CC BY
52
UDK 691.311: 691.335
M. I. Khaliullin, R. Z. Rakhimov, A. R. Gayfullin, O. V. Stoyanov
CONCRETES BASED ON NO-CLINKER COMPOSITE GYPSUM BINDER WITH ENHANCED WATER RESISTANCE AND INDUSTRIAL WASTE
Keywords: concrete, ground blastfurnace slag, expanded-clay dust, composite gypsum binders.
Production developing and use of gypsum building materials and products meet one of the urgent problems of further sustainable development of the construction industry, aimed at reducing energy consumption and reducing harmful emissions during building products manufacturing. The author studied the variation of the linear deformation and strength characteristics of artificial stone based on composite gypsum binders with prolonged maturing under different conditions. No-clinker gypsum binders with enhanced water resistance were developed using integrated hydraulic additive. The components of this additive are lime and large-tonnage industrial waste - ground blast furnace slag and ex-panded-clay dust. It is specified that heavy and fine-grained concrete with the range strength of M75 to M300 can be obtained based on no-clinker composite gypsum binders. The softening coefficient is 0,8 that stands to water resistant materials with F50 frost resistance.
Ключевые слова: бетоны, молотый доменный шлак, керамзитовая пъть, композиционные гипсовые вяжущие.
В работе исследованы изменения линейных деформаций и прочностных показателей искусственного камня на основе композиционных гипсовых вяжущих при длительном твердении в различных условиях. Разработаны бесклинкерные композиционные гипсовые вяжущие повышенной водостойкости с применением комплексной гидравлической добавки. Компонентами добавки являются известь и многотоннажные промышленные отходы - молотый доменный шлак и керамзитовая пыгль. Установлено, что на основе бесклинкерных композиционных гипсовых вяжущих могут быть получены тяжелые и мелкозернистые бетоны марок по прочности от М75 до М300 с коэффициентом размягчения более 0,8, то есть соответствующим водостойким материалам, марками по морозостойкости F50.
Introduction
One of the urgent problems to further sustainable development of the production of building materials is to reduce energy consumption in the production of construction products and the reduction of harmful emissions.
Production of Portland cement, which is the main mineral binder in the production of construction products in our country, is a very energy consuming process. For example, to produce 1 ton of Portland cement the total costs of fuel and energy are equal to 215 kg of conventional fuel.
In addition, the manufacture of Portland cement is associated with significant amounts of gaseous products released into the atmosphere. In particular, over 7% of the total volume of carbon dioxide (which is formed during industrial activities of mankind and which is causing the greenhouse effect) goes into the environment as a result of cement plants operation around the world.
To produce 1 ton of another widely used mineral binder - construction lime, we need to spend about 204 kg of conventional fuel, which generates about 223 m3 of carbon dioxide.
As a result, production of basic binder for gypsum building materials and products - gypsum plaster, has a relatively low energy consumption and ecological compatibility. Fuel consumption for the production of gypsum is 4,6 times less than for the production of Portland cement. The chemical process of the gypsum plaster production during gypsum rock firing is associated with the release of water vapor only, which is environmentally friendly.
Production of gypsum building materials, gypsum concrete in particular, has lower cost and energy consumption compared to cement concretes (4 and 5 times respectively), small investment and metal specific quantity of the equipment (2 and 3 times, respectively) and forms turnover during the production of the items accelerates 10-15 times as much.
However, at present time the range of application of gypsum building materials and products in connection with their little durability and water resistance is significantly inferior to the similar materials based on Portland cement. Basically, gypsum materials and products are used indoors with dry and normal humidity conditions.
One of the most effective ways to increase water resistance and durability of gypsum building materials are composite gypsum cement, gypsum slag and gypsum lime binders with pozzolanic additives proposed by V.A. Volzhenskiy and other researchers in the mid-twentieth century [1-2]. Industrial waste such as milled blast furnace slag, fly ash, crushed glass, microsilica and etc. are widely used as components of such binders.
Further A.V. Ferronskaya, V.F. Korovyakov and other researchers have developed composite waterresistant gypsum binders [3-7].
