Effect of Mica Content in Stone Powder of Manufactured Sand on Performance of Cement Mortar

2014 ◽  
Vol 1044-1045 ◽  
pp. 624-628
Author(s):  
Jie Quan Xing ◽  
Shu Lin Zhan ◽  
Xin Yu Li
Keyword(s):  
Compressive Strength ◽  
Loss Rate ◽  
Cement Mortar ◽  
Mass Loss Rate ◽  
Strength Loss ◽  
Freezing Resistance ◽  
River Sand ◽  
Manufactured Sand ◽  
Freeze Thaw ◽  
Different Content

This paper studies the influence on compressive strength, freezing resistance and microstructure of cement mortar with different content of mica in stone powder, in the tests, manufactured sand with high content of mica and natural river sand were mixed with different proportion, and the content of stone powder was the same in mixed sand. Experiment results indicate that, with the increasing of mica content in stone powder, 28d and 60d compressive strength of cement mortar decreases obvious, mass loss rate and strength loss rate with 50 freeze-thaw cycles increase a little. Microstructure of cement mortar with higher content of mica is not compactly by SEM, the internal defects of cement hardened pastes could be increased because of the flake mica which surface is smooth, and it will cause the spread of micro crack.

scholarly journals Experimental Investigation on the Freeze–Thaw Resistance of Steel Fibers Reinforced Rubber Concrete

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1260
Author(s):  
Tao Luo ◽  
Chi Zhang ◽  
Chaowei Sun ◽  
Xinchao Zheng ◽  
Yanjun Ji ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Mass Loss ◽  
Loss Rate ◽  
Bending Strength ◽  
Mass Loss Rate ◽  
Steel Fibers ◽  
Freeze Thaw ◽  
Four Point Bending ◽  
Rubber Concrete

The reuse of rubber in concrete results in two major opposing effects: an enhancement in durability and a reduction in mechanical strength. In order to strengthen the mechanical properties of rubber concrete, steel fibers were added in this research. The compressive strength, the four-point bending strength, the mass loss rate, and the relative dynamic elastic modulus of steel fiber reinforced rubber concrete, subjected to cyclic freezing and thawing, were tested. The effects of the content of steel fibers on the freeze–thaw resistance are discussed. The microstructure damage was captured and analyzed by Industrial Computed Tomography (ICT) scanning. Results show that the addition of 2.0% steel fibers can increase the compressive strength of rubber concrete by 26.6% if there is no freeze–thaw effect, but the strengthening effect disappears when subjected to cyclic freeze–thaw. The enhancement of steel fibers on the four-point bending strength is effective under cyclic freeze–thaw. The effect of steel fibers is positive on the mass loss rate but negative on the relative dynamic elastic modulus.

scholarly journals Frost Resistance Test Research on Hybrid Fiber Concrete Based on Range Analysis

2015 ◽  
Vol 9 (1) ◽  
pp. 292-297 ◽  
Author(s):  
Liu Faming ◽  
Zhao Lisha ◽  
Ma Jie
Keyword(s):  
Compressive Strength ◽  
Frost Resistance ◽  
Loss Rate ◽  
Steel Fiber ◽  
Polypropylene Fiber ◽  
Strength Loss ◽  
Hybrid Fiber ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Fiber Concrete

The research of single doped fiber concrete is relatively mature. But the research about different varieties and different geometry shape of hybrid fiber concrete was very poor. Across the research in theory, hybrid fiber concrete can improve the balance of fiber three-dimensional distribution and coordinating role of aggregate and fiber, improve the efficiency of toughening crack resistance. In this paper, through the orthogonal experiment design method for hybrid fiber reinforced concrete, the mass and compressive strength loss rate after 50 times, 75 times, 100 times freeze-thaw cycle had been studied. Use range analysis quantified the influence level of various factors on the mechanical properties. It was analyzed the hybrid fiber influence on improving the efficiency of toughening crack resistance and frost resistance. It is concluded that adding the fiber can enhance the performance of concrete frost resistance. Long steel fiber have great influence on compressive strength loss rate of hybrid fiber concrete, such as the compressive strength loss rate was reached 65.47% after 75 times freeze-thaw cycle. Short steel fiber have certain influence on mass loss of concrete which were after less freeze-thaw cycles. The influence of polypropylene fiber on concrete frost resistance increases significantly, the effect can reach 36.78% after 50 times of freeze-thaw cycle. The optimal combination of the hybrid fiber concrete ultimately determined was A2B2C3 (simultaneously mixed with 50kg/m3 short steel fiber and long steel fiber as well as 0.9kg/m polypropylene fiber). The addition of steel fiber and polypropylene fiber are both beneficial to increase the internal air content of concrete, strengthening the frost resistance of concrete. However, with the increase of dosage, the internal porosity of concrete is gradually increasing, the density is reduced, and, as a result, the corresponding increase of the compressive strength loss rate is also improved.

