S. LI et al.: RESEARCH ON REDUCING ALKALINITY OF AN ECOLOGICAL POROUS CONCRETE MIXURE ...
575–581
RESEARCH ON REDUCING ALKALINITY OF AN ECOLOGICAL
POROUS CONCRETE MIXURE WITH CARBONIZATION
RAZISKAVA ZMANJ[ANJA ALKALNOSTI EKOLO[KE POROZNE
BETONSKE ME[ANICE S KARBONIZACIJO
Sheng Li
1,2
, Jian Yin
1*
, Gui Zhang
1
, Ting Gao
1
1
College of Civil Engineering, Central South University of Forestry and Technology, Changsha 410018, China
2
Key Laboratory for Green and Advanced Civil Engineering Materials and Application Technology of Hunan Province, College of Civil
Engineering, Hunan University, Changsha, Hunan 410082, China
Prejem rokopisa – received: 2018-11-22; sprejem za objavo – accepted for publication: 2019-02-25
doi:10.17222/mit.2018.251
In this article, XRD was utilized to analyze the alkalinity affecting the pore size of an ecological porous concrete mixture
(EPCM). Variations in the pore alkalinity and compressive strength of the EPCM with different mineral admixtures were
investigated using accelerated carbonization and natural carbonization. The experimental results demonstrate that the content of
calcium hydroxide is positively related to the pH value of EPCM pores and both indexes increase with age. Combining
accelerated carbonization and additions of mineral admixtures considerably reduced alkalinity and showed no harmful effect on
the compressive strength. The lowest pH value (8.57) was achieved after 56 d and the compressive strength was slightly
improved. Having such an environment, tall fescue can grow in an EPCM and the height of plants is more than 15 cm on the
56th day.
Keywords: alkalinity, carbonation, compressive strength, ecological porous concrete mixture, mineral admixtures
Avtorji opisujejo analizo sestave ekolo{ke porozne me{anice betona (EPCM) z rentgensko difrakcijo (XRD), da bi ugotovili
vpliv alkalnosti me{anice na njeno poroznost. Ugotavljali so spreminjanje alkalnosti por in tla~ne trdnosti EPCM zaradi naravne
in pospe{ene karbonizacije (prepihavanje s CO2) ter pri dome{avanju razli~nih mineralnih dodatkov. Eksperimentalni rezultati
so pokazali, da vsebnost kalcijevega hidroksida pozitivno vpliva na pH vrednost v EPCM in njegovih porah in da oba indeksa
nara{~ata s staranjem me{anic. Kombiniranje pospe{ene karbonizacije in dodajanja mineralnih dodatkov je mo~no zni`alo
alkalnost, vendar ni imelo {kodljivega vpliva na tla~no trdnost betona. Najni`jo pH vrednost (8,57) so dosegli po 56 dneh
staranja betona in tla~na trdnost se je rahlo izbolj{ala. Preizkusi rasti trave na EPCM podlagi s 30 % dodatkom dimni{kega
pepela so pokazali, da le-ta zraste dokaj visoko in sicer ve~ kot 15 cm v 56-tih dneh.
Klju~ne besede: alkalnost, karbonizacija, tla~na trdnost, ekolo{ka porozna me{anica betona, mineralni dodatki
1 INTRODUCTION
The EPCM is an environmentally friendly concrete,
in which plants can grow. The skeleton structure of the
EPCM is made of a coarse aggregate with a large particle
size and many pores. Then, as the pores are filled with
nutrients prepared for plants, the roots of plants can
continuously grow through the pore. When used for a
city pavement, parking area or the revetment of an
expressway, it can improve the city’s atmospheric
environment, vegetation coverage and has promising
application prospects.
1–4
However, calcium hydroxide in concrete causes
interior alkalinity of the pores, making the pH value rise
to 12–13, which is very harmful to the growth of pave-
ment plants and aquatic plants.
5
Numerous traditional
alkali-reducing technologies, such as adding additives,
can effectively reduce the alkalinity of concrete but, at
the same time, its mechanical properties are remarkably
lower than those of ordinary porous concrete.
6
In addi-
tion, by soaking the EPCM in an oxalic acid solution, the
oxalic acid reacts with the alkaline substances in the
EPCM, reducing the alkali content, which also has an
adverse influence on the strength of the EPCM. Some
scholars added fly ash, silica fume and other mineral
admixtures into the EPCM to reduce the alkali content,
but the reduction efficiency was low.