No-clinker composite gypsum binders with enhanced water resistance using integrated hydraulic additives have been developed in the works that were performed by the authors of this article earlier. Lime and tonnage industrial waste - milled blast furnace slag and expanded clay dust (compositional gypsum lime expanded clay binder (CGLECB) and compositional gypsum lime expanded clay slag binder (CGLECSB)) are mineral components of the additive [4]. Furthermore,
superplasticizer was added into the binder composition during its preparation.
The aim of this research is to develop structures and study basic physical and technical properties of fine-grained and heavy gypsum concretes on the basis of the obtained no-clinker composite gypsum binders with enhanced water resistance.
Methods and materials
Silica sand was used as fine aggregate in the manufacture of fine and heavy gypsum concretes. It has the following characteristics: bulk density is 1552 kg/m3; real density is 2650 kg/m3 , granulometric composition of the sand meets the requirements of the GOST 8736-93, gradation factor is 2,6; content of dust and clay particles is 1,2 %; porosity is 42 %; maximum grain size is 2.5 mm.
Carbonate broken stone was used as coarse aggregate in the manufacture of heavy gypsum concretes. It has the following characteristics: bulk density is 1300 kg/m3; real density is 2500 kg/ m3, the average density is 2150 kg/m3, broken stone brand by durability is 300, water absorption by weight is 7,5 %, maximum size is 20 mm, granulometric composition is 5-10 mm - 96 %, 10-20 mm - 4 %.
The calculation of heavy and fine-grained gypsum concretes composition based on no-clinker composite gypsum binders of various grades by density was carried out in accordance with the procedure described in the research [3].
Indicators of porosity of the artificial stone obtained during solidification of no-clinker composite gypsum binder with enhanced water resistance were determined in accordance with the GOST 12730.012730.4.
Determination of the relative deformation and changes in the strength of samples of artificial gypsum stone based on composite gypsum lime expanded clay binder and composite gypsum lime expanded clay slag binder were made on samples - prisms with 40x40x160 mm size made of paste binder with normal density in accordance with the GOST 24544.
To determine the basic physical and technical properties of the gypsum concretes samples with cube shapes and of 100x100x100 mm size were made. Concrete strength test was carried out in accordance with the GOST 10180. Frost resistance test of the concrete was carried out by basic approach according to the GOST 10060.0-10060.1. The determination of the concrete softening coefficient under the conditions of samples storage during the tests was carried out under technical conditions 21-0284757.
Methods of X-ray diffraction analysis using X-ray diffractometer D8 ADVANCE of «Bruker» corporation; integrated differential thermal analysis using synchronous thermoanalyzer STA 409 PC of «NETZSCH» company; electron microscopy using an electron microscope REMMA-202M PA «Elektron» were used in the research.
Results and discussion
Binders taken to develop concrete mixtures have the following characteristics of properties (Table 1).
Table 1 - Physical and mechanical properties of no-clinker composite gypsum binders
Binder Setting time, min.-sec. Ultimate compressive strength, MPa Softening coefficient
Start Finish
CGLECB 8-00 12-00 17,1 0,67
CGLECSB 8-10 13-10 31,2 0,96
Retarding agent additive - citric acid was added into the composite gypsum binder during the preparation of gypsum concrete. Citric acid is produced at the LLC "Citrobel" (Belgorod).
Retarding agent additive increased the setting time for CGLECB and CGLECSB: setting time start -up to 52 minutes and 77 minutes and the setting time end - up to 76 minutes and 124 minutes respectively.