Study on Freeze-Thaw Performance of Polypropylene Fiber Reinforced Cement-Stabilized Aggregate

2012 ◽  
Vol 446-449 ◽  
pp. 2595-2598 ◽  
Author(s):  
Yin Hua Ma ◽  
Jian Yi Gu
Keyword(s):  
Compressive Strength ◽  
Mass Loss ◽  
Fiber Length ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Polypropylene Fiber ◽  
Strength Increase ◽  
Freeze Thaw ◽  
Splitting Strength ◽  
Reinforced Cement

In this paper, the authors study the anti-freeze-thaw performance of a new type of semi-rigid base material named polypropylene fiber reinforced cement-stabilized aggregate, and freeze-thaw mass loss rate, freeze-thaw compressive strength, freeze-thaw splitting strength are used to evaluate the effect of polypropylene fiber on the anti-freeze-thaw performance, and the relationship of polypropylene fiber content, polypropylene fiber length with the anti-freeze-thaw performance are analyzed. The test after 10 freeze-thaw cycle shows that the mix of polypropylene fiber increase the freeze-thaw compressive strength and freeze-thaw splitting strength, and decrease the mass loss rate greatly. At the same time, the paper also determine the reasonable fiber content and fiber length, under this mix proportion, the mass loss rate reduce by 80%, the freeze-thaw compressive strength increase more than 12.1% and freeze-thaw splitting strength increase more than 13.4%. This research has laid an important foundation for the follow-up research and practice.

Experimental Study on Frost Resistance Properties of Pumice Mixed Aggregate Concrete

2012 ◽  
Vol 476-478 ◽  
pp. 1661-1664
Author(s):  
Jun Fang Huo ◽  
Jian Jun Chu ◽  
Hui Yang
Keyword(s):  
Elastic Modulus ◽  
Mass Loss ◽  
Frost Resistance ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Strength Loss ◽  
Dynamic Elastic Modulus ◽  
Aggregate Concrete ◽  
Freeze Thaw ◽  
Thaw Cycle

Different amount of pumice were used to replace gravel to make mixed aggregate concrete, the fast freeze-thaw cycle test were conducted and the influence of pumice rate substitution to the frost resistance properties of concrete were studied.The mass loss rate, strength loss and relative dynamic elastic modulus were regarded as the evaluation index of frost resistance properties of concrete. Results showed that the mass loss rate and strength loss rate gradually decreased and the relative dynamic elastic modulus gradually increased with the increase of pumice rate, the mass loss rate, strength loss rate and the relative dynamic elastic modulus gradually decreased with the increase of freeze-thaw cycles. Polypropylene fibers could reduce the strength loss rate, improved the relative dynamic elastic modulus, but had little effect to improve the mass loss. Through the frost resistance, the frost resistance of concrete improved with the increase of pumice content, at the same time, polypropylene fiber also could improve the frost resistance of concrete.

Preparation and Properties of Concrete Containing Iron Tailings/Manufactured Sand as Fine Aggregate

2013 ◽  
Vol 838-841 ◽  
pp. 152-155 ◽  
Author(s):  
Guo Dong Zhang ◽  
Xiu Zhi Zhang ◽  
Zong Hui Zhou ◽  
Xin Cheng
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Drying Shrinkage ◽  
Strength Loss ◽  
Fine Aggregate ◽  
River Sand ◽  
Manufactured Sand ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

High performance concrete was prepared by using iron tailings mixed with manufactured sand. Effects of the content of iron tailings on the performance of concrete were studied. The results show that the slump of concrete containing iron tailings is equal to concrete with river sand when the content of iron tailings is 60%. With the increase of the content of iron tailings, compressive strength of concrete shows a trend of decrease at same age; meanwhile drying shrinkage decreases and is less than the concrete prepared river sand. After 200 times of freeze-thaw cycle, mass loss of concrete with mixed sand is less than 5% and compressive strength loss is less than 25% which are close to concrete with river sand.