7–9
Other scholars
prevented an alkali release with wax-sealing treatment
used on the surfaces of the internal pores of the EPCM,
but the effect of alkali reduction was not obvious.
10
The
carbonation of concrete is a complex physical and
chemical process, in which carbon dioxide from air
interacts with alkaline substances. This process can be
simply described with Equation (1):
CO
2
+H
2
O=H
2
CO
3
Ca(OH)
2
+H
2
CO
3
= CaCO
3
+2H
2
O (1)
Carbon dioxide from air usually penetrates the
interior of concrete through tiny pores or cracks on the
surface, interacting with hydrated products such as cal-
cium hydroxide and forming calcium silicate. Then, the
chemical composition of concrete is changed. Most
importantly, the amount of alkalinity from calcium
hydroxide in concrete decreases.
11
Although carbonation
impairs the durability of reinforced concrete, it can
Materiali in tehnologije / Materials and technology 53 (2019) 4, 575–581 575
UDK 620.1:631.41:625.821.5:66.046.562 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 53(4)575(2019)
*Corresponding author's e-mail:
350489714@qq.com

reduce the alkali content and improve the strength of
plain concrete. However, the EPCM does not use rein-
forcement, and the growth of plants requires low
alkalinity in the pore interior of the EPCM. Therefore, it
is theoretically feasible to reduce the alkalinity of the
EPCM with an accelerated-carbonization test; mineral
admixtures also have a certain degree of influence on the
carbonation resistance of concrete.
12,13
Based on three
factors including the carbonization method, carboni-
zation age and mineral-admixture content, the alkali-
reduction technology of the EPCM will be further
studied in this paper.
2 MATERIALS AND METHODS
2.1 Raw materials
The cement used in this research was produced by
China Wannianqing Cement Co., Ltd. P.O 42.5 cement
was selected; its performance indexes are shown in
Table 1 and the details of mineral admixtures are shown
in Table 2. There was only single-sized coarse aggre-
gate, no fine aggregate. A coarse aggregate with a parti-
cle size of 19–26.5 mm was adopted for this research.
Table 1: Performance indexes of cement
SSA
/m
2
/kg
SO
3
/%
Stabil-
ity
IS
/min
FS
/min
3d FS
/MPa
3d CS
/MPa
28d
FS
/MPa
28d
CS
/MPa
355 2.42
quali-
fied
155 210 5.7 25.3 8.9 53.0
Note: SSA = specific surface area; IS = initial setting; FS = final
setting; 3d FS = 3d flexural strength; 3d CS = 3d compressive strength
Table 2: Performance indexes of mineral admixtures
Mineral
admixture
Fineness
/%
LOI
/%
WDR
/%
SD
/g/cm
3
MC
/%
7d AI
/%
28d
AI
/%
Fly ash 23.33 3.8 92 2.22 0.1 69 96
Slag 6.07 0.9 80 2.51 0.1 95 98
Note: LOI = loss on ignition; WDR = water demand ratio; SD =
stacking density; MC = moisture content;7dAI=7dactivity index;
28d AI = 28d activity index
2.2 Experimental part
2.2.1 Preparation simulation
For the plants to have enough pores to grow in the
EPCM, the effective porosity (20–35 %) and compres-
sive strength after 28 d (5–15 MPa) were used as the
control criteria. The W/C for the EPCM was 0.30. In
order to study the influence of mineral admixtures on the
alkalinity of eco-porous concrete, fly ash and slag were
mixed into the EPCM.
2.2.2 Specimen preparation
Fly ash and slag were used to replace the cement in
the amounts of (0, 10, 20 and 30) %. We used the
improved "paste-coating-gravel" method, that is, we
mixed the cement, mineral admixtures and 70 % of water
in a blender for 1.5 min, then we mixed the coarse aggre-
gates for 1 min, and added the remaining 30 % of water,
mixing it for 1 min.
