Improving the stability of clay for construction

Jul 08, 2014 by Juhaizad Bin Ahmad
Credit: wikimedia

Researchers at the Universiti Teknologi MARA mixed clay with various waste materials to enhance its engineering quality.

This research set out to improve the engineering quality of using waste materials and a secret binder ingredient.

Clay is a composed primarily of fine-grain minerals. It consists of that have plastic and . Clay also possesses small voids and pores, so it's capable of retaining water. In this condition, it tends to expand and shrink, which can lead to settlement.

When exposed to increments of water, clay tends to soften and liquefy. Clay often causes difficulties in construction with its low strength and stiffness. This has caused serious problems in geotechnical engineering because weak soil may cause damage to the foundation of buildings and cracks along the road pavement.

Due to the rapid growth development of infrastructures facilities in Malaysia, it is impossible to avoid constructing on clay. Clay makes up 20% of the total soils in Peninsular Malaysia. It can be found in the West and East Coast of Peninsular Malaysia. This type of soil is generally classified as marine clay. This clay originates from flooding during ancient times. The sedimentation of seabed was very thick and can be up to 60 metres in depth, or roughly the height of a 20 storey-building. Hence, the construction over clay may experience bearing capacity failure and excessive settlement.

Stabilization of soil using cementitious material becomes optional to solve this problem. Cementitious materials are several binding materials that may mix with water to form a plastic paste.

Ordinary Portland Cement (OPC) is used as a common cementitious binding agent. From a previous study, stabilization of soil using cement was one of the soil treatment applied to improve soil plasticity and workability. Therefore, this research focuses on determination of the strength that can be produced by using ashes as part of the additive mixture.

This will decrease the use of Ordinary Portland Cement (OPC) to help stabilize clay. By doing this, more economical soil mixes can be produced.

The selected waste materials are bottom ash (BA) and fly ash (FA). They are a byproduct from electric power plant. These waste materials are disposed and generally have no economical value.

BA is physically coarse, porous, glassy, granular, greyish and incombustible materials that are collected from the bottom of furnaces that burned coal whereas FA is grey in colour and dust-like material.

It is found that they have pozzolonic properties which make it possible to replace cement in deep soil mixing. On top of that, a secret ingredient has been added to promote better pozzolonic reactions between the additives and clay.

This research was conducted for soil engineering properties and strength test for various inclusions of ashes into the clay soil. The percentage of additives is 5%, 10% and 15% of each ash. Improvement levels were evaluated from the results of unconfined compression test (UCT) carried out at different curing times.

Other soil characteristics like plasticity, particle density and compaction properties were also monitored.

The results showed that by using these admixtures, the strength development can be increased over time. This proved that these admixtures can be promising ingredients in deep mixing. By doing so, a high performance clay cement column can be produced in the near future.

Explore further: A new, greener cement to meet future demand

add to favorites email to friend print save as pdf

Related Stories

A new, greener cement to meet future demand

Jun 03, 2014

An EPFL-led consortium is developing a new blend of cement that promises to reduce the carbon footprint of concrete by up to 40%. Now it has received financial backing from the Swiss Agency for Development and Cooperation ...

Computer power clicks with geochemistry

Jan 28, 2014

Sandia National Laboratories is developing computer models that show how radioactive waste interacts with soil and sediments, shedding light on waste disposal and how to keep contamination away from drinking ...

Sea floor conditions mimicked for drilling platforms

Apr 24, 2014

Mobile jack-up drilling platforms used in the oil and gas industry are at risk of rejection before installation due to their use in harsher environments and deeper waters—but University of WA scientists ...

Deforestation of sandy soils a greater climate threat

Apr 01, 2014

Deforestation may have far greater consequences for climate change in some soils than in others, according to new research led by Yale University scientists—a finding that could provide critical insights ...

Recommended for you

Wireless sensor transmits tumor pressure

Sep 20, 2014

The interstitial pressure inside a tumor is often remarkably high compared to normal tissues and is thought to impede the delivery of chemotherapeutic agents as well as decrease the effectiveness of radiation ...

Seeing through the fog (and dust and snow) of war

Sep 19, 2014

Degraded visibility—which encompasses diverse environmental conditions including severe weather, dust kicked up during takeoff and landing and poor visual contrast among different parts of terrain—often ...

User comments : 0