Study on the Sulfate Erosion Behavior of Cement-based Materials with Different Water-to-binder Ratios Containing Stone Powder in a Low-Temperature Saline Soil Area

Bentian Yu,Haoqi Zhou,Junying Xia,Xiaolin Liu,Chao Xie,Kai Zhang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.9

To research the performance of low-temperature sulfate corrosion resistance of concrete mixed with stone-powder in saline soil area of Qinghai-Tibet Plateau. In this work, the influence of the water-to-binder ratio and stone powder types on the low-temperature sulfate erosion behavior of cement-based materials was studied, and in order to predict its erosion life, a Wiener stochastic process model was established. The results show the following: 1) The samples of limestone powder cement-based materials (LCBM) with different water-to-binder ratios showed the same law in sulfate erosion; the greater the water-to-binder ratio is, the more serious the sample is eroded, and the difference is the rate of erosion reaction. The greater the water-to-binder ratio is, the earlier the characteristic peak of thaumasite appears. The electric pulse accelerated erosion lifetimes of the cement-based limestone powder with water binder ratios of 0.3, 0.4 and 0.5 were 185 days, 136 days and 110 days, respectively. 2) Quartz stone powder cement-based materials (QCBM) showed different erosion laws compared with LCBM. When soaked in sulfate, the macroscopic and microscopic changes of QCBM were basically in a mineral additives state, However, when the electric pulse accelerated the erosion, the QCBM was more severely attacked than the LCBM. The final erosion products of the cement-based limestone powder with water binder ratios of 0.4 are not only gypsum and ettringite but also thaumasite, while the quartz powder cement-based materials with water-binder ratios of 0.4 are only gypsum and ettringite.

물-결합재 비와 잔골재-결합재 비에 따른 알칼리 활성화 슬래그 모르타르의 기초특성

김태완,함형길,이성행,엄장섭 한국구조물진단유지관리공학회 2013 한국구조물진단유지관리공학회 논문집 Vol.17 No.5

This study investigates the fundamental properties of the water-binder (W/B) ratio and fine aggregate-binder (F/B) ratio in the alkali-activated slag cement (AASC) mortar. The W/B ratios are 0.35, 0.40, 0.45, and 0.50, respectively. And then the F/B ratios varied between 1.00 and 3.00 at a constant increment of 0.25. The alkali activator was an 2M and 4M NaOH. The measured mechanical properties were compared, flow, compressive strength, absorption, ultra sonic velocity, and dry shrinkage. The flow, compressive strength, absorption, ultra sonic velocity and dry shrinkage decreased with increases W/B ratio. The compressive strength decreases with increase F/B ratio at same W/B ratio. Also, at certain value of F/B ratio significant increase in strength is observed. And S2 (river sand 2) had lower physical properties than S1 (river sand 1) due to the fineness modulus. The results of experiments indicated that the mechanical properties of AASC depended on the W/B ratio and F/B ratio. The optimum range for W/B ratios and F/B ratios of AASC is suggested that the F/B ratios by 1.75~2.50 at each W/B ratios. Moreover, the W/(B+F) ratios between 0.13 and 0.14 had a beneficial effect on the design of AASC mortar.

Influences of superabsorbent polymers on the strength and shrinkage properties of low water-to-binder ratio expansive concrete

Rongfeng Lin,Lufeng Pang 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.3

Low water-to-binder ratio (W/B) is the main method to obtain the excellent mechanical properties of high performanceconcrete, which is also the main factor causing its shrinkage. Expansive agent is often used to reduce or even eliminateshrinkage. But the expansion effect isn’t obvious in the middle and later stage because of water shortage. Internal curing hasbeen considered to be a very effective way to maintain the relative humidity of the interior. This paper studied the influenceof SAP and additional water diversion on the strength and the limit expansion ratio of the expansive concrete with low W/B. SAP could reduce the shrinkage of 0.62 μm/m ~1.91 μm/m, and the compressive strength was further influenced. Inmicroscopic analysis, SAP was confirmed to promote the hydration degree of cement and expansive agent, especially in themiddle and later stages of hydration; the hydration products and the expansion products AFt intergrowth, the structure wasmore compact. Considering the influence of SAP on its expansion and mechanical properties, the reasonable amount of SAPwas recommended as 0.2 %, and the reasonable water flow was 10~20 times.

