This chapter delves into the impact of polymer content on the properties of polymer cement mortar (PCM), moving beyond the traditional polymer-cement ratio (P/C) to consider the volume fraction of polymer solids. It introduces equations to estimate flexural and compressive strengths, water permeability, carbonation depth, and chloride ion penetration depth based on water-cement ratio, polymer content, and volume fractions of air and sand. The chapter presents detailed test results and discussions, highlighting the significant influence of polymer content on the durability and strength of PCM. The established equations offer a valuable tool for predicting and optimizing the performance of polymer cement mortar in various applications.
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Abstract
In this paper, the volume fraction of polymer as a solid in the polymer cement mortar (PCM) is defined as the polymer content. The effect of the polymer content on the properties such as the flexural and compressive strengths, water permeability, carbonation and chloride ion penetration of PCM is discussed. As a result, the equation of the effective factor (F) for the properties of the PCM by using the water-cement ratio (W/C), polymer content (Vp), and volume fractions of air (Va) and sand (Vs) is established as “F = (1-W/C)(1 + AVp)(1-Va)(1 + 5Vs)”. The empirical constant (A) is the 4, -6, -8, -6 and -4 for the flexural strength, compressive strength, water permeability, carbonation depth and chloride ion penetration depth of PCM, respectively. The equation for estimating the properties of PCM by using the effective factor and the properties of cement mortar (Plain) is established as “PP = B(FP0) + C”. Where, PP, F, and P0 are the properties of PCM, the effective factor and the properties of Plain with the same W/C, sand-cement ratio and curing condition as the PCM. The empirical constants B and C in this equation are depending on the type of polymer used and curing condition.
1 Introduction
In general, the properties of polymer cement mortar are discussed by the effectiveness of polymer-cement ratio (P/C). However, P/C is the mass ratio of polymer solid to the cement in PCM. Therefore, the volume fraction of the polymer solid is affected by the cement content of PCM. However, PCM is the composite material with cement, sand, water and polymer. The properties of such composite material are generally explained by the volume fraction of materials used.
In this paper, the volume fraction of the polymer in PCM as a solid is defined as the polymer content. The effect of the polymer content on the properties of PCM is discussed. The equation of the effective factor for the properties of PCM by using the water-cement ratio (W/C), the polymer content, the volume fractions of air and sand of PCM, and the estimating equation of its flexural strength, compressive strength, water permeability, carbonation depth and chloride ion penetration depth are established by using the effective factor and those properties of Plain with the same W/C, sand-cement ratio (S/C) and curing condition as PCM.
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2 Materials
2.1 Cement and Fine Aggregate
Ordinary portland cement and standard sand were used for the mix proportions of PCMs.
2.2 Redispersible Polymer Powders and Anti-Forming Agent
Four types of redispersible polymer powder (PAE-N, PAE-C, SA, VA/VeoA) with silicone-type anti-forming agent were used. Their properties are listed in Table 1.
Table 1.
Properties of redispersible polymer powder for cement modifier.
Type of polymer
Apparent
density
(g/cm3)
Glass-
transition temp., Tg (℃)
Non-volatile
matter
(%)
Type
of
charge
PAE-N
0.5
0
99 ± 1
Non-ion
PAE-C
0.5
0
99 ± 1
Cation
SA
0.5
0
99 ± 1
―
VA/VeoA
0.53
0
99 ± 1
―
3 Testing Procedures
3.1 Preparation of Specimens
Table 2 shows the mix proportions of Plain with the polymer content of 0%. According to JIS A 1171 (Test Methods for Polymer Cement Mortar), PCM were mixed by addition of the redispersible polymer powder to Plain. The combinations of the mix proportioning factors of PCMs are shown in Table 3. The polymer content was calculated by using the density of polymer solid of 1.06 g/cm3 as an approximate value.
Table 2.
Mix Proportions of Plain (unmodified cement mortar).
S/C
W/C (%)
Mix proportion by volume (%)
Cement
Sand
Water
Air
2
45
19.8
48.5
28.1
3.6
3
45
15.6
57.1
22.1
5.3
50
15.3
56.2
24.2
4.4
55
15.0
55.1
26.1
4.0
60
14.6
53.9
27.8
3.8
Table 3.
Combinations of mix proportioning factors of PCMs using redispersible polymer powders.
Type of polymer
S/C*
W/C (%)*
Polymer content (%)**
PAE-N, PAE-C, SA,
VA/VeoA
2
45
0, 2，4，6
3
45，50，55，60
Notes * S/C: Sand-cement ratio by mass, W/C: Water-cement ratio by mass
** Polymer content is calculated by volume
Mortar specimens having the size of 40x40x160 mm were molded and then given following curing conditions;
a)
Standard Cure (W5D21): 2d-moist (20℃, 90%(RH)), 5d-water (20℃) and 21d-dry (20℃, 60%(RH) cure
3.2 Tests for Air Content, Strength and Properties of Durability
The tests for air content, flexural and compressive strengths, water permeability, and accelerated carbonation and chloride ion penetration for 28d and 56d were conducted by JIS A 1171 and JIS A 6205 (Corrosion Inhibitor for Reinforcing Steel in Concrete).
