Proceedings of the International rilem conference Materials, Systems and Structures in Civil Engineering 2016

17

International RILEM Conference on Materials, Systems and Structures in Civil Engineering 

Conference segment on Service Life of Cement-Based Materials and Structures 

22-24 August 2016, Technical University of Denmark, Lyngby, Denmark 

 

Application of sodium gluconate as ingredient of CA positively affected formation of pore 

structure of the modified AAC concretes (Fig. 1, Fig. 2). Addition of admixture of this type to 

the AAC concretes in case of the AACs with 50...69% of slag allowed obtaining values of 

water absorption close to those of the reference composition. However, modification of the 

AAC concretes by this admixture with simultaneous increase in slag contents up to 88% gave 

a significant increase in water absorption of the AAC concretes (4.3%) compared to the 

reference composition (3.1%). 

 

A similar trend was observed for changes in porosity of the AAC concretes plasticized by 

sodium gluconate as ingredient of CA. With 50% of slag in the AAC the volume of open 

capillary pores in the AAC concrete was 8.1% (reference) and 7.9% with the admixture. With 

increase in slag contents up to 69% the volume of these pores tended to decrease. However, 

the addition of this type of admixture to the AAC concretes with 88% of slag in the AAC 

deteriorated pore structure and volume of the open capillary pores increased up to 10.1%. 

 

The sodium gluconate-based CA added to the plasticized AAC concretes provides them a 

compliance with a class F200 in freeze/thaw resistance in case of the AAC with 50…69% of 

the slag (Table 3). However, even with 88% of slag in the AAC the freeze/thaw resistance of 

the plasticized AAC concrete tended to decrease to class F150 and loss of strength after 5 

cycles of alternate freezing/thawing cycles exceeded 5%. 

 

Table 3: Freeze/thaw resistance of the AAC concretes. 

ement 

omposition 

(see Table 2) 

Type of admixture  Loss of strength after number of 

freezing/thawing cycles  

by third (accelerated) method, % 

Number of  

cycles by 

first (basic) 

method 

Class in 

freeze/thaw 

resistance 

3 4 5 

#1 

polyester 

1.4 

   4.4 

    4.9* 

200 

F200 

sodium gluconate 

0.6 

   2.4 

    4.2* 

200 

F200 

#2 

polyester 

0.9 

   3.1 

    5.0* 

200 

F200 

sodium gluconate 

1.0 

   2.6 

    4.4* 

200 

F200 

#3 

polyester 

1.6 

   4.9* 

    8.1 

150 

F150 

sodium gluconate 

1.1 

   3.2 

    4.7* 

200 

F200 

#4 

polyester 

1.9 

   5.0* 

    9.9 

150 

F150 

sodium gluconate 

0.8 

   2.9 

    5.0* 

150 

F150 

#5 

polyether 

1.0 

   2.8 

    4.9* 

200 

F200 

sodium gluconate 

1.5 

   4.9* 

    7.9 

150 

F150 

#6 

polyether 

0.9 

   2.3 

    4.7* 

200 

F200 

* - permissible value 

 

The relationship between porosity (P) and freeze/thaw resistance (F) of the plasticized AAC 

concretes is shown in Fig. 3 and Fig. 4. The curves F = f (slag content) and P = f (slag content) 

reflect the greater volume of open capillary pores and, respectively, decline of freeze/thaw 

resistance of the modified AAC concretes.  

 

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18

International RILEM Conference on Materials, Systems and Structures in Civil Engineering 

Conference segment on Service Life of Cement-Based Materials and Structures 

22-24 August 2016, Technical University of Denmark, Lyngby, Denmark 

 

Freeze/thaw resistance of the modified AAC concrete (Table 3) was found to be dependent on 

type of porosity. Increase in volume of the open capillary pores and respective reduction in 

conditionally in volume of closed pores resulted in the lower freeze/thaw resistance (Fig. 3, 

Fig. 4).  

 

a)                                                                    b) 

Figure 3: Open capillary porosity (P

o

), conditionally closed porosity (P

c

) and freeze/thaw 

resistance (F) of the AAC concretes plasticized by sodium gluconate vs. slag contents in the 

AAC (see Table 2): a) #1, #3, #5; b) #2, #4.  

 

                                     a)                                                                        b) 

Figure 4: Open capillary porosity (P

o

), conditionally closed porosity (P

c

) and freeze/thaw 

resistance (F) of the AAC concretes vs. main active substance of plasticizing admixture as 

ingredient of CA and slag contents in the AAC (see Table 2): a) #1, #3; b) #5, #6.  

 

Thus, it can be concluded about multifactor influence of AACs composition on the porosity 

and, consequently, on the freeze/thaw resistance of AAC concretes. 

 

Increase in slag content from 50% to 100% and corresponding maintenance in content of 

alkaline component in AACs cause reduction of water absorption of AAC concrete. At the 

same time the volume of open capillary pores decreases and thus the volume of conditionally 

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