Effects of Silica Fume Content and Polymer-Binder Ratio on Properties of Ultrarapid-Hardening Polymer-Modified Mortars

Jong Yun Choi,Myung-Ki Joo,Byeong Cheol Lho 한국콘크리트학회 2016 International Journal of Concrete Structures and M Vol.10 No.2

This paper deals with the effects of silica fume content and polymer-binder ratio on the properties of ultrarapidhardening polymer-modified mortar using silica fume and ethylene-vinyl acetate redispersible polymer powder instead of styrenebutadiene rubber latex to shorten the hardening time. The ultrarapid-hardening polymer-modified mortar was prepared with various silica fume contents and polymer-binder ratios, and tested flexural strength, compressive strength, water absorption, carbonation depth and chloride ion penetration depth. As results, the flexural, compressive and adhesion strengths of the ultrarapid-hardening polymer-modified mortar tended to increase as increasing polymer-binder ratio, and reached the maximums at 4 % of silica fume content. The water absorption, carbonation and chloride ion penetration resistance were improved according to silica fume content and polymer-binder ratio.

Effects of Silica Fume Content and Polymer-Binder Ratio on Properties of Ultrarapid-Hardening Polymer-Modified Mortars

Choi, Jong Yun,Joo, Myung-Ki,Lho, Byeong Cheol Korea Concrete Institute 2016 International Journal of Concrete Structures and M Vol.10 No.2

This paper deals with the effects of silica fume content and polymer-binder ratio on the properties of ultrarapid-hardening polymer-modified mortar using silica fume and ethylene-vinyl acetate redispersible polymer powder instead of styrene-butadiene rubber latex to shorten the hardening time. The ultrarapid-hardening polymer-modified mortar was prepared with various silica fume contents and polymer-binder ratios, and tested flexural strength, compressive strength, water absorption, carbonation depth and chloride ion penetration depth. As results, the flexural, compressive and adhesion strengths of the ultrarapid-hardening polymer-modified mortar tended to increase as increasing polymer-binder ratio, and reached the maximums at 4 % of silica fume content. The water absorption, carbonation and chloride ion penetration resistance were improved according to silica fume content and polymer-binder ratio.

Tests on magnesium potassium phosphate composite mortars with different water-to-binder ratios and molar ratios of magnesium-to-phosphate

Lee, Kyung-Ho,Yoon, Hyun-Sub,Yang, Keun-Hyeok Elsevier 2017 Construction & building materials Vol.146 No.-

<P><B>Abstract</B></P> <P>The objective of the present study is to examine the effect of the water-to-binder ratio (<I>W/B</I>) and the molar ratio (<I>M<SUB>mp</SUB> </I>) of magnesium-to-phosphate on the fluid characteristics, compressive strength development, and pH variation of magnesium potassium phosphate composite (MKPC) mortars. A total of 25 mortar mixes were prepared, with the <I>W/B</I> varying from 20% to 40% and <I>M<SUB>mp</SUB> </I> varying from 3.4 to 30.4. Using the present test data, the compressive strength development of MKPC mortars was empirically formulated, which reflects rapid strength gain. Considering practical qualifications, including a relatively good 28-day compressive strength above 30MPa, delayed setting time, and a near-neutral pH not exceeding 9.4, it can be recommended that the <I>M<SUB>mp</SUB> </I> and <I>W/B</I> be chosen to be below 5.1 and above 25%, respectively, in the MKPC system. With a decrease in the <I>M<SUB>mp</SUB> </I> value, the peak intensities for struvite-k increased slightly, whereas the peak intensities for unreacted MgO were considerably weakened as the <I>M<SUB>mp</SUB> </I> value fell below 5.1. The total porosity of the MKPC pastes was governed by the macro-capillary pores, implying that the 28-day compressive strength is inversely proportional to the macro-capillaries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We provide lots of test data for magnesium potassium phosphate composites (MKPC). </LI> <LI> We found that the molar ratio of MgO-KH<SUB>2</SUB>PO<SUB>4</SUB> for the highest strength depends on <I>W/B</I>. </LI> <LI> For practical application of MKPC, adequate molar ratio and <I>W/B</I> are recommended. </LI> <LI> Compressive strength development of MKPC mortars is formulated. </LI> </UL> </P>

Effects of Silica Fume Content and Polymer-Binder Ratio on Properties of Ultrarapid-Hardening Polymer-Modified Mortars

최종윤,주명기,노병철 한국콘크리트학회 2016 International Journal of Concrete Structures and M Vol.10 No.2

This paper deals with the effects of silica fume content and polymer-binder ratio on the properties of ultrarapidhardeningpolymer-modified mortar using silica fume and ethylene-vinyl acetate redispersible polymer powder instead of styrenebutadienerubber latex to shorten the hardening time. The ultrarapid-hardening polymer-modified mortar was prepared with varioussilica fume contents and polymer-binder ratios, and tested flexural strength, compressive strength, water absorption, carbonationdepth and chloride ion penetration depth. As results, the flexural, compressive and adhesion strengths of the ultrarapid-hardeningpolymer-modified mortar tended to increase as increasing polymer-binder ratio, and reached the maximums at 4 % of silica fumecontent. The water absorption, carbonation and chloride ion penetration resistance were improved according to silica fume contentand polymer-binder ratio.