The obtained binders have the following physical and technical characteristics: samples tested under the technical conditions 21-0284757-1 have a compressive strength at 28 days (marks) from 10 to 30 MPa, softening coefficient rate is from 0,8 to 0,96. Artificial stone based on the developed no-clinker composite gypsum binders has a compressive strength from 1.5 time to twice as much higher and softening coefficient is 3 times higher, compared to no additive gypsum plaster. Studies have shown that the introduction of optimal amounts of milled expanded clay dust and granulated blast furnace slag, together with lime and superplasticizer into the composite gypsum binders during the maturing process of the binders provides pore filling of the stone by the obtained low basic calcium hydro silicates and a denser and fine-grained structure is formed. Compared with the samples obtained during solidification of the original gypsum plaster artificial stone based on CGLECB and CGLECSB and of 28 days of normal curing has a decrease: in total porosity, by 10 and 21,5 % respectively, volume of open pores by 15,4 and 21 % respectively. There is an increase in the proportion of closed pores to the total pore volume by 6,38 and 19,84 % as well as average pore size decreasing at a greater homogeneity of their size distribution. Increased strength and water resistance of the developed no-clinker composite gypsum binders with enhanced water resistance result from changes in the structure of the pore space during formation of the increased volume of water resistant new growths at maturing process of artificial stone based on CGLECB and CGLECSB. This is confirmed by research data of mineralogical composition of the artificial stone based on CGLECB and CGLECSB and by methods of differential thermal analysis, X-ray diffraction and electron microscopy [4].
Researches of mineralogical composition of the artificial stone based on CGLECB and CGLECSB at long maturing time have shown growth discontinuance of ettringite amount, which is an essential factor in ensuring durability of artificial stone. This is confirmed by studies of changes in linear deformation and strength characteristics of artificial stone based on CGLECB and CGLECSB during long maturing under different conditions, which are given, in Fig. 1 and 2, respectively.
<n 0,1
N
Ip
—f
f
r
\
0 40 SO 120 160 200 240 280 320 360 Maturing period, days
a
0,2
0,15
C
(S
tn 0,1
0,05
0
A
A -U
f -v"
0 40 SO 120 160 200 240 280 320 360 Maturing period, days b
Fig. 1 - Changes in deformation of artificial stone samples based on CGLECB (a) and on CGLECSB (b) during long maturing under different conditions: 1 - air-dry conditions; 2 - aqueous conditions; 3 -normal humidity conditions
Research results presented in Fig. 1 show the development of enlargement deformations, which is characteristic of the initial period of composite binders maturing. After 2 or 3 days period, enlargement process slows down and further stabilization of deformations can be observed. For all the above-mentioned storage conditions deformations become stable at a period of 28-40 days. For samples of artificial stone based on CGLECB deformation ration at 12 months hydraulic setting is 0,22 % and at air setting is 0,145 %.
Fig. 2 shows the results of durability changes at a compression of artificial stone based on CGLECB and CGLECSB during prolonged maturing under air-dry conditions, normal humidity conditions (at a relative air humidity of 85-90 % and a temperature of 20-22 0C) and aqueous conditions.
The analysis data shown in Fig. 2, obtained during the test of artificial stone samples based on CGLECB and CGLECSB with prolonged maturing under different conditions shows the following.
When storing the samples of artificial stone based on CGLECB and CGLECSB in air-dry conditions, the growth of strength occurs in the period up to 28 days and during further maturing is not observed. When stored in normal humidity conditions within one year after an intense period of strength growth of 28 days monotonous and slow strength growth of the samples of artificial stone based on CGLECB and CGLECSB is observed. Strength growth of the samples based on CGLECB and CGLECSB aged 1 year is 3,8 and 10,9 % respectively if compared to the strength at
the age of 28 days. Intensive strength growth in the early stages is determined by maturing of gypsum component of the composite binder. Further maturing of the artificial stone happens due to the formation and maturing of hydraulic products of the interaction of composite binders components.
120 160 200 240 280 320 360 Maturing period, days
120 160 200 240 280 320 360 Maturing period, days
b
Fig. 2 - Changes in durability of artificial stone samples based on CGLECB (a) and on CGLECSB (b) during prolonged maturing under different conditions: 1 - air-dry conditions; 2 - aqueous conditions; 3 - normal humidity conditions
Optimum conditions of CGLECB compositions maturing are normal humid conditions.
Basic physical and technical properties of the developed heavy and fine-grained gypsum concretes based on no-clinker gypsum binder with enhanced water resistance are given in Tables 2 and 3 respectively.