14
The mixture was poured into a
mold in three layers. After each layer was poured, a
vibrating bar was used to ensure a good compaction
effect and the specimens were demolded 24 h after
having been casted (in Figure 1, a 3D model was used to
show the EPCM molding process. Based on the images
of the EPCM scanned with CT, the pore structure of the
EPCM could be reconstructed with Mimics 15.0, and a
clear three-dimensional model was obtained. Then, a
three-dimensional fault model of the EPCM with a
designated thickness could be obtained using a three-
dimensional cutting angle. According to Chinese speci-
fication GB/T 50081-2009, the dimensions of a speci-
men for the compression test and alkalinity test were
S. LI et al.: RESEARCH ON REDUCING ALKALINITY OF AN ECOLOGICAL POROUS CONCRETE MIXURE ...
576 Materiali in tehnologije / Materials and technology 53 (2019) 4, 575–581
Figure 1: CT scanning test and EPCM molding process (3D model)
Table 3: Mix proportion of the EPCM
Batch
Grain
size
/mm
Cement
/kg/m
3
Water
/kg/m
3
FA
/kg/m
3
SG
/kg/m
3
Water
binder
ratio
A1/B1 19 26.5 300 90 0 0 0.30
A2/B2 19 26.5 270 90 30 0 0.30
A3/B3 19 26.5 240 90 60 0 0.30
A4/B4 19 26.5 210 90 90 0 0.30
A5/B5 19 26.5 270 90 0 30 0.30
A6/B6 19 26.5 240 90 0 60 0.30
A7/B7 19 26.5 210 90 0 90 0.30
Note: FA = fly ash; SG = slag

(150 × 150 × 150) mm.
15
The specimen was solidified in
standard condition (the temperature was 20±2 °C and the
relative humidity was 95 %) for 28 d. Then, we removed
the specimen and put it into an oven and set the
temperature to 105 °C, drying it to its constant weight.
The mix proportions for the EPCM are presented in
Table 3.
2.3 Measurement methods
2.3.1 Carbonization test
The test is based on Chinese specification GB/T
50082-2009.
15
The specimens of group A were placed in
a carbonization box for an accelerated carbonization test,
and the specimens of group B were placed in the external
environment for natural-carbonization test. The carbo-
nization ages were (7, 14, 28 and 56) d.
2.3.2 Compressive strength
A TYE-2000E pressure-testing machine was used to
test the compressive strength of the specimens.
Assuming the compressive strength of the EPCM is low,
the loading rate is 2.25 KN/1 s. Compressive strength of
the EPCM was determined according to Chinese
specification GB/T 50081-2009.
15
2.3.3 Alkalinity test
The alkalinity of the internal pores of the EPCM was
determined using the alkalinity-release principle.
16
The
steps of the alkalinity test were as follows: after crushing
a specimen, we weighed 100-g fragments and put them
into a cup; we added 100 ml of water to ensure that the
fragments were immersed in water, and then we sealed
the cup mouth with a fresh-keeping film to prevent water
evaporation. After 24 h of immersion, a PHS-3E pH
tester was used to test the pH value of the water solution
of the immersed sample, and then we replaced fresh
water to immerse it for another 24 h to continue the test
until the data become stable. The situation at the testing
site is shown in Figure 2.
S. LI et al.: RESEARCH ON REDUCING ALKALINITY OF AN ECOLOGICAL POROUS CONCRETE MIXURE ...
Materiali in tehnologije / Materials and technology 53 (2019) 4, 575–581 577
Figure 3: XRD diffraction analysis of EPCM surface cement (Note: 1 = calcium carbonate; 2 = calcium hydroxide)
Figure 2: Situation at the testing site

2.3.4 Vegetation test
According to the existing research data of the
research group, tall fescue is a subtropical plant with the
advantages of cold resistance, heat resistance and
trampling resistance. The fibrous roots of tall fescue are
hard, easily penetrating the inner pores of the EPCM; the
diameter of its rhizome is small, having little effect on
the pore structure of the EPCM during the root growth.
Therefore, tall fescue was chosen as the experimental
grass species that should be watered regularly during the
germination process.
3 RESULTS AND DISCUSSION
3.1 Influence of mineral admixtures on the EPCM
alkalinity
The main characteristic parameter of the alkalinity of
the EPCM is the calcium hydroxide content. The cement
on the EPCM surface cured for (7, 14, 28 and 56) d was
ground into powder, and XRD was used for a diffraction
analysis. Figure 3 shows the analysis results. The con-
tent of calcium hydroxide produced due to cement
hydration and the pH value in the EPCM pores increase
with age, indicating that the former is positively related
to the latter.
