Long Term Behavior of Ultra High-Performance Concrete

Ultra-High-Performance Concrete (UHPC) is one of the important types of concrete technology breakthroughs in the 21st century. It achieved high results of mechanical properties, durability (resistance fire) and bonding strength. The aim of paper is to evaluate the long-time behavior of UHPC. The main variables were finesse modulus of sand, crushed quartz powder, fly ash and metakaolin and methods of curing (water& hot).The sand with different fineness modulus(3.2, 2.36 and 1.9) were used, Crushed quartz powder with ratio (10%, 20% and 30%) as a replacement of sand was used. Fly ash and metakaolin, with of (10%, 20%, 30 and 40%) and (5%, 10% and 15%) as a replacement of cement; respectively. The effect of these variables on the mechanical properties (compressive, tensile, flexural strength) at different ages. Also, the drying shrinkage strain was evaluated. The results showed that using and with fineness modulus (1.9), 20% ratio of crushed quartz powder to fine sand (CQ/S), 20% of fly ash to cement (FA/C) and 5% of metakaolin to cement (MK/C) give the best proportions of UHPC. The compressive strength for this mix was 900 kg/ cm2 .

Critical Evaluation for Grading and Fineness Modulus of Concrete Sands used in Sulaymaniyah City-Iraq

Fine aggregates used for concrete works in Sulaymaniyah city frequently fail to meet the standard requirements for gradation and fineness modulus in cement concrete. This paper aims to critically evaluate gradation, fineness modulus, and clay contents of various natural sands produced and used for concrete work in the region. Sixteen field sand samples were collected from various sites in Darbandikhan (5 samples), Qalat Dizah (5 samples), Koysinjaq (5 samples), and Piramagroon (1 sample) confirming to ASTM D75. The field samples were parted into test specimens based on ASTM C702. Then, sieve analysis was carried out on the oven-dry test specimens in compliance with ASTM C136. The test results of fine aggregates were compared with American, British, and Iraqi specification standards using ASTM C33, BS 882, and IQS No. 45. It was revealed that only three sands satisfy the ASTM gradation limits while others do not comply and are on the coarser side. Also, eight samples meet the requirements recommended by BS 882, whereas five samples meet limits by IQS No. 45. It was found that only three sands have the fineness modulus within the ranges recommended by ACI 211.1 and ACI 211.4, while the others have high values. Furthermore, it was found that all sands include an allowable amount of finer particles passing sieve size 0.075 mm. In order to improve particle size distributions, it is recommended to use the blending method to obtain a suitable fine aggregate from two or more failed sands.

Effect of Fine Aggregate Particle Characteristics on Mechanical Properties of Fly Ash-Based Geopolymer Mortar

This research aimed to investigate the effect of fine aggregate particles on mechanical properties of fly ash-based geopolymer mortar. In this work, seven kinds of river sand particles were designed based on different fine aggregate characteristics. The fineness modulus was adopted to quantitatively describe the gradation of sands. The fluidity, compressive, flexural, and tensile strengths of geopolymer mortar with different sand gradations were analyzed by laboratory tests. Furthermore, the composition and morphology of fly ash-based geopolymer mortar was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The reasonable gradation range and filling effect of sand were obtained. The results show that fluidity and compressive and flexural strengths of geopolymer mortar both improve with the increase of the fineness modulus, while specific surface area and voidage are opposite. The tensile strength of mortar largely lies on the interface properties between the geopolymer binder and fine aggregates. When the pass rate of the key sieving size 1.18 mm is 75–95%, the pass rate of the key sieving size 0.15 mm is 15–25%, the fineness modulus is 2.2–2.6 and the appropriate filling coefficient of geopolymer paste is around 1.0–1.15, the comprehensive performance of geopolymer mortar is the best. This research paper could provide a basis for the design of geopolymer mortar based on fly ash, and it is of great significance for its popularization and application.

Research on the influence of manufactured sand gradation on concrete performance

Based on experiments of C30 concrete with manufactured sand, this paper studied on the workability and compressive strength of the manufactured sand concrete with 7 different fineness modulus and different weight fractions (0%, 2%, 4%, 6%, 8%, 10%) of stone powder. The results show that the fineness modulus and the stone powder content in the gradation parameters of manufactured sand have great effects on the concrete performance. When the fineness modulus of manufactured sand is about 2.8, the workability and compressive strength of concrete can be improved. As the content of stone powder increases, the workability and compressive strength of concrete firstly increase and then decrease, and the optimal weight fraction of stone powder is about 6%. The research results can provide reference for the production and application of gneiss manufactured sand.

