Strength and Microstructural Study of Lightweight Aggregate Concrete (LWAC) Using Lightweight Expended Clay Aggregates (LECA)

2020 ◽  
Vol 1010 ◽  
pp. 678-683
Author(s):  
Khairul Nizar Ismail ◽  
Fatihah Halim
Keyword(s):  
Lightweight Aggregate ◽  
Interfacial Transition Zone ◽  
Lightweight Aggregate Concrete ◽  
Small Scale ◽  
Strength Development ◽  
Aggregate Concrete ◽  
Microstructural Study ◽  
Digital Microscope ◽  
Crushed Aggregate ◽  
Clay Aggregates

Concrete is a composite material that consists of a cement and aggregate particles. Microstructure is the small scale structure of a material, defined as the structure of a prepared surface of material as revealed by a microscope. There is strong evidence that aggregate type is a factor in the strength of concrete. The objective of this research is to investigate the properties of concrete that are containing the lightweight expanded clay aggregates (LECA). Digital microscope was used to analyses the formation mechanism of microstructure in concrete. LECA were used in production of lightweight aggregate concrete (LWAC) with the size 50 mm x 50 mm x 50 mm. This paper deals with observation of the concrete microstructure to point out some differences that would be responsible for strength of concrete. The results show that, LECA has several improvements when compared with conventional crushed aggregate. The concrete specimens were used to validate the existence of an interfacial transition zone (ITZ) in concrete. The microstructure features are discussed with respect to their influence on the strength development of concrete.

scholarly journals Influencing Factors on the Interface Microhardness of Lightweight Aggregate Concrete Consisting of Glazed Hollow Bead

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Gang Ma ◽  
Yu Zhang ◽  
Zhu Li
Keyword(s):  
Cement Paste ◽  
Lightweight Aggregate ◽  
Interface Structure ◽  
Interfacial Transition Zone ◽  
Lightweight Aggregate Concrete ◽  
Hydration Degree ◽  
Zone Structure ◽  
Interface Zone ◽  
Aggregate Concrete ◽  
Rational Control

Lightweight aggregate concrete consisting of glazed hollow bead (GHB) as lightweight aggregate is studied for the influence of nanosilica (NS) content, prewetting time for GHB, water-cement ratio, and curing humidity, on the interface structure between GHB and cement paste. This research analyzed the influences of various factors on the interface zone structure by measuring microhardness (HV) and hydration degree of cement paste (HD) nearby the interface zone (1 mm) between GHB and cement paste at different periods of aging. Due to the sampling limitation, the interface zone in this test is within 1 mm away from the surface of lightweight aggregate. The HD of cement paste was determined through chemically combined water (CCW) test. The results were expected to reflect the influence of various factors on the interface zone structure. Results showed that the rational control of the four factors studied could fully mobilize the water absorption and desorption properties of GHB to improve the characteristics of the interfacial transition zone.

Experimental Study on Frost Resistance Durability of Lightweight Aggregate Concrete in Na2SO4 Solution

2010 ◽  
Vol 152-153 ◽  
pp. 1565-1569
Author(s):  
Jun Fang Huo ◽  
Hui Yang ◽  
Xiang Dong Shen ◽  
Xiao Xia Ji ◽  
Qi Cui
Keyword(s):  
Frost Resistance ◽  
Steel Fiber ◽  
Polypropylene Fiber ◽  
Lightweight Aggregate ◽  
Strength Loss ◽  
Interfacial Transition Zone ◽  
Lightweight Aggregate Concrete ◽  
Test Results ◽  
Aggregate Concrete ◽  
Resistance Durability

Pumice was used to make up lightweight aggregate concrete (LWAC). Frost resistance durability of LWAC in 5% Na2SO4 solution was studied. The test results showed that LWAC durability deteriorates more rapidly under freezing-thawing in salt solution than in water. The strength loss of LWAC was reduced by steel fiber and polypropylene fiber regardless of Na2SO4 solution and water. Fly ash and silica fume can improve Interfacial Transition Zone（ITZ）and the frost resistance of fibers reinforcement LWAC dramatically.

An Investigation on the Interfacial Transition Zone of Lightweight Aggregate Concrete

2013 ◽  
Vol 753-755 ◽  
pp. 610-615
Author(s):  
Hsi Chi Yang ◽  
Miao Ying Cheng
Keyword(s):  
Transition Zone ◽  
Lightweight Aggregate ◽  
Concrete Specimen ◽  
Pozzolanic Reaction ◽  
Normal Weight ◽  
Interfacial Transition Zone ◽  
Lightweight Aggregate Concrete ◽  
Hydration Products ◽  
Aggregate Concrete ◽  
Shihmen Reservoir

The technique of linking the SEM photographs taken around the interfacial transition zone area is applied to observe the development of hydration products for lightweight aggregate and paste at the different curing ages. This research first determines the mixture proportions of the two types of concrete specimens with different aggregate unit weights. The lightweight aggregate used is the sludge kilned aggregate from Shihmen reservoir. The very small SEM samples to be observed are taken from the concrete compressive test specimens and must include both aggregate and paste. The research then observes the hydration products (such as CH, C-S-H) of calcium ion and the pozzolanic reaction on the samples. Finally it assesses if the aggregate will produce ion exchange with cement and generate the hydration products. The hydration products on either side of the interface with a range of 100μm are observed using 2000x magnification. From the results, it is found that (1) the development of hydration products of the lightweight aggregate concrete is similar to that of the normal-weight aggregate concrete, (2) the failure at the 91 days age is that the lightweight aggregate is sheared, (3) the bond stress of aggregate and paste is controlled by hydration products of paste, (4) the aggregate has not interacted with cement paste to produce hydration products, and (5) the development of hydration products proves that the amount of binder used in the concrete specimen will affects its compressive strength.

Effect of Lightweight Aggregate Moisture Content on Pore Structure of Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 647-651
Author(s):  
Shu Hui Dong ◽  
Yong Ge ◽  
Bao Sheng Zhang ◽  
Jie Yuan
Keyword(s):  
Moisture Content ◽  
Pore Structure ◽  
Transition Zone ◽  
Cement Paste ◽  
Lightweight Aggregate ◽  
Interfacial Transition Zone ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Water Rate ◽  
High Absorption

To understand the impacting law of lightweight aggregate moisture content on the cement paste pore structure and its relationship with humidity and deformation of the lightweight aggregate concrete, it is necessary to study the effect of water absorptivity and pre-wet moisture content of lightweight aggregate on the pore structure interfacial transition zone (ITZ) cement paste. The experimental results indicated that the species and moisture content of lightweight aggregate have a greater effect on the pore structure in interfacial transition zone of cement paste in low w/c concrete than that in high w/c concrete. With the saturation level of lightweight aggregate increased, the overall pore structure shows a refinement tendency. The porosity and the larger pore of ITZ in ordinary aggregate are notably higher than those in the basal body cement paste. Meanwhile, we find that the pore structure of ITZ in lightweight aggregate concrete is much different from that in ordinary aggregate concrete. Especially in the concrete using the lightweight aggregate with a high absorption–desorbtion water rate, the pore aperture in ITZ is significantly lower than that in the cement paste, the pore content below 50nm can reach as high as 80%.

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