Papers by Keyword: Admixture

Abstract: The paper is focused on the mechanical fracture properties of hardened cement mortars in which Portland cement is partially replaced by reactive admixtures. These properties are evaluated in relation to the mortars’ microstructure through the size and content of pores. The cement in the mortars was partially replaced by a diatomite that contains amorphous SiO₂. The three-point bending fracture tests were performed on beams with a central edge notch. The investigated mechanical fracture properties of the aforementioned cement-based composites included flexural strength, compressive strength, elasticity modulus, effective fracture toughness and specific fracture energy.

Abstract: The objective of this paper is to examine the solidification possibilities of selected waste in form of industrial waste sludge, within the paper solidification formulas are designed which are subsequently laboratory tested by compressive strength tests after 28 and 60 days, leachability tests and other tests considering environmental impacts – ecotoxicological tests.

Abstract: In order to reveal the effect of admixture type and quantity on the strength of stabilized soil, a series of indoor test is done on the stabilized soil by means of unconfined compressive strength test. The raw material soil used in the experiment is sludge soil, and cement, triethanolamine, caustic soda are used as admixture. A lot of solidified samples are prepared according to test scheme in different admixture’s proportion. From the test results, it can be seen that different admixture and it’s quantity affect the strength of stabilized soil by analyzing the sample’s unconfined compressive strength test results.

Abstract: In order to reveal the effect of type of admixture and its content on the strength of stabilized soil, this paper uses the sludge as raw soil and cement, fly ash as curing agent, and analyzes the strength characteristics of samples mixed stabilized according to certain content. Using the unconfined compressive strength test, the compressive strength of the samples is tested. The effect of curing agent type and its content on the compressive strength is investigated. From the experimental results, it can be seen that the content of cement and fly ash has much effect on the strength. The conclusions obtained can have some conference values on the foundation treatment and reuse of waste resources utilization.

Abstract: The article presents the influence of the addition of microsilica, finely divided sodium bentonite and air-entraining admixture for concrete frost-resistance and characteristics of examined concrete pores. Examination of frost-resistance was conducted for 150 cycles of freezing and thawing. For selected series of concrete the examination of the porosity structure of concrete composites was conducted with the use of a device for automatic image analysis and computer program Lucia Concrete. What is more, there was made a designation of: consistency of concrete mix, air content in concrete mix, compression strength, water penetration depth and concrete absorbability.

Abstract: The fluorine gypsum was used as research object in this paper. In order to recognize the basic properties of fluorine gypsum fully, the physical and chemical properties were analyzed through different testing means. The chemical modification (additive A, sodium sulfate, quick lime) on the activity of fluorine gypsum excitation effect were studied. The best way to compound modification was determined and the mechanism of the admixture was analyzed. On this basis, the fluorine gypsum base self-leveling mortar materials was prepared and its performances were tested. Research shows that, the optimal ratio of: additive A content 2.0% (mixed), sodium sulfate content 0.8%, quick lime content 1.5%, the fluorine gypsum self-leveling material initial setting time is 2.4h, the final setting time is 5.3h, 24h flexural strength of 2.60MPa, compressive strength of 6.05MPa, the dry flexural strength of 7.68MPa, compressive strength of 22.89MPa, the performance indicators have reached the JC/T1023-2007《Gypsum based self-leveling mortar》 requirements.

Abstract: In this paper, a new method is proposed to measure the early shrinkage of airport pavement concrete material. Also, the effect of fly ash with different grades and dosage on early shrinkage and late shrinkage deformation of commercial concrete were studied. The effect of fly ash with different grades and dosage on volume stability of commercial concrete was assessed by using the test method of shrinkage cracking, and the causes and mechanism of the effect were analyzed.

Abstract: At present, our country norms on the permeability of concrete is mainly determined by its strength, without considering the influence of admixtures on the permeability. This paper studies the permeability of different strength concrete rules of different kinds and dosage of admixture. The results show that, the permeability of concrete is closely related to the w/b, but also it has a strong correlation with admixture dosage, the relevance between the permeability of concrete and the kinds of admixture is relatively small. The results of this paper can provide some reference value to the relevant standards of durability in our country.

Abstract: Natural zeolite is one of the raw materials whose application can reduce the content of cement in concrete. The reasons for the constant reduction of the amount of cement are not only its economical demands but also a strain on the environment. The paper describes basic characteristics of concretes with increasing substitution of cement with zeolite. The designed concretes with natural zeolite are being compared with a reference concrete without zeolite.

Abstract: The article discusses the physical mechanical concrete properties of five different concrete recipes. The objective of the composition of the concrete is to use the lowest quantity of Portland cement by adding additives (fly ash, slag and limestone) and the various combinations.