# Experimental Study on the Strength and Durability for Slag Cement Mortar with Bentonite
## 5 Conclusions  
An experimental study for slag cement mortar with partial substitution of binders by bentonite material was carried out in this study. Both properties of fresh mixtures and the hardened specimens were examined experimentally. Based on the testing results and the corresponding discussions, some valuable conclusions are drawn as follows.  
1. The capacity of moisture absorption for the slag cement mortar may be influenced by the increase of the substitution ratio of the bentonite to the binders in the mortar,  
Figure 9: SEM images of cement mortar with 0.25% bentonite (**a**) before and (**c**) after the sulfate test; SEM images of cement mortar with 0.50% bentonite (**b**) before and (**d**) after the sulfate test.  
but not significantly. However, the increase of w/b ratio may cause a significant increment of moisture absorption of the mortar for most cases.
2. The moisture absorption capacity is increased for the slag cement specimen subjected to the sulfate resistance test due to the erosion effect of the chemical reactions on the surface of the specimens. A replacement of a small amount of the binder in the slag cement mortar by bentonite may improve the moisture absorption, such as was the case of 0.25% replacement, where the moisture absorption was reduced for every w/b ratio compared to specimens without bentonite replacements.
3. The addition of bentonite material in slag cement mortar may influence the compressive strength. For an appropriate addition of bentonite to the slag concrete, the strength can be upgraded by as much as by 14.6%. However, if the replacement ratio of the bentonite is higher than 0.25%, the compressive strength of the mortar will be reduced corresponding to the replacement ratio of bentonite.
4. For the variation of compressive strength after the sulfate resistance test, the usage of bentonite can effectively reduce the strength-reduction phenomenon for the slag cement mortar. Generally, the mitigation effect of strength reduction of slag cement mortar due to sulfate attack was more significant for the specimens with lower w/b ratios (0.445 and 0.485) and higher replacement ratios of bentonite (0.75).
5. After the sulfate resistance test, the weight-loss of the slag cement mortar specimens due to the sulfate reactions can be improved by the replacement of a small amount of the binder by bentonite when the w/b ratio is smaller (0.445 in this case). However, if the w/b ratio is higher, the mitigation of weight loss is not very significant.
6. The chloride penetration to the slag cement mortar can also be effectively reduced with the application of bentonite.  
Therefore, it is concluded that a slight replacement, such as 0.25%, of slag cement with bentonite material may effectively improve the durability of the slag cement mortar in terms of the moisture absorption, compressive strength, and weight loss after the sulfate resistance test and the chloride permeability test.  
Conceptualization, H.H.L., C.-W.W., and P.-Y.C.; methodology, H.H.L., C.-W.W., and P.-Y.C.; validation, H.H.L., C.-W.W., and P.-Y.C.; formal analysis, H.H.L., C.-W.W., and P.-Y.C.; investigation, H.H.L., C.-W.W., and P.-Y.C.; resources, H.H.L.; data curation, H.H.L., C.-W.W. and P.-Y.C.; writing--original draft preparation, H.H.L.; writing--review and editing, H.H.L.; visualization, H.H.L. and C.-W.W.; supervision, H.H.L. and P.-Y.C.; project administration, H.H.L.; funding acquisition, H.H.L. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The authors declare no conflict of interest.