Figure 4 shows the influence of mineral admixtures
on the alkalinity of the EPCM. With an increase in the
fly ash or slag content, the alkalinity of the EPCM tends
to decrease; fly ash has a better alkali-reducing ability
than slag, and the maximum decrease occurs after 56
th
day. The hydration reaction of the EPCM produces
hydrated calcium silicate gel and calcium hydroxide. The
principal components of the mineral admixture are silica
S. LI et al.: RESEARCH ON REDUCING ALKALINITY OF AN ECOLOGICAL POROUS CONCRETE MIXURE ...
578 Materiali in tehnologije / Materials and technology 53 (2019) 4, 575–581
Figure 5: Alkalinity of EPCM after accelerated carbonization and natural carbonization
Note: NC = natural carbonization; AC = accelerated carbonization
Figure 4: Influence of mineral admixtures on alkalinity of EPCM

and calcium oxide. Activated silica and alumina can
react with calcium hydroxide to form calcium silicate
gel, thereby reducing the incidence of calcium hydro-
xide. With the increase of the mineral-admixture content,
the content of active silica increases and the consump-
tion of calcium hydroxide increases, which makes the pH
value of the EPCM decrease. However, the effect of
adding mineral admixtures on the alkali reduction is
limited. The pH value of mineral admixtures in each age
group is still around 11–13, which is far from meeting
the requirements for plant growth.
3.2 Influence of carbonation and mineral admixture
on the alkalinity of the EPCM
The test results of the pH values of the EPCM for two
carbonization methods and different carbonization ages
are shown in Figure 5. It can be seen that the pH value
of the EPCM after accelerated carbonization decrease
significantly. The pH value of the EPCM with the same
mix ratio decreases by about 0.49–1.15 units after7dof
accelerated carbonization compared with that after7dof
natural carbonization; after 56 d of accelerated carboni-
zation, the pH value decreases by about 2.98–3.55 units.
This is because carbon dioxide gas permeates into the
pores and surface of the EPCM and reacts with alkaline
substances such as calcium hydroxide in the EPCM to
form carbonate and water, changing the chemical com-
position and micro-structure of the EPCM and reducing
its alkalinity. The data show that the concentration of
carbon dioxide in the atmosphere of some parts of China
reaches 388 ppm (0.038 %), while the concentration of
carbon dioxide in the accelerated carbonization test
reaches about 20 %, and the relative humidity remains at
70 %.
Under the accelerated carbonization test environ-
ment, the carbonization rate of the porous EPCM will be
greatly accelerated and the alkalinity will be consider-
ably reduced. It can also be seen from Figure 5 that with
the increase in the carbonization time, the decreasing
trend of the pH value slows down, which indicates that
the effect of carbonization on the pH value of the pore
environment in the EPCM is limited. Under the action of
a low-content mineral admixture, the pH value of
slag-mixed specimens in the early stage of carbonization
is lower than that of fly-ash-mixed specimens; thus, the
opposite result is presented in the later stage of carbo-
nization. Under the action of a high-content mineral
admixture, the pH value of fly-ash specimens is lower
than that of slag specimens.
After 56 d of accelerated carbonization, the pH value
of groups B4 and B7 decreased to 8.57 and 8.72, res-
pectively, meeting the requirement for the pH value of
plant growth to be 7–9. This indicated that the alkalinity
of the EPCM internal pores was sharply reduced by the
coupling effect of mineral admixture and accelerated
carbonization. In accordance with the data, two curve
formulas can be fitted to describe the relationship bet-
ween the carbonization time and alkalinity. Equation (2)
refers to the B4 group, Equation (3) refers to the B7
group and detailed curves are shown in Figure 6.
P = 12.202D
–0.087
R
2
= 0.9333 (2)
P = 13.406D
–0.109
R
2
= 0.9326 (3)
Here, P is the pH value and D is the age of accele-
rated carbonization.
