Performance of geopolymer concrete containing recycled rubber

This research evaluates performance of rubberised concrete prepared with sodium hydroxide (NaOH) treated rubber. Numerous studies have investigated the method of treating rubber with NaOH. However, the level of improvement achieved by this method has not been consistent between different studies. Hence, it is worthwhile to study application of this treatment method. Ten series of concrete specimens with different water cement ratios and a variety of rubber content were prepared. The fresh and hardened mechanical tests were conducted on concrete samples. It was found that the duration of 24 h for treatment of crumb rubber was the most promised duration, which resulted in favourable fresh and hardened concrete characteristics. Compared to rubberised concrete prepared with untreated rubber, rubberised concrete prepared with the 24-h NaOH treated method had 25 and 5 % improvement in compressive and flexural strength, respectively. It is experimentally indicated that using this treatment method resulted in notable improvement for the compressive strength, and moderate enhancement in the flexural strength.

Enhancing mechanical performance of rubberised concrete pavements with sodium hydroxide treatment

In-depth assessment of Crumb Rubber Concrete (CRC) prepared by water-soaking treatment method for rigid pavements

Effects of chloride on the early mechanical properties and microstructure of gangue-cemented paste backfill

Performance enhancement of rubberised concrete via surface modification of rubber: A review

In the field of soil stabilization, only calcium silicate hydrate (CSH) and ettringite (AFt) as hydration products have been reported to directly contribute to the strength enhancement of the soil. A chloride dredger fill, an artificial chloride saline soil, and a non-saline soil were stabilized by Portland cement (PC) and PC with Ca(OH)2 (CH) with different contents. A series of unconfined compressive strength (UCS) tests of stabilized soil specimen after curing for 7 d and 28 d were carried out, and the hydration products and microstructure of the specimens were observed by X-ray diffractometry (XRD), scanning electronic microscopy (SEM), and energy-dispersive X-ray analysis (EDXA). The results showed that the strengths of PC+CH-stabilized chloride saline soils were much higher than those of PC-stabilized soils. A new hydration product of calcium aluminate chloride hydrate, also known as Friedel’s salt, appeared in the PC+CH-stabilized chloride saline soils. The solid-phase volume of Friedel’s salt expanded during the formation of the hydrate; this volume filled the pores in the stabilized soil. This pore-filling effect was the most important contribution to the significantly enhanced strength of the PC+CH-stabilized chloride saline soils. On the basis of this understanding, a new optimized stabilizer was designed according to the concept that the chloride in saline soil could be utilized as a component of the stabilizer. The strength of the chloride saline soils stabilized by the optimized stabilizer was even further increased compared with that of the PC+CH-stabilized soils.

Effect of Friedel’s salt on strength enhancement of stabilized chloride saline soil

Eight interfacial modifiers were used to improve the interfacial bonding strength between the crumb rubber and matrix of Crumb Rubber Mortar (CRM), and the physical and mechanical properties and microstructure of CRM were also studied. The results show that, the interfacial modifiers obviously improve the interface bonding strength between the crumb rubber and matrix and the whole strength of CRM, and silicone modified styrene-acryl ate-emulsion has the best effect. The rubber-cement matrix interface was proved by SEM that the interfacial modifiers treated rubber showed good adhesion to the matrix.

Physical and mechanical properties of Crumb Rubber Mortar(CRM)with interfacial modifiers

A stabilized soil structure formation model was introduced. In order to form compact stabilized soil structure, cementitious hydrates were needed to wrap and bind the soil aggregates. Meanwhile, expansible hydrates were needed to squeeze and fill the pores, especially the pores in the aggregates. The experimental results show that the influences of various chemical characteristic factors of soil on the strength of the stabilized soil are boiled down, for the influence on the concentration of Ca(OH)2 in the pore solution of the stabilized soil, and the amount of CSH generated by cement. Finally an optimization design method is proposed, with which the stabilizer can be designed according to characteristics of soil samples.

Principle and method of optimization design for soft soil stabilizer

Cementitious capillary crystalline waterproofing coating was developed, whose doping quantity of active substances was primarily determined by using orthogonal tests, the doping quantity of the active substances and the cement-sand ratio were optimized, and the formulation of the waterproofing coating was: 50.45% of silicate cement, 40% of quartz sand, 2.4% of assistants and 7.15% of active chemical substances. Test results showed that all the properties of the developed waterproofing coating conform to standard requirements, the bonding strength of wet substrate reached 1.8 MPa, and 28d seepage resistance reached 1.3 MPa.

Research on Cementitious Capillary Crystalline Waterproofing Coating for Underground Concrete Works

In this paper, based on understanding the design theories on soil stabilization, a series of soil stabilizers were prepared with different kinds of industrial wastes such as calcined coal gangue (CCG), blast furnace slag (SS), steel slag (SL), carbide slag (CS), waste alkali liquor (JY), and phosphogypsum (PG). The results indicated that when the Portland cement (PC) proportion was lower than 20% in the stabilizer, for the soil sample selected from Wuhan (WT) and Beijing (BT), the unconfined compress strength (UCS) of the stabilized soil specimens could increase 4.8 times and 5.4 times respectively than that of the specimens stabilized only by PC; compared with the UCS of the specimen stabilized only by PC, the UCS of the specimen which was made from soil sample WT and stabilized by the stabilizer composed only by CCG, CS, and PG increased 1.5 times, and UCS of the specimen which was made from soil sample BT and stabilized by the stabilizer composed only by SS, JY, and PG increased 4.5 times.

Zhan Guo Li

Papers

Effect of Friedel’s salt on strength enhancement of stabilized chloride saline soil

Physical and mechanical properties of Crumb Rubber Mortar(CRM)with interfacial modifiers

Principle and method of optimization design for soft soil stabilizer

Research on Cementitious Capillary Crystalline Waterproofing Coating for Underground Concrete Works

Improving performance of soil stabilizer by scientific combining of industrial wastes