4 Test Results and Discussion
4.1 Strength Properties
Figures 1 and 2 show the effect of the polymer content on the flexural and compressive strengths of W5D21-Cured PCMs.
The same tendency of the effect of the polymer content on those strengths of D26-cured PCMs is recognized.
Fig. 1.
Polymer content vs. flexural strength of W5D21-cured PCMs with variations of S/C at W/C of 45% and W/C at S/C of 3.
Fig. 2.
Polymer content vs. compressive strength of W5D21-cured PCMs with variations of S/C at W/C of 45% and W/C at S/C of 3
×
×
From those results, the effectiveness of mix proportioning factors on the flexural and compressive strengths of PCM is explained as follows regardless of the curing conditions;
i)
PCM with large S/C shows higher flexural strength and lower compressive strength.
ii)
PCM with lower W/C shows higher flexural and compressive strengths.
iii)
In increasing the polymer content of PCM, the flexural strength is increased, but the compressive strength is decreased.
PCM is prepared by the modification with polymer addition to Plain. Therefore, the properties of PCM may be explained by inconsideration of the effectiveness of the mix proportioning factors mentioned above and air content, and the properties of Plain as a base material of PCM.
In this paper, the water-cement ratio (W/C), the volume fractions of polymer (Vp), air (Va) and sand (Vs) are intervened as mix proportioning factors for effecting the properties of PCM.
Following equations are proposed as the effective factors for the flexural and compressive strengths of PCM.
where, \({\sigma}_{{\text{f}}_{\text{p}}}\), \({\sigma}_{{\text{c}}_{\text{p}}}\): Flexural and compressive strengths of PCM.
\({\sigma}_{{\text{f}}_{0}}\), \({\sigma}_{{\text{c}}_{0}}\): Flexural and compressive strengths of Plain with same S/C, W/C and curing condition as PCM.
Figures 3 and 4 show the multiplied values of the flexural and compressive strengths of Plain and those strength-effective factors vs. the flexural and compressive strengths of PCM. There is good correlation between the multiplication values and the strength-effective factors and the strengths of PCMs.
Fig. 3.
Multiplied value of flexural strength of plain and flexural strength-effective factor vs. flexural strength of PCMs.
Fig. 4.
Multiplied value of compressive strength of Plain and compressive strength-effective factor vs. compressive strength of PCMs.
×
×
Therefore, the flexural and compressive strengths of PCM may be explained by the following general equations;
Polymer content vs. carbonation and chloride ion penetration depths of PCMs at test period of 56d.
×
×
In the bases of the discussion results for the strength properties, the effective factors for the water permeability, carbonation depth and chloride ion penetration depth of PCMs using the redispersible polymer powders of PAE-N and PAE-C are discussed.
Figures 5 and 6 show the polymer content vs. the water permeability, carbonation depth and chloride ion penetration depth at the test period of 56d of PCMs. The water permeability, carbonation depth and chloride ion penetration depth of PCMs are decreased with an increase in the polymer content.
In the consideration of the effect of the polymer content on the water permeability, carbonation depth and chloride ion penetration depth, following equations are introduced for the effective factors for those properties of PCMs.
Where, Fw : water permeability-effective factor, Fc : carbonation depth-effective factor, Fcl : chloride ion penetration depth-effective factor.
Figures 7–9 show the multiplied values of the values of water permeability (W0), carbonation depth (C0), chloride ion penetration depth (Cl0) of Plain and the effective factors calculated by the equations of (7) to (9) vs. those properties of PCMs. Here, Plain has same W/c, S/C and curing condition of PCM. There is good correlation between the multiplication values and the properties of PCMs.
Therefore, the water permeability (Wp), carbonation depth (Cp) and chloride ion penetration depth (Clp) of PCM may be explained by the following general equations;
$$Wp=\text{E}(W_0 \cdot Fw)+\text{G}$$
(10)
Fig. 7.
Multiplied value of water permeability-effective factor and water permeability of Plain vs. water permeability of PCMs.
Fig. 8.
Multiplied value of carbonation depth-effective factor and its depth of Plain vs. carbonation depth of PCMs at test periods of 28d and 56d.
Fig. 9.
Multiplied value of chloride ion penetration depth-effective factor and its depth of Plain vs. chloride ion penetration depth of PCMs at test periods of 28d and 56d.
where, E, G, H, I, J and K are empilical constants.
5 Conclusions
The equations for the effective factors for the strength, water permeability, carbonation depth and chloride ion penetration depth of PCM are established as the equations of (1), (2), and (7) to (9). Such propertiess of PCM may be estimated by using the equations of (5), (6), and (10) to (12). The empilical constants of those equations are depending on the type of polymere used and curing condision.
[This paper is the summary of two papers prepared by the authors in Japanese; Nishida, A., Saito, T., Demura, K., Gakiya, M.,: Effect of polymer content on flexural and compressive strengths of polymer-modified mortars. Cement science and concrete technology 72, 99–105(2019), and Demura, K., Saito, T., Takeda, M.,: Eeffect of polymer content on resistance to water permeability and durability of polymer-modified mortars, Cement science and concrete technology 73, 95–102(2020).]
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