (2009) 548–555.

16. Rendell F., Jauberthie, R. 1999. The deterioration of mortar in sulphate environments. Construction and building materials. 13(6): 321-327.