Mineral Addition and Mixing Methods Effect on Recycled Aggregate Concrete

This paper presents influence of treatment and mixing methods on recycled aggregate concretes (RAC) designed regarding various techniques. Absolute Volume Method (AVM) according to TS 802, Equivalent Mortar Volume Method (EMV), silica fume (SF) as a mineral addition were considered in the design of concretes. In total, four groups of concretes were produced in the laboratory: (1) natural aggregate concrete (NAC) designed with AVM as control concrete, (2) RAC designed with AVM as control RAC, (3) RAC with SF as a mineral addition designed with AVM as treated RAC and (4) RAC designed with EMV as treated RAC. The tests were performed at 28th days and the statistical analysis were made on the test results. According to the results, EMV and SF increased the compressive strength of concretes and this resulted an increase in the strength class of concrete. A significant statistical difference between the concretes were determined. According to multiple comparison analysis, it was found that especially there was a significant relationship among NAC, RAC and RAC-EMV. In addition, it was recommended that EMV and AVM with 5% SF could be used in the design of RAC rather than AVM only to achieve the target strength class C30/37.

Comparison of Degradation of Concretes with High Portions of Mineral Additions and Ordinary Portland Cement Based Concretes due to Simulated Acidic Rain

The paper deals with investigation of changes in selected properties of concretes which have been exposed to acid rain. The experiments took place in laboratory under model solution representing acid rain (40 % HNO3, 60% H2SO4) over a period of 7 weeks. The concrete samples investigated were concretes with ordinary Portland cement only as well as concretes of high-portion-mineral-addition-cements as well. Disruptions, cracking and samples' falling apart at the end after 7-week exposure to acid rain were observed by evaluation of visual changes. Based on the determination of the other parameters the results are not so uniform that is why the clear statement of more suitable concrete resistant to acid rain is not given. The assumption that a high-mineral concrete mix would be more suitable for environments exposed to acidic rain was not confirmed in this experiment.

PENGARUH BIODELIGNIFIKASI DAUN SAWIT MENGGUNAKAN KAPANG Phanerochaete Chrysosporium YANG DISUPLEMENTASI DENGAN MINERAL CA TERHADAP KARAKTERISTIK CAIRAN RUMEN SECARA In Vitro

The aims of this research to see the effect of biodelignification of palm leaves using Phanerochaete chrysosporium againts total VFA, NH3 and pH. This study used factorial randomized block design (4x3) with 3 replications. Factor A is a dose of mineral addition in which A0 = 0 ppm Ca mineral, A1 = 1000 ppm Ca mineral, A3 = 1500 ppm Ca mineral, and A4 = 2000 ppm Ca mineral. Factor Y is the time of fermentation Y1 = 10 days, Y2 = 15 days, and Y3 = 20 days. Fermentation of palm leaves using Phanerochaete chrysosporium at a dose of Ca 2000 ppm mineral with a fermentation time of 10 days showed a total of 121.25 mM VFA more than any other treatment, and the amount of NH3 produced 14.80 mg / 100 ml of rumen fluid, and pH ranges from 6.79 to 6.86. The resulting pH is still in a condition where rumen microbes can grow optimally.Keywords: Biodelignification, Phanerochaete chrysosporium, NH3, pH, Volatille Fatty Acid (VFA)

ВЛИЯНИЕ ЦЕМЕНТА С МИНЕРАЛЬНЫМИ ДОБАВКАМИ ИЗ МОЛОТОГО ПРИРОДНОГО ПЕСКА И ГРАНИТНОГО ОТСЕВА НА СВОЙСТВА ТЯЖЕЛОГО БЕТОНА

В материале статьи приведены результаты экспериментальной оценки физико-механических свойств тяжелого конструкционного бетона, полученные в сравнительном варианте: при его приготовлении на чистоклинкерном (бездобавочном) вяжущем, а также с использованием песчанистого цемента, содержащего 20 молотого природного кварцевого песка, и цемента с 20 -ой минеральной добавкой из гранитного отсева, при соблюдении правила прочих равных условий . Бетон во всех случаях готовили на вяжущем марки М500 (класс по прочности 42,5 ) исследования осуществили по стандартизированным методикам (оценка прочности, усадки, морозостойкости и др.) и нестандартизированнным при определении упруго-деформативных характеристик бетона. В результате экспериментов установлено, что бетон на песчанистом цементе характеризуется ростом деформаций усадки на 70 и повышенной предрасположенностью к трещинообразованию, что приводит к снижению прочности на сжатие до 10 , на растяжение при изгибе до 27 , к снижению водонепроницаемости и морозостойкости на 12 марки и упруго-деформативных свойств по сравнению с бетоном на цементе с добавкой гранитного отсева, а кроме этого, им не обеспечивается защитная способность по отношению к стальной арматуре. Причиной является переизмельчение его клинкерной части при совместном помоле клинкера с песком, что вызывает рост водопотребности, изменения в механизме гидратации цемента и сопровождается повышенной усадкой и трещинообразованием в цементном камне и бетоне. На этом основании сделан вывод о необходимости и рациональности замены природного песка на гранитный отсев в производстве вяжущего с минеральной добавкой белорусскими производителями цемента. С учетом изложенного экспериментально обосновано рациональное содержание добавки из гранитного отсева в цементе (в количестве до 20 его массы) и исследовано ее влияние на технологические свойства бетонных смесей (увеличивается на 2550 время сохранения формуемости, снижается водоотделение до 1015 и раствороотделение до 1020 ), а также на прочностные, упруго-деформативные и эксплуатационные свойства бетона, что позволило обосновать вывод о возможности использования полученного цемента для конструкционного бетона классов С12/15С32/40 общестроительного назначения без ограничений, включая изделия (конструкции) с преднапрягаемой арматурой.The article presents the results of an experimental evaluation of the physicomechanical properties of heavy structural concrete, obtained in a comparative version: when manufactured on a pure linker (additive-free) binder, as well as using sandy cement containing 20 ground natural quartz sand, and cement with mineral addition (in the amount of 20) from granite screening and observance of the other equal conditions rule. Concrete in all cases made on the binder brand M500 (strength class 42.5) studies were carried out according to standardized methods (strength, shrinkage, frost resistance, etc.) and non-standardized in determining the elastic-deformative characteristics of concrete. As a result of the experiments, the following was established. Concrete on sandy cement (due to overgrinding of its clinker part, which causes an increase in water demand, changes in the hydration mechanism and is accompanied by increased shrinkage) is characterized by an increase in shrinkage deformations by 70 and an increased susceptibility to cracking, which leads to a decrease in compressive strength up to 10, tensile bending up to 27, elastic-defformative properties, as well as reduction of water resistance and frost resistance - by 1 ... 2 marks in comparison with concrete on cement with the addition of granite sifting, and does not provide protective ability in relation to steel reinforcement.Taking into account the above, a rational content of an additive from granite sifting in cement in an amount of up to 20 of its mass and its influence on the technological properties of concrete mixtures (an increase of (25 ... 50) of the time to maintain moldability, reduction of water separation to (10 ... 15) and dissolution to (10 ... 20) ), as well as the strength, elastic-deformative and operational properties of concrete, which made it possible to substantiate the conclusion that the obtained cement can be used for structural concrete of classes C12 / 15 ... C32 / 40 of general construction Nogo destination without limitation, including articles (structures) with prestressing reinforcement.