초고강도 콘크리트의 건조수축에 관한 연구

임서형,강현식 진주산업대학교 2001 산업과학기술연구소보 Vol.- No.8

The purpose of this study is to investigate drying shrinkage of the ultra high strength concrete using silica fume. For this purpose, the properties of concrete are examined with varing water/binder ratio, binder content, sand/aggregate ratio. As a rusult of this study, shrinkage is larger the higher wate/binder ratio because the latter determines the amount of evaporable water in the cement paste and the rate at which water can move towards the surface of the specimen. At a constant water/binder ratio, shrinkage increases with an increase in the sand/aggregate ratio. And the rate of shrinkage occurs rapidly at an earlier age.

공동주택 바닥용 건조모르타르의 물-결합재비에 따른 유동성 및 압축강도 변화 특성 연구

박지선 사단법인 한국융합기술연구학회 2023 아시아태평양융합연구교류논문지 Vol.9 No.12

설계보다 높은 물-결합재비로 인하여 바닥마감 모르타르의 강도가 낮아지고 균열 발생율이 높아진다면 궁극적으로 바닥 충격음 차단 성능의 저하로 연결되어 건조모르타르의 사용성에 대한 문제로 귀결될 수 있다. 따라서 이러한 균열 발생이 없이 밀실한 구조를 가질 수 있는 건조모르타르 제품에 대한 설계와 현장관리가 필요하다. 이를 위해서는 제조단계와 현장 관리단계에서의 품질관리 규정을 동일하게 하는 것이 가장 바람직하며, 만약 동일한 관리가 어려울 경우에는 현장 시공시 적용하는 물-결합재비가 어느 정도의 강도를 발현할 수 있는지에 대한 예측과 이를 통한 품질관리가 수반되어야 한다. 따라서 이 연구에서는 공동주택 바닥에 사용되는 건조모르타르의 물-결합재비 및 시험방법의 차이에 따른 물리적 특성 변화를 비교 측정하여 현장에서 활용할 수 있는 물-결합재비별 압축강도의 상관값을 도출하고자 하였다. 국내 현장에서 널리 사용되고 있는 2종의 프리믹스형 바닥용 건조모르타를 대상으로 현장시공성, 흐름성, 압축강도를 측정하였다. 측정 결과로부터 공동주택 바닥의 안정적인 품질확보를 위해서는 동일한 물-결합재비에서 고유동성 확보가 필요함을 확인할 수 있었다. Due to a higher water-cementitious ratio than designed, the strength of the floor finishing mortar decreases, and the crack occurrence rate increases. Ultimately, this can lead to a deterioration in the soundproofing performance of the floor, resulting in usability issues with dry mortar. Therefore, design and on-site management of dry mortar products that can have a crack-free structure are necessary. To achieve this, it is most desirable to have consistent quality control regulations in both the manufacturing and on-site management stages. If achieving the same level of control is difficult, predictive measures of the strength that can be achieved with the applied water-cementitious ratio during on-site construction and quality control based on this prediction should be implemented. Hence, this study aims to compare and measure the changes in physical properties of dry mortar used for residential floorings according to differences in water-cementitious ratios and testing methods to derive correlation values of compressive strength for different water-cementitious ratios that can be utilized in the field. Two types of premixed dry mortars widely used in domestic construction were tested for on-site workability, flowability, and compressive strength. From the results, it was confirmed that ensuring consistent workability at the same water-cementitious ratio is essential for securing stable quality in residential floorings.

Lightweight Self-consolidating Concrete with Expanded Shale Aggregates

Abdurrahmaan Lotfy,Khandaker M. A. Hossain,Mohamed Lachemi 한국콘크리트학회 2015 International Journal of Concrete Structures and M Vol.9 No.2

This paper presents statistical models developed to study the influence of key mix design parameters on the properties of lightweight self-consolidating concrete (LWSCC) with expanded shale (ESH) aggregates. Twenty LWSCC mixtures are designed and tested, where responses (properties) are evaluated to analyze influence of mix design parameters and develop the models. Such responses included slump flow diameter, V-funnel flow time, J-ring flow diameter, J-ring height difference, L-box ratio, filling capacity, sieve segregation, unit weight and compressive strength. The developed models are valid for mixes with 0.30?0.40 water-to-binder ratio, high range water reducing admixture of 0.3?1.2 % (by total content of binder) and total binder content of 410?550 kg/㎥. The models are able to identify the influential mix design parameters and their interactions which can be useful to reduce the test protocol needed for proportioning of LWSCCs. Three industrial class ESH?LWSCC mixtures are developed using statistical models and their performance is validated through test results with good agreement. The developed ESH?LWSCC mixtures are able to satisfy the European EFNARC criteria for self-consolidating concrete.