The High Performance Concrete Curing Agent Based on Polyacrylic Emulsion with Hydroxyl Monomer HPMA

2014 ◽  
Vol 584-586 ◽  
pp. 1126-1129 ◽  
Author(s):  
Rui Wang ◽  
Lei Li ◽  
Hong Song Wang ◽  
Wen Bin Wang ◽  
Wei Wang ◽  
...  

The influence of the chemical structures of styrene/butyl acrylate/hydroxyl propyl methacrylate emulsion on some properties of ordinary Portland cement concretes has been investigated as concrete curing agent. The structural parameters that are varied included the fractions of HPMA and the polymer structure of the shell-core. The result of the study showed that the hydroxyl monomer HPMA played an important role on the improvement of water retention and the optimal proportion is about 5 wt% of the polymer. In addition, the shell-core structure of the emulsion with HPMA located in shell polymer can further enhance the water-retention rate. Besides, the emulsion with hydroxyl groups could smooth the surface of the concrete, inhibit the carbonation and had positive influence on the compressive strength.

Author(s):  
Ariful Hasnat ◽  
Nader Ghafoori

AbstractThis study aimed to determine the abrasion resistance of ultra-high-performance concretes (UHPCs) for railway sleepers. Test samples were made with different cementitious material combinations and varying steel fiber contents and shapes, using conventional fine aggregate. A total of 25 UHPCs and two high-strength concretes (HSCs) were selected to evaluate their depth of wear and bulk properties. The results of the coefficient of variation (CV), relative gain in abrasion, and abrasion index of the studied UHPCs were also obtained and discussed. Furthermore, a comparison was made on the resistance to wear of the selected UHPCs with those of the HSCs typically used for prestressed concrete sleepers. The outcomes of this study revealed that UHPCs displayed excellent resistance against abrasion, well above that of HSCs. Amongst the utilized cementitious material combinations, UHPCs made with silica fume as a partial replacement of cement performed best against abrasion, whereas mixtures containing fly ash showed the highest depth of wear. The addition of steel fibers had a more positive influence on the abrasion resistance than it did on compressive strength of the studied UHPCs.


2017 ◽  
Vol 898 ◽  
pp. 2076-2080 ◽  
Author(s):  
Xing Qi Huang ◽  
Xiao Rong Li ◽  
Da Wei Zhang ◽  
Chang Jun Xue ◽  
Ai Qin Zhang

Compared with the traditional water reducer, polycarboxylicwater-reducing agent exhibits the advantages of high water-reducing rate, cement paste fluidity and low slump loss, etc. The structure of polycarboxylates water reducing agent molecular is comb type. Water reducing agent can be used in the molecular design because it has high water reducing rate, low dosage, good slump stability, and have great potential in increase strength. In recent years, it has attracted many researchers' attention. Water reducing agent can block or destroy cement granular flocculation structure, through the surface function, complexation, electrostatic repulsion force and stereo repulsive force. Research on water reducing agent based on the application of poly carboxylic acid can realize functional design of water reducing agent, so as to promote the development of high-performance concrete.


2017 ◽  
Vol 7 (1.1) ◽  
pp. 71
Author(s):  
S. Sharmila ◽  
P. Chandrasekaran

High performance concrete essentially consists of the same ingredients as in conventional concrete but the proportions are designed to provide the strength and durability which are needed for the structural and environmental requirements of the structure. Fiber-reinforced concrete is a concrete containing ingredients of conventional concrete and fibres which increases its structural integrity. Fibers act as crack arrester which are primarily due to plastic shrinkage and drying shrinkage. They also reduce the permeability of concrete. The main aim of the present experimental investigation is to combine different fibres namely crimped stainless steel fibre and Aramid fibre to produce HFRC and thus to evaluate its mechanical performance. In Addition Micro silica and Quartz powder is added to obtain high performance. Based on I.S. Code method of mix design, proportion of different ingredients was obtained to get M60 grade concrete. Samples were prepared by varying the volume fraction of Steelfibre and aramid fibre from 0 to 1.5%. Three specimens of Cubes, Cylinders, and Prisms for each volume fraction of fibers are casted. Mechanical properties of each concrete composite were studied. The structural parameters such as load carrying capacity, ductility characteristics and energy absorption capacity of HPHFRC beams were assessed.


2020 ◽  
Vol 309 ◽  
pp. 26-30 ◽  
Author(s):  
Josef Fládr ◽  
Petr Bílý ◽  
Tomáš Trtík ◽  
Roman Chylík ◽  
Vladimír Hrbek

The paper compares macromechanical and micromechanical properties of high-performance concrete containing supplementary cementitious materials and basalt aggregate. The aggregate was either a common unprocessed crushed basalt aggregate or crushed basalt aggregate the coarse fractions (4/8 and 8/16 mm) of which were washed by water and dried before use. The observed macro-mechanical properties were compressive strength, tensile strength, elastic modulus and depth of penetration of water under pressure; the paper is focused on the first observed property, which is the basic material characteristic. On the microscale, the thickness of the interfacial transition zone (ITZ) was determined by nanoindentation. The positive influence of supplementary cementitious materials and aggregate washing on compressive strength was confirmed and the correlation between macromechanical and micromechanical characteristics was proved.


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