Expanded Polystyrene Concrete
Abstract
EPS concrete was produced by mixing the expanded polystyrene spheres (EPS) and polymer emulsion and thickener to the matrix concrete, and this concrete had good vibration energy absorption characteristics. Based on the experimental data obtained on EPS volume ratio of 0%, 20%, 30%, and 40% by replacing matrix or coarse aggregate, the two design styles had nearly the same compressive strength. By applying frequency of 5 Hz, 50000 or 100000 times, 40 KN, 50 KN, and 60 KN cyclic loading, it is shown that the higher the inclusion size was, the lower the compressive strength of the EPS concrete would be; the larger the applying dynamic cyclic load was, the more obvious the compressive strength changing would be. Meanwhile, the strength of EPS concrete had no evident change after durability test. The results of this research had practical significance on using EPS concrete in some long-term cyclic dynamic load engineering.
EPS concrete was produced by mixing the expanded polystyrene spheres (EPS) and polymer emulsion and thickener to the matrix concrete, and this concrete had good vibration energy absorption characteristics. Based on the experimental data obtained on EPS volume ratio of 0%, 20%, 30%, and 40% by replacing matrix or coarse aggregate, the two design styles had nearly the same compressive strength. By applying frequency of 5 Hz, 50000 or 100000 times, 40 KN, 50 KN, and 60 KN cyclic loading, it is shown that the higher the inclusion size was, the lower the compressive strength of the EPS concrete would be; the larger the applying dynamic cyclic load was, the more obvious the compressive strength changing would be. Meanwhile, the strength of EPS concrete had no evident change after durability test. The results of this research had practical significance on using EPS concrete in some long-term cyclic dynamic load engineering.
1. Introduction
Because the expanded polystyrene (EPS) light weight concrete has the characteristics of lightweight, energy absorption, and heat preservation, it is used in many specific construction industries like high rise buildings, floating marine platforms, and large-sized and long-span concrete [1, 2]. The lightweight concrete (LWC) has no pollution to the environment because manufacture EPS particle consumes little energy, and the particle has no poison and harm. The EPS concrete has the characteristics of economy, environmental protection, and energy saving, meeting the design concept of modern construction material.
Because the expanded polystyrene (EPS) light weight concrete has the characteristics of lightweight, energy absorption, and heat preservation, it is used in many specific construction industries like high rise buildings, floating marine platforms, and large-sized and long-span concrete [1, 2]. The lightweight concrete (LWC) has no pollution to the environment because manufacture EPS particle consumes little energy, and the particle has no poison and harm. The EPS concrete has the characteristics of economy, environmental protection, and energy saving, meeting the design concept of modern construction material.
2. Materials and Mix Design Principles
The test specimens were made with the same type as that used for very high strength concrete, and the EPS particle took the place of part of the concrete or coarse aggregate.
(1) Cement. It was made with CEM I 52.5 cement.
(2) Fine Aggregate. It is made with rounded river sand with a fineness modulus of 2.85.
(3) Coarse Aggregate. It is gravel with a diameter range of 4–20 mm.
(4) EPS Particles. EPS particles are expanded polystyrene spheres particle with a diameter range of 1–3 mm and density of 20 kg/m3 which is shown in Figure.
The test specimens were made with the same type as that used for very high strength concrete, and the EPS particle took the place of part of the concrete or coarse aggregate.
(1) Cement. It was made with CEM I 52.5 cement.
(2) Fine Aggregate. It is made with rounded river sand with a fineness modulus of 2.85.
(3) Coarse Aggregate. It is gravel with a diameter range of 4–20 mm.
(4) EPS Particles. EPS particles are expanded polystyrene spheres particle with a diameter range of 1–3 mm and density of 20 kg/m3 which is shown in Figure.
(5) Silica Fume. Because the fineness of silica fume is very low, it is about 80–100 compared to normal cement and it is used in the concrete to fill up the pore among the cement granules and the hydrate products are similar to cement in water; the other mixture would been bonded by the gel.
(6) Admixture. A polycarboxylate-based superplasticizer was used to improve the workability and the compressive strength of the EPS concrete. Expanded polystyrene spheres particles are hydrophobic material, extremely light with the density of only 12–20 kg/m3 which can cause segregation in mixing and make the inhomogeneity of the EPS concrete, leading to the decrease of the compressive strength.
(7) Mixing Method. Because of the hydrophobic material of the EPS particles, the workability and durability of EPS concrete were poor during the mixing process. Indeed, after numerous mixing, a mixing method similar to the “sand-wrapping” technique was utilized to make EPS concrete. Firstly, it pulled the EPS particles and 1/3 water and 1/2 polymer emulsion into the mixed hopper. After mixing of one minute, it introduced the gravel into the mixed hopper and then mixed it for one minute and finally it pulled all the other aggregates into the mixed hopper and mixed them for two minutes. The mixing method would ensure the workability and homogeneousness of the EPS concrete.
3. Compressive Strength Test
Cubes of 100 mm size of EPS concrete were used for studying the compressive strength after being stored in laboratory conditions for 28 days. Water-cement ratio is an important index to influence the compressive strength. The compressive strength significantly reduces as the water-cement ratio is set to 0.36, because the EPS particles are of hydrophobic material and the workability falls when the water-cement ratio increases. The compressive strength changes slightly when the water-cement ratio increases from 0.32 to 0.34, considering the economics as it applied to practical engineering the water-cement ratio is set to 0.32 in this paper.