S. LI et al.: RESEARCH ON REDUCING ALKALINITY OF AN ECOLOGICAL POROUS CONCRETE MIXURE ...
Materiali in tehnologije / Materials and technology 53 (2019) 4, 575–581 579
Figure 6: Relationship between the alkalinity and carbonization age
of EPCM
Table 3: Compressive strength of EPCM after two carbonation methods
Batch SC 28 d Compressive strength/MPa
7d 14d 28d 56d
AC NC AC NC AC NC AC NC
A1/B1 8.9(0.4) 9.3(0.2) 9.1(0.1) 9.7(0.3) 9.2(0.5) 10.7(0.6) 9.8(0.8) 11.0(0.7) 10.0(0.4)
A2/B2 9.1(0.3) 9.6(0.6) 9.3(0.4) 9.8(0.7) 9.4(0.1) 11.0(0.3) 10.2(0.5) 11.4(0.4) 10.4(0.6)
A3/B3 9.1(0.5) 9.7(0.1) 9.5(0.4) 10.0(0.5) 9.5(0.2) 10.9(0.2) 10.4(0.3) 11.5(0.5) 10.5(0.3)
A4/B4 9.0(0.2) 9.9(0.2) 9.6(0.6) 9.8(0.2) 9.5(0.7) 11.5(0.4) 10.5(0.4) 11.9(0.2) 10.7(0.2)
A5/B5 8.7(0.6) 9.5(0.4) 9.3(0.3) 9.4(0.5) 9.6(0.4) 10.9(0.2) 10.5(0.1) 11.0(0.1) 10.6(0.2)
A6/B6 9.1(0.1) 9.5(0.3) 9.4(0.5) 9.6(0.2) 9.7(0.2) 11.0(0.1) 10.7(0.6) 11.3(0.6) 11.0(0.1)
A7/B7 8.8(0.2) 9.7(0.4) 9.4(0.1) 9.7(0.5) 9.8(0.5) 11.4(0.2) 10.8(0.2) 11.7(0.3) 11.1(0.5)
Note: SC = standard curing; AC = accelerated carbonization; NC = natural carbonization

3.3 Influence of carbonation and mineral admixture
on the compressive strength of the EPCM
Table 3 shows the effects of two carbonization
methods on the compressive strength of the EPCM. The
compressive strength of the EPCM is increased by
1.9–2.6 MPa compared with that of the EPCM cured for
standard 28 d after accelerated carbonization. Compared
with natural carbonization, the strength of the EPCM
after accelerated carbonization for 56 d is enhanced by
2–11.2 %.
There are two main effects of carbonization: 1) the
water released during carbonization can further hydrate
the unhydrated cement particles, and the calcium hyd-
roxide in the cement paste absorbs carbon dioxide from
air to form calcium carbonate crystals, which can fill the
pores and compact the microstructure of the EPCM; 2)
the reduction of alkalinity caused by carbonization re-
sults in a decomposition of a certain proportion of the
C-S-H gel, which may decrease the compressive strength
of the EPCM. From the overall trend, the first effect
overtakes the second one. Consequently, the compressive
strength is increased. Mineral admixtures also improve
the compressive strength of the EPCM and the bigger
their amount, the larger is the strength improvement.
This is due to the physical filling effect of the mineral
admixture. At the same time, active silica and alumina in
the admixture react with calcium hydroxide to form
hydrate products. These hydrate products can also
effectively fill in the pores between cement particles and
improve the interface transition zone of the EPCM. The
results demonstrate that the mechanical properties of the
EPCM can be improved with a combination of a mineral
admixture and carbonization test.
3.4 Vegetation test of the EPCM
Grass planting was carried out using the EPCM
mixed with 30 % FA and 56-day accelerated carboni-
zation. Figure 7 shows the growth of tall fescue after (3,
28 and 56) d. The growth was observed. The roots of tall
fescue began to germinate on the 3
rd
day; on the 28
th
day,
the roots penetrated the pores of the EPCM and tall
fescue was rooted in the bottom soil. On the 56
th
day, the
height of tall fescue exceeded 15 cm. This suggests that
tall fescue grows well in the EPCM treated with mineral
admixtures and the appropriate carbonation method.
4 CONCLUSIONS
By studying the effects of two carbonization methods
and mineral admixtures on the pore alkalinity and com-
pressive strength of the EPCM, the following conclu-
sions are drawn:
The content of calcium hydroxide produced due to
cement hydration and the pH value of the EPCM pores
increase with age, indicating that the former is positively
related to the latter.
2) Adding mineral admixtures such as fly ash or slag
can reduce the alkalinity of the EPCM, but the common
amount of the mixture (10–30 %) is not enough to
achieve the required pH value for a plant-growth en-
vironment. It must be combined with other alkali-
reducing technologies.
3) Coupling the addition of mineral admixtures and
accelerated carbonization can significantly reduce the
alkalinity of the EPCM pores. After 56 d of accelerated
carbonization, the pH value can be decreased to 8.57,
which is suitable for plant growth.
4) The compressive strength of the EPCM increases
by 2–11.2 % after accelerated carbonization, indicating
that the accelerated-carbonization technology can be
applied to the EPCM.
5) Tall fescue grew well in the EPCM (30 % FA and
56-d accelerated carbonation); its roots began to germi-
nate on the 3
rd
day. On the 56
th
day, the height of the tall
fescue planted in the EPCM exceeded 15 cm.
Acknowledgments
The authors greatly appreciate the support of The
National Key Research and Development Program of
China (Project No.: 2016YFC0700801-01) and The
Hunan Province Science and Technology Department
(Project No.: 2013FJ2002, 14JJ4055). This study was
also supported by Central South University of Forestry
and Technology (CX2017B41).