Effects of waste ceramic aggregate on compressive strength of cement mortar

In Bangladesh, the cost of building materials is increasing gradually, available raw materials of construction are not sufficient to meet up the needs of the country. For that we have to find out cheaper and waste materials (such as ceramic waste) to reuse for construction. The study was conducted to observe the physical properties of waste ceramics and compressive strength of ceramics mortar for different curing ages. The study was done to check the probability of using waste ceramics instead of natural aggregates (sand).The fineness modulus of ceramics aggregates was 2.94. Ceramic aggregate absorbs 5.89% moisture whereas sand absorbs 14.33%. Generally, finer the aggregate shows greater the compressive strength. Though the fineness modulus of ceramics was greater than that of sand, it possessed higher compressive strength because of its self-strength. The ratio of mortar mixture was (1:2) and (1:3) for different curing periods both sand and ceramics samples. The compressive strength of sand and ceramic mortar was 2603 psi and 3500 psi respectively at the ratio of (1:2) for 3 days curing. On the other hand the compressive strength of sand and ceramics mortar was 2340 psi and 3075 psi respectively at the ratio of (1:3) for 3 days curing. Between the sand and ceramic mortar, the compressive strength of ceramic mortar was found maximum at 28 days curing period. It can be concluded that recycled ceramic aggregates will be used in comparatively low load bearing, low cost temporary and medium category farming etc. concrete structure. Progressive Agriculture 30 (3): 311-316, 2019

Modifikasi Cara Penentuan Kandungan Pasir pada Perancangan Campuran Beton Cara SNI dengan Metode Dreux Gorrise. (Hal. 21-32)

ABSTRAK Pencampuran beton cara SNI menunjukkan bahwa kuat tekan hanya dipengaruhi oleh faktor air-semen, sedangkan jika dievaluasi dengan metode Dreux Gorisse diduga akan menghasilkan kuat tekan yang berbeda karena kuat tekan juga dipengaruhi oleh volume pasir. Modifikasi sedemikian rupa pada penentuan pasir dalam agregat gabungan pada cara SNI agar tidak mempengaruhi kuat tekan beton yang akan dihasilkan, dilakukan dengan cara Dreux Gorisse. Pengujian yang dilakukan menggunakan agregat maksimum 10 mm dan 20 mm, slump rencana 30-60 mm dan 60-180 mm. Modulus kehalusan pasir yang ditinjau adalah 1,5; 2,0; 2,5; 3,0; dan 3,5. Hasil pengujian modifikasi menggunakan agregat maksimum 10 mm dengan slump 30-60 mm dan slump 60-180 mm pada modulus kehalusan pasir 1,5; 2,0; dan 2,5 membuktikan kuat tekan beton tidak dipengaruhi oleh kadar volume pasir. Pada pengujian modifikasi menggunakan agregat maksimum 20 mm dengan slump 30-60 mm dan slump 60-180 mm pada modulus kehalusan pasir 1,5; 2,0; dan 2,5 membuktikan juga bahwa kuat tekan beton tidak dipengaruhi oleh kadar volume pasir. Kata kunci: modulus kehalusan pasir, volume pasir, SNI, kuat tekan ABSTRACT Concrete mixing with the SNI method shows that compressive strength is only influenced by water-cement factors, whereas if evaluated by the Dreux Gorisse method it is assumed that the compressive strength value will be different because the compressive strength is also influenced by the volume of sand. Modifications are made in such a way as to the determination of sand in the combined aggregate on the SNI method so as not to affect the compressive strength of the concrete to be produced by Dreux Gorisse. Tests carried out using a maximum aggregate of 10 mm and 20 mm, slump plans are used 30-60 mm and 60-180 mm. The modulus of sand smoothness reviewed was 1.5, 2.0, 2.5, 3.0 and 3.5. The modified test results using a maximum aggregate of 10 mm with 30-60 mm slump and 60-180 mm slump on sand fineness modulus 1,5, 2,0, and 2,5 prove that the compressive strength of the concrete is not affected by the sand volume level. In testing the modification using a maximum aggregate of 20 mm with 30-60 mm slump and 60-180 mm slump on sand smoothness modulus of 1.5, 2.0, and 2.5 also prove that the compressive strength of the concrete is not affected by the volume level of the sand. Keywords: sand fineness modulus, sand volume, SNI, compressive strength