scholarly journals Performances of Cement Mortar Incorporating Superabsorbent Polymer (SAP) Using Different Dosing Methods

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1619 ◽  
Author(s):  
Yawen Tan ◽  
Huaxin Chen ◽  
Zhendi Wang ◽  
Cheng Xue ◽  
Rui He
Keyword(s):  
Compressive Strength ◽  
Cement Mortar ◽  
Tap Water ◽  
Mass Loss Rate ◽  
Drying Shrinkage ◽  
Superabsorbent Polymer ◽  
Water Desorption ◽  
Cement Ratio ◽  
Freeze Thaw ◽  
Water To Cement Ratio

Modified cement mortar was prepared by incorporating a superabsorbent polymer (SAP) with two kinds of dosing state, dry powdery SAP and swelled SAP (where the SAP has been pre-wetted in tap water), respectively. The mechanical properties, drying shrinkage and freeze–thaw resistance of the mortars were compared and analyzed with the variation of SAP content and entrained water-to-cement ratios. Additionally, the effect of SAP on the microstructure of mortar was characterized by scanning electron microscopy (SEM). The results indicate that agglomerative accumulation is formed in the voids of mortar after water desorption from SAP and there are abundant hydration products, most of which are C-S-H gels, around the SAP voids. The incorporation of the powdery SAP increases the 28 d compressive strength of the mortars by about 10% to 50%, while for the incorporation of swelled SAP, the 28 d compressive strength of the mortar can be increased by about −26% to 6%. At a dosage of 0.1% SAP and an entrained water–cement ratio of 0.06, the powdery SAP and the swelled SAP can reduce the mortar shrinkage rate by about 32.2% and 14.5%, respectively. Both the incorporation of powdery and swelled SAP has a positive effect on the freeze–thaw resistance of cement mortar. In particular, for powdery SAP with an entrained water-to-cement ratio of 0.06, the mass loss rate after 300 cycles is still lower than 5%.

Experimental Research on a New-Type Concrete Antifreeze

2011 ◽  
Vol 148-149 ◽  
pp. 1209-1213
Author(s):  
Bao Min Wang ◽  
Kai Song ◽  
Ni Tu
Keyword(s):  
Compressive Strength ◽  
Loss Rate ◽  
Performance Test ◽  
Setting Time ◽  
Strength Loss ◽  
Freeze Thaw ◽  
Performance Indexes ◽  
Thaw Cycle ◽  
Basic Performance ◽  
Freeze Thaw Cycle

Basic performance test was performed on a newly-developed compound antifreeze and experiment was carried out to study the basic performance, mechanical property and durability of the concrete mixtures containing 0%, 4% and 5% antifreeze. The result shows the antifreeze may be used for the concrete construction at 20°C below zero and it has favorable performance for winter construction. When the amount to be added is 4% and 5%, the ratio of compressive strength of 28 days shall be 105% and 107% respectively; the ratio of compressive strength of 56 days shall be 114% and 112% respectively. In freeze-thaw cycle experiment, 50 times of freeze-thaw strength loss rate is 45.3% and 44.8% of the strength loss rate of the concrete without the antifreeze. The water-reducing ratio of the antifreeze, ratio of bleeding rate, air content, difference in setting time, strength ratio, ratio of shrinkage, permeated height ratio and other performance indexes all satisfy specification requirements.

Study on the Mechanical Properties and Frost Resistance of Recycled Concrete Prepared by Village Construction Wastes

2011 ◽  
Vol 418-420 ◽  
pp. 406-410
Author(s):  
Jun Liu ◽  
Yao Li ◽  
Dan Dan Hong ◽  
Yu Liu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Frost Resistance ◽  
Cement Mortar ◽  
Strength Loss ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Replacement Rate ◽  
Concrete Mechanical Properties ◽  
Better Than

Abstract. Recycled aggregate—rural building material wastes pretreated by cement mortar—are applied into concrete with different replacement rates: 0, 25%, 50%, 75%, and 100%. Results from measurements of compressive strength, cleavage tensile strength, mass loss after fast freeze-thaw cycles, and compressive strength loss indicate that a different recycled aggregate replacement rate certainly influences concrete mechanical properties and frost resistance. Recycled aggregate replacement rates less than 75% performs better than common concrete. Data from the 100% replacement rate is worse than that of rates less than 75% but still satisfy the general demands of GB standard on C30 concrete.

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