S. LI et al.: RESEARCH ON REDUCING ALKALINITY OF AN ECOLOGICAL POROUS CONCRETE MIXURE ...
580 Materiali in tehnologije / Materials and technology 53 (2019) 4, 575–581
Figure 7: Growth of fescue in the EPCM

5 REFERENCES
1
S. Shen, M. Burton, B. Jobson, L. Haselbach, Pervious concrete with
titanium dioxide as a photocatalyst compound for a greener urban
road environment, Constr. Build. Mater., 35 (2012) 10, 874–883,
doi:10.1016/j.conbuildmat.2012.04.097
2
R. Yu, P. Spiesz, H. J. H. Brouwers, Development of an eco-friendly
ultra-high performance concrete (UHPC) with efficient cement and
mineral admixtures uses, Cement and Concrete Composites, 55
(2015) 1, 383–394, doi:10.1016/j.cemconcomp.2014.09.024
3
B. Huang, H. Wu, X. Shu, E. G. Burdette, Laboratory evaluation of
permeability and strength of polymer-modified pervious concrete,
Constr. Build. Mater., 24 (2010) 5, 818–823, doi:10.1016/
j.conbuildmat.2009.10.025
4
K.-H. Lee, K.-H. Yang, Development of a neutral cementitious
material to promote vegetation concrete, Construction and Building
Materials, 127 (2016), 442–449, doi:10.1016/j.conbuildmat.2016.
10.032
5
L. Xiangzhou, Eco concrete technology for sustainable development,
China Building Materials, (2003) 1, 344–350, doi:10.16291/
j.cnki.zgjc.2003.01.016
6
W. Guiling, W. Longzhi, Z. Haixia, Mixture design, alkalinity
control, selection of planting soil and plant for planting eco-concrete,
Concrete, (2013) 2, 102–109, doi:10.3969/j.issn.1002-3550.2013.
02.029
7
H. F. W. Taylor, K. Mohan, G. K. Moir, Analytical study of pure and
extended Portland cement pastes: II, Fly-ash- and slag-cement
pastes, Journal of the American Ceramic Society, 68 (1985) 12,
685–690, doi:10.1111/j.1151-2916.1985.tb10125.x
8
M. H. Shehata, M. D. A. Thomas, R. F. Bleszinski, The effects of fly
ash composition on the chemistry of pore solution in hydrated
cement pastes, Cement and Concrete Research, 29 (1999) 11,
1915–1920, doi:10.1016/S0008-8846(99)00190-8
9
J. L. Garcia Calvo, A. Hidalgo, Development of low-pH cementitious
materials for HLRW repositories: Resistance against groundwater
aggression, Cement and Concrete Research, 40 (2010) 8, 1290–1297,
doi:10.1016/j.cemconres.2009.11.008
10
H. Chunming, H. Yongyou, Improvement on alkaline water in the
pores of eco-concrete, China Concrete and Cement Products, (2006)
3, 8–10, doi:10.3969/j.issn.1000-4637.2006.03.003
11
Y. Hongsheng, The study of sensitivity factors for concrete carbo-
nization, Industrial Construction, (2014) 44, 94–97, doi:10.13204/
j.gyjz201401021
12
L. Wenyu, S. Xian, Study on decreasing alkalinity of planting
concrete and the resulting planting effect, Concrete, (2013)7 ,
155–158, doi:10.3969/j.issn.1002-3550.2013.07.044
13
B. Aruhan, Peiyu Yan, Carbonation Characteristics of Concrete with
Different Fly-Ash Contents, Journal of the Chinese Ceramic Society,
(2011) 1, 7–12, doi:10.14062/j.issn.0454-5648.2011.01.022
14
G. Zhang, J. Yin, S. Li, Investigation on freeze-thaw resistance of
eco-porous concrete containing fly ash, Mater. Tehnol., 52 (2018)2,
183–188, doi:10.17222/mit.2017.073
15
Chinese Standard, Standard for Test Method of Mechanical
Properties on Ordinary Concrete, 2009
16
M. Zhiliang, W. Zhongbing, Alkalinity of pore fluid of high-addition
fly-ash concrete, Journal of Chongqing University, 21 (1999)1 ,
24–27, doi:10.11835/j.issn.1674-4764.1999.01.006
S. LI et al.: RESEARCH ON REDUCING ALKALINITY OF AN ECOLOGICAL POROUS CONCRETE MIXURE ...
Materiali in tehnologije / Materials and technology 53 (2019) 4, 575–581 581