Cubes of 100 mm size of EPS concrete were used for studying the compressive strength after being stored in laboratory conditions for 28 days. Water-cement ratio is an important index to influence the compressive strength. The compressive strength significantly reduces as the water-cement ratio is set to 0.36, because the EPS particles are of hydrophobic material and the workability falls when the water-cement ratio increases. The compressive strength changes slightly when the water-cement ratio increases from 0.32 to 0.34, considering the economics as it applied to practical engineering the water-cement ratio is set to 0.32 in this paper.
Failure Mode. Different ratio of the EPS particles volume had different failure mode which is shown in Figure. The matrix was fracture after the compressive strength test, and the scale of crack was smaller along with the increase of the EPS particles volume ratio. This phenomenon was caused by the characteristics of energy absorption of EPS particles, and the appearance was still intact even if the EPS concrete was under destruction.
4. The Durability of EPS Concrete
EPS concrete has the characteristics of vibration resistance and energy absorption, which can be used in civil construction based on cycle loading to reduce vibration of system. However, it has great significance to test the durability of EPS concrete with vibration property since vibration load infliction often goes with the characteristic of low durability. This paper qualitatively analyzes the influence of EPS volume ratio, vibration cyclic times, and vibration load on EPS concrete durability by cycle loading test.
Cyclic dynamic vibration test used a 370.50 MTS electrohydraulic servo fatigue test system shown in Figure which had 500 KN load capacity and 150 mm dynamic travel and test data could be real-time shown and stored in the computer. EPS volume ratio was 0%, 20%, 30%, and 40%, times of vibration cycle were 50000 and 100000, vibration load was 60 KN, 50 KN, and 40 KN, and vibration frequency was 5 Hz; the sine wave was adopted to simulate the vibration process.
EPS concrete has the characteristics of vibration resistance and energy absorption, which can be used in civil construction based on cycle loading to reduce vibration of system. However, it has great significance to test the durability of EPS concrete with vibration property since vibration load infliction often goes with the characteristic of low durability. This paper qualitatively analyzes the influence of EPS volume ratio, vibration cyclic times, and vibration load on EPS concrete durability by cycle loading test.
Cyclic dynamic vibration test used a 370.50 MTS electrohydraulic servo fatigue test system shown in Figure which had 500 KN load capacity and 150 mm dynamic travel and test data could be real-time shown and stored in the computer. EPS volume ratio was 0%, 20%, 30%, and 40%, times of vibration cycle were 50000 and 100000, vibration load was 60 KN, 50 KN, and 40 KN, and vibration frequency was 5 Hz; the sine wave was adopted to simulate the vibration process.
5. Conclusions
EPS concrete has the advantages of small density, thermal insulation, and good seismic performance. So it is of great significance on the study of modern structural materials and practical engineering to research new concrete materials. The experimental investigations were conducted on three types of EPS concrete having EPS concrete of particles volume ratio ranging from 0% to 40%, with a view to confirming the presence of an intrinsic particle content effect on the EPS concrete compressive strength and durability.
EPS concrete has the advantages of small density, thermal insulation, and good seismic performance. So it is of great significance on the study of modern structural materials and practical engineering to research new concrete materials. The experimental investigations were conducted on three types of EPS concrete having EPS concrete of particles volume ratio ranging from 0% to 40%, with a view to confirming the presence of an intrinsic particle content effect on the EPS concrete compressive strength and durability.
The conclusions are drawn as follows.
(1)In order to increase the compressive strength the polymer emulsion is mixing in the concrete grout which would bound other mixtures together, and the relationship between its mixing ratio and compressive strength is discussed. The hydroxypropyl cellulose is mixed in the EPS concrete for improving the workability of the grout and the influence of its mixing ratio on the concrete compressive strength is studied.
(2)The compressive strength of two types of EPS concrete in which concrete is replaced or only gravel replaced by EPS particles was basically identical; the result showed that the compressive strength of the two design styles was basically coinciding. The compressive strength of EPS concrete decreased obviously with the increase of EPS particles volume ratio; the reduction curve was similar to exponential type curve.
(3)The value of applying dynamic cyclic load had great effect on the compressive strength after durability test. The compressive strength of EPS concrete of particles volume ratio of 40% was increased after applying 40 KN and 50 KN cyclic dynamic load, and the other ratio of EPS particles volume concrete was reduced after durability test; meanwhile, the degree of compressive strength reduction was inversely proportional to EPS particles volume ratio. Also, the bigger the applying dynamic cyclic load was, the bigger the gap of compressive strength between before and after durability test would be. The compressive strength of EPS concrete of particles volume ratio of 0% and 30% would fall when dynamic cyclic load is applied 100000 times, and the reduction of matrix compressive strength was much more bigger than EPS concrete particles volume ratio of 30% compared with applying dynamic vibration load 50000 times.
(4)Through the results from the designed durability test, it proved that the EPS lightweight concrete has good durability and it has a very good use in practical engineering which has certain seismic requirements and applied cyclic load.
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