Table 2 - Basic physical and technical properties of the heavy gypsum concretes based on no-clinker gypsum binder of different made by strength
Binder made Concrete made by strength Concrete grade by strength Softening coefficient Concrete made by frost resistance
10 M75 B7,5 0.70 F15
15 M100 B10 0.75 F25
20 M150 B10 0.80 F25
25 M200 B15 0.82 F50
30 M250 B20 0.88 F50
a
Table 3 - Basic physical and technical properties of fine-grained gypsum concretes based on no-clinker gypsum binder of different made by strength
Analysis of the data presented in Tables 2 and 3 shows the possibility of obtaining heavy and finegrained gypsum concretes made with strength range M75-M300 and strength grade range B7,5-B20 based on no-clinker gypsum binders.
Conclusions
Consequently, heavy and fine-grained gypsum concretes made with strength range M75-M300 and strength grade range B7,5-B20 with softening coefficient more than 0,8 (that corresponds to water resistant products with frost resistant made of F50) can be obtained based on the developed no-clinker compositional
gypsum binders. Concretes based on the no-clinker compositional gypsum binders can be used in the manufacture of interior and exterior building constructions at dry, normal and aqueous operating conditions according to Construction Norms and Regulations 23-02-2003 subject to the measures taken against wet influence.
References
1. Yu^. Bazhenov, V.F. Korovyakov, GA. Denisov. Technology of Dry Construction Mixtures. Publishing house АСВ, Moscow, 2003. 96 p.
2. А.V. Volzhenskiy, М.I. Rogovoy, V.I. Stambulko. Gypsum Cement and Gypsum Slag Binding Materials and Products. Gosstoyizdat, Moscow, 1960. 162 p.
3. А.V. Ferronskaya. Gypsum Materials and Products. (Manufacture and Usage). Reference book. Publishing house АСВ, Moscow, 2004. 488 p.
4. R.Z. Rakhimov, M.I. Khaliullin, A.R. Gayfullin, Construction Materials, 7, p. 13-16 (2012).
5. Y. Tokarev., G. Yakovlev, Pollack Periodica. 4, 3, p. 79-85 (2009).
6. V.V. Babkov, V.M. Latypov, L.N. Lomakina, V.S. Asyanova, R.I. Shigapov, Construction Materials, 7, p. 4-8 (2012).
7. Y. Wang, L. Urbonas, D. Heinz, "Einfluss von verschiedenen Puzzolanen auf die Eigenschaften von Gips-Zement-Puzzolan-Bindemitteln. Ibausil 18. Internationale Baustofftagung, Tagungsbericht (Weimar, Germany, September 12-14, 2012). F.A. Figner - Institut fur Baustoffkunde, Bauhaus - Universitat Weimar, Weimar, 2012, B. 1. P. 1-0424-1-0431.
Binder made Concrete made by strength Concrete grade by strength Softening coefficient Concrete made by frost resistance
10 М75 В5 0.75 F15
15 М100 В7,5 0.78 F25
20 М150 В10 0.81 F25
25 М200 В15 0.82 F50
30 М250 В20 0.88 F50
© M. I. Khaliullin - docent, Kazan State University of Architecture and Engineering, khaliullin@kgasu.ru; R. Z. Rakhimov - professor, Kazan State University of Architecture and Engineering, rahimov@ksaba.ru; A. R. Gayfullin - docent, Kazan State University of Architecture and Engineering, gaifi@list.ru; O. V. Stoyanov - professor, Kazan National Research Technological University, Department of Plastics Technology, ov_stoyanov@mail.ru.
© М. И. Халиуллин - канд. техн. наук, доц. КГАСУ, khaliullin@kgasu.ru; Р. З. Рахимов - д-р техн. наук, проф. КГАСУ, Rahimov@ksaba.ru; А. Р. Гайфуллин - канд. техн. наук, асс. КГАСУ, gaifi@list.ru; О. В. Стоянов - д-р техн. наук, проф., зав. каф. технологии пластических масс КНИТУ, ov_stoyanov